Strategies for Improved Electrochemical CO2 Reduction to Value-added Products by Highly Anticipated Copper-based Nanoarchitectures

Uncontrolled CO2 emission from various industrial and domestic sources is a considerable threat to environmental sustainability. Scientists are trying to develop multiple approaches to not only reduce CO2 emissions but also utilize this potent pollutant to get economically feasible products. The electrochemical reduction of CO2 (ERC) is one way to effectively convert CO2 to more useful products (ranging from C1 to C5). Nevertheless, this process is kinetically hindered and less selective towards a specific product and, consequently, requires an efficient electrocatalyst with characteristics like selectivity, stability, reusability, low cost, and environmentally benign. Owing to specified commercial features, copper (Cu)-based materials are highly anticipated and widely investigated for the last two decades. However, their non-modified polycrystalline Cu forms usually lack selectivity and lower overpotential of CO2 reduction. Therefore, extensive research is in progress to induce various alterations ranging from morphological and surface chemistry tuning to structural and optoelectrical characteristics modifications. This review provides an overview of those strategies to improve the CO2 conversion efficiency through Cu-based ERC into valuable C1, C2(,) and higher molecular weight hydrocarbons. The thermodynamics and kinetics of CO2 reduction via Cu-based electrocatalysts are discussed in detail with the support of the first principle DFT-based models. In the last portion of the review, the reported mechanisms for various products are summarized, with a short overview of the outlook. This review is expected to provide important basics as well as advanced information for experienced as well as new researchers to develop various strategies for Cu and related materials to achieve improved ERC.