Surface iodine and pyrenyl-graphdiyne co-modified Bi catalysts for highly efficient CO2 electroreduction in acidic electrolyte

CO2 electroreduction to formic acid/formate would contribute to alleviating the energy and climate crisis. This work reports a Bi-based catalyst derived from the in-situ electroreduction of Bi2O2CO3 modified with iodine and pyrenyl-graphdiyne (PGDY) on the surface for efficient electroreduction of CO2 in acidic electrolyte, with a high partial current density of 98.71 mA·cm−2 and high Faradaic efficiency (FE) > 90% over the potential range from −1.2 to −1.5 V vs. reversible hydrogen electrode (RHE), as well as the long-term operational stability over 240 h without degradation in H-type cell. Experimental results and density function theory calculations show that the synergistic effect of surface iodine and PGDY is responsible for this active and extremely stable process of CO2 electroreduction via lowering the energy barriers for formation of *OCHO intermediate, suppressing the competitive HER by enhancing the concentration of both K+ and CO2 at reaction interface, as well as preventing the dissolution and re-deposition of active Bi atoms on surface during catalytic reaction. This work provides new insight into designing highly active and stable electrocatalysts for CO2 reduction.