Copper and Copper‐Based Bimetallic Catalysts for Carbon Dioxide Electroreduction

Among many alternatives, CO2 electroreduction (CO2ER) is an emerging technology to alleviate its level in the atmosphere and simultaneously to produce essential products containing high energy density using various electrocatalysts. Cu‐based mono‐ and bimetallics are electrocatalysts of concerns in this work due to the material's abundance and versatility. Intrinsic factors affecting the CO2ER are first analyzed, whereby understanding and characterizing the surface features of electrocatalysts are addressed. An X‐ray absorption spectroscopy‐based methodology is discussed to determine electronic and structural properties of electrocatalyst surface which allows the prediction of reaction mechanism and establishing the correlation with reduction products. The selectivity and faradaic efficiency of products highly depend on the quality of surface modification. Preparation and modification of electrocatalyst surfaces through various techniques are critical to increase the number of activity sites and the corresponding site activity. Mechanisms of CO2ER are complicate and thus are discussed in accordance with main products of interests. The authors try to concisely compile the most interesting, recent, and reasonable ideas that are agreeable to experimental results. Finally, this review provides an outlook for designing better Cu and Cu‐based bimetallic catalysts to obtain selective products through CO2ER. This review identifies the gaps in CO2ER and forward new insights via detailed electronic and structural characterizations of Cu‐based bimetallic and monometallic electrocatalysts. Intrinsic factors affecting CO2ER and the reduction mechanism are discussed, as well as characterization techniques for Cu–M bimetallics or alloys. Due to the range of versatile products, selectivity of the electrocatalysts is also reviewed.