Latest ArticlesExploring the intrinsic reasons for the dynamic reconstruction of catalysts during electrocatalytic reactions and their impact on activity enhancement still face severe challenges. Herein, the bifunctional catalyst Ru/V-CoO/CP with doping strategy and heterostructure was synthesized for overall water splitting. The Ru/V-CoO exhibits excellent activity for HER and OER with low overpotentials of 49, 147 mV at a current density of 10 mA/cm2 in 1.0 mol/L KOH, respectively. The assembled electrolytic cell just needs voltages of 1.47 and 1.71 V to achieve 10 and 350 mA/cm2 current density under the same conditions and delivers an outstanding stability for over 100 h, which is far superior to the commercial RuO2Pt/C cell. Experimental and theoretical results indicate that the doping of V species and the formation of heterostructures lead to charge redistribution. More importantly, the leaching of V species induces electron transfer form Co to O and then Ru through the Co-O-Ru electron bridge, optimizes the adsorption strength of the key intermediate, thereby reducing the free energy barrier of the rate-determining step and improving catalytic activity. This work proposes an effective strategy of using cation dissolution to induce electron transfer through the electron bridge and thus regulate the electronic structure of catalysts, providing new ideas for the design and development of efficient and stable electrocatalysts.
Natural hydraulic lime (NHL) has garnered increasing attention for its sustainable and suitable performance in the field of historical building restoration. However, the prolonged hardening time and sluggish hydration rate of NHL influence the workability, strength development, and durability of construction structures in which it is used. In this study, nano-metakaolin (NMK) was applied as a highly reactive supplementary cementitious material (SCM) for NHL-based mortars to enhance their properties with various ratios. Meanwhile, the effects of NMK and its related enhancement mechanism on the physical properties and chemical structures of NHL composites were systematically investigated, mainly involving the modifications in their microstructure, chemical composition, and C-S-H structure. Results demonstrated that NMK-modified samples showed distinct and superior properties to pure NHL sample, such as shorter initial/final setting times (15.1%–49.1%, 27.1%–50.0%), and higher compactness (67.8%–81.4%, 38.1%–44.8%), lower shrinkage (25.0%–56.3%, 12.5%–25.0%), enhanced compressive strength (404.5%–546.0%, 180.8%–354.1%) and flexural strength (227.5%–351.1%, 59.9%–125.7%) for both early and late curing times (7 and 28 days). The inclusion of NMK not only acts as a fine filler, but also promotes NHL's hydrate rate by its super high pozzolanic activity, thus optimizing the pore structures and increasing the content and the average silicate chain length of hydration gel in NHL. Overall, this study can contribute to a deeper understanding of the enhancement mechanism of NMK on the physical properties and chemical structures of NHL from a meso/microscopic perspective, with a view to broadening NHL's potential applications.
Polyphosphazene with phenoxy or 4-ester phenoxy as pendent groups are demonstrated as both ligands and host matrices for CsPbBr3 perovskite nanocrystals (NCs). These polymers produced flexible nanocomposite films with excellent NCs dispersion, optical transparency and stability in various extreme conditions. Both films remained stable even after 30 days of air storage. CsPbBr3/poly[bis(phenoxy phosphazene)] (PBPP) delivered better air and light stability, and CsPbBr3/poly[bis(4-esterphenoxy)phosphazene] (PBEPP) exhibited superior water and heat resistance. CsPbBr3/PBEPP showed a greater increase in fluorescence intensity under 365 nm UV light and demonstrated a 10% luminescence increase after 96 h of water immersion and even at high temperature (150 ℃). These findings thus provide new insight into flexible luminescent CsPbBr3 films with high stability in optoelectronic applications.
Metal phosphosulfides have been recognized as advanced anode materials for sodium/potassium ion batteries due to their high theoretical capacities and the incorporation of the advantage of metal sulfides and phosphates. However, they also suffer from the shortcomings of frustrating cycling stability due to the large volume expansion and unsatisfactory electrical conductivity. Herein, hexapod cobalt phosphosulfide nanodots based nanorods encapsulating into N, P, and S hetero-atoms tri-doped carbon framework (CoP/CoS2@NPSC) have been triumphantly designed and synthesized. The six nanorods constructed hexapod framework and multi-atom doped carbon matrix not only provides more active sites, but also contribute to maintain the structure integrity from avoiding the agglomeration of internal CoP and CoS2 nanodots. The synergistic effect between CoP and CoS2 components, as well as the CoP/CoS2 and the NPSC carbon framework can improve the electrochemical conductivity. Besides, the kinetics analysis demonstrated that N/P/S tri-doping could greatly increase the interlayer distance and introduce enough active sites, which effectively facilitate the transport, adsorption, insertion and diffusion of Na+ and K+. CoP/CoS2@NPSC demonstrated excellent electrochemical properties and battery performances including excellent cycle stability with 404.63 mAh/g at 5.0 A/g around 700 cycles for SIBs and 115.33 mAh/g at 5.0 A/g around 800 cycles for PIBs. This presented strategy establishes a novel and adaptable method for the integration of doped carbon with metal phosphosulfide and guides a new research approach and direction for secondary batteries electrode materials.
Electrocatalytic reduction of NO (NORR) is an effective method for NH3 synthesis, due to low bonding energy of NO bond. In this work, we have investigated many CrS2 based catalysts, including pristine CrS2, CrS2 with one S vacancy (v-CrS2), and Ti doped CrS2 (Ti@CrS2). The results have shown that the pristine CrS2 exhibits inert character for NO activation. However, v-CrS2 and Ti@CrS2 can exhibit enhanced interaction with NO, due to increased charge transfer between NO and substrates (0.52–0.75 e) and enhanced adsorption energies of NO on the catalysts (-0.96~-1.64 eV), compared to the situation of CrS2 (0.065 e/-0.30 eV). From the free energy profiles of NO electro-reduction to NH3, we can see that the v-CrS2 and Ti@CrS2 all exhibit ultralow limiting potentials of -0.03~-0.47 V, following both *NOH and *NHO mechanisms. Therefore, introducing vacancy and doping are all promising modification strategies for NORR catalysts. The results have provided a new idea for the search of catalysts for efficient electrocatalytic reduction of NO.
Self-trapping excitons (STEs) emission in metal halides has been a matter of interest, correlating with the strength of electron-phonon coupling in the lattice, which are usually caused by ions with ns2 electronic structure. In this work, Sb3+/Te4+ ions doped Zn-based halide single crystals (SCs) with two STEs emissions have been synthesized and the possibility of its anti-counterfeiting application was explored. Further, the relationship between the strength of electron-phonon coupling and photoluminescence quantum yields (PLQYs) for STEs in a series of metal halides has been studied. And the semi-empirical range of the Huang-Rhys factors (S) for metal halides with excellent photoluminescence (PL) property has been summarized. This work provides ideas for further research into the relationship between luminescence performance and electron-phonon coupling of metal halides, and also provides a reference for designing the metal halides with high PLQYs.
In the field of lithium-ion battery cathode materials, lithium-rich layered oxide materials have garnered significant attention due to their exceptional discharge specific capacity and high operating voltage. However, their limitations in terms of cycling stability and rate capability remain major impediments to their wider application. In this study, an innovative approach was employed by simultaneously utilizing the acidic and oxidative properties of phosphomolybdic acid to generate a spinel structure and in-situ coating of a conductive polymer (polypyrrole) on the surface of lithium-rich layered oxide materials. This strategy aimed to mitigate structural degradation during charge-discharge cycles, enhance the ionic/electronic conductivity, and suppress side reactions. Experimental results demonstrated that after 200 cycles at a current density of 1 C, the modified sample exhibited a discharge specific capacity of 193.4 mAh/g, with an improved capacity retention rate of 83.3% and a minimal voltage decay of only 0.27 V. These findings provide compelling support for the development and application of next-generation high-performance lithium-ion batteries.
Unstable electrode/electrolyte interfaces and heterogeneous Zn deposition would reduce the Coulombic efficiency and cycle life of Zn metal batteries (ZMBs). Applying water-in-salt (WIS) electrolytes has proven to be an effective strategy to address the above issues. However, an understanding of the reaction mechanisms on the Zn anode at nanoscale is still elusive. Here we utilize in situ atomic force microscopy to visualize the solid electrolyte interphase (SEI) formation and Zn deposition/dissolution processes in WIS electrolyte and construct relationships between interfacial behavior and electrochemical performance. The formation processes, chemical properties, and structure of the on-site formed SEI are deeply explored. The SEI with a “plum-pudding” model can guide uniform Zn deposition and reversible dissolution. Mechanistic understanding of the interfacial evolution of the SEI layer and Zn deposition/dissolution has been achieved and will benefit the structural optimization and interfacial engineering of ZMBs.
Mo2N has been identified as a highly promising carrier for electrocatalysis. However, its complex synthesis method, use of toxic gases, and serious effects on supported noble metals catalyst during high-temperature sintering processes have seriously affected its hydrogen evolution reaction (HER) activity and stability. Here, we report an efficient strategy for synthesizing Mo2N using the high temperature shock (HTS) method in just 1.67 s, while also uniformly loading Ru onto Mo2N nanosheets. The HTS enables the homogeneous dispersion of the noble metal Ru, leading to an increased electrocatalytic activity, along with a strong charge transfer between Mo2N and Ru. Ru/Mo2N exhibited an overpotential of 66 mV at 10 mA/cm2 in 1 mol/L KOH. In the evaluation of catalytic activity, Ru/Mo2N demonstrates superiority over commercial Pt/C catalysts in terms of mass activity (1.71 A/mgRu vs. 0.91 A/mgPt at 200 mV) and turnover frequency (1.41 s−1 vs. 0.18 s−1 at 100 mV). This result provides a rational and effective pathway for the preparation of efficient electrocatalysts.
In recent years, sodium-ion batteries (SIBs) have become one of the hot discussions and have gradually moved toward industrialization. However, there are still some shortcomings in their performance that have not been well addressed, including phase transition, structural degradation, and voltage platform. High entropy materials have recently gained significant attention from researchers due to their effects on thermodynamics, dynamics, structure, and performance. Researchers have attempted to use these materials in sodium-ion batteries to overcome their problems, making it a modification method. This paper aims to discuss the research status of high-entropy cathode materials for sodium-ion batteries and summarize their effects on sodium-ion batteries from three perspectives: Layered oxide, polyanion, and Prussian blue. The influence on material structure, the inhibition of phase transition, and the improvement of ion diffusivity are described. Finally, the advantages and disadvantages of high-entropy cathode materials for sodium-ion batteries are summarized, and their future development has prospected.