Graphene enhanced α-MnO2 for photothermal catalytic decomposition of carcinogen formaldehyde

Abstract

Formaldehyde (HCHO) causes increasing concerns due to its ubiquitously found in indoor air and being irritative and carcinogenic to humans. Photothermal-catalysis developed in recent years has been considered as a significant strategy for enhancing catalytic activity. Manganese oxides, compared with its strong thermocatalytic activity, generally suffer from much lower photocatalytic activity make its photochemical properties less concerned. Herein, α-MnO2 nanowires were composited with the graphene oxide (GO) via mechanical grinding and co-precipitating method, respectively. α-MnO2/GO nanohybrids prepared by co-precipitating method exhibits excellent activity, achieving 100% decomposition of HCHO with the solar-light irradiation at ambient temperature. It is found that, besides the photo-driven thermocatalysis, the photocatalysis mechanism made a major contribution to the decomposition of HCHO. The incorporation of GO, on the one hand, is beneficial to improve the optical absorption capacity and photothermal conversion efficiency; on the other hand, is conductive to electron transfer and effective separation of electrons and holes. These synergistic effects significantly improve the catalytic activity of α-MnO2/GO nanohybrids. This work proposes a new approach for the utilization of solar energy by combining manganese oxides, and also develops an efficient photothermal-catalyst to control HCHO pollution in indoor air.