Efficient degradation of formaldehyde based on DFT-screened metal-doped C3N6 monolayer photocatalysts: performance evaluation and mechanistic insights

Abstract

Photocatalytic oxidation is an efficient and promising technology for reducing indoor pollution levels of formaldehyde (HCHO). However, developing efficient and low-cost photocatalysts for the removal of HCHO remains challenging due to the time-consuming and expensive nature of traditional “trial and error” and “directed research” approaches. To achieve this goal, first-principles density functional theory (DFT) calculations were conducted to high-throughput screen candidate TM–C₃N₆ photocatalysts for high-performance degradation of HCHO. The results revealed that Zr–C₃N₆ and Hf–C₃N₆ in functionalizing C₃N₆ with 28 transition metals showed excellent adsorption energy of HCHO, boosting the highly effective capture of HCHO. Meanwhile, an excellent adsorption performance mechanism was further elicited by the electric structure–property relationship. In addition, reaction mechanisms for HCHO degradation and three potential reaction pathways for HCHO degradation were systematically evaluated. Our findings indicated that hydroxyl-assisted dehydrogenation and oxygen-assisted dehydrogenation are the most favorable pathways, with rate-limiting steps involving the formation of ˙OH and ˙O radicals. Overall, this study may provide new insights into a high-throughput screening of novel photocatalysts that are both high-performing and low-cost for the removal of formaldehyde. This, in turn, can accelerate the experimental development process and reduce the associated costs and time consumption.