Rational design of covalent organic frameworks/NaTaO3 S-scheme heterostructure for enhanced photocatalytic hydrogen evolution.

As a typical perovskite material, NaTaO3 has been regarded as a potential catalyst for photocatalytic hydrogen evolution (PHE) process, due to its excellent photoelectric property and superior chemical stability. However, the photocatalytic activity of pure NaTaO3 was largely restricted by its poor visible-light absorption ability and rapid recombination of photogenerated charge carriers. Therefore, a covalently bonded TpBpy covalent organic framework (COF)/NaTaO3 (TpBpy/NaTaO3) heterostructure was designed and synthesized by the post modification strategy with (3-aminopropyl) triethoxysilane (APTES) and the in situ solvothermal process. Benefiting from the enhanced built-in electric field by the interfacial covalent bonds and the formation of S-scheme heterostructure between TpBpy and NaTaO3, which were proved by the Ar+-cluster depth profile and X-ray photoelectron spectroscopy (XPS), as well as density functional theory (DFT) calculation results, both the charge transfer efficiency and the PHE performance of the TpBpy/NaTaO3 composites were significantly improved. Additionally, the composites exhibited an excellent absorption performance in the visible region, which was also beneficial for the photocatalytic process. As expected, the optimal TpBpy/20%NaTaO3 composite achieved a remarkable hydrogen evolution rate of 17.3 mmol·g-1·h-1 (10 mg of catalyst) under simulated sunlight irradiation, which was about 173 and 2.4 times higher than that of pure NaTaO3 and TpBpy, respectively. This work provided a novel strategy for constructing highly effective and stable semiconductor/COFs heterostructures with strong interfacial interaction for photocatalytic hydrogen evolution.

Facile construction of a robust CuS@NaNbO3 nanorod composite: A unique p-n heterojunction structure with superior performance in photocatalytic hydrogen evolution.

The construction of heterojunctions is commonly regarded as an efficient way to promote the production of hydrogen via photocatalytic water splitting through the enhancement of interfacial interactions. The p-n heterojunction is an important kind of heterojunction with an inner electric field based on the different properties of semiconductors. In this work, we reported the synthesis of a novel CuS/NaNbO3 p-n heterojunction by depositing CuS nanoparticles on the external surface of NaNbO3 nanorods, using a facile calcination and hydrothermal method. Through the screening of different ratios, the optimum hydrogen production activity reached 1603 µmol·g-1·h-1, which is much higher than that of NaNbO3 (3.6 times) and CuS (2.7 times). Subsequent characterizations proved semiconductor properties and the existence of p-n heterojunction interactions between the two materials, which inhibited the recombination of photogenerated carriers and improved the efficiency of electron transfer. This work provides a meaningful strategy to utilize the p-n heterojunction structure for the promotion of photocatalytic hydrogen production.

Robust S-scheme hierarchical Au-ZnIn2S4/NaTaO3: Facile synthesis, superior photocatalytic H2 production and its charge transfer mechanism.

Designing Step-scheme (S-scheme) heterojunction with the directional charge transfer pathway has been considered as a promising strategy for realizing effective spatial separation of photo-generated carriers in a photocatalytic system by utilizing broadband solar energy. Herein, the novel and ternary S-scheme heterojunction photocatalysts were fabricated by embedding Au nanoparticles (NPs) on the surface of ZnIn2S4/NaTaO3 composites through a facile two-step hydrothermal method for the first time. As expected, it showed an enhanced hydrogen evolution rate of 11404 µmol g-1 h-1, which was approximately 58 and 10 times higher than that of the pristine NaTaO3 nanocubes (197 µmol g-1 h-1) and ZnIn2S4 microspheres (1180 µmol g-1 h-1) under simulated sunlight irradiation, respectively. An intimate heterojunction interface as well as Au nanoparticles as electron reservoir and reactive sites, which enhanced light absorption capacity and accelerated charge carrier separation, was answerable to the huge promotion in the photocatalytic performance. Most notably, XPS, EPR analysis and density functional theory (DFT) calculation results, revealed that the presence of strong interfacial electric fields promoted superior separation efficiency in the Au-ZnIn2S4/NaTaO3 S-scheme heterojunction. This innovative work may shed light on a more appealing and meaningful approach to modify sodium tantalate for the promising application in photocatalytic hydrogen generation.

Application of the Cycle Management Model in Improving Outpatient Appointment Services.

To explore the application of plan-do-check-action (PDCA) cycle management model in the management outpatient appointment, and improve the efficiency of outpatient appointment services. The data of outpatients from January 2019 to December 2020 were collected from a tertiary class B general hospital affiliated to a university in Shanghai. Through the investigation and analysis of the current situation, the reasons were found for the low rate of outpatient appointment. PDCA management was carried out, and measures were formulated for continuous improvement and the effective measures were standardized. The appointment rate, recognition rate and the utilization rate of self-service appointment (handheld hospital and self-service machine) were analysed after the intervention of PDCA. Through PDCA cycle management model, the appointment rate of outpatients increased from 9.93% before improvement to 82.50% after improvement, and the recognition rate of patients increased from 51.39% to 92.76%. The utilization rate of self-service appointment increased from 1.03% to 56.38%. Through the construction of multi-channel, wide coverage and convenient operation of the appointment service system, the PDCA cycle management model effectively improves the efficiency of the outpatient appointment services.

Embedding indium nitride at the interface of indium-oxide/indium-zinc-sulfide heterostructure with enhanced interfacial charge transfer for high photocatalytic hydrogen evolution.

Enhancing the interfacial charge carriers transfer efficiency is important for designing photocatalysts with excellent hydrogen evolution performance. In this work, we have successfully constructed a In2O3@InN/ZnIn2S4 ternary heterostructure by embedding InN at the interface of thin-layered ZnIn2S4 and tubular In2O3 derived from metal-organic frameworks (MOFs) nanorods for the first time. The InN can not only adjust the energy band structure of In2O3, but also boost the photogenerated charge carriers transfer at the interface of In2O3 and ZnIn2S4. The optimum photocatalytic hydrogen evolution rate of In2O3@InN/ZnIn2S4 composite reaches 275 µmol/h (50 mg of catalyst) under simulated sunlight irradiation, which is obviously higher than pure In2O3 (12.5 times), ZnIn2S4 (2.5 times) and binary In2O3/ZnIn2S4 (1.8 times) photocatalysts. This work can offer a meaningful strategy to promote the interfacial charge separation in the heterostructure for excellent photocatalytic hydrogen evolution activity.

Which Is More Efficient in Promoting the Photocatalytic H2 Evolution Performance of g-C3N4: Monometallic Nanocrystal, Heterostructural Nanocrystal, or Bimetallic Nanocrystal?

Generally, an excellent cocatalyst could promote the photocatalytic hydrogen (H2) evolution performance of g-C3N4 significantly. Herein, a superior cocatalyst of gold-platinum (AuPt) nanocrystal with an ultralow content of Pt was successfully decorated on carbon self-doping g-C3N4 nanosheets (AuPt/CCN) via a facile photodeposition route. The corresponding Pt/CCN, Au/CCN, Au/Pt/CCN, and Pt/Au/CCN were also prepared for comparison. It is found that AuPt/CCN exhibits much superior photocatalytic H2 evolution performance (1135 µmol/h) when irradiated with a 300 W Xe lamp, up to 20, 12, 5, 2, and 1.5 times that of the pristine CCN, Pt/CCN, Au/CCN, Au/Pt/CCN, and Pt/Au/CCN, respectively. The quantum efficiency (QE) of AuPt/CCN at 420 nm reaches 12.5%. The experimental and density functional theory calculation results suggested that the improved AuPt performance can be mainly ascribed to the non-plasmon-related synergistic effect of Au and Pt atoms in AuPt nanocrystal: (1) the proximity and the electronegativity difference of Au and Pt atoms in AuPt accelerate the transfer and separation of charge carriers and (2) the synergistic interaction between Pt and Au atoms optimizes the Gibbs free energy (ΔGH*) of H* (atom) adsorption on AuPt, promoting the H2 generation kinetics of AuPt/CCN.

Hierarchical fabrication of hollow Co2P nanocages coated with ZnIn2S4 thin layer: Highly efficient noble-metal-free photocatalyst for hydrogen evolution.

The directional synthesis of transition metal phosphides was considered to be an effective strategy to solve the overdependence of noble metals on photocatalytic hydrogen evolution (PHE) reactions. Inspiringly, this work reported a facile method for constructing hollow Co2P nanocages (Co2P NCGs) that derived from ZIF-67 by calcining and phosphiding procedure in nitrogen atmosphere to act as non-noble metal cocatalysts. Followed with further coating thin-layered ZnIn2S4 (ZIS) on the surface of Co2P NCGs through a hydrothermal reaction, the hierarchical robust Co2P/ZnIn2S4 nanocages (Co2P/ZIS NCGs) were then delicately fabricated as efficient photocatalysts for PHE reactions. The uniquely hollow structure of Co2P NCGs largely diffused the photogenerated chargers that induced from ZIS and the closely interfacial contact significantly promoted the separation and transfer of electrons from ZIS to Co2P according to density functional theory (DFT) calculation, synergistically resulting in an efficient hydrogen generation performance. PHE results showed that an efficient H2 evolution rate of 7.93 mmol/g/h over 10% Co2P/ZIS NCGs was achieved, about 10 times higher than that of pristine ZnIn2S4. More importantly, the hierarchically hollow Co2P/ZIS NCGs exhibited ascendant PHE activity in comparison with that of 1% noble metal (Pt, Au, Ag) loaded ZnIn2S4 with superior sustainability, all indicating the efficient and stable photocatalysts of Co2P/ZIS NCGs for PHE reactions.

Ordered Mesoporous Ni-P Amorphous Alloy Nanowire Arrays: High-Efficiency Catalyst for Production of Polyol from Sugar.

Mesoporous metals have shown significant potential for use in catalysis; however, controllably synthesizing highly ordered mesoporous amorphous alloys is a serious challenge. In this paper, a synthesis strategy was developed for generating ordered amorphous alloy nanowire arrays from mesoporous Ni-P by combining mesoporous silica templating with electroless plating. Mesoporous silica is externally grafted with -CH3 and internally covered with -NH2 acting as an efficient template, ensuring the formation of Ni-P nanowires inside the pore channels and endowing the final product with an ordered mesoporous array structure. The resulting ordered mesoporous Ni-P amorphous alloy nanowire arrays were subjected to a liquid-phase sugar hydrogenation to polyols and exhibited a highly superior catalytic performance (97% glucose conversion and 94% maltose conversion) within 4 h at 4 MPa hydrogen pressure and 373 K relative to those reference catalysts, including conventionally prepared Ni-P amorphous alloy nanoparticles (87% glucose conversion and 86% maltose conversion), ordered mesoporous Ni nanowire arrays (90% glucose conversion and 87% maltose conversion), and the commercial Raney Ni catalyst (76% glucose conversion and 66% maltose conversion). According to a comparative study, the enhanced catalytic efficiencies can be ascribed to the integration of amorphous alloy properties and mesoporous material characteristics. The composition- and morphology-controllable synthesis presented here might supply a general synthetic methodology for rationally designing ordered mesoporous amorphous alloys for a broader range of applications.

An efficient defect engineering strategy to enhance catalytic performances of Co3O4 nanorods for CO oxidation.

Catalytic oxidation of CO at ambient temperature is an important reaction for many environmental applications. Here, we employed a defect engineering strategy to design an extraordinarily effective Sn-doped Co3O4 nanorods (NRs) catalyst for CO oxidation. Our combined theoretical and experimental data demonstrated that Co2+ in the lattice of Co3O4 were substituted by Sn4+. Based on a variety of characterizations and kinetic studies, this catalyst was found to combine the advantages of the nanorod-like morphology for largely exposing catalytically active Co3+ sites and the promotional effect of Sn dopant for adjusting the textural/redox properties. Additionally, the Sn-substituted Co3O4 NRs can be further activated via heat treatment to achieve low-temperature CO oxidation (T100 ∼ -100 °C) with excellent stability at ambient temperature. This study reveals the importance of Sn-substitution of inactive Co2+ in Co3O4 and provides an ultra-efficient catalyst for CO oxidation, making this robust material one of the most powerful catalysts available up to now.

Mesoporous Metal-Metalloid Amorphous Alloys: The First Synthesis of Open 3D Mesoporous Ni-B Amorphous Alloy Spheres via a Dual Chemical Reduction Method.

Selective hydrogenation of nitriles is an industrially relevant synthetic route for the preparation of primary amines. Amorphous metal-boron alloys have a tunable, glass-like structure that generates a high concentration of unsaturated metal surface atoms that serve as active sites in hydrogenation reactions. Here, a method to create nanoparticles composed of mesoporous 3D networks of amorphous nickel-boron (Ni-B) alloy is reported. The hydrogenation of benzyl cyanide to ß-phenylethylamine is used as a model reaction to assess catalytic performance. The mesoporous Ni-B alloy spheres have a turnover frequency value of 11.6 h-1 , which outperforms non-porous Ni-B spheres with the same composition. The bottom-up synthesis of mesoporous transition metal-metalloid alloys expands the possible reactions that these metal architectures can perform while simultaneously incorporating more Earth-abundant catalysts.