Nonmetal Atom Doping Induced Orbital Shifts and Charge Modulation at the Edge of Two-Dimensional Boron Carbonitride Leading to Enhanced Photocatalytic Nitrogen Reduction

Electronic structure, particularly charge state analysis, plays a crucial role in comprehending catalytic mechanisms. This study focuses on metal-free boron carbonitride (BCN) nanosheets as a case study to investigate the impact of heteroatom doping on the charge state of active sites at the edge of two-dimensional (2D) metal-free nanomaterials. Our observations revealed that the doping induces a shift in the frontier py orbital near the Fermi level, accompanied by alterations in its charge state. These changes provide insights into the nitrogen adsorption descriptors and the critical hydrogenation step, ultimately leading to the proposal of a competitive charge transfer mechanism. Additionally, this exploration has led to the screening of five BCN-type structures (P@T1-C1, S@T1-B1, O@T1-B1, P@T1-B1C2, and P@T1-B1C3) with promising nitrogen reduction reaction (NRR) performances. The BCN structure (S@T1-B1) exhibited the lowest NRR overpotential reaching −0.2 V, which is associated with the proposed charge competition mechanism. Furthermore, the investigation delves into the key step hydrogenation mechanism, descriptors, and volcano diagrams of the conformational relationships. In addition, the proposed doping strategy endows the 2D-BCN with more sensitivity toward the solar spectrum, suggesting its application as a potential photocatalyst. Overall, this study establishes a strong foundation for the advancement of nonmetal-atom-doped BCN nanosheets in nitrogen reduction applications, while also providing a versatile framework for fine-tuning edge-site activity within the broader context of two-dimensional photo/electrocatalytic materials.