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• This work meticulously details strategies for enhancing CO 2 mass transport in eCO 2 RR. • A comprehensive discussion on the effects of electrode are provided. • Effects of electrolyzer designs and electrolysis conditions are also discussed. • Potential solutions for CO 2 mass transfer in eCO 2 RR industrialization are summarized. The imperative to address climate change and CO 2 emissions has elicited substantial interest in the field of electrochemical CO 2 reduction reaction (eCO 2 RR) as an avenue to both environmental sustainability and the production of value-added fuels. However, the selectivity and efficiency of eCO 2 RR remain below the industrial requirement for its implementation at high current density. One pivotal strategy to ameliorate this deficiency involves augmenting the mass transport of CO 2 to electrode, thereby alleviating the competing hydrogen evolution reaction and consequently enhancing eCO 2 RR performance. Herein, we primarily discuss the CO 2 mass transport enhancement strategies through electrode and electrolyzer designs, as well as electrolysis conditions. The electrode designs are first presented, including wettability regulation, porous substrates construction, catalyst layer and gas diffusion layer designs. Then, we highlight state-of-the-art electrolyzer designs, including the bipolar membrane structure, interdigitated flow field and in-situ exsolution of CO 2 structure. The electrolyzer based gas–liquid Taylor flow is also introduced. Following this, we delve into the impact of various electrolysis conditions, encompassing the electrolyte, electrolysis potentials, CO 2 pressure, CO 2 flow rate and reaction temperature. Finally, we conclude this review by delineating persisting challenges and potential solutions aimed at advancing CO 2 mass transport for the industrial implementation of eCO 2 RR technology. [ABSTRACT FROM AUTHOR]

In this study, a novel mesoporous CdS/TiO 2 /SBA-15@carbon paper composite membrane was developed to enhance the visible-light responsive CO 2 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/TiO 2 /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 TiO 2 /SBA-15 in the composite membrane, too high dosage of TiO 2 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/TiO 2 /SBA-15@carbon paper composite membrane for the CO 2 photoreduction. [ABSTRACT FROM AUTHOR]