Abstract:

The realization of carbon and nitrogen cycles is an urgent requirement for the development of human society, and is also a hot research topic in the field of catalysis. Electrocatalysis driven by renewable energy has attracted considerable attention, and the target products can be obtained by varying the applied potentials. Accordingly, electrocatalysis is considered to be an effective strategy to alleviate the current energy crisis and environmental problems and is of great significance in realizing carbon neutrality. Electrocatalytic CO₂ reduction reaction (CO₂RR) and N₂ reduction reaction (N₂RR) are also promising strategies for the conversion of small molecules. However, the high dissociation energies of the C＝O and N≡N bonds in the linear molecules of CO₂ and N₂, respectively, lead to their high chemical inactivity. In addition, the large energy gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) further results in high chemical stability. Besides, the low proton affinity of CO₂ and N₂ makes direct protonated difficult. However, because of the similar redox potentials of CO₂RR, N₂RR, and hydrogen evolution reaction (HER), HER competes with CO₂RR and N₂RR, affecting the CO₂RR and N₂RR performance. Therefore, both CO₂RR and N₂RR still face challenges, such as high overpotential and low Faradaic efficiency. To overcome these bottlenecks, considerable efforts have been made to improve the performance of the CO₂RR and N₂RR electrocatalysts. The electrocatalytic process primarily occurs on the catalyst surface and involves mass diffusion and electron transfer; thus, the performance of the catalysts is closely related to their mass and electron transfer abilities. Modulating the catalyst surface structure can regulate the mass and electron transfer behavior of the active sites during the electrocatalytic process. Defect and interface engineering of electrocatalysts is important for enhancing the adsorption of gas, inhibiting HER, enriching the gas, stabilizing the intermediates, and modifying the electronic structure by engineering the surface atoms. To date, various defective and composite electrocatalysts have shown great potential to enhance the CO₂RR and N₂RR performance. Herein, recent advances in defect and interface engineering for CO₂RR and N₂RR are reviewed. The effects of four different defects (vacancy, high-index facet, lattice stain, and lattice disorder) on the CO₂RR and N₂RR performance are discussed. Then, the main roles of interface engineering of polymer-inorganic composite catalysts are further reviewed, and representative examples are presented. Finally, the opportunities and challenges for defect and interface engineering in the electroreduction of CO₂ and N₂ are also proposed, suggesting directions for the future development of highly efficient CO₂RR and N₂RR catalysts.

Key words: Defect, Interface, Nanocomposites, CO₂ Reduction reaction, N₂ Reduction reaction