Jialei Jin,Yuanzhi Zhu,Yizhe Liu,Yang Li,Wenchao Peng,Guoliang Zhang,Fengbao Zhang,Xiaobin Fan
Producing hydrogen through hydrogen evolution reaction by electrolyzing water is a great alternative to solve the energy crisis and air pollution. Earth abundant transition-metal phosphides, especially CoP , have emerged as promising hydrogen evolution reaction catalysts for recent years. Nowadays, attention is focused on combining CoP with other materials to improve its catalytic activity . Herein, in order to get better hydrogen evolution reaction catalyst, we combined CoP nanoparticles with WS 2 nanosheets. Different CoP to WS 2 mass ratios were set to find the best catalytic activity. CoP/WS 2 composites were prepared through a simple ultrasound induced mixing method. And all the CoP/WS 2 composites have enhanced hydrogen evolution reaction catalytic activity than pure CoP nanoparticles and WS 2 nanosheets. Especially, the optimized CoP/WS 2 composite has the lowest onset overpotential of 50 mV, the largest current density of 78 mA/cm 2 at the overpotential of 300 mV, and the smallest Tafel slope of 64.63 mV/decade, indicating excellent hydrogen evolution reaction catalytic activity.
W. X. Chen,J. S. Yu,W. Hu,Z. L. Chen,H. Memon,G. L. Chen
A core/shell heterostructured nanonanocomposite catalyst based on NiO nanoflakes and titanate nanowires (TNWs) was fabricated. The experimental results showed that the precursor concentration and the reaction time for NiO deposition played significant roles in determining the resulting heterostructure, and an optimal precursor's concentration would result in a well-defined core/shell heterostructure. The XRD analysis demonstrated the existence of the (1 1 1), (2 0 0) and (3 1 1) lattice planes of the NiO nanoflakes. Nearly 100% of the MB pollutant (10 mg L−1) was photodegradaded by the TNWs/NiO catalyst within 50 minutes under UV light irradiation.
Selective reduction of nitroarenes is extremely valuable in industrial chemical production. The main reduced products are usually aniline derivatives obtained using single-component noble- or transition-metal catalysts; however, other important products such as hydrazobenzene derivatives always involve in harsh conditions and multiple reaction steps. Here, we realize an unexpected switchable reduction of nitroarenes into aniline or hydrazobenzene derivatives with high yield and selectivity just by controlling the molar ratio of nitroarenes to N 2 H 4 ·H 2 O with a nickel–tungsten carbide composite nanocatalyst loaded on carbon (Ni-WC/C). A series of control experiments and density functional theory (DFT) calculations indicate that the multiple interfaces between Ni and WC can induce a synergistic effect, significantly modulating the electronic structure of the Ni-WC/C catalyst, and endowing the catalyst with switchable selectivity and high activity for the reduction of nitroarenes by hydrogenation. This synergistic multi-interfacial catalyst may offer a new way to design and explore highly efficient and selective catalysts for the controllable reduction of nitroarenes and similar hydrogenation reactions.
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