CO2和N2电还原中缺陷及界面工程的最新进展

实现碳氮循环是人类社会发展的迫切要求，也是催化领域的热门研究课题。在可再生能源的推动下，电催化技术引起了人们的广泛关注，且可以通过改变反应电压获得不同的目标产品。基于此，电催化技术被认为是缓解当前能源危机和环境问题的有效策略，对实现碳中和具有重要意义。其中，电催化CO₂还原反应(CO₂RR)和N₂还原反应(N₂RR)是一种有前途的小分子转化策略。然而，CO₂和N₂均为线性分子，其中C＝O和N≡N键的高解离能导致了它们高的化学惰性。此外，最高占据分子轨道(HOMO)和最低未占分子轨道(LUMO)之间的巨大能量间隙使它们具有高的化学稳定性；且CO₂和N₂的低质子亲和力使它们难以被直接质子化。另一方面，由于CO₂RR和N₂RR与析氢反应(HER)具有相近的氧化还原电位，造成其与HER之间存在竞争性关系，这也是致使催化剂在CO₂RR和N₂RR转化效率低的重要影响因素。因此，CO₂RR和N₂RR仍然面临着过电位高及法拉第效率低等问题。为了克服这些瓶颈，人们为提升CO₂RR和N₂RR电催化剂性能做出了很多努力。众所周知，电催化过程发生在催化剂表面，主要涉及质量传递和电子转移等过程。由此可见，催化剂的性能与其质量和电子传输能力密切相关，而调控催化剂表面结构可以优化活性点的质量和电子转移行为。电催化剂的缺陷和界面工程可通过表面原子工程来实现电子结构调控，对于提高气体吸附能力、抑制HER、富集气体及稳定中间产物等具有重要意义。到目前为止，所报道的各种缺陷和复合电催化剂在提高CO₂RR和N₂RR催化性能等方面均表现出巨大的潜力。在此，我们综述了CO₂RR和N₂RR中催化剂缺陷工程及界面工程的最新进展；首先讨论了四种不同的缺陷(空位、高指数晶面、晶格应变和晶格无序)对CO₂RR和N₂RR性能的影响；然后，总结了界面工程在聚合物-无机复合材料催化剂中的重要作用，并给出了典型实例；最后，展望了原子级电催化剂工程的发展前景，提出了开发和设计高效CO₂RR和N₂RR电催化剂的未来发展方向。

Recent Advances in Defect and Interface Engineering for Electroreduction of CO2 and N2

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.