Pt/NiCo2O4 nanowire arrays on Ni foam as catalysts for efficient formaldehyde oxidation at room temperature

Catalytic oxidation of formaldehyde (HCHO) at room temperature is a low-cost and efficient solution for indoor HCHO removal. In this work, NiCo2O4 nanowires were in-situ synthesized on nickel foam (NF) by a simple hydrothermal reaction and then decorated with platinum nanoparticles (NPs). The Pt/NiCo2O4-NF catalyst exhibited excellent HCHO oxidation capacity at ambient temperature, realizing a conversion rate of 90 % within 60 min. The nickel foam substrate prevents the aggregation of NiCo2O4 nanowire arrays. It also enables the growth of large-area and aligned nanowires, contributing to the uniform dispersion of Pt NPs. Moreover, due to the unique redox property and high reactivity of NiCo2O4, numerous surface oxygen vacancies and active oxygen species are generated together with Pt by NaBH4 reduction, which is beneficial to the adsorption and oxidation of HCHO. Moreover, the hierarchical macro-/mesoporous structure of Pt/NiCo2O4-NF facilitates the diffusion of gaseous reactants and provides easily accessible active sites. In contrast with nanosized catalysts, the three-dimensional (3D) Pt/NiCo2O4-NF catalyst possesses high machinability and practicability. This work may shed light on the fabrication of 3D hierarchical catalysts for oxidative HCHO removal and indoor air purification.