Co–N–C anchored g-C₃N₄ plate enhancing surface activity for efficient visible-light photocatalytic rhodamine-B elimination and CO₂ conversion

Poor light-harvesting, fast recombination of photo-induced charge carriers, and unfavorable surface adsorption remain the major issues restricting the photocatalytic activity of g-C₃N₄. In this study, the Co-N-C decorated g-C₃N₄ (Co-N-C/g-CN) plate was developed by constructing Co-N-C on the surface of g-CN plate to improve photocatalytic rhodamine-B (RhB) degradation and CO₂ conversion. The as-prepared 0.5Co-N-C/g-CN plate exhibited an exceptionally high efficiency in photocatalytic RhB degradation, with a rate of 99.5 % achieved in mere 30 min. Besides, the 0.5Co-N-C/g-CN plate also demonstrated an outstanding photocatalytic CO₂ conversion rate of 33.7 μmol g⁻¹_cat h⁻¹ within 4 h, which was more than 3.4-fold that of g-CN (9.9 μmol g⁻¹_cat h⁻¹). Experiments demonstrated that the surface-constructed Co-N-C enhanced the visible light-harvesting and the separation of photo-induced charge carriers, boosting the optical property. Moreover, the density functionalized theory (DFT) calculations verified that the Co-N-C cocatalyst optimized O₂ adsorption for the generation of superoxide radicals (·O^-₂), accelerating the photocatalytic RhB removal. Meanwhile, the Co-N-C was advantageous for the adsorption and activation of CO₂, facilitating the photocatalytic CO₂ conversion. This study provides a perspective on the surface engineering of g-CN toward enhanced photocatalytic performance.