Photochemical Carbon Dioxide Reduction on Mg-Doped Ga(In)N Nanowire Arrays under Visible Light Irradiation

The photochemical reduction of carbon dioxide (CO2) into energy-rich products can potentially address some of the critical challenges we face today, including energy resource shortages and greenhouse gas emissions. Our ab initio calculations show that CO2 molecules can be spontaneously activated on the clean nonpolar surfaces of wurtzite metal nitrides, for example, Ga­(In)­N. We have further demonstrated the photoreduction of CO2 into methanol (CH3OH) with sunlight as the only energy input. A conversion rate of CO2 into CH3OH (∼0.5 mmol gcat –1 h–1) is achieved under visible light illumination (>400 nm). Moreover, we have discovered that the photocatalytic activity for CO2 reduction can be drastically enhanced by incorporating a small amount of Mg dopant. The definitive role of Mg dopant in Ga­(In)­N, at both the atomic and device levels, has been identified. This study reveals the potential of III-nitride semiconductor nanostructures in solar-powered reduction of CO2 into hydrocarbon fuels.