Energy-efficient bifunctional CoB _<i>x</i> /GDY catalyst for urea-assisted hydrogen production <i>via</i> electrochemical urea oxidation and hydrogen evolution

Efficient and durable bifunctional electrocatalysts for the urea oxidation reaction (UOR) and hydrogen evolution reaction (HER) are vital for sustainable hydrogen production coupled with wastewater remediation. Herein, we present a CoB _<i>x</i> /GDY catalyst electrode that delivers outstanding activity and stability for both reactions. CoB _<i>x</i> /GDY requires only 1.41 V <i>vs.</i> RHE to achieve 50 mA cm^-2 for UOR, while for HER it exhibits an overpotential of 118 mV at 10 mA cm^-2 with a Tafel slope of 97.2 mV dec^-1. The superior performance is attributed to the conductive π-conjugated GDY framework, which provides abundant accessible active sites and facilitates rapid electron transfer. These results highlight CoB _<i>x</i> /GDY as a promising bifunctional catalyst for energy-efficient hydrogen production from urea-rich wastewater and offer a general strategy for designing advanced transition-metal/graphdiyne hybrid electrocatalysts.