Modulation of energy barrier of reaction steps over S-doped Ni(OH)2/Cu composites to achieve high-performance urea electrolysis catalysts

Abstract

Ni(OH)2 has been found a cost-effective and promising electrocatalyst for urea oxidation reaction (UOR). However, HER activity is challenging due to its weak adsorption of active H atoms, poor water dissociation, and low conductivity. In this study, heteroatomic S-doped Ni(OH)2/Cu composite has been synthesized using the one-pot electrodeposition process. The incorporation of S atoms significantly enhanced the electron transfer rate and adsorption of active H atoms, which promoted the UOR and HER process. Similarly, the metallic Cu with S-doped Ni(OH)2 also exhibited the synergistic effect and promoted water dissociation, adsorption of active H atoms. As expected, S-doped Ni(OH)2/Cu composites exhibit remarkable urea electrolysis activity with a small cell voltage of 1.35 V to approach the current density of 10 mA cm−2. Results indicate that the adopted strategy has been found effective and the prepared composite is a good bifunctional urea electrolysis catalyst.