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

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 H-2 evolution.