Electrocatalytic oxidation of benzyl alcohol for simultaneously promoting H2 evolution by a Co0.83Ni0.17/activated carbon electrocatalyst

Abstract

Electrocatalytic water splitting as an environmentally friendly method to produce clean H₂ has attracted wide attention. However, efficient improvement of the performance of the oxidation half-reaction during water splitting, thus enhancing H₂ evolution efficiency, has become an urgent issue. Herein, non-precious metal Co_0.83Ni_0.17 alloy nanoparticles on activated carbon (Co_0.83Ni_0.17/AC) have been successfully fabricated by a simple thermal-treatment method. The resulting Co_0.83Ni_0.17/AC with a dominant alloy particle size of 45 nm exhibits a microporous and mesoporous structure with a surface area of 159.2 m² g⁻¹. As an electrocatalyst, the as-prepared Co_0.83Ni_0.17/AC demonstrates bifunctional electrocatalytic activity toward the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline media, delivering overpotentials of 193 and 325 mV at 10 mA cm⁻², respectively. Importantly, it is found that the electrocatalytic oxidation of benzyl alcohol to benzoic acid on Co_0.83Ni_0.17/AC is more favourable than the OER process, with almost 224 mV less overpotential at 10 mA cm⁻² and 96% faradaic efficiency at 1.425 V vs. RHE (passing charge amount of ∼40C). As a simultaneous anode and cathode electrocatalyst for water splitting, Co_0.83Ni_0.17/AC displays a H₂ generation rate of 8.98 μmol min⁻¹ in 1.0 M KOH solution containing 10 mM benzyl alcohol, almost 1.4 times that obtained by an OER-introduced water splitting system, with near 98% faradaic efficiency for H₂. This work would be helpful to develop low-cost and abundant bifunctional electrocatalysts for electrocatalytic organic synthesis and simultaneously improving H₂ generation from water splitting.