Interface-Rich Highly Oxophilic Copper/Tin-Oxide Nanocomposite on Reduced Graphene Oxide for Efficient Electroreduction of CO2 to Formate

In recent days, it has been reported that bimetallic electrocatalysts can increase the activity for electrochemical formate (HCOO-) production during CO2 reduction. However, they still have some apparent drawbacks such as poor selectivity and durability. In the current work, notable improvements in the electrochemical CO2 reduction (CO2RR) to formate production were accomplished by incorporation of reduced graphene oxide (rGO) into nanostructured bimetallic CuSnOx electrocatalysts (CuxSnOx/rGO). The interface-rich mixed crystalline-amorphous nanostructured Cu0.33SnOx/rGO nanocomposite is able to enhance the electrocatalytical activity, resulting in conversion of CO2 to formate with lower overpotential of 590 mV vs RHE. The control experiments show that the presence of SnOx in the catalyst considerably increased electrocatalytic activity and product selectivity toward formate production. Further, the increased oxophilicity of the Cu0.33SnOx/rGO nanocomposite supports the plausible CO2 reduction mechanism through the formation of bicarbonate intermediate, as demonstrated by CO stripping studies. The Cu0.33SnOx/rGO had maximum formate faradaic efficiency (80.62%) at lower potential of -0.69 V (RHE), which is 2.09 and 1.85 times better than those of CuSnOx/rGO and Cu3SnOx/rGO nanocomposites, respectively. The catalytic performance may be attributed to synergistic interaction, the presence of interfaces, higher electrochemical surface area, and the mixed crystalline-amorphous nature of Cu0.33SnOx/rGO nanocomposite. Thus, the obtained results gave rise to a practical method for boosting the activity and product selectivity of electrocatalysts for efficient CO2 conversion.