1D NiHPO4 nanotubes prepared using dissolution equilibrium as bifunctional electrocatalyst for high-efficiency water splitting

Abstract

In this work, one-dimensional NiHPO 4 nanotubes are successfully fabricated on nickel foam by hydrothermal reaction, in which a dissolution equilibrium between phosphates is controlled by tuning the proportion of the mixed solvent and amounts of KOH. As the dissolution equilibrium is broken, the morphology of NiHPO 4 transfers from solid nanowires to hollow nanotubes. The resulting 1D NiHPO 4 nanotubes exhibit good electrocatalytic activity and stability in oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). Notably, a water-splitting voltage of 1.62 V at a current density of 10 mA cm −2 is obtained in an electrolyzer setup assembled using 1D NiHPO 4 nanotubes as cathode and anode, demonstrating NiHPO 4 nanotubes are promising catalysts for overall water splitting. Moreover, the revealed mechanism of forming tube morphology can be extended to fabricate other metal phosphates with hollow structures. • Ni foam-supported NiHPO 4 nanotubes catalyst is prepared without any template. • The mechanism of evolving NiHPO 4 nanotubes based on dissolution equilibrium is proposed. • NiHPO 4 nanotubes shows good bifunctional performance for overall water solitting • The present work provides a strategy to explore efficient electrocatalysts.