Heteroatom Transition Metal Based Catalysts for High Efficiency Electrochemical CO2 Reduction Reaction to Hydrocarbons

The electrochemical conversion of CO₂ to value-added products driven by renewable energy is an attractive approach to fulfill the global energy demand and closing the anthropogenic carbon cycle. The main challenge of this technology is the development of a highly active catalyst that is selective toward high-energy density fuels such as methane (CH₄), methanol (CH₃OH) and ethylene (C₂H₄). Among various catalysts developed for this reaction, only copper (Cu) based catalysts have shown to be promising candidates for hydrocarbon fuel formation. However, none of them appear to be efficient for practical use due to the high required overpotential and low activity.

Here, we are presenting an earth-abundant nanostructured heteroatom transition metal-based class of materials (HATM) as highly active catalysts with remarkable selectivity for hydrocarbon fuels. The electrocatalytic performance of these catalysts was studied in three-electrode cell using 1 M KHCO₃ electrolyte saturated with CO₂ and compared to gold (Au) and Cu nanoparticles (NPs). The results show a CO₂RR current density of 130.6 mA/cm², faradaic efficiency (FE) of about 90±5% at the potential of 0.85 V vs RHE. A CO₂RR overpotential of as low as 12.7 mV was also recorded for these catalysts. Furthermore, the product analyses results indicate that these catalysts are selective for CO, CH₄, C₂H₄, CH₃OH and C₂H₅OH with FEs of 43.76, 37.75, 2.06, 3.89 and 1.63%, respectively. Moreover, at the potential of 0.85 V, a CO₂RR turnover frequency (TOF_CO2RR) of 3.66 s^-1 was obtained for HATM where the TOF_CO2RR of Au and Cu NPs were calculated to be 1.25 and 0.037 s^-1, respectively. The density functional theory (DFT) calculations also revealed that a lower work function of HATM compare to Au NPs and spontaneous chemisorption of water and CO₂ compared with Cu make this catalyst an effective candidate for electrochemical CO₂RR.