Metal-based nanomaterials for efficient CO2 electroreduction: Recent advances in mechanism, material design and selectivity

Increasing global demands for energy supply have accelerated fossil fuel consumption, triggering a gradual increase in atmospheric CO2, leading to adverse environmental effects of global warming, desertification and ocean acidification. Thus, reducing carbon emissions to mitigate climate change is an urgent imperative. Among several feasible strategies, electrochemical reduction of CO2 into value-added feedstocks is a promising one since such processes can be integrated with renewable electricity and powered by intermittent energy sources: wind, solar and hydro among others. The efficiency of CO2 reduction reaction (CO2RR) and its resulting economic feasibility strongly depends on the intrinsic properties of catalyst used. Several approaches have been proposed to attain high electrocatalytic performance of heterogenous electrocatalysts by controlling their size, morphology, surface defects, grain boundaries and crystal facets and by coupling with other synergistic components to synthesize nanocomposites, e.g., metallic alloys or metal/carbon-based nanomaterials. This review presents the latest achievements with metal-based nanomaterials for efficient electrochemical CO2 reduction reaction, their mechanism of action, and promising applications in selective conversions valuable chemicals/fuels, including carbon monoxide, formic acid, hydrocarbons and alcohols.