Structural design of thiadiazole-based donor-acceptor COF/Fe-doped N vacancy g-C3Nx nanosheets for photocatalytic nitrogen fixation under visible light

Hui Wang; Yuhan Xiong; Liang Wang; Yi He; Meihui Chen; Jie Ding; Nanqi Ren

doi:10.1016/j.jcis.2024.02.034

Structural design of thiadiazole-based donor-acceptor COF/Fe-doped N vacancy g-C₃N_x nanosheets for photocatalytic nitrogen fixation under visible light

J Colloid Interface Sci. 2024 May 15:662:357-366. doi: 10.1016/j.jcis.2024.02.034. Epub 2024 Feb 9.

Authors

Hui Wang¹, Yuhan Xiong², Liang Wang³, Yi He², Meihui Chen², Jie Ding⁴, Nanqi Ren²

Affiliations

¹ State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, China. Electronic address: huiwang432@hit.edu.cn.
² State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, China.
³ General Water of China Co., Ltd, Beijing 100022, China.
⁴ State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, China. Electronic address: dingjie123@hit.edu.cn.

PMID: 38354562
DOI: 10.1016/j.jcis.2024.02.034

Abstract

The rational design of efficient photocatalysts to achieve artificial nitrogen fixation is an urgent challenge. Herein, we combined donor-acceptor covalent organic framework with iron-doped nitrogen vacancy graphitized carbon nitride (D-A COF/Fe-g-C₃N_x) for photocatalytic nitrogen fixation. The photocatalyst exhibited good crystallinity, high porosity, and a large specific surface area. Without a sacrificial agent, the optimal 40 % D-A COF/Fe-g-C₃N_x exhibited an excellent rate of ammonia production (646 μmol h^-1 g^-1) at 420 nm, and durable stability after successive cycling. Exhaustive experimental research and theory calculations verified that the D-A unit and Fe doping redistributed the distribution of the charge, which enhanced the visible light utilization and provided chemisorption sites for further polarization. Besides N-vacancies can serve as electron-trapping active sites to promote the directional migration of carriers. The reaction mechanism demonstrated that superoxide radical and hydrogen peroxide were formed by electron and hole, respectively, which promote the reduction of nitrogen to ammonia. This work provides a new idea for the rationalizing design of efficient catalysts for photocatalytic nitrogen fixation under mild conditions.

Keywords: Covalent organic framework; Donor–acceptor; Fe-g-C(3)N(x); Nitrogen fixation; Photocatalysis.