In situ construction of NiCo2O4 nanosheets on nickel foam for efficient electrocatalytic oxidation of benzyl alcohol

Abstract

The electrocatalytic oxidation of benzyl alcohol to benzoic acid has aroused great attention owing to its mild operation conditions. However, the development of cheap and efficient electrocatalysts with high selectivity is still a great challenge. Here we report the in situ growth of NiCo₂O₄ nanosheets on nickel foam (NF) (NiCo₂O₄/NF) as the free-standing electrode for high-efficiency electrocatalytic oxidation of benzyl alcohol to benzoic acid. The results demonstrate that the as-synthesized NiCo₂O₄/NF requires only 1.46 V (vs. RHE) to achieve a current density of 100 mA cm⁻² in the presence of 50 mM benzyl alcohol. After 2 h of reaction under the optimized experimental conditions, the NiCo₂O₄/NF can afford over 95% of benzyl alcohol conversion and benzoic acid selectivity with high faradaic efficiency and stability. In addition, the NiCo₂O₄/NF also exhibits high hydrogen evolution reaction (HER) activity in 50 mM benzyl alcohol introduced into 1.0 M KOH solution. We further constructed the two-electrode system using the NiCO₂O₄/NF as the bifunctional electrocatalyst, which can concurrently achieve superior electrocatalytic performance toward electro-oxidation of benzyl alcohol at the anode and the HER at the cathode. Based on all experimental results containing in situ Raman measurements, the electrocatalytic oxidation path of benzyl alcohol to benzoic acid was proposed. This work would be helpful in the design and development of bifunctional electrocatalysts for efficient electrocatalytic oxidation of organics to concurrently facilitate H₂ evolution.