Boosting borohydride oxidation by control lattice-strain of Ni@NiP electrocatalyst with core-shell structure

Abstract

Here we fabricate an efficient Ni@NiP catalyst for borohydride oxidation by simple electrodeposition, which has a core-shell structure consisting of crystalline Ni core and amorphous NiP shell. The introduction P into the shell of Ni@NiP causes the expansion of Ni lattice, raising d-band center of Ni, strengthening adsorption to reactants, and improving intrinsic activity to BOR. Ni@NiP catalyst exhibits a superior intrinsic activity of 6.3 mAcmCat.-2 than most PGM and PGM-free catalysts. When using Ni@NiP catalyst anode, DBFC gives a peak power density of 474 mW cm−2, 2.5 times higher than that with commercial Pt/C anode. Density functional theory research reveals that tensile lattice strain effectively promoted BOR activity by reducing B* intermediate formation energy on Ni@NiP surface, which is the rate-determining step in BOR and verified by electrochemical measurement results. This work brings new insights into design efficient noble-metal-free catalysts to promote practice application of DBFC technology.