The Synthesis And Characterization Of Iron-Cobalt Bimetal Phosphide,Its Study On Hydrogen Evolution Reacion

Hydrogen,a clean energy with high energy density,shows great potentiality to solve the energy and environmental problems.Due to the abundant of raw materials and cleanliness,electrocatalytic hydrogen evolution reaction can be an excellent hydrogen production route.Pt-based catalysts,which is expensive and limited reserves,are the main catalysts for hydrogen evolution reaction.So developing the catalysts with high activity and low cost has become an urgent problem to be solved.In this work,We focus on preparing a composite structure transition bimetal phosphide with high electrocatalytic hydrogen evolution performance.Different types of precursors of metal organic framework materials,oxyhydroxides and alloy are selected to prepare composite structure bimetallic phosphides with different structures.The key point is the effects of composition and structure for the hydrogen evolution reaction performance of transition metal phosphide,reflecting the experimental idea of composition and structure double regulation.First,we prepared the metal-organic framework(FeCo-MIL88)by solvothermal merthod.Through the carbonization and phosphating process,multi-layered FeCo@FeCoP@C hollowspheres were synthesized,which showed the outstanding electrocatalytic activity and great stability for HER.It only need 66 mV overpotential to reach 10 mA/cm2 current density,superior to the HER electrocatalysts by most reported.Comparing with Fe@FeP@C and Co@CoP@C,the high hydrogen evolution reation activity can be attributed to the compositon effect;Comparing with FeCoP-direct(directly phosphating production),the composite of FeCo and carbon of FeCo@FeCoP@C enhance the electron transportation ability and protect the FeCoP from oxidation,which resulting the greater hydrogen evolution reaction activity(structure effect).Second,we prepared the Fe/CoOOH as the precursor by hydrothermal,then prepared the FeCoP/Fe3O4 hollow nanorobds.The composition effect on hydrogen evolution reaction can be proved by compareing with the FeP/Fe3O4;To prove the structure effect,we prepared FeCoP by acid treatment,the Fe3O4 of FeCoP/Fe3O4 can enhance the electron transportation ability,leading FeCoP/Fe3O4 owning the higher hydrogen evolution reaction activity.Finally,we prepared the FeCo alloy reducted by sodium borohydride and got the production FeCo@FeCoP by partially phosphating.The hydrogen evolution reaction activity of FeCo@FeCoP is much higher than FeP,CoP,(Fe@Co)P and(Co@Fe)P.Comparing with FeP and CoP,the composition effect can be proved.The difference of the activity between FeCo@FeCoP and(Co@Fe)P can be attributed to the FeCo alloy of FeCo@FeCoP,which leads the high electron transportation ability and protects the FeCoP from oxidation.As for the(Fe@Co)P,the lower overpotioanl of FeCo@FeCoP at the same current density can be attributed to the uniform mixing of iron and cobalt,leading the uniform mixing of FeP and CoP,it's important for the composition effect.Based the different precursors,the transition bimetal phosphides with composite structures are successfully prepared,and show the greater hydrogen evolution reaction than non-composite transition metal phosphides.It can be attributed to the structure effect.At the same time,compared with the transition metal phosphide of single metal,it can be proved that the composition effect is also an important factor affecting the performance of electrocatalytic hydrogen evolution reaction.