Two-dimensional Pt2P3 monolayer: A promising bifunctional electrocatalyst with different active sites for hydrogen evolution and CO2 reduction

Two-dimensional Pt₂P₃ monolayer: A promising bifunctional electrocatalyst with different active sites for hydrogen evolution and CO₂ reduction

PDF

Yuting Sun^a^,¹, Shuang Wang^a^,¹, Dongxu Jiao^a, Fengyu Li^b^,^*, Siyao Qiu^c, Zhongxu Wang^a, Qinghai Cai^a, Jingxiang Zhao^a^,^*, Chenghua Sun^d^,^*

Chinese Chemical Letters | 2022, 33(8) : 3987 - 3992

Less

Chinese Chemical Letters | 2022, 33(8): 3987-3992

• Communication •

Two-dimensional Pt₂P₃ monolayer: A promising bifunctional electrocatalyst with different active sites for hydrogen evolution and CO₂ reduction

Full

Yuting Sun^a^,¹, Shuang Wang^a^,¹, Dongxu Jiao^a, Fengyu Li^b^,^*, Siyao Qiu^c, Zhongxu Wang^a, Qinghai Cai^a, Jingxiang Zhao^a^,^*, Chenghua Sun^d^,^*

Affiliations

^a College of Chemistry and Chemical Engineering, Key Laboratory of Photonic and Electronic Bandgap Materials, Ministry of Education, Harbin Normal University, Harbin 150025, China

^b School of Physical Science and Technology, Inner Mongolia University, Hohhot 010021, China

^c School of Chemical Engineering and Energy Technology, Dongguan University of Technology, Dongguan 523808, China

^d Department of Chemistry and Biotechnology, and Centre for Translational Atomaterials, Swinburne University of Technology, Hawthorn, VIC 3122, Australia

Published: 2022-08-15 doi: 10.1016/j.cclet.2021.11.034

Outline

Abstract

Less

Green hydrogen production and CO₂ fixation have been identified as the fundamental techniques for sustainable economy. The open challenge is to develop high performance catalysts for hydrogen evolution reaction (HER) and CO₂ electroreduction (CO₂ER) to valuable chemicals. Under such context, this work reported computational efforts to design promising electrocatalyst for HER and CO₂ER based on the swarm-intelligence algorithm. Among the family of transition-metal phosphides (TMPs), Pt₂P₃ monolayer has been identified as excellent bifunctional catalysts due to high stability, excellent conductivity and superior catalytic performance. Different from typical d-block catalysts, p-band center presented by P atoms within Pt₂P₃ monolayer plays the essential role for its reactivity towards HER and CO₂ER, underlining the key value of p-electrons in advanced catalyst design and thus providing a promising strategy to further develop novel catalysts made of p-block elements for various energy applications.

Key words

Bifunctional electrocatalysts / HER/CO₂ER / Swarm-intelligence structure search / Density functional theory / Two-dimensional Monolayer

Cite this Article

Yuting Sun, Shuang Wang, Dongxu Jiao, Fengyu Li, Siyao Qiu, Zhongxu Wang, Qinghai Cai, Jingxiang Zhao, Chenghua Sun. Two-dimensional Pt₂P₃ monolayer: A promising bifunctional electrocatalyst with different active sites for hydrogen evolution and CO₂ reduction[J]. Chinese Chemical Letters, 2022 , 33 (8) : 3987 -3992 . DOI: 10.1016/j.cclet.2021.11.034

Full Text

Less

In recent decades, the over-consumption of conventional fossil fuels results in two severe problems: the energy crisis and global warming [1, 2]. Hydrogen (H₂), which is regarded as the cleanest fuel, represents one of the most promising energy sources to alleviate the energy shortage by potentially reducing the fossil fuel dependence [3, 4]. H₂ production through electrochemical water splitting (also referred as hydrogen revolution reaction, HER) has been regarded as one of the most important technologies for the energy source of the next generation. On the other hand, CO₂ conversion has been widely considered as a promising strategy in alleviating the greenhouse effect and solving the environmental concern [5, 6]. More importantly, as an abundant C₁ feedstock, the reduction of CO₂ to high-value carbonaceous with improved energy density, such as methane (CH₄) and formic acid (HCOOH), is extremely appealing for renewable energy storage, resulting in an eco-friendly carbon-neutral cycle [7, 8]. Among various methods for CO₂ reduction, the electroreduction of CO₂ (CO₂ER) has attracted considerable attention owing to its ambient aqueous operation environment [9, 10]. In addition, it converts the intermittent electricity into stable chemical energy and generates valuable products, which can be readily controlled by changing the operating potential, the electrolyte, pH, etc. [11, 12].

As well known, catalysts are the core components in catalysis. To date, Pt-based materials often serve as HER benchmark catalysts due to their high exchange current density and small Tafel slope [13], while the high cost and scarcity greatly hamper their widespread utilization. In recent years, although some non-Pt and metal-free HER catalysts have been reported, their catalytic activity and long-term durability are obscured by Pt-based catalysts [14]. On the other hand, metal-based materials, such as (especially) Cu [15], Pd [16], Au [17], Ag [18] and Pt [19], were extensively utilized as the CO₂ER catalysts, however, which were significantly hindered by their large overpotential, poor selectivity, high cost or low stability. Thus, developing highly efficient, low cost, and sustained catalysts for HER and CO₂ER is paramount and apparently rewarding for the sustainable and large-scale implementation of clean energy devices.

Incorporating non-metal elements, such as phosphorus (P), sulfur (S) and boron (B) into metals to form multicomponent alloys is a promising strategy to eliminate the usage of these precious metal-based catalysts for cost-effective applications [20-24]. In particular, the introduction of non-metal elements can effectively tailor the electronic structure and surface properties of metal catalysts, endowing them better catalytic performance. In this regard, as one of the most earth-abundant elements, P-based materials have been emerging as a kind of promising electrocatalysts due to their intrinsic electrochemical activity and widely tunable properties [25].

Recently, transition-metal phosphides (TMPs), with the formula of M_xP_y, have attracted immense attention as promising HER catalysts due to their hydrogenase-like catalytic mechanisms and good conductivity [26-33], in which the P atom plays a key role, since it not only performs as the active site for HER, but also tunes the electronic properties of metal sites with an appropriate ratio to boost the catalytic performance. Notably, P anions can also protect the TMPs from dissolving in the electrolyte, thus endowing TMPs a high durability during the electrocatalysis. In addition to HER, TMPs can also been widely applied in other energy-related electrocatalysis. For example, Li's and coworkers reported that their synthesized rhodium phosphide (Rh₂P) catalyst exhibits higher catalytic activity for water splitting [27]. Kucernak et al. fabricated the PdP₂ and Pd₅P₂ particles dispersed on carbon and found that the PdP₂ material showed good activity towards the oxygen reduction and formic acid oxidation [28]. Sun's group proposed that FeP nanoarray can be utilized as an efficient catalyst for CO₂ER to methanol and alcohol [29]. Although considerable efforts have been made to explore the potential of bulk TMPs as electrocatalysts, the precisely controllable design of specific function-oriented TMPs-based catalysts with tunable compositions, sizes, and morphology constraints is still challenging [34]. Especially, the density of the exposed active sites is rather limited in bulk materials. Thus, the development of novel TMPs with uniform and specific exposed facets is essential to further boost their catalytic activity. Thus, designing novel TMPs-based catalysts with abundant exposed active sites, favorable structure and optimized chemical composition is highly desirable.

Since the discovery of grapheme in 2004 [35], two-dimensional (2D) materials have triggered increasing interest for developing efficient electrocatalysts [36-38]. Compared with the traditional materials, 2D materials exhibit obvious structural advantages benefiting to their application in the field of catalysis, including high specific surface area and large surface atomic ratio. Inspired by the extensive studies of 2D materials, many 2D TMPs-based nanosheets have been reported experimentally and theoretically, which show interesting properties for various applications [39-48]. For example, Yang et al. proposed a topochemical strategy to successfully synthesize 2D Co₂P and Fe₂P using phosphorene templates, which can perform as promising OER electrocatalysts due to the effective charge-transport modulation and improved surface exposure [39], while Sun et al. obtained high-quality 2D MnP single crystals on liquid metal Sn, which exhibit intrinsic ferromagnetism for the development of spintronic devices [40]. Theoretically, Yoon et al. proposed that the layered Sr₂P and Ba₂P sheets are thermodynamically stable and could be applied as 2D electrides [41]. In addition, Shao et al. showed that 2D W₂P and Fe₂P monolayers exhibit high HER catalytic activity [42], whereas Chen's group showed that the doped Mo₂P monolayers can act as promising candidates for high-performance lithium-ion battery anode materials [43].

Having in mind the excellent properties and the great potential applications of 2D TMPs, in this work, we carried out a comprehensive swarm structural search to study if P alloying can alter the electronic structure of TMPs, in which the P-rich platinum phosphide was chosen as an example, because 1) Pt is the commonly-used element to form TMPs for energy conversion and storage, and 2) P-rich TMPs generally exhibit higher catalytic activity. Interestingly, we successfully identified a new Pt₂P₃ monolayer as the electrocatalyst, which exhibits high stability and inherent metallic feature. More interestingly, different p band-center reflected by the P atoms within Pt₂P₃ monolayer endows this material excellent HER and CO₂ER activity, which is different from the typical d-block catalyst. Our findings suggested that our proposed Pt₂P₃ monolayer can serve as an ideal bifunctional catalyst for H₂ production and CO₂ conversion with superior catalytic performance, large surface area, good conductivity, and high stability.

The particle swarm optimization algorithm within the CALYPSO code [49], was employed to explore the atomic structure of the 2D Pt₂P₃ monolayer, which can efficiently search for the ground or metastable structures just through the given chemical compositions. Especially, this method has successfully predicted many novel 2D materials with excellent properties and wide applications [50-55], among which some materials have been experimentally synthesized [56, 57]. Furthermore, the structural optimization and property computations were performed using the density functional theory (DFT) method, as implemented in the Vienna ab initio simulation package (VASP) [58, 59], in which the ion–electron interaction was treated by the projector-augmented wave (PAW) method [60, 61]. We adopted the Perdew-Burke-Ernzerhof (PBE) functional within the generalized gradient approximation (GGA) for structural optimization [62], while the HSE06 functional was employed to compute the band structures and density of states [63]. The cut-off energy for the plane-wave basis set was set to 550 eV with an energy precision of 10⁻⁵ eV, and the atomic positions were fully relaxed until the force on each atom was less than 10⁻³ eV/Å.

A 3 × 3 supercell was built to simulate the Pt₂P₃ monolayer, in which a vacuum distance of 20 Å in the z-direction was employed to avoid the interactions between adjacent layers. A 5 × 5 × 1 Γ-centered Monkhorst−Pack (MP) kpoint grid was adopted for the geometry relaxation and self-consistent calculations. The van der Waals (vdW) interactions were determined using the DFT + D3 correction [64]. Dynamic stabilities and phonon dispersion curves were obtained according to the supercell approach within the Phonopy code [65]. At the same time, first-principles molecular dynamics (MD) simulations were performed to evaluate the thermal stability of the predicted Pt₂P₃ monolayer for 10 ps with a time step of 1.0 fs, in which the temperature was controlled by employing the Nosé-Hoover method [66]. The free energy profiles, which are efficient in estimating the performance of electrocatalytic reactions, were determined by applying the computational electrode model (CHE, see Supporting information for the further computational details) [67, 68].

After an extensive structure search (Figs. S1 and S2 in Supporting information), a hitherto unknown 2D Pt₂P₃ monolayer with space group Cm was achieved (Fig. 1a, and its corresponding POSCAR file was presented in Supporting Information). The unit cell of Pt₂P₃ monolayer with the lattice of 3.68 Å, consists of two inequivalent Pt's posistions (Pt₁: 0.0609, 0.9759, 0.5838) and (Pt₂: 0.6229, 0.6176, 0.4098) and three inequivalent P atoms occupying at the (P₁: 0.4488, 0.2341, 0.6239), (P₂: 0.6943, 0.5093, 0.5235), and (P₃: 0.9953, 0.8759, 0.3086). As a result, the coordination numbers of the two Pt atoms are different: the former is coordinated by six P atoms with the Pt−P bond length in the range of 2.36~2.46 Å, while the latter is tetracoordinated with four P atoms, leading to the formation of a tetra-sublayer structure with the thickness of ~5.27 Å (Fig. 1b). On the other hand, the three P atoms are surrounded by three Pt atoms with Pt-P bond length ranging in 2.02~2.61 Å. Specially, P₁ and P₂ atoms are interconnected with each other, forming the quasi-square Pt₂P₂ units and exhibiting covalent bonding character with the P₁-P₂ bond length of 2.55 Å.

According to Hirshfeld charge analysis [69], P atoms can accept electrons from Pt, thus showing negative charge. Specifically, about 3.07 electrons are transferred from Pt to P atoms in the 3 × 3 supercell, and the Pt₁, Pt₂, P₁, P₂ and P₃ carry 0.16, 0.18, −0.13, −0.12 and −0.09 electrons, respectively. Interestingly, the exposed P atoms with negative charges normally play an important role in the electrocatalytic reaction process. For example, P atoms in TMPs can perform as the active site to capture the positively charged H protons during electrochemical HER. Furthermore, we computed the electron localization function (ELF) to analyze the bond nature in Pt₂P₃ monolayer, where a large ELF value (> 0.5) represents the covalent bond or core electrons, while the ionic bond is obtained by a small ELF value (< 0.5). As shown in Fig. 1c and d, the Pt−P bond exhibits ionic bonding character, and the two nearest P atoms are obviously covalent bond. The coexistence of ionic and covalent bonds is beneficial to stabilize Pt₂P₃ monolayer.

The material stability is the most fundamental and critical factor for its practical applications. To this end, we computed the cohesive energy of the Pt₂P₃ monolayer (more computational details were presented in Supporting information), which is shown to be a well-accepted parameter to ascertain the feasibility of the experimental synthesis of the predicted 2D materials [58-64]. Our results showed that the cohesive energy of the Pt₂P₃ monolayer was computed to be 4.74 eV per atom, which is higher than those of the experimentally available phosphorene (3.30 eV per atom) [70] and silicene (3.98 eV per atom) [71], at the same level of theory. Thus, the predicted Pt₂P₃ monolayer is quite likely to be synthesized under certain experimental conditions.

To examine the dynamical stability, phonon dispersion has been calculated with Phonopy code. No imaginary frequency was observed in the entire Brillouin zone (Fig. S1h), suggesting the dynamic stability of this 2D Pt₂P₃ monolayer. Furthermore, AIMD simulations were performed at 500 K using a 3 × 3 supercell with a time step of 1 fs. As shown in Fig. S3 (Supporting information), the snapshots of the obtained structure indicated that Pt₂P₃ monolayer can well maintain its structure, implying good thermal stability. Also, we assessed the mechanical property of Pt₂P₃ monolayer by computing its elastic constants with the finite distortion method, with elastic constants C₁₁ = 88.21, C₂₂ = 94.05, C₁₂ = 49.79, and C₄₄ = 20.84 N/m, which satisfy the criteria of a mechanically stable 2D material (C₁₁C₂₂ – C₁₂² > 0 and C₄₄ > 0) [72], indicating good mechanical stability.

Another more interesting fact is that the electrochemical stability of materials is also crucial for their practical applications in electrocatalysis, as the electrochemical reactions usually proceed under realistic electrochemical environments. We thus adopted the dissolution potential (U_dis) to assess the electrochemical stability of the Pt₂P₃ monolayer against dissolution under HER and CO₂ER conditions (more computational details were summarized in Supporting information). Our results showed that the computed U_dis value of Pt atom in Pt₂P₃ monolayer is 2.38 V, which is much higher than the U⁰ of 0.00 and 0.43 V for generating H₂ and HCOOH products (the main products for HER and CO₂ER on Pt₂P₃ monolayer, as discussed latter). Thus, we predicted that Pt₂P₃ monolayer can survive under realistic experimental conditions, which could be ascribed to the strong binding strength between Pt and P atoms within 2D Pt₂P₃ framework, thus suggesting its excellent electrochemical stability.

In general, the electronic property of catalyst strongly correlates with its activity in the electrochemical reaction, since good electrical conductivity can ensure the fast charge transfer. In this regard, we computed the electronic band structures and projected density of states (PDOS) of the Pt₂P₃ monolayer using the HSE06 functional. Our results demonstrated that the Pt₂P₃ monolayer exhibits intrinsic metallicity, as some band levels are crossing the Fermi level (Fig. 2a). On the other hand, the PDOS peaks at Fermi levels are high, which are mainly composed of P-3p states, suggesting the available electrons that can participate the electronic transport and thus facilitating to its performance in electrocatalysis. In addition, there are obvious hybridizations between Pt-5d orbitals and P-3p, and P₁–3p and P₂–3p orbitals (Figs. 2b-d), further suggested the strong chemical bonding between Pt atoms and P atoms, and two P atoms in the Pt₂P₃ monolayer. Overall, these above results showed that the novel Pt₂P₃ monolayer exhibits high stability and excellent electronic properties, thus holding great promise for its applications in electrocatalysis.

According to previous studies [73], TMPs-based materials have been widely reported as the promising catalysts for HER. Inspired by the unique structure, good stability, and outstanding electrical conductivity of the Pt₂P₃ monolayer, we further explored its catalytic activity towards the HER.

In HER, a key descriptor to evaluate the activity of a catalyst is the Gibbs free energy of hydrogen adsorption (ΔG_H), and the site with ΔG_H close to zero is considered to be the active site for HER [74]. To this end, we first examined the adsorption of the hydrogen atom on the Pt₂P₃ monolayer by considering various adsorption sites. As expected, the negatively charged and exposed P atoms in the Pt₂P₃ monolayer perform as the active sites to trap the positively charged H⁺ protons due to the strong electrostatic interaction between each other, well consistent with the HER on other TMPs-based catalysts. Herein, both the average process (a-ΔG_H) and individual process (d-ΔG_H) were computed to assess the HER activity of the Pt₂P₃ monolayer. In detailed, a-ΔG_H represents the collective process, in which all H atoms on the surface are assumed to be simultaneously converted to molecules, whereas d-ΔG_H was employed to assess the individual process, in which H₂ molecule can be produced one by one. To explore the effect of hydrogen coverage on HER performance, a 3 × 3 × 1 supercell of the Pt₂P₃ sheet was constructed for the adsorption of n hydrogen atoms with n varying from 1 to 9, corresponding to the hydrogen coverage (θ) ranges from 1/9 to 9/9.

Due to the existence of two different exposed P atoms in the Pt₂P₃ monolayer, namely, the P₁ and P₃ atoms (Fig. 1b), we first examined the adsorption of one H atom (θ = 1/9) on the two P atoms. Interestingly, the ΔG_H values were computed to be −0.31 and −0.06 eV, respectively, on the P₁ and P₃ sites, suggesting that the latter will exhibit superior HER catalytic activity. Based on the above results, we studied the effect of hydrogen coverage on the HER activity of the Pt₂P₃ monolayer, in which all H atoms were adsorbed on the side that the P₃ atoms are locating. Encouragingly, as shown in Figs. 3a and b, the computed a-ΔG_H values are −0.03, −0.02, −0.03, −0.01, −0.02, −0.02, −0.03 and −0.04 eV, respectively, at θ = 2/9, 3/9, 4/9, 5/9, 6/9, 7/9, 8/9 and 9/9, which are close to zero and comparable to that of Pt (−0.09 eV), further indicating the superior HER performance of the Pt₂P₃ monolayer at whether low or high H coverage. In the individual process, however, d-ΔG_H values are computed to be −0.01, 0.01, −0.04, 0.04, −0.03, −0.04, −0.09 and −0.10 eV, respectively, at θ from 2/9 to 9/9 (Figs. 3c and d). Thus, at lower H coverages (θ from 1/9 to 7/9), the collective and individual processes can simultaneously take place, and at higher H coverages (θ = 8/9 and 9/9), the collective process exhibits higher catalytic activity, because its ΔG_H values is closer to 0.

In the CO₂ER, the first step is the hydrogenation of CO₂ molecule to HCOO* or COOH* intermediates. To this end, we examined the adsorption of the two species at various sites, including the exposed P₁, P₃, and their adjacent Pt atoms. Our results showed that HCOO* and COOH* intermediates are energetically favorable to adsorb on the P₁ site with the adsorption energies of −2.95 and −2.44 eV (Fig. S4 in Supporting information), respectively, which are slightly larger than those of on the P₃ site (−2.77 and −2.24 eV), indicating that P₁ atom will perform as the active site for CO₂ER.

Next, we studied the CO₂ER mechanism on the P₁ site of the Pt₂P₃ monolayer (Fig. 4), and the corresponding intermediates were presented in Fig. S5 (Supporting information). According to the computed free energy profiles (Fig. 4), we found that the formation of HCOO* species is uphill by 0.35 eV, which is smaller than that of COOH* (0.55 eV), implying that CO₂ molecule is energetically favorable to be hydrogenated to the HCOO* species, as compared with COOH* one. Subsequently, the approaching of the second (H⁺ + e⁻) to the HCOO* yields the HCOOH product with the ΔG of 0.08 eV. During the CO₂ER to HCOOH product, the potential-determining step (PDS) locates at the first hydrogenation step (CO₂ → HCOO*) due to its ΔG value (0.35 eV). Thus, the computed limiting potential (U_L) for CO₂ER on the designed Pt₂P₃ monolayer is −0.35 V, which is comparable (even less negative) to those of some traditional metal-based benchmark (−0.19 ~−0.60 V) [75-78], implying its superior catalytic performance for CO₂ reduction to HCOOH product.

In addition, we also explored the product distribution for CO₂ER on the Pt₂P₃ monolayer by examining the reaction pathway along the COOH* hydrogenation. As shown in Fig. 4, we found that the approach of a second hydrogen induces the dissociation of COOH* into CO* and H₂O, which is mildly endothermic by 0.27 eV. The CO* is further hydrogenated to HCO*, H₂CO*, H₃CO*, and the final product CH₄, with the computed ΔG values of −0.32, −0.39, −0.48 and −0.87 eV, respectively. Notably, the remaining O atom on the P₁ active site can be further reduced to OH* and H₂O (ΔG = −0.14 and 0.36 eV). Specially, in this process for CO₂ER to CH₄ production, the COOH* formation is identified as the PDS owing to its maximum ΔG value of 0.55 eV, corresponding to the U_L of −0.55 V. Clearly, HCOOH production is thermodynamically favorable by 0.20 eV relative to CH₄ production. To estimate the distribution of different products (HCOOH vs. CH₄), the thermodynamic formula exp[−(ΔG)/(RT)] can be employed according to their free energy difference, in which the values of ΔG and T are 0.20 eV and 291.65 K. Thus, the HCOOH: CH₄ molar ratio is about 2000:1 at ambient temperature, suggesting a strong selectivity toward the HCOOH product.

Finally, it is important to consider the completion between CO₂ER and HER on the P₁ active site, since the HER might affect the Faradaic efficiency significantly. To this end, we computed the difference between the limiting potentials for CO₂ER and HER (U_L^CO – U_L^HER) to assess the catalytic selectivity of P₁ site towards the two reactions. According to previous reports [79], a less negative value of (U_L^CO – U_L^HER) represents a higher selectivity towards the CO₂ER. Interestingly, the (U_L^CO – U_L^HER) value on P₁ site is computed to be only −0.04 V, which is much less negative than that of metal-based benchmark (−0.50 V), suggesting the excellent selectivity of the P₁ active site towards the CO₂ER.

Inspired by the superior bifunctional activity of the Pt₂P₃ monolayer, we further accessed its viability in other TMPs with stoichiometry of TM₂P₃, in which Fe, Co, Ni, Mo, Ru, Rh and Pd were chosen to substitute the Pt atom in Pt₂P₃ monolayer, as they are the most frequently employed elements among TMPs. After fully geometrical optimizations, we found that similar two-dimensional structures can be obtained in TM₂P₃ monolayers for TM = Fe, Co, Ni, Mo, Ru, Rh and Pd. Unfortunately, these systems are dynamically unstable due to imaginary frequencies in phonon dispersions (Fig. S1), thus highlighting the special role of Pt in stabilization of the novel 2D structure.

Similarly, we also tried to search for other Pt-based TMPs, including PtP, PtP₂ and PtP₃ monolayers. Our results showed that significant imaginary vibrational frequencies can be observed in their computed phonon dispersion curves, thus indicating their dynamical instability, whereas the PtP₃ monolayer is dynamically stable due to the absence of imaginary frequencies. Yet, the structure of the PtP₃ monolayer will be greatly distorted and reconstructed after performing AIMD computations by annealing at 300 K for 1 ps with a time step of 1 fs, suggesting that the predicted PtP₃ monolayer is thermally unstable at ambient conditions. In addition, the morphology of a given catalyst may affect its catalytic activity. Thus, we took the Pt₂P₃ bilayer (Fig. S6 in Supporting information) as an example to examine the effect of the morphology on the catalytic activity of Pt₂P₃ material toward HER and CO₂ER. Our results showed that the limiting potentials for the two reactions on P₁ and P₃ sites of Pt₂P₃ bilayer are computed to be −0.64 and −0.36 eV, which are more negative than those of on Pt₂P₃ monolayer, indicating that the stacking of two Pt₂P₃ monolayers will hamper its catalytic performance. Also, we noted that no prior study was reported on the experimental synthesis of our proposed Pt₂P₃ monolayer to date. However, recently, Yang et al. proposed a general bottom-up topochemical method to synthesize a series of 2D metal phosphides, such as Co₂P, Ni₁₂P₅ and Co_xFe_2-xP by using phosphorene sheets as the phosphorus precursors and 2D templates [39], which exhibited efficient electrocatalytic ability for OER. This pioneering study could open a promising strategy to synthesize Pt₂P₃ monolayer by adopting similar experimental procedure in the near future, in which 2D phosphorene and soluble PtCl₄ coordination compounds may be employed phosphorus and Pt precursors, respectively.

As demonstrated above, Pt₂P₃ monolayer exhibits excellent catalytic performance for HER and CO₂ER, which can proceed on two different sides. Then, an interesting question naturally arises: why do different sides of the Pt₂P₃ monolayer exhibit different catalytic activity, especially for HER? To gain a profound understanding on this question, the projected density of states (PDOSs) of different active sites were analyzed, since the chemical activity of a given catalyst is generally dependent on its underlying electronic properties. The PDOSs of various active sites, including P₁ and P₃ within the Pt₂P₃ monolayer, were presented in Fig. S7 (Supporting information), where the 3p-PDOSs of P sites were mainly examined. To elucidate the remarkable difference between the adsorption strength of H* species on the P₁ and P₃ sites, we evaluated their energy levels of the p-band center of (ɛ_p) model as [80-86]: ɛ_p =

where D(E) is the density of states of p band of the P site at a given energy E, and the Fermi level is set to zero. Our results demonstrated that the ɛ_p values for P₁ and P₃ sites are computed to be −0.86 and −1.58 eV, respectively. Obviously, the position of the ɛ_p for P₁ site closer to the Fermi level can induce antibonding states to a higher energy, normally making them more difficult to be filled and thus resulting in a stronger H* adsorption on the P₁ active site (ΔG = −0.31 eV). For P₃ site, however, its smaller ɛ_p value indicates a relatively weak interaction of H* species, which is responsible for the good catalytic performance for the HER on P₃ site. Similarly, the formed HCOO* species during CO₂ER prefers to adsorb the P₁ active site due to its less negative ɛ_p value (−0.86 eV), leading to its high catalytic performance for CO₂ER.

In summary, by performing first-principles swarm-intelligence structural search computations, we predicted a hitherto unknown Pt₂P₃ monolayer with metallic nature. Remarkably, the high cohesive energy, excellent thermal and dynamic stability, and outstanding mechanical properties of the Pt₂P₃ monolayer, originating from its unique bonding arrangement, i.e., the coexistence of Pt−P ionic bond and p−p covalent bond, render it great promise for experimental synthesis. Interestingly, the different P sites on the two sides of the Pt₂P₃ monolayer endow its ultra-high catalytic activity towards HER and CO₂ER to HCOOH product, which can be mainly ascribed to their differences in p-band center, thus suggesting that the as-designed Pt₂P₃ monolayer can perform as a promising bifunctional catalyst for H₂ production and CO₂ conversion. Our results are encouraging further experimental and theoretical research to explore novel 2D materials with appealing properties and potential applications in catalysis.

Declaration of competing interest

Less

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgments

Less

This work was financially supported by the Natural Science Funds for Distinguished Young Scholar of Heilongjiang Province (No. JC2018004), the National Natural Science Foundation of China (No. 11964024), the "Grassland Talents" project of Inner Mongolia autonomous region (No. 12000-12102613), and the Young science and technology talents cultivation project of Inner Mongolia University (No. 21221505). We also thank the computational resource supported by Harbin Normal University and Beijing Paratera Technology Co., Ltd.

Supplementary materials

Less

Supplementary material associated with this article can be found, in the online version, at doi:10.1016/j.cclet.2021.11.034

References

Less

[1]

S. Chu, A. Majumdar, Nature 488 (2012) 294–303.

[2]

A.M. Omer, Renew. Sust. Energr. Rev. 12 (2008) 2265–2300.

[3]

J.A. Turner, Science 305 (2004) 972–974.

[4]

M.S. Dresselhaus, I.L. Thomas, Nature 414 (2001) 332–337.

[5]

A. Vasileff, Y. Zheng, S. Qiao, Adv. Energy Mater. 7 (2017) 1700759.

[6]

W. Wang, Y. Himeda, J.T. Muckerman, G.F. Manbeck, E. Fujita, Chem. Rev. 115 (2015) 12936–12973.

[7]

H. -R.M. Jhong, S. Ma, P.J.A. Kenis, Curr. Opin. Chem. Eng. 2 (2013) 191–199.

[8]

D.T. Whipple, P.J.A. Kenis, J. Phys. Chem. Lett. 1 (2010) 3451–3458.

[9]

M. Gattrell, N. Gupta, A. Co, J. Electroanal. Chem. 594 (2006) 1–19.

[10]

E.V. Kondratenko, G. Mul, J. Baltrusaitis, G.O. Larrazábal, J. Pérez-Ramírez, Energ. Environ. Sci. 6 (2013) 3112–3135.

[11]

M. Asadi, B. Kumar, A. Behranginia, et al., Nat. Commun. 5 (2014) 4470.

[12]

A.S. Varela, M. Kroschel, T. Reier, P. Strasser, Catal. Today 260 (2016) 8–13.

[13]

Y. Zheng, Y. Jiao, M. Jaroniec, S. Qiao, Angew. Chem. Int. Ed. 54 (2015) 52–65.

[14]

Y. Zheng, Y. Jiao, A. Vasileff, S. Qiao, Angew. Chem. Int. Ed. 57 (2018) 7568–7579.

[15]

S. Nitopi, E. Bertheussen, S.B. Scott, et al., I. Chorkendorff, Chem. Rev. 119 (2019) 7610–7672.

[16]

D. Gao, H. Zhou, F. Cai, et al., ACS Catal. 8 (2018) 1510–1519.

[17]

Y. Chen, C.W. Li, M.W. Kanan, J. Am. Chem. Soc. 134 (2012) 19969–19972.

[18]

E.L. Clark, S. Ringe, M. Tang, et al., ACS Catal. 9 (2019) 4006–4014.

[19]

Y. Wang, H. Arandiyan, J. Scott, K.F. Aguey-Zinsou, R. Amal, ACS Appl. Energy Mater. 1 (2018) 6781–6789.

[20]

H. Li, P. Wen, Q. Li, et al., Adv. Energy Mater. 7 (2017) 1700513.

[21]

S. Anantharaj, S.R. Ede, K. Sakthikumar, et al., ACS Catal. 6 (2016) 8069–8097.

[22]

X. Zheng, L. Peng, L. Li, et al., Chem. Sci. 9 (2018) 1822–1830.

[23]

H. Li, P. Wen, D.S. Itanze, et al., Nat. Commun. 10 (2019) 5724.

[24]

H. Li, P. Wen, D.S. Itanze, et al., Nat. Commun. 11 (2020) 3928.

[25]

X. Li, J. Wang, Adv. Mater. Interfaces 7 (2020) 2000676.

[26]

Z. Pu, T. Liu, I.S. Amiinu, et al., Adv. Funct. Mater. 30 (2020) 2004009.

[27]

H. Duan, D. Li, Y. Tang, et al., J. Am. Chem. Soc. 139 (2017) 5494–5502.

[28]

A.R.J. Kucernak, K.F. Fahy V.N.N. Sundaram, Catal. Today 262 (2016) 48–56.

[29]

L. Ji, L. Li, X. Ji, Angew. Chem. Int. Ed. 59 (2020) 758–762.

[30]

C. Weng, J. Ren, Z. Yuan, ChemSusChem 13 (2020) 3357–3375.

[31]

Y. Shi, M. Li, Y. Yu, B. Zhang, Energ. Environ. Sci. 13 (2020) 4564–4582.

[32]

C. Li, D. Zhu, S. Cheng, et al., Chin. Chem. Lett. (2021) doi. org/10.1016/j. cclet. 2021.07.057.

[33]

Y. Wei, X. Zhang, Z. Wang, et al., Chin. Chem. Lett. 32 (2021) 119–124.

[34]

S. Li, M. Qi, Z. Tang, Y. Xu, Chem. Soc. Rev. 50 (2021) 7539–7586.

[35]

K.S. Novoselov, A.K. Geim, S.V. Morozov, et al., Science 306 (2004) 666–669.

[36]

H. Jin, C. Guo, X. Liu, et al., Chem. Rev. 118 (2018) 6337–6408.

[37]

H. Tao, Y. Gao, N. Talreja, et al., J. Mater. Chem. A 5 (2017) 7257–7284.

[38]

Y. Wang, Z. Zhang, Y. Mao, X. Wang, Energy Environ. Sci. 13 (2020) 3993–4016.

[39]

S. Yang, G. Chen, A.G. Ricciardulli, et al., Angew. Chem. Int. Ed. 59 (2020) 465–470.

[40]

X. Sun, S. Zhao, A. Bachmatiuk, et al., Small 16 (2020) 2001484.

[41]

W. Ming, M. Yoon, M. Du, K. Lee, S.W. Kim, J. Am. Chem. Soc. 138 (2016) 15336–15344.

[42]

Y. Shao, X. Shi, H. Pan, Chem. Mater. 29 (2017) 8892–8900.

[43]

X. Liu, S. Lin, J. Gao, et al., Phys. Chem. Chem. Phys. 23 (2021) 4030–4038.

[44]

S. Zheng, T. Yu, J. Lin, et al., J. Mater. Chem. A 7 (2019) 25665–25671.

[45]

Y. Ying, K. Fan, X. Luo, H. Huang, J. Mater. Chem. A 7 (2019) 11444–11451.

[46]

B. Mortazavi, M. Shahrokhi, M. Makaremi, T. Rabczuk, Appl. Mater. Today 9 (2017) 292–299.

[47]

M. Jiang, J. Li, J. Li, et al., Y. Du, Nanoscale 11 (2019) 9654–9660.

[48]

Q. Liu, J. Xing, Z. Jiang, et al., Nanoscale 12 (2020) 6776–6784.

[49]

Y. Wang, L. Jian, Z. Li, Y.J.C.P.C. Ma, Comput. Phys. Commun. 183 (2012) 2063–2070.

[50]

T. Yu, Z. Zhao, Y. Sun, et al., J. Am. Chem. Soc. 141 (2019) 1599–1605.

[51]

Y. Wang, F. Li, Y. Li, Z. Chen, Nat. Commun. 7 (2016) 11488.

[52]

H. Zhang, Y. Li, J. Hou, K. Tu, Z. Chen, J. Am. Chem. Soc. 138 (2016) 5644–5651.

[53]

C. Wang, T. Yu, A. Bergara, X. Du, F. Li, G. Yang, J. Phys. Chem. C 124 (2020) 4330–4337.

[54]

T. Yu, Z. Zhao, L. Liu, et al., J. Am. Chem. Soc. 140 (2018) 5962–5968.

[55]

S. Zheng, C. Huang, T. Yu, et al., J. Phys. Chem. Lett. 10 (2019) 2733–2738.

[56]

L. Yang, V. Bačić, I.A. Popov, et al., J. Am. Chem. Soc. 137 (2015) 2757–2762.

[57]

B. Feng, B. Fu, S. Kasamatsu, et al., Nat. Commun. 8 (2017) 1007.

[58]

G. Kresse, J. Hafner, Phys. Rev. B 47 (1993) 558–561.

[59]

G. Kresse, J. Furthmüller, Phys. Rev. B 54 (1996) 11169–11186.

[60]

P.E. Blochl, Phys. Rev. B 50 (1994) 17953–17979.

[61]

G. Kresse, D. Joubert, Phys. Rev. B 59 (1999) 1758–1775.

[62]

J.P. Perdew, K. Burke, M. Ernzerhof, Phys. Rev. Lett. 77 (1996) 3865–3868.

[63]

J. Heyd, G.E. Scuseria, M. Ernzerhof, J. Chem. Phys. 118 (2003) 8207–8215.

[64]

S. Grimme, J. Comput. Chem. 27 (2006) 1787–1799.

[65]

A. Togo, F. Oba, I. Tanaka, Phys. Rev. B 78 (2008) 134106.

[66]

G.J. Martyna, M.L. Klein, M. Tuckerman, J. Chem. Phys. 97 (1992) 2635–2643.

[67]

J.K. Nørskov, J. Rossmeisl, A. Logadottir, et al., J. Phys. Chem. B 108 (2004) 17886–17892.

[68]

A.A. Peterson, F. Abild-Pedersen, F. Studt, J. Rossmeisl, J.K. Nørskov, Energy Environ. Sci. 3 (2010) 1311–1315.

[69]

F.L. Hirshfeld, Theor. Chim. Acta 44 (1977) 129–138.

[70]

J. Guan, Z. Zhu, D. Tománek, Phys. Rev. Lett. 113 (2014) 046804.

[71]

B. Feng, Z. Ding, S. Meng, et al., Nano Lett. 12 (2012) 3507–3511.

[72]

J. Wang, S. Yip, S.R. Phillpot, D. Wolf, Phys. Rev. Lett. 71 (1993) 4182–4185.

[73]

S.M. El-Refaei, P.A. Russo, N. Pinna, ACS Appl. Mater. Inter. 13 (2021) 22077–22097.

[74]

J.K. Nørskov, T. Bligaard, A. Logadottir, et al., J. Electrochem. Soc. 152 (2005) J23.

[75]

M. Ren, H. Zheng, J. Lei, et al., ACS Appl. Mater. Inter. 12 (2020) 41223–41229.

[76]

P. Lu, X. Tan, H. Zhao, et al., Z. Yin, ACS Nano 15 (2021) 5671–5678.

[77]

Y. Li, H. Su, S.H. Chan, Q. Sun, ACS Catal. 5 (2015) 6658–6664.

[78]

G. Zhu, Y. Li, H. Zhu, et al., ACS Catal. 6 (2016) 6294–6301.

[79]

A.A. Peterson, F. Abild-Pedersen, F. Studt, J. Rossmeisl, J.K. Nørskov, Energ. Environ. Sci. 3 (2010) 1311–1315.

[80]

Y. Ouyang, C. Ling, Q. Chen, et al., Chem. Mater. 28 (2016) 4390–4396.

[81]

C. Ling, L. Shi, Y. Ouyang, J. Wang, Chem. Mater. 28 (2016) 9026–9032.

[82]

Y. Ouyang, Q. Li, L. Shi, C. Ling, J. Wang, J. Mater. Chem. A 6 (2018) 2289–2294.

[83]

N. Liu, Y. Zhao, S. Zhou, J. Zhao, J. Mater. Chem. A 8 (2020) 5688–5698.

[84]

S. Zhou, W. Pei, J. Zhao, A. Du, Nanoscale 11 (2019) 7734–7743.

[85]

S. Zhou, X. Yang, W. Pei, N. Liu, J. Zhao, Nanoscale 10 (2018) 10876–10883.

[86]

S. Zhou, X. Yang, X. Xu, et al., J. Am. Chem. Soc. 142 (2020) 308–317.

Appendix

Less

Year 2022 volume 33 Issue 8

PDF

Cite this Article

BibTeX

Article Info

doi: 10.1016/j.cclet.2021.11.034

Receive Date：2021-10-04
Online Date：2025-12-19
Published：2022-08-15

Article Data

Affiliations

History

Received：2021-10-04
Revised：2021-11-03
Accepted：2021-11-09

Affiliations

^a College of Chemistry and Chemical Engineering, Key Laboratory of Photonic and Electronic Bandgap Materials, Ministry of Education, Harbin Normal University, Harbin 150025, China

^b School of Physical Science and Technology, Inner Mongolia University, Hohhot 010021, China

^c School of Chemical Engineering and Energy Technology, Dongguan University of Technology, Dongguan 523808, China

^d Department of Chemistry and Biotechnology, and Centre for Translational Atomaterials, Swinburne University of Technology, Hawthorn, VIC 3122, Australia

References

Share

https://castjournals.cast.org.cn/joweb/ccl/EN/10.1016/j.cclet.2021.11.034

Share to

Scan QR to access full text

Cite this article

BibTeX

Citations

表12种不同金属材料的力学参数

科 Family	属数 Number of genus	种数 Number of species	占总种数比例 Percentage of total species (%)	属 Genus	种数 Number of species	占总种数比例 Percentage of total species (%)
鹅膏菌科Amanitaceae	2	11	5.26	鹅膏菌属 Amanita	10	4.78
小菇科 Mycenaceae	2	12	5.74	丝盖伞属 Inocybe	5	2.39
多孔菌科 Polyporaceae	8	14	6.70	蜡蘑属 Laccaria	5	2.39
红菇科 Russulaceae	3	23	11.00	小皮伞属 Marasmius	6	2.87
				小菇属 Mycena	11	5.26
				光柄菇属 Pluteus	5	2.39
				红菇属 Russula	17	8.13
				栓菌属 Trametes	5	2.39

关闭全屏

BibTeX
EndNote
RefWorks
TxT

Fig. 1 (a) Top and (b) side views of the predicted Pt₂P₃ monolayer. The unit cell is indicated by a gray dashed rhombus. Electron localization function (ELF) maps of a Pt₂P₃ monolayer along planes containing specified (c) Pt₁−P₁ and (d) Pt₂−P₃ bonds.

Fig. 2 (a) The computed band structure and projected density of states (PDOSs) of (b) P₁–3p and Pt₁–5d, (c) P₃–3p and Pt₂–5d, and (d) P₁–3p and P₂–3p for Pt₂P₃ monolayer. The Fermi level was set to zero.

Fig. 3 The computed average Gibbs free profiles and the corresponding free energy changes (a, b) a-ΔG_H and (c, d) d-ΔG_H in individual process as a function of H coverage (θ) on the Pt₂P₃ monolayer. The free energy window (± 0.1 eV) with catalytic activity comparable to that of Pt is highlighted in light area.

Fig. 4 The free energy profile for CO₂ER along various pathways on the Pt₂P₃ monolayer.

Articles: Latest Articles; Most Read; Collections

Updates: Events; News; Multimedia

About: About Us

Contact

No. 86 Xueyuan South Road, Haidian District, Beijing

100081

010-62199257

qkjq@cast.org.cn

Copyright © 2025 China Association for Science and Technology. All rights reserved. For all open access content, the relevant licensing terms apply.
Sponsored by the Office of the Leading Group for Cybersecurity and Informatization of CAST, and supported by Science and Technology Review Publishing House