J.Y. Do, N. Son, J. Kim, J.N. Heo, M. Kang
Keywords: CdS@Fe2O3, heterojunction, CO2 photo-reduction, photocatalyst
Summary:Carbon dioxide accelerates global warming as a contributor to greenhouse gas emissions. After the Paris Climate Convention in 2015, global emissions of carbon dioxide are regulated due to environmental problems caused by greenhouse gases. In recent years, technologies to convert CO2 into other energy sources such as methane and methanol have been attracting much attention, with the reduction of CO2 emissions. Among the various carbon dioxide conversion technologies, the photochemical conversion technology of CO2 utilizing solar energy is an environmentally friendly future technology, so it is essential to develop a high efficiency photocatalyst. In this study, we tried to improve the photocatalytic performance by bonding Fe2O3 to CdS which is one of promising photocatalyst in visible light region. Fe2O3 is also used as a photocatalyst in many applications because of its narrow band gap of about 2.0 eV. However, pure CdS and Fe2O3 single materials are limited due to the fast recombination rate between photo-generated electrons and hole pairs. Therefore, the stability of the catalyst was improved by combining two materials having an ideal band gap, and the effective light absorption and charge separation efficiency were expected by the synergistic effect. CdS nanowire-based heterojunction CdS@Fe2O3 catalysts were applied to the carbon dioxide photo-reduction reaction to evaluate the photocatalytic activity. The optimal ratio of CdS to Fe2O3 was investigated. As a result, CdS@Fe2O3 (1:1) catalyst showed maximum methane production efficiency after 10 h reaction under visible light irradiation. Ultimately, the photocurrent and IMVS results show that heterojunction CdS@Fe2O3 catalysts promote charge separation as compared to pure CdS, Fe2O3, and maintain stable high catalyst performance at slow recombination rates.