High-valence Zr-incorporated nickel phosphide boosting reaction kinetics for highly efficient and robust overall water splitting

Expediting the kinetics of electrochemical hydrogen (HER) and oxygen evolution reaction (OER) is a critical segment in water electrolysis, however, it remains a great challenge. Here, we address this issue via incorporating high valence Zr into Ni2P (ZrxNi2-xP) to lower the energy barrier of reaction intermediates. The as-prepared Zr0.1Ni1.9P catalyst exhibits unexceptionable catalytic activities for both HER and OER. It possesses low overpotential of 68 and 239 mV for the HER and OER at the current density of 10 mA cm−2 (j10), respectively, with the excellent long-term durability more than 100 h. Particularly, the catalytic activity of Zr0.1Ni1.9P is superior to that of noble metal catalysts (Pt/C and RuO2) at high current density (>j300). Furthermore, the electrolytic cell achieves a low potential of only 1.54 V at j10 to drive overall water splitting in alkaline medium. Density functional theory (DFT) calculations reveal that high-valence Zr incorporating promotes the adsorption and dissociation processes of H2O to boost alkaline HER and decreases the free energy change of the potential-determining step (O*→OOH*) to facilitate the OER process. This strategy of incorporating high valence Zr to boost reaction kinetics provides a new avenue for designing high performance electrocatalysts.