Latest ArticlesBlack phosphorus (BP) has attracted an ever-growing interest due to its unique anisotropic two-dimensional structure, impressive photoelectronic properties and attractive application potential. However, the tools for bandgap engineering and passivation via covalent modification of BP nanosheets remain limited to diazonium salt and nucleophilic addition methods, so that developing new modification strategies for BP nanosheets is crucial to explore its physical and chemical properties and enrich the toolbox for functionalization. Herein, we report the covalent modification of liquid-phase exfoliated BP nanosheets based on a rational analysis of BP structure. The modification of BP is achieved via carbene, a highly reactive organic mediate. The carbene modification improves the solubility and stability of BP nanosheets. Detailed microscopic and spectroscopic characterizations including infrared spectra, Raman spectra, X-ray photoelectron spectra, SEM and TEM were conducted to provide insights for the reaction. The proof of the existence of covalent bonds between BP nanosheets and organic moieties confirms the successful modification. Moreover, theoretical calculations were conducted to unveil the reaction mechanism of the two different types of bonds and the chemical property of two-dimensional BP.
Improving the utilization of excitons has always been an important topic for the development of electroluminescence devices. In this work, we designed and synthesized three red TADF emitters TPA-DBT12, TPA-DBT3 and DTPA-DBT by employing dibenzothioxanthone (DBT) acceptor framework to stabilize the locally excited triplet state to participate in the reverse intersystem crossing (RISC) process. The fast RISC process and singlet radiation decay process gave rise to evidently enhanced exciton utilization. All of the red OLEDs based on these materials showed maximum EQE over 11% and high exciton utilization close to 100%. This work not only extend the acceptor framework for red materials but also provide a new perspective for the design of highly efficient red TADF materials with 100% exciton utilization by managing locally excited triplet state.
Amino acids are basic units to construct a protein with the assistance of various interactions. During this building process, steric hindrance derived from amino acid side groups or side chains is a factor that could not be ignored. In this contribution, adsorption behaviors of C-terminal amino acid derivatives with amino acid residues fused in 3, 4, 9, 10-perylenetetracarboxylic dianhydride were investigated by scanning tunneling microscopy (STM) and density functional theory (DFT) calculations at various liquid/solid interfaces. STM results at 1-phenyloctane/HOPG interface show that N, N'-3, 4, 9, 10-perylenedicarboximide (GP) and N, N'-methyl-3, 4, 9, 10-perylenedicarboximide (AP) formed linear and herringbone structures, respectively. The driving force could be attributed to different H-bonding sites induced by steric hindrance at side groups. N, N'-Benzyl-3, 4, 9, 10-perylenedicarboximide (PP) generates both linear and herringbone structures because steric hindrance changes the H-bonding sites between PP molecules, whereas N, N'-isopropyl-3, 4, 9, 10-perylenedicarboximide (LP) failed to be imaged because of strong steric hindrance coming from larger side group. To further investigate the impact of steric hindrance, we utilized octanoic acid (OA) as solvent to capture the adsorption details of LP and PP. We found that OA molecules drag PP and LP molecules in a different direction to generate linear structure, impeding the molecular rotation. The structure–solvent relationship shows that the steric hindrance is brought by the large side group, which makes it easier to recognize OA molecules at the interface. These results demonstrate that steric effect plays a significant role in altering interaction sites of the compounds during the adsorption process at the liquid/solid interface.
Electrochemical nitrogen reduction reaction (NRR) has been considered as an appealing and sustainable method to produce ammonia from N2 under ambient conditions, attracting increasing interest. Limited by low solubility of N2 in water and high stability of NN triple bond, developing NRR electrocatalysts with both strong N2 adsorption/activation and high electrical conductivity remain challenging. Here, we demonstrate an efficient strategy to develop NRR electrocatalyst with synergistically enhanced N2 adsorption/activation and electrical conductivity by heteroatom doping. Combining computational and experimental study, the DFT-designed Ti-doped SnO2 exhibits significantly enhanced NRR performance with ammonia yield rate of 13.09 µg h−1 mg−1 at −0.2 V vs. RHE. Particularly, the Faradaic efficiency reaches up to 42.6%, outperforming most of Sn-based electrocatalysts. The fundamental mechanism for improving NRR performance of SnO2 by Ti doping is also revealed. Our work highlights a powerful strategy for developing high-activity electrocatalysts for NRR and beyond.
Small-molecule organic solar cells (SMOSCs) have attracted considerable attention owing to the merits of small molecules, such as easy purification, well-defined chemical structure. To achieve high-performance SMOSCs, the rational design of well-matched donor and acceptor materials is extremely essential. In this work, two new small molecular donor materials with subtle change in the conjugated side thiophene rings are synthesized. The subtle change significantly affects the photovoltaic performance of molecular donors. Compared with chlorinated molecule MDJ-Cl, the non-chlorinated analogue MDJ exhibits decreased miscibility with the non-fullerene acceptor Y6, can more efficiently quench the excitons of Y6. As a result, a improved PCE of 11.16% is obtained for MDJ: Y6 based SMOSCs. The results highlight the importance of fine-tuning the molecular structure to achieve high-performance SMOSCs.
Construction of two RuⅢ cations and six lacunary Keggin fragments resulted in a novel Ru2W12-cluster {(RuO6)2(WO3)12(H2O)12} bridged polyoxometalate, NaH11[(RuO6)(AsW9O33)3{(W6O3)(H2O)6}]2 53H2O (NaH11·1·53H2O), which represent the largest cluster in all the Ru-containing polyoxometalates. The most interesting characteristic is that the symmetry-related Ru2W12-cluster-based hexamers contain two windmill-shaped [(RuO6)(AsW9O33)3{(W6O3)(H2O)6}] trimers or the Ru2W12 cluster was tightly wrapped by six segments of B-β-AsW9O33. The other remarkable feature is that there have one intriguing cubane structure: which is composed of the Ru(1, 2) and W(1, 28, 50, 51, 52, 53) atoms. The oxygenation reactions of anilines to azoxybenzenes was evaluated when NaH11·1·53H2O served as effective catalyst by probing various reaction. The inherent redox property of oxygen-rich polyoxometalate surfaces and high photocatalytic activity of the Ru-containing metal cluster imbedded in NaH11·1·53H2O provide sufficient driving force for the photocatalytic transformation from anilines to azoxybenzenes. The oxidation of anilines can be realized with higher selectivity to afford various azoxybenzene compounds. The durability test shows that Ru-doping catalyst displays excellent chemical stability during the photocatalytic process.
The existing industrial ammonia synthesis usually adopts the Haber-Bosch process, which requires harsh conditions of high temperature and high pressure, and consumes high energy. Under this circumstance, photoelectrochemical (PEC) catalysis is regarded as a promising method for N2 reduction reaction (NRR), but bears problems of low efficiency and yield. Thus, exploring active catalysts remains highly desirable. In this work, BiVO4@MXene hybrids have been facilely synthesized by a hydrothermal route. The heterojunctions by the in situ growth of BiVO4 onto two-dimensional (2D) MXene greatly increase the NRR efficiency: under photoelectric conditions, the optimized NH3 yield is 27.25 μg h -1 cm-2, and the Faraday efficiency achieves 17.54% at -0.8 V relative to the reversible hydrogen electrode (RHE), which are higher than most state-of-the-art NRR (photo) electrocatalysts. The mechanism speculation shows the enhanced light absorption range and the heterojunction formation largely promote the separation and the transfer efficiency of photogenerated carriers, thereby improving the PEC catalytic ability. Therefore, this work provides a hybrid route to combine the advantages of photo and electric catalysis for effective artificial nitrogen fixation.
Peroxide ligation of aqueous metal–oxo clusters provides rich speciation and structural diversity. Here, three novel transition-metal derivatives of polyoxometalate anions, [Ni2(H2O)10{P4Ta6(O2)6O24}]6– (1a), [Zn(H2O)4{P4Ta6(O2)6O24}]8– (2a) and [Cd(H2O)4{P4Ta6(O2)6O24}]8– (3a), have been successfully synthesized by adopting a one-pot reaction strategy. All of these hexatantalates are built from a new-type phosphorus-incorporated hexatantalates. We investigated the solution behaviors, and the peak assignments of the MS spectra indicated some degree of stability of them in water. Furthermore, the proton-conducting ability of compound 1a was also explored and it has shown well conductivity at high relative humidities, with conductivity achieved 1.22 × 103 S/cm (85 ℃, 90%RH).
Ground-level ozone is one of the primary pollutants detrimental to human health and ecosystems. Catalytic ozone decomposition still suffers from low efficiency and unsatisfactory stability. In this work, we report a manganese-based layered double hydroxide catalyst (Co3Mn-LDH), which exhibited a superior ozone decomposition performance with the efficiency of 100% and stability over 7 h under a GHSV of 2,000,000 mL g-1h-1 and relative humidity of 15%. Even when the relative humidity increased to 50%, the ozone decomposition also reached 86%, which significantly exceeds as-synthesized MnO2 and commercial MnO2 in performance. The catalytic mechanism was studied by H2-TPR, FT-IR and XPS. The excellent performance of Co3Mn-LDH can be attributed to its abundant surface hydroxyl groups that ensured the preferentially surface enrichment of ozone, as well as the cyclic dynamic replenishment of electrons between multivalent Co2+/Co3+, Mn2+/Mn3+/Mn4+ and oxygen species that endowed the stable ozone decomposition. This work offers new insights into the design of efficient catalysts for ozone pollution control.
Aerogels have become a hot topic of research due to their extremely low density and special interconnected structure as well as their enzyme-like activity. The development of new multifunctional nano-enzyme aerogels with high activity and good stability is still a considerable challenge. In this paper, AuRu aerogels with peroxidase and oxidase activities were synthesized using a simple one-step method and successfully used to construct colorimetric sensors for the detection of Fe2+ and glucose based on their enzyme-like activities. Furthermore, we are fortunate to find that AuRu aerogels have good photothermal properties. This suggests that AuRu aerogels can be used not only for in vitro testing but also for promising applications such as disease treatment.
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