| The exploration of clean,efficient and sustainable energy is highly demanded nowadays due to the challenge caused by the growing global economy and environmental issues.Hydrogen is one of the most ideal and promising renewable energy sources with the merits of zero-emission and high energy density,which is regarded as the best substitute for fossil fuels in the current CO2-emitting fuel-based energy systems.Electrochemical water splitting is a cost-effective way for hydrogen production.Noble metals such as Pt-based materials are the state-of-the-art catalysts for hydrogen evolution reaction?HER?with a slightly negative hydrogen adsorption energy and low overpotential.However,the high price and scarcity of noble metals limit their practical application especially in harsh acidic environment.Thus,the development of non-noble-metal catalysts with remarkable activity for HER has attracted much attention.Among the non-noble-metal HER catalysts,Mo S2 with hexagonally packed layered structure has received intensive attentions for their excellent electrocatalytic activity and high abundance.However,the layered-structure Mo S2 tends to grow into large pieces and form aggregates to minimize surface free energy during the formation process,which severely weaken its catalytic activity by the insufficient exposure to active edge sites and increase mass transfer resistance.Hence,designing small size of Mo S2 material that expose abundant active edge sites is an available approach to boost its intrinsic activity for HER.The main research content of this work are listed as follows:The Mo S2 flower-ball was successfully prepared by using reduced polyoxometalates as the molybdenum source and thioacetamide as the sulfur source,respectively.Compared with Mo S2 sheet,the Mo S2 flower-ball has a lower overpotential(287 m V of 10 m A cm-2)and a smaller Tafel slope?96.2 m V/dec?.After2000 cycles,the current density of Mo S2flower-ball only slightly decreased,which shows good stability and durability.The shape of Mo S2 flower-ball is conducive to exposing more terminal S atoms,and the size of Mo S2 flower-ball is much smaller than that of Mo S2 sheet through employing the nano-scale r POM as the template,which lead to the exposure of active sites and the boost of catalytic performance of HER.The porous,uniform and defect-rich Co Mo S/KB nanoclusters catalyst was successfully prepared via employing tiny r POMs as the template and anchor sites,and the sequent solvothermal reaction promote the formation of Co Mo S nanoparticles in-situ grown on carbon support.The simultaneous electronic configuration modification through Co-doping create more exposed edge with terminal sulfur atoms of the Mo S2 nanoclusters catalyst and strengthen the interaction between Co Mo S and KB substrate,therefore the Co Mo S/KB catalyst shows excellent catalytic activity(81m V of 10 m A cm-2,and the stability better than that of 20%Pt/C). |
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