High-performance optofluidic membrane microreactor with a mesoporous CdS/TiO2/SBA-15@carbon paper composite membrane for the CO2 photoreduction

In this study, a novel mesoporous CdS/TiO2/SBA-15@carbon paper composite membrane was developed to enhance the visible-light responsive CO2 photoreduction in an optofluidic membrane microreactor. The microscopic morphological and pore volume characterizations indicated that the incorporation of the mesoporous SBA-15 into the membrane development could greatly improve the specific surface area and pore volume. The optofluidic membrane microreactor with the newly-developed composite membrane was evaluated in terms of the methanol concentration and yield. Experimental results showed that the optofluidic membrane microreactor with mesoporous CdS/TiO2/SBA-15@carbon paper composite membrane yielded much better performance than did the one without the mesoporous SBA-15. For a given total amount of TiO2/SBA-15 in the composite membrane, too high dosage of TiO2 in the composite membrane caused the reduction in the specific surface area and pore volume, thereby lowering the photocatalytic performance. In addition, it was found that the methanol concentration and yield firstly increased and then decreased with increasing the liquid flow rate. The increase of both the light intensity and NaOH concentration was able to enhance the methanol generation. The obtained results fully demonstrate the superiority of the newly-developed CdS/TiO2/SBA-15@carbon paper composite membrane for the CO2 photoreduction.