Efficient photocatalytic H2 evolution and α-methylation of ketones from copper complex modified polymeric carbon nitride

Establishing effective non-platinum active sites on polymeric carbon nitride (PCN) remains a great demanding to achieve highly efficient photocatalytic hydrogen generation performance. Modification with molecular complex catalysts on PCN skeletons has been demonstrated as a promising strategy. Herein, hybrid photocatalytic material was successfully synthesized by modifying PCN with copper molecular ligand (CuL, Schiff-based copper complex) via pi-pi stacking. Interestingly, atomically dispersed Cu is formed in CuL/PCN. Compared to PCN, the pi-pi stacking in CuL/PCN is beneficial for facilitating the migration of photogenerated electrons from PCN to CuL. Furthermore, photo-redox ability of the atomically dispersed Cu is regulated by the ligand (Schiff base) in CuL and the introduction of CuL provides abundant active sites to capture the photogenerated electrons, whereby the reductive reaction of H2O/H+ to H-2 for CuL/PCN was significantly promoted. Consequently, an optimal hydrogen evolution rate of 15.90 mu mol.h(-1) was obtained on 3CuL/PCN, which was 2.02 times higher than that of 3.0 wt% Pt/PCN (7.86 mu mol.h(-1)). More importantly, the hybrid material exhibits an outstanding conversion efficiency (90 %) and selectivity (99 %) for alpha-methylation of ketones by making full use of the in-situ generated H species and photogenerated holes under visible light irradiation.

Automated summary

In this study, a hybrid photocatalytic material was synthesized by modifying PCN with a copper molecular ligand via pi-pi stacking, which led to an optimal hydrogen evolution rate. Atomically dispersed Cu in the material exhibited regulated photo-redox ability by the ligand, significantly promoting the reductive reaction for hydrogen generation. Additionally, the hybrid material showed outstanding conversion efficiency and selectivity for alpha-methylation of ketones under visible light irradiation.