Solar-driven CO2 reduction using modified earth-abundant ilmenite catalysts

Photocatalytic CO2 reduction is an alternative technology to the depletion of highly pollutant fossil fuels through the generation of renewable solar-based fuels. This technology requires that the photocatalysts be obtained directly from nature to scale up the process. Taking that into consideration, this work proposed the fabrication of sodium iron titanate (NaFeTiO4) photocatalysts from earth-abundant ilmenite mineral. The photocatalysts exhibited full spectrum light response, good electron transfer due to its unique tunnel structure that favored the formation of rod-like morphology. These properties promoted the solar-driven CO2 reduction to generate formic acid (HCOOH) with high selectivity (157 μmol g−1 h−1). It was found that higher synthesis temperatures promoted the formation of Fe3+ species, which decreased the efficiency for CO2 reduction. Also, the possibility of reduced the CO2 molecules in the air was studied with the NaFeTiO4 samples, which resulted in an efficiency of up to 93 μmol g−1 h−1 of HCOOH under visible light. The stability of the solar-driven CO2 reduction with the NaFeTiO4 photocatalysts was confirmed after seven days of continuous evaluation

Comparative study of CO₂ photoreduction using different conformations of CuO photocatalyst:Powder, coating on mesh and thin film

The use of CuO-based photocatalysts for CO2 photoreduction has been extensively reported in the literature. However, the comparison of the photocatalytic activity and selectivity from the published results becomes difficult due to different experimental conditions (i.e., synthesis method, configuration of photocatalyst, flow rate of gas, water content, light intensity) and reactor geometry employed. Hence, in this work different conformations of CuO-based photocatalyst, namely powder (i.e., synthesized using precipitation, sonochemical and hydrothermal-microwave treatment), coating on glass fiber mesh, and thin film, were tested using the same photoreactor and experimental conditions. All CuO photocatalysts exhibited 100 % product selectivity towards CH4 over CO and the CuO coating on the glass fiber mesh exhibited the highest production of CH4 (56.3 μmol gcat − 1h− 1). The morphology, particle size, particle dispersity, and presence of impurities/defects within the CuO photocatalysts had a significant effect on photocatalytic activity. A numerical model, which was built using COMSOL, revealed that the experimental data obtained in this simulated photocatalytic activity study fitted well, however, further optimization was needed