Heterojunction‐Induced Rapid Transformation of Ni³⁺/Ni²⁺ Sites which Mediates Urea Oxidation for Energy‐Efficient Hydrogen Production

Abstract Water electrolysis is an environmentally‐friendly strategy for hydrogen production but suffers from significant energy consumption. Substituting urea oxidation reaction (UOR) with lower theoretical voltage for water oxidation reaction adopting nickel‐based electrocatalysts engenders reduced energy consumption for hydrogen production. The main obstacle remains strong interaction between accumulated Ni³⁺ and *COO in the conventional Ni³⁺‐catalyzing pathway. Herein, a novel Ni³⁺/Ni²⁺ mediated pathway for UOR via constructing a heterojunction of nickel metaphosphate and nickel telluride (Ni₂P₄O₁₂/NiTe), which efficiently lowers the energy barrier of UOR and avoids the accumulation of Ni³⁺ and excessive adsorption of *COO on the electrocatalysts, is developed. As a result, Ni₂P₄O₁₂/NiTe demonstrates an exceptionally low potential of 1.313 V to achieve a current density of 10 mA cm⁻² toward efficient urea oxidation reaction while simultaneously showcases an overpotential of merely 24 mV at 10 mA cm⁻² for hydrogen evolution reaction. Constructing urea electrolysis electrolyzer using Ni₂P₄O₁₂/NiTe at both sides attains 100 mA cm⁻² at a low cell voltage of 1.475 V along with excellent stability over 500 h accompanied with nearly 100% Faradic efficiency.