Enhanced photocatalytic CO2 reduction of covalent triazine-based photocatalyst: Mechanistic insights from time-resolved spectroscopy

Abstract

Photocatalytic conversion of waste carbon dioxide (CO₂) into fine chemicals is crucial for solar energy utilization and mitigating the global climate crisis. Artificial photocatalysis based on the integrated biocatalyst offers a promising approach for converting CO₂ into high-value chemicals. The development of metal-free heterogeneous photocatalysts has gained significant attention as a sustainable platform for practical artificial photocatalytic systems. In this study, we report a one-pot synthesis of covalent triazine-based photocatalysts (CTPs) and their photocatalytic applications. The as-synthesized CTPs exhibit excellent photocatalytic performance, achieving the generation of HCOOH from CO₂ with a yield of 224.85 μM. The underlying photo-physical properties of CTPs were investigated by using systematic time-resolved laser spectroscopies. These measurements reveal that the formation of a long-lived charge transfer state in CTPs at the late time window is strongly correlated with the enhanced photocatalytic efficiency by delaying the ultrafast charge recombination. This study will serve as a benchmark example of heterogeneous photocatalysts and their wide applications for CO₂ fixation and solar chemical production.