Regulating the Electronic Structure of Tungsten Carbide‐Induced Co(OH) ₂ for Efficient Water and Urea Electrolysis in Hydrogen Production from Urea‐Containing Water

Urea oxidation reaction (UOR) is considered a capable method for simultaneously producing hydrogen and treating urea-rich wastewater. The development of well-designed, high-performance electrocatalysts is crucial for efficient urea oxidation. In this study, a tungsten carbide (WC) and Co(OH)₂ nanocomposite (WC@Co(OH)₂) is synthesized through a simple hydrothermal process for electrocatalytic UOR performance. X-ray absorption spectroscopy revealed that WC@Co(OH)₂-2 exhibited higher levels of high-spin Co³⁺ electronic states compared to pristine Co(OH)₂. The optimized WC@Co(OH)₂ electrocatalysts showed remarkable activity in the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and UOR, with potentials of 0.152, 1.475, and 1.38 V, @ 10 mA cm^-2, respectively. The WC@Co(OH)₂-2 catalyst also exhibited a high turnover frequency of 31.2 s^-1. Moreover, an overall urea electrolysis system constructed with the prepared WC@Co(OH)₂, attained 1.55 V at 10 mA cm^-2, which is 0.21 V lower than the potential required for overall water splitting. In situ Raman result revealed the quick reconstruction of WC_1-x@Co(OH)₂, where tungsten species infiltrate into CoOOH, forming a restored WC_1-x@CoOOH layer that serves as the active species for water splitting. Furthermore, the WC@Co(OH)₂-2 exhibited a high Faradaic efficiency of 92.18% and exceptional durability. This work broadens the UOR electrocatalyst and contributes the advancement of energy-efficient hydrogen production technologies.