Chlorine in NiO promotes electroreduction of CO2 to formate

We report the exceptional finding that NiO, a known electroactive catalyst for reduction of CO2 to CO, can be tuned become an active electrocatalyst formate when chlorine is synthetically incorporated into NiO. The reaction (CO2RR) carried out on chlorine-containing NiO octahedral particles made by solid-state synthesis method yielding Faradaic efficiency (FE) 70 % production at -0.8 V vs. RHE with partial current density 14.7 mA/cm2. XPS confirms presence Ni3+ and Ni2+ species, indicating existence uncoordinated Ni. Ni3+/Ni2+ ratio increases Cl concentrations are also confirmed STEM-EDX. DFT modeling provides insights thermodynamic stability CO2RR mechanism over Cl-containing surface. It suggested occupy defective sites created oxygen vacancies model (O-alpha+Cl). surface Pourbaix diagrams constructed from indicate preferred terminations favorable operating conditions CO2RR, which closely agrees experimental findings. O-alpha+Cl has been found promote formate. Our results create new possibilities in development earth-abundant electrocatalysts selective