Preparation Of Cobalt-Based Transition Metal Boride And Electrocatalysis For Hydrogen Evolution Reaction

Hydrogen energy is recognized as one of the most promising clean energy sources in the future,because of its zero pollution and high energy.Compared to other hydrogen production technologies,hydrogen production technology by electrolysis of water is a simple technology for preparing high purity hydrogen and has come into the practical application stage.However,due to the limited reserves and high prices commerical catalysts such as precious metal Pt limit the large-scale application of hydrogen production technology from electrolysis of water.Therefore,it is necessary to develop high efficient and inexpensive catalysts.In this paper,we take transition metal borides with unique electronic structures as the research object.Transition metal borides doped with P,Fe and W have been synthesized and researched hydeogen evolution reaction performance and mechanisms by means of XRD,SEM,HRTEM and XPS.The main content of the paper is as follows:（1）The catalyst Co-B-P was synthesized through a hydrothermal-alternate immersion-calcination pathway.The results show that the interwoven network Co-B-P is composed of amorphous Co-B-O and crystalline Co₂P₂O₇.In 1.0 M KOH electrolyte,Co-B-P requires an overpotential of 51 m V to achieve a current density of 10 m A cm^-2,and the Tafel slope is 44 m V dec^-1.After 1000 CV circles,Co-B-P still maintains outstanding stability performance.（2）CoB,FeB and CoFeB were prepared by electrodeposition and explored the influences of boric acid content,deposition time,deposition potential and Co/Fe molar ratio on catalysts activities.According to the experimental results,Co Fe B is prepared under the following conditions:the boric acid content is 0.05 mol L^-1,the deposition time is one hour,the deposition potential is-0.9 V vs.Ag/Ag Cl and Co/Fe molar ratio of 1:1.To driving a current density of 50 m A cm^-2,Co Fe B reqiures the overpotential of 255 m V.After 1000 CV circles,the overpotential at 50 m A cm^-2increases by 26 m V,which displays the good stability.（3）The CoB/CNFs and CoWB/CNFs were obtained by electrospining-Na BH₄chemical reduction-calcination method.And we investigated the influence of different calcination temperatures on the HER performance of borides.Co WB/CNFs-800 prepared at800℃requires an overpotential of 243 m V to achieve the current density of 10 m A cm^-2.Comparing to the polarization curves before and after 1000 circles,the overpotential at current density of 50 m A cm^-2rises by 7 m V.Its excellent catalytic activity and stability is attributed to the larger electrochemical active areas and the elemental Co and Co-N_xactive sites.In summary,it is feasible to adjust the HER performance of Co-based borides by doping non-metals and metals,which provides the idea for the design,preparation and application of transition metal borides.