The impact of flue gas impurities and concentrations on the photoelectrochemical CO2 reduction

The photoelectrochemical reduction of CO2 provides a clean and sustainable route to produce value-added chemicals and fuels using sunlight as the energy source and greenhouse gas CO2 as the feedstock. However, the use of pure CO2 decreases the economic feasibility of the technology. Direct utilization of industrial flue gas is desirable for practical applications, but the effect of flue gas impurities and concentrations on the photoelectrochemical CO2 reduction remains unknown. Herein, we investigate the influence of NOx, SOx and O2 impurities and low CO2 concentrations on photoelectrochemical CO2 reduction performance using Au nanoparticles decorated GaN nanowire arrays on Si wafer as the model photoelectrode. It is found that the presence of NOx, SOx impurities, and low CO2 concentrations are compatible with photoelectrochemical CO2 reduction. In contrast, the inclusion of O2 impurity reduces the CO2 conversion efficiency. However, the effect of O2 impurity is reversible and the photoelectrocatalytic activity is recovered once O2 impurity is removed.