Engineering surface bromination in carbon nitride for efficient CO2 photoconversion to CH4

Pengcheng Yan; Fawei Ji; Wei Zhang; Zhao Mo; Junchao Qian; Linhua Zhu; Li Xu

doi:10.1016/j.jcis.2022.12.063

Engineering surface bromination in carbon nitride for efficient CO₂ photoconversion to CH₄

J Colloid Interface Sci. 2023 Mar 15:634:1005-1013. doi: 10.1016/j.jcis.2022.12.063. Epub 2022 Dec 16.

Authors

Pengcheng Yan¹, Fawei Ji¹, Wei Zhang², Zhao Mo¹, Junchao Qian³, Linhua Zhu⁴, Li Xu⁵

Affiliations

¹ Institute for Energy Research, School of Materials Science and Engineering, School of Energy and Power Engineering, Jiangsu University, 212013 Zhenjiang, PR China.
² Institute for Energy Research, School of Materials Science and Engineering, School of Energy and Power Engineering, Jiangsu University, 212013 Zhenjiang, PR China. Electronic address: wzhang@ujs.edu.cn.
³ Jiangsu Key Laboratory for Environment Functional Materials, Suzhou University of Science and Technology, 215009 Suzhou, PR China.
⁴ College of Chemistry and Chemical Engineering, Key Laboratory of Water Pollution Treatment and Resource Reuse of Hainan Province, Hainan Normal University, 571158 Haikou, PR China.
⁵ Institute for Energy Research, School of Materials Science and Engineering, School of Energy and Power Engineering, Jiangsu University, 212013 Zhenjiang, PR China. Electronic address: xulichem@ujs.edu.cn.

PMID: 36571854
DOI: 10.1016/j.jcis.2022.12.063

Abstract

The direct conversion of CO₂ into reusable CH₄ fuel by solar energy can effectively solve the problems of energy crisis and carbon emissions. However, the challenge of photocatalytic CO₂ reduction to produce CH₄ is still low conversion efficiency and poor selectivity. Here, surface brominated carbon nitride (named CNBr) is fabricated for stable and efficient photocatalytic CO₂ reduction to produce CH₄ with a rate of 16.68 μmol h^-1 g^-1 (70.27 % selectivity). Br atom in CNBr can substitute the N atom in the tri-s-triazine unites, which promotes local charge separation, narrows band gap and deepens the conduction band of CNBr. Benefiting from Br as active sites, CO₂ can be enriched on the catalyst surface, and localized photogenerated electrons can activate the adsorbed CO₂ to form CH₄ through subsequent hydrogenation. Density functional theory results suggest that Br doping can effectively reduce the energy barrier of the rate-limiting step, accelerate the reaction, and induce the formation of *CHO, thereby improving the selectivity of CH₄. This work reveals that surface modification can simultaneously increase the activation site of CO₂ adsorption activation, enhance light absorption and accelerate charge, laying a solid foundation for the future design of carbon nitride based photocatalyst with high performance.

Keywords: Bromine doping; CH(4); Carbon nitride; Charge separation; Photocatalytic CO(2) reduction.