Study On Iron(Cobalt)-Based Compounds For Hydrogen Evolution Reaction

Water electrolysis was a promising method for sustainable hydrogen production,one of the most promising solutions to meet the growing global demand for hydrogen and buffer large-scale fluctuating renewable energy sources.The precious metal catalysts（platinum,iridium oxide）used in the electrolysis process had low overpotential and fast reaction kinetics,but precious metals were expensive.Considering the cost,the method of using precious metal catalysts to produce hydrogen cannot achieve electrolysis of water to develpo large-scale applications of hydrogen.Therefore,the development of high-activity and low-cost non-precious metal electrocatalysts was an important research direction in the future.In this paper,the electrolytic hydrogen production was mainly carried out by the alkaline electrolyzer（alkaline method）and proton exchange membrane method（PEM）,and the anode noble metal catalyst is combined with the as-prepared cathode non-precious metal catalyst to achieve high-efficient hydrogen production.The main research contents were as follows:（1）Fe OOH flakes supported on nickel foam as electrocatalysts for hydrogen evolution（HER）and oxygen evolution（OER）were prepared using ethylenediaminetetraacetic acid（EDTA）-assisted impregnation method.The experimental results showed that the catalyst had excellent catalytic activity when the ratio of Fe/Ni was 4:1.A hydrogen evolution of this electrocatalysts was obtained a overpotential of 145 m V and a Tafel slope of 88.6 m V dec^-1 at the current density of 10m A cm^-2and marked the oxygen evolution overpotential of 358 m V and a Tafel slope of 56 m V dec^-1at the current density of 100 m A cm^-2.In addition,the catalyst could effectively split water at 1.64 V.（2）Co/Mn O@NC hydrogen evolution catalyst was successfully prepared via mixing cobalt source,manganese source,glucose and melamine after two high-temperature calcinations.When the ratio of Co/Mn is 1:2,the catalyst exhibited excellent hydrogen evolution performance,involving the hydrogen evolution overpotential is 79 m V at the current density of 10 m A cm^-2,and the Tafel slope was103 m V dec^-1.（3）In order to study the practical large-scal electrode,Co/Mn O@NC hydrogen evolution catalyst was coated on Ti sheet as cathode,the commercial precious metal catalyst was used as anode,combined with 117 proton exchange membrane,a compact and practical PEM water electrolyzer was designed for hydrogen production.The research results showed that the PEM electrolysis device could effectively and stably produce hydrogen after 6-hour electrochemical activity.At voltages above 2.5 V,the electrolytic hydrogen production was obviously effective.At the same time,the amount of hydrogen production increased rapidly with the increase of temperature and voltage,and the effect of voltage was much remarkable than that of temperature for hydrogen production.Furthermore,when the voltage was increased to 8 V,the device could generate 375 ml of hydrogen per hour.