Photo-assisted electrolysis of urea using Ni-modified WO3/g-C3N4 as a bifunctional catalyst

Urea splitting to produce H2 is as an energy-saving alternative to water electrolysis. However, efficient catalysts are required for the practical implementation of urea splitting because of the high overpotentials of the urea oxidation reaction and the hydrogen evolution reaction. Herein, a Ni-modified direct Z-scheme photocatalyst for the urea oxidation and hydrogen evolution reactions was synthesized by electroplating a WO3/g-C3N4 nanocomposite on Ni-decorated carbon felt (WO/CN–Ni@CF). The 2D/2D nanostructure of the as-synthesized WO3/g-C3N4 composite was confirmed by SEM and TEM. The WO/CN–Ni@CF catalyst electrode exhibited excellent bifunctional photocatalytic activity for the urea oxidation and hydrogen evolution reactions. Consequently, the potential required to generate 100 mA cm−2 in an illuminated photoelectrochemical cell using WO/CN–Ni@CF as the anode and the cathode was reduced from 1.80 to 1.50 V. The photoelectrochemical cell exhibited good stability for 18 h with stable H2 generation.