Electroreduction of Carbon Dioxide into Selective Hydrocarbon Using Isomorphic Atomic Substitution in Stable Copper Oxide

The conversion of carbon dioxide into selective hydrocarbons is vital for green energy generation. Due to the chemical instability and lower activity, environmentally stable transition metal oxides (e.g. CuO) are unpopular for CO2 electroreduction catalysis. Here, we demonstrate substitution of Cu with isomorphic atom i.e. Ni in the CuO and utilize it for improving the hydrocarbon selectivity by 4 times as compared to pristine CuO. Hydrocarbon formation is achieved at the lowest possible applied potential (-0.2 V RHE). This gives the overpotential of about 0.37 V for methane and 0.28 V for ethylene, the lowest ever reported. Employing the ionic interaction between Ni and Cu, this catalyst suppresses the hydrogen evolution reaction (HER) to improve the hydrocarbon selectivity prominently. It is observed that current normalized by the BET surface area gives 15 to 20 times enhancement in the case of Ni substituted CuO compared to undoped CuO. The in situ experiments indicate that Ni doped CuO prefers CO pathways compared to formate resulting into high hydrocarbon selectivity. The experimental observation is further supported by DFT studies, which reveals that the CO molecule is stabilized on Cu0.9375Ni0.0625O surface rather than the CHO intermediate, in comparison to the pristine CuO surface.