Structural optimization of carbon-based diatomic catalysts towards advanced electrocatalysis

As an extension of single-atom catalysts (SACs), diatomic catalysts (DACs) perfectly inherit the advantages of SACs but break some theoretical limitations of SACs due to the interaction between dual-atom sites. However, there are still challenges for the electrocatalytic applications of carbon-based DACs, such as difficult in controllable synthesis and identification of bimetallic dimer, hard to adjust the coordination environments of bimetallic sites, poor structural stability, and unclear reaction mechanisms. Here, we summarize controllable synthesis methods for the fabrication of DACs and introduce the characterization techniques in comprehending the geometrical configuration of bimetallic dimer, local electronic structure, coordination environments, and insights into reaction mechanisms by combining in situ characterization and theoretical investigation. Moreover, several important electrocatalytic applications of DACs, including for the hydrogen evolution reaction, oxygen evolution reaction, oxygen reduction reaction, CO2 reduction reaction, and nitrogen reduction reaction are reviewed. To precipitate the future development of high-performance carbon-based DACs, we put forward several strategies to adjust the electronic structure for optimizing the electrocatalytic performances, including adjusting the electronic structure of bimetallic central atoms, regulating the local coordination environment of bimetallic central atoms, and tuning the base environment. Finally, future research directions of developing advanced carbon-based DACs for electrocatalytic application are proposed.