The efficient CO2 fixation catalyzed by K-doped g-C3N4 catalyst for synthesizing benzimidazoles at atmospheric pressure

The conversion of CO₂ into valuable chemicals to reduce greenhouse gas emissions has received extensive attention. Converting CO₂ into pharmaceutical intermediates via graphitic carbon nitride (CN) at atmospheric pressure is a challenge. In this work, a series of novel graphitic carbon nitrides (K-CN) catalysts with different doping ratios of K were synthesized by post-treatment of CN with KOH as a dopant under magnetic stirring. Herein, substrates of o-phenylenediamine with different electron-donating/withdrawing groups were employed to convert CO₂ into high-value heterocyclic benzimidazoles. The optimal reaction conditions were determined by a single factor optimization approach. A series of benzimidazole derivatives were synthesized with a yield of up to 96% under atmospheric pressure, indicating that the catalyst can efficiently fix CO₂. This work not only designs a simple and low-cost K-CN catalyst but also provides a new pathway for converting CO₂ into valuable benzimidazole derivatives at atmospheric pressure. © 2023 Society of Chemical Industry and John Wiley & Sons, Ltd.