Defect Engineering Simultaneously Regulating Exciton Dissociation in Carbon Nitride and Local Electron Density in Pt Single Atoms Toward Highly Efficient Photocatalytic Hydrogen Production

• Published in: Small (Weinheim an der Bergstrasse, Germany) Germany), 2024-08, Vol.20 (34), p.e2310289-n/a
• Main Authors: Liu, Dongjie, Zhang, Chunyang, Shi, Jinwen, Shi, Yuchuan, Nga, Ta Thi Thuy, Liu, Maochang, Shen, Shaohua, Dong, Chun‐Li
• Format: Article
• Language: English
• Subjects: Acceleration; Carbon; Carbon nitride; Electron density; electron trap; Electron traps; Energy of dissociation; exciton dissociation; Excitons; Free electrons; high electron density; Hybrid systems; Hydrogen; Hydrogen production; moderate binding strength; Nitrogen; Nitrogen defects; Photocatalysis; Reaction kinetics; Self-assembly; Surface reactions
• ISSN: 1613-6810; 1613-6829; 1613-6829
• DOI: 10.1002/smll.202310289

The high exciton binding energy (Eb) and sluggish surface reaction kinetics have severely limited the photocatalytic hydrogen production activity of carbon nitride (CN). Herein, a hybrid system consisting of nitrogen defects and Pt single atoms is constructed through a facile self‐assembly and photodeposition strategy. Due to the acceleration of exciton dissociation and regulation of local electron density of Pt single atoms along with the introduction of nitrogen defects, the optimized Pt‐MCT‐3 exhibits a hydrogen production rate of 172.0 µmol h−1 (λ ≥ 420 nm), ≈41 times higher than pristine CN. The apparent quantum yield for the hydrogen production is determined to be 27.1% at 420 nm. The experimental characterizations and theoretical calculations demonstrate that the nitrogen defects act as the electron traps for the exciton dissociation, resulting in a decrease of Eb from 86.92 to 43.20 meV. Simultaneously, the stronger interaction between neighboring nitrogen defects and Pt single atoms directionally drives free electrons to aggregate around Pt single atoms, and tailors the d‐band electrons of Pt, forming a moderate binding strength between Pt atoms and H* intermediates. The nitrogen defects act as electron trapping sites, enhancing exciton dissociation into charge carriers. As a result, abound free electrons accumulate around Pt single atoms. The formation of high electron density of Pt sites significantly improves the photocatalytic hydrogen production activity.