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

• Published in: Advanced materials (Weinheim) 2024-05, Vol.36 (18), p.e2311766-n/a
• Main Authors: Guo, Peng, Cao, Shoufu, Huang, Wenjing, Lu, Xiaoqing, Chen, Weizhe, Zhang, Youzi, Wang, Yijin, Xin, Xu, Zou, Ruiqing, Liu, Sibi, Li, Xuanhua
• Format: Article
• Language: English
• Subjects: Electric potential; Electrocatalysts; Electrolysis; Energy consumption; Heterojunctions; Hydrogen; Hydrogen evolution reactions; Hydrogen production; Ni2P4O12/NiTe; Ni3+ sites; Nickel; nickel‐based electrocatalysts; Oxidation; Tellurides; urea oxidation coupled hydrogen production; Ureas; Voltage; water electrolysis
• ISSN: 0935-9648; 1521-4095
• DOI: 10.1002/adma.202311766

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. A novel Ni3+/Ni2+‐mediated urea oxidation pathway is achieved via constructing heterojunction of nickel metaphosphate and nickel telluride (Ni2P4O12/NiTe), resulting in a record‐high electrocatalytic urea oxidation performance. Furthermore, achieving excellent hydrogen evolution property in a urea electrolysis electrolyzer equipped with Ni2P4O12/NiTe as bi‐functional electrocatalysts (Ni2P4O12/NiTe || Ni2P4O12/NiTe), steadily delivering 100 mA cm−2 at 1.475 V over 500 h.