One-step energy-saving hydrogen production via methanol oxidation using ultrasound-assisted electrodeposition of CoP electrocatalyst

The development of bifunctional electrocatalysts for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is essential for efficient electrochemical water-splitting. To address the sluggish OER kinetics, the methanol oxidation reaction (MOR) can serve as an alternative anodic reaction. Herein, we report a one-step ultrasonic-assisted electrodeposition strategy for synthesizing cobalt phosphide (CoP) nanocomposites as hybrid electrocatalysts for HER, OER, and MOR. The optimized CoP-39 catalyst exhibited low overpotentials (55.2 mV and 315.3 mV at 10 mA/cm²) and small Tafel slopes (48.5 and 55.0 mV/dec). For overall water-splitting, CoP-39 achieved low cell voltages (1.63, 1.73, and 1.77 V at 10, 50, and 100 mA/cm²) and superior durability, outperforming Pt/C and IrO₂. Furthermore, a hybrid electrolyzer pairing HER with MOR using CoP-39 showed a reduced cell voltage of 1.47 V at 10 mA/cm², which is 160 mV lower than that of conventional HER/OER systems. The outstanding performance is attributed to the interconnected nanoflake morphology and high porosity, which promote charge transfer and increase active sites. This study presents a promising strategy for efficient hydrogen production.