Mimicking Frustrated Lewis Pairs on Graphitic Carbon Nitride for CO2 Photoreduction

Photocatalytic carbon dioxide (CO2) reduction is an emerging approach to synthesizing carbon monoxide (CO) but still suffers from poor selectivity and low catalytic efficiency because of the high energy barrier toward the *COOH formation. Herein, we report the selective and high-efficiency photosynthesis of CO with a boron (B)- and sulfur (S)-codoped graphitic carbon nitride (g-C3N4) catalyst (B,S-CN), which shifts the rate-determining-step (RDS) from CO2 protonation to CO2 adsorption. This is realized by the local mimicking frustrated Lewis pairs (M-FLPs) constructed with abundant electron-deficient S and electron-rich N adjacent to B. The push-pull effect provided by the as-designed metal-free M-FLP configuration allows the spontaneous formation of *COOH and *CO intermediates through balancing the *COOH adsorption energy, as evidenced by theoretical calculations and in situ characterizations. In addition to the free-energy changes, B and S codoping can also promote the separation and transfer of charges and improve the utilization rate of light. Strikingly, the B,S-CN catalyst exhibits a high CO selectivity of 100% with an average yield of 313.20 mu mol g(-1) h(-1) (70.7 times that of bulk g-C3N4). This study provides a strategy for the development of highly selective photocatalysts and paves the way for rational intermediate regulation by mimicking the FLP configuration.

Automated summary

In this study, a boron- and sulfur-doped graphitic carbon nitride catalyst was used to selectively and efficiently synthesize CO from CO2 through a photochemical process. The catalyst showed high selectivity and significantly improved catalytic efficiency compared to bulk graphitic carbon nitride due to the unique mimicking frustrated Lewis pairs configuration.