Uleashing efficient and CO-resilient alkaline hydrogen oxidation of Pd3P through phosphorus vacancy defect engineering

A high-performance and highly CO-resilient hydrogen oxidation reaction (HOR) electrocatalyst is heralded as core material to solve the commercial deployment of hydrogen fuel cells. Phosphorus vacancies, as a type of delicate point defect, could effectively and flexibly modulate the catalytic performance. Therefore, based on the vacancy design philosophy of "less is more", we synthesize a phosphorus-vacancy-rich Pd3P@C (Vp-Pd3P@C) catalyst with bowl-like hemisphere structure for alkaline HOR, for the first time. The Vp-Pd3P@C catalyst exhibits remarkable mass activity and exchange current density of 1.66 mA μgPd–1 and 3.2 mA cm–2, respectively, surpassing those of Pd3P@C (0.45 mA μgPd–1, 1.78 mA cm–2) and commercial Pt/C (0.3 mA μgPt–1, 2.29 mA cm–2). Intriguingly, the catalyst can tolerate 1000 ppm CO that Pt/C catalyst lacks. Density functional theory calculations uncover that the optimal local coordination environment and favorable electronic structure that rooted from phosphorus vacancy enable optimum adsorption kinetics of hydrogen and hydroxyl while concomitantly suppressing Pd 4d → CO 2π* back donation, contributing to the remarkable HOR reactivity and CO tolerance.