Abundant Amorphous/Crystalline Interfaces of C/A-NixP/NiOH Heterojunction Catalyst for Efficient Urea Oxidation Reaction

Replacing the kinetically slow oxygen evolution reaction (OER) with urea electro-oxidation significantly reduces the energy requirement for electrolysis of water. However, designing and optimizing efficient electrocatalysts for the industrial application of urea oxidation coupled to hydrogen production remains a challenge. Herein, we construct a C/A-Ni_xP/NiOH heterojunction catalyst with actually abundant amorphous/crystalline interfaces for the urea oxidation reaction (UOR) by an interfacial-sequential treatment method of electrodeposition and low-temperature gas-phase phosphatization on carbon cloth (CC). Remarkably, in UOR, the C/A-Ni_xP/NiOH catalyst required only 1.332 V to reach a current density of 10 mA cm^-2 with negligible potential decay over 12 h. The excellent performance is attributed to the synergistic interaction between the inner amorphous NiOH layer and the outer crystalline Ni_xP layer, as well as the abundant amorphous/crystalline interface, an interfacial structure that can expose more active sites as well as enhance the intrinsic activity, thus improving the reaction kinetics and stability of UOR. This work paves the way for the development of low-cost and high-efficiency catalysts for urea oxidation.