In situ growth of single-layered α-Ni(OH)2 nanosheets on a carbon cloth for highly efficient electrocatalytic oxidation of urea

Abstract

The electrochemical urea oxidation reaction (UOR) is useful for the simultaneous elimination of urea-rich wastewater and generation of hydrogen. In theory, nickel-based catalysts, as non-precious metal catalysts, show great advantages in this regard. However, poor conductivity and insufficient active sites on common nickel-based nanomaterials hinder their catalytic performance. Herein, we report methanol-directed one-step growth of single-layered (SL) α-Ni(OH)₂ nanosheets on a conductive carbon cloth (CC) (SL α-Ni(OH)₂ NS/CC) for highly efficient electrocatalytic urea oxidation. Without the use of any other pretreatment and modification methodology, it is found that huge SL α-Ni(OH)₂ NS with a thickness of ∼0.8 nm densely and fully covers every CC fiber in the form of nanowalls. Taking advantage of the good conductivity of CC and the sufficiently exposed active surface of SL α-Ni(OH)₂ NS, the resulting SL α-Ni(OH)₂ NS/CC-integrated electrode displays superior UOR performance. A current density as high as 436.4 mA cm⁻² at 0.5 V vs. Ag/AgCl is achieved, which represents the best UOR performance among those of the reported nickel-based electrocatalysts. This convenient approach opens a new way to obtain ultrafine heterogeneous catalysts and their integrated electrodes with the assistance of methanol solvent instead of water.