掺杂、应变对析氢反应催化剂NiP_(2)性能的影响

Doping and strain effect on hydrogen evolution reaction catalysts of NiP_(2)

电解水制氢可以将太阳能、风能等可持续能源中的能量转移到氢气这种高能量密度的清洁能源载体中.NiP_(2)作为一种具有较高析氢反应(HER)催化活性的廉价催化剂而备受关注.本文计算了NiP_(2)(100)表面上氢的吸附能、吉布斯自由能、交换电流密度等属性,得出其表面上P的top位点是催化活性位点的结论.并着重分析了掺杂和应变对NiP_(2)催化活性的影响:1)基于常见的实验手段能产生的应变范围,计算了1%和3%的拉伸和压缩应变的影响,发现在NiP_(2)上施加1%的压缩应变可以提高其HER催化性能;2)计算了过渡金属元素及非金属元素(N,C,S)掺杂对NiP_(2)催化性能的影响,发现掺杂S可以显著提高P的top位点的HER催化性能,而过渡金属元素(催化活性:Mn>Mo>W>Co>Cr>Fe>Ni)中Mn的掺杂,可以将NiP_(2)非活性位点的催化性能提升到跟活性位点同一个数量级,从而间接提升NiP_(2)的催化性能.本工作揭示了掺杂和应变对HER催化剂性能影响的微观机理,为设计高性能HER催化剂提供了指导.

Hydrogen production through electrolyzing water can transfer the energy from solar energy,wind energy and other sustainable energy to hydrogen,a clean energy carrier with high energy density.The NiP_(2) has attracted much attention as a cheap electrocatalyst with high catalytic performance for hydrogen evolution reaction(HER).In this paper,the adsorption energy,Gibbs free energy and exchange current densities at different sites on NiP_(2)(100)surface are calculated.On this basis,the effect of strain and doping on the HER catalytic performance of NiP_(2) are studied.By calculation,we find that when H is adsorbed on the top site of P atom on NiP_(2)(100)surface,the exchange current density is the closest to the top of volcanic curve,so the top site of P atom on NiP_(2)(100)surface is the catalytic active site.The effect of doping and strain on the catalytic performance of NiP_(2) are analyzed.1)According to the range of strain produced by the common experimental technology,the effects of 1%and 3%tensile and compressive strain are calculated.It is found that 1%compressive strain can improve the catalytic performance of NiP_(2),while when 3%compressive strain or a 1%or 3%tensile strain is applied,the catalytic performance of NiP_(2) is not enhanced.2)The effects of doping transition metal elements(Co,Fe,Mn,Mo,Cu,W,Cr)and non-metallic elements(N,C,S)on the catalytic performance of NiP_(2) are calculated.It is found that doping non-metallic element S can significantly improve the HER catalytic performance of the top site of P atom,while the doping of transition metal elements Mn,Mo,W,Co,Cr,Fe,Cu and non-metallic elements N,C have no effect on this site.The doping of transition metal element(catalytic activity:Mn>Mo>W>Co>Cr>Fe>Ni)Mn can make the catalytic performance of inactive site improved to that of the active site,thus indirectly improving the catalytic performance of NiP_(2).Our work reveals the micro mechanism of the effect of doping and strain on the performance of HER electrocatalyst,which provides a new perspective for designing the high performance HER electrocatalyst.