Sulfoxide‐Functionalized Mesoporous C <sub>3</sub> N <sub>5</sub> as a Metal‐Free and Visible‐Light‐Driven Efficient Photocatalyst for CO <sub>2</sub> Reduction
Aathira M. Sadanandan, Mohammed Fawaz, Ayona K. Jose, Nithinraj Panangattu Dharmarajan, Matej Huš, CI Sathish, Xuan Minh Chau Ta, Vibin Perumalsamy, Ana Oberlintner, Issatay Nadinov, Lijie Wang, Gurwinder Singh, Antonio Tricoli, Omar F. Mohammed, Blaž Likozar, Chung‐Hwan Jeon, Prashant Kumar, Jae‐Hun Yang, Ajayan Vinu
Abstract
Abstract Photocatalytic CO 2 reduction reaction provides a promising green strategy to mitigate atmospheric CO 2 levels and simultaneously achieve valuable chemicals. C 3 N 5 has emerged as an excellent metal‐free photocatalyst for CO 2 RR due to its narrow bandgap with a lower conduction band edge, which provides high reduction potential to reduce thermodynamically stable CO 2 molecules. Surface functionalization and enhanced porosity can yield superior catalytic performance in C 3 N 5 . The recent efforts to synthesize sulfoxide‐functionalized mesoporous C 3 N 5 is reported, which enhances CO 2 RR up to 4.4 times (94.8 ± 11.2 µmol·g −1 in 8 h) that of intact C 3 N 5 . According to Ultraviolet Photoelectron Spectroscopy analysis, while the functionalization of the C 3 N 5 surface with sulfoxide groups leaves the valence band position unchanged, it significantly shifts the conduction band position toward a more negative potential, thereby enhancing material reduction capabilities. Additionally, steady‐state photoluminescence and transient absorption and time‐resolved photoluminescence spectra indicate a significant reduction in exciton recombination. Insights from theoretical calculations reveal that SO‐functionalization enhances CO 2 adsorption and CO desorption, thereby facilitating enhanced photocatalytic CO 2 reduction.