In this work, electrochemical CO2 reduction reaction (eCO2 RR) has been performed on two intermetallic compounds formed by copper and gallium metals (CuGa2 and Cu9 Ga4 ) for the first time. Among them, CuGa2 selectively converts CO2 to methanol with remarkable Faradaic efficiency (FE) of 77.26% at an extremely low potential of -0.3 V versus RHE. The, high performance of CuGa2 compared to Cu9 Ga4 has been driven by its unique two-dimensional structure that retains surface and sub-surface oxide species (Ga2 O3 ) even in the reduction atmosphere. The Ga2O3, species have been mapped by XPS and XAFS techniques and electrochemical measurements. The eCO2 RR activity and selectivity to methanol have been decreased at higher potential due to the lattice expansion caused by the reduction of the Ga2 O3 , which has been probed by in-situ XAFS, quasi in-situ powder XRD and ex-situ XPS measurements. The mechanism of the formation of methanol from CO2 at various potentials has been visualized by in-situ IR spectroscopy and source of carbon of methanol at the molecular level confirmed from the isotope labelling experiments in the presence of 13 CO2 . Finally, to minimize the mass transport limitations and improve the overall eCO2 RR performance, PTFE-based gas diffusion electrode (GDE) has been employed in the flow cell configuration.
The electrochemical conversion of carbon dioxide to value-added chemicals provides an environmentally benign alternative to current industrial practices. However, current electrocatalytic systems for the CO2 reduction reaction (CO2RR) are not practical for industrialization, owing to poor specific product selectivity and/or limited activity. Interfacial engineering presents a versatile and effective method to direct CO2RR selectivity by fine-tuning the local chemical dynamics.
Electrochemical CO2 reduction is a promising way to mitigate CO2 emissions and close the anthropogenic carbon cycle. Among products from CO2RR, multicarbon chemicals, such as ethylene and ethanol with high energy density, are more valuable. However, the selectivity and reaction rate of C2 production are unsatisfactory due to the sluggish thermodynamics and kinetics of C–C coupling.