Synergistic Effects of B-F/B-S and Nitrogen Vacancy Co-Doping on g-C3N4 and Photocatalytic CO2 Reduction Mechanisms: A DFT Study

Abstract

Nonmetallic co-doping and surface hole construction are simple and efficient strategies for improving the photocatalytic activity and regulating the electronic structure of g-C3N4. Here, the g-C3N4 catalysts with B-F or B-S co-doping combined with nitrogen vacancies (Nv) are designed. Compared to the pristine g-C3N4, the direction of the excited electron orbit for the B-F-co-doped system is more matching (N2pz→C2pz), facilitating the separation of electrons and holes. Simultaneously, the introduced nitrogen vacancy can further reduce the bandgap by generating impurity states, thus improving the utilization rate of visible light. The doped S atoms can also narrow the bandgap of the B-S-Nv-co-doped g-C3N4, which originates from the p-orbital hybridization between C, N, and S atoms, and the impurity states are generated by the introduction of N vacancies. The doping of B-F-Nv and B-S-Nv exhibits a better CO2 reduction activity with a reduced barrier for the rate-determining step of around 0.2 eV compared to g-C3N4. By changing F to S, the origin of the rate-determining step varies from *CO2→*COOH to *HCHO→*OCH3, which eventually leads to different products of CH3OH and CH4, respectively.

Decade Milestone Advancement of Defect-Engineered g-C3N4 for Solar Catalytic Applications

“…In another typical work, multiple defects-modified g-C 3 N 4 catalysts with B-F or B-S co-doping combined with N vacancies (donated as B-F-N v , B-S-N v ) have also shown great potential for the optimization of electronic band structure and enhancement of photocatalytic CRR performance [187]. As shown in Fig.…”

Graphitic carbon nitride with the pyridinic N substituted by Al and Si as efficient photocatalysts for CO2 reduction

“…46 First-principles calculations have computed free energy changes along this reaction path on the pristine, and the S-, Band F-doped g-C 3 N 4 . [46][47][48] Reaction barriers are important parameters to judge the reaction rates. However, there is no theoretical study yet on the reaction barriers in the CO 2 RR on both the pristine and the nonmetal-doped g-C 3 N 4 .…”