Heteroatom‐ and Bonded Z‐Scheme Channels‐Modulated Ultrafast Carrier Dynamics and Exciton Dissociation in Covalent Triazine Frameworks for Efficient Photocatalytic Hydrogen Evolution
Rongchen Shen, Neng Li, Chaochao Qin, Xiuzhi Li, Xiuzhi Li, Peng Zhang, Xin Li, Xin Li, Junwang Tang
Abstract
Abstract Covalent triazine frameworks (CTF) offer a tunable platform for photocatalytic H 2 generation due to their diverse structures, low costs, and precisely tunable electronic structures. However, high exciton binding energy and short lifetimes of photogenerated carriers restrict their application in photocatalytic hydrogen evolution. Herein, a novel phosphorus‐incorporated CTF is introduced to construct a chemically bonded PCTF/WO 3 (PCTFW) heterostructure with a precise interface electron transfer channel. The phosphorus incorporation is found to dominantly reduce the exciton binding energy and promote the dissociation of singlet and triplet excitons into free charge carriers due to the regulation of electronic structures. High‐quality interfacial WN bonds improve the interfacial transfer of photogenerated electrons, thus prolonging the lifetime of photogenerated electrons. Femtosecond transient absorption spectroscopy characterizations and DFT calculations further confirm both phosphorus incorporation and Z‐scheme heterojunctions can synergistically boost the in‐built electric field and accelerate the migration and separation of photogenerated electrons. The optimized photocatalytic H 2 ‐evolution rate of resultant PCTFW is 134.84 µmol h −1 (67.42 mmol h −1 g −1 ), with an apparent quantum efficiency of 37.63% at 420 nm, surpassing many reported CTF‐based photocatalysts so far. This work highlights the significance of atom‐level interfacial exciton dissociation, and charge transfer and separation in improving photocatalysis.