Recent Advances in Electrochemical, Photochemical, and Photoelectrochemical Reduction of CO2 to C2+ Products.

Environmental problems such as global warming are one of the most prominent global challenges. Researchers are investigating various methods for decreasing CO2 emissions. The CO2 reduction reaction via electrochemical, photochemical, and photoelectrochemical processes has been a popular research topic because the energy it requires can be sourced from renewable sources. The CO2 reduction reaction converts stable CO2 molecules into useful products such as CO, CH4 , C2 H4 , and C2 H5 OH. To obtain economic benefits from these products, it is important to convert them into hydrocarbons above C2 . Numerous investigations have demonstrated the uniqueness of the CC coupling reaction of Cu-based catalysts for the conversion of CO2 into useful hydrocarbons above C2 for electrocatalysis. Herein, the principle of semiconductors for photocatalysis is briefly introduced, followed by a description of the obstacles for C2+ production. This review presents an overview of the mechanism of hydrocarbon formation above C2 , along with advances in the improvement, direction, and comprehension of the CO2 reduction reaction via electrochemical, photochemical, and photoelectrochemical processes.

Electrodeposition: An efficient method to fabricate self-supported electrodes for electrochemical energy conversion systems.

The development of electrocatalysts for energy conversion systems is essential for alleviating environmental problems and producing useful energy sources as alternatives to fossil fuels. Improving the catalytic performance and stability of electrocatalysts is a major challenge in the development of energy conversion systems. Moreover, understanding their electrode structure is important for enhancing the energy efficiency. Recently, binder-free self-supported electrodes have been investigated because the seamless contact between the electrocatalyst and substrate minimizes the contact resistance as well as facilitates fast charge transfer at the catalyst/substrate interface and high catalyst utilization. Electrodeposition is an effective and facile method for fabricating self-supported electrodes in aqueous solutions under mild conditions. Facile fabrication without a polymer binder and controlability of the compositional and morphological properties of the electrocatalyst make electrodeposition methods suitable for enhancing the performance of energy conversion systems. Herein, we summarize recent research on self-supported electrodes fabricated by electrodeposition for energy conversion reactions, particularly focusing on cathodic reactions of electrolyzer system such as hydrogen evolution, electrochemical CO2 reduction, and electrochemical N2 reduction reactions. The deposition conditions, morphological and compositional properties, and catalytic performance of the electrocatalyst are reviewed. Finally, the prospective directions of electrocatalyst development for energy conversion systems are discussed.