Synthesis And Study Of Transition Metal Nanocatalyst Toward Water Splitting

Hydrogen is clean energy carrier with high energy density.Electrochemical water splitting is an effective way to take full advantage of renewable energy resources?e.g.,sunlight and wind?to product hydrogen.However,hydrogen evolution reaction?HER?need effective electrocatalyst to low the overpotential.Pt and noble metal oxides?RuO2 and IrO2?are regarded as the state-of-the-art catalysts to promote kinetic for HER and OER,respectively.Due to high cost and low reserve of noble metals,transition non-noble metal compounds are extensively studies as promising candidate to dwindle global energy challenges.1.Ultrafine MoP Nanoparticles Well Embedded in Carbon Nanosheets as Electrocatalyst with High Active Site Densityfor Hydrogen EvolutionIt has been provedthat MoP provides P sites as a good‘H delivery'system to obtain nearly zero binding to H at certain coverage for HER.Preparing high specific surface area can greatly improve the catalytic performance.Ultrafine MoP nanoparticles?NPs?were synthesized via a solid-state reaction.To overcome the aggregation of MoP NPs caused by high surface energy,glucose as a low-cost environmentally friendly carbon source was used to anchor metal ions.Transmission electron microscopy reveals that the resulting product exhibits an average size of3.15 nm.Due to the presence of exposed active sites in ultrafine MoP NPs and the laminar structure of carbon nanosheets,the MoP/NPS shows remarkable high catalytic activity having a low overpotential of 90 and 115 mV to achieve the current density of 10 mA cm^-22 in both,acidic and alkaline media.2.Morphology engineering of CoSe₂ as efficient electrocatalyst for water splittingSuitable morphologies can effectively improve the surface area and performance of the materials.Herein,we reported a simple and controlled strategy to fabricate the CoSe₂ with various shapes and applied these in water splitting.We successfully synthesized the spheres,wires and rods of CoSe₂ via facile hydrothermal process through regulating the addition of NH₄F to alter the morphologies of samples.Among these samples,the as-prepared CoSe₂ spheres have urchin-like morphology with highly hollow structure,leading to large specific surface area and a great number of channels for promoting mass transfer efficiency.Therefore,the CoSe₂ spheres as electrocatalyst exhibits excellent oxygen evolution reaction and hydrogen evolution reaction performance in alkaline and acidic conditions,respectively.