Interspersed Bi Promoting Hot Electron Transfer of Covalent Organic Frameworks Boosts Nitrogen Reduction to ammonia
Mingfei Yu, Yueling Chen, Ming Gao, Guocheng Huang, Qiaoshan Chen, Jinhong Bi
Abstract
Abstract Seeking highly‐efficient, non‐pollutant, and chemically robust photocatalysts for visible‐light‐driven ammonia production still remained challenging, especially in pure water. The key bottle‐necks closely correlate to the nitrogen activation, water oxidization, and hydrogen evolution reaction (HER) processes. In this study, a novel Bi decorated imine‐linked COF‐TaTp (Bi/COF‐TaTp) through N–Bi–O coordination is reasonably designed to achieve a boosting solar‐to‐ammonia conversion of 61 µmol −1 g −1 h −1 in the sacrificial‐free system. On basis of serial characterizations and DFT calculations, the incorporated Bi is conducive to the acceleration of charge carriers transfer and N 2 activation through the donation and back‐donation mode. The N 2 adsorption energy of 5% Bi/COF‐TaTp is calculated to be −0.19 eV in comparison with −0.09 eV of the pure COF‐TaTp and the electron exchange between N 2 and the modified catalyst is much more intensive. Moreover, the accompanied hydrogen production process is effectively inhibited by Bi modification, demonstrated by the higher energy barrier for HER over Bi/COF‐TaTp (2.62 eV) than the pure COF‐TaTp (2.31 eV) when using H binding free energy (Δ G H* ) as a descriptor. This work supplies novel insights for the design of photocatalysts for N 2 reduction and intensifies the understanding of N 2 adsorption and activation over covalent organic frameworks‐based materials.