Oxygen vacancy-rich Ni2P2O7 modified g-C3N4 heterojunction for highly-efficient CO2 photoreduction
Xin Li, Baoyan Sun, Hougang Fan, Xiaoyan Liu, Jian Cao, Huilian Liu, Lili Yang, Maobin Wei, Alberto Vomiero
Abstract
Oxygen vacancy-rich Ni 2 P 2 O 7 /g-C 3 N 4 heterojunction with high photogenerated carrier supply and excellent CO 2 adsorption ability was prepared for efficient CO 2 photoreduction. The yields of CO and CH 4 with Ni 2 P 2 O 7 /g-C 3 N 4 (3-NC) as the catalyst were about 53.85 and 14.28 μmol·g −1 ·h −1 , which were 5 and 16 times greater than that of g-C 3 N 4 under the UV–Vis irradiation. Experiments and DFT calculations revealed the modification of g-C 3 N 4 with Ni 2 P 2 O 7 can significantly accelerate the photogenerated electrons’ transfer from g-C 3 N 4 to Ni 2 P 2 O 7 through the built-in electric field. CO 2 -adsorption test and CO 2 -adsorption energy displayed Ni 2 P 2 O 7 can effectively act as the CO 2 capture unit to increase the reaction probability of electrons and CO 2 , thereby enhancing the CO 2 photoreduction performance. 13 CO 2 isotope experiment, in-situ FTIR, in-situ XPS and Gibbs free-energy calculations were applied to explore the CO 2 photoreduction process. Finally, a potential CO 2 photoreduction mechanism with synergistic enhancement of oxygen vacancy and the built-in electric field was proposed.