In September 2025, the Acta Physico-Chimica Sinica published online the latest research results of Associate Professor Xu Quanlong's team from Wenzhou University in the field of photocatalytic hydrogen evolution.
This work reports an in-situ growth strategy that combines gold nanobipyramidal structures with strong local electric fields (TpBD-COF) to significantly improve the photocatalytic hydrogen evolution performance of the material. The first authors are Yujin Deng and Yishuang Chen, and the co-corresponding author is Quanlong Xu.
With the increasingly severe energy crisis and environmental pollution problems, the development of clean and renewable energy has become a global focus. Hydrogen energy, due to its high energy density and green, pollution-free characteristics, is considered one of the ideal energy carriers. Photocatalytic hydrogen evolution is an important pathway to convert solar energy into chemical energy, and COF materials, due to their tunable electronic structure and high specific surface area, have become a research hotspot. However, COF materials generally suffer from problems such as difficult exciton separation and rapid carrier recombination, which limit their photocatalytic efficiency. This paper describes an in-situ growth strategy that combines Au NBs with strong local electric fields (TpBD-COF) to significantly improve their photocatalytic hydrogen evolution performance.
Electromagnetic field simulations and femtosecond transient absorption spectroscopy confirm that the local electric field promotes exciton separation through a plasma resonance energy transfer mechanism, providing more hot carriers for the hydrogen evolution reaction.
Equipment used in the article
Graph Analysis
1. Plasma-Enhanced Photocatalysis Mechanism
Plasma-enhanced metal nanostructures can significantly enhance light absorption and charge separation efficiency through localized surface plasmon resonance effects. In this study, Au NBs with sharp tips were prepared by seed synthesis, and their amino groups were modified to enhance the interfacial bonding between Au NBs and TpBD-COF. Experiments showed that the apparent quantum efficiency of the AuNBs/TpBD-COF composite material reached 0.58% under 420 nm illumination, and the hydrogen evolution rate was increased to 3.5 times that of pure TpBD-COF.
Figure 1. Schematic diagram of the photocatalytic mechanism of 2% AuNBs/TpBD-COF photocatalyst under visible light.
2. Interfacial Charge Separation and Energy Transfer Mechanism
Femtosecond transient absorption spectroscopy and FDTD simulation results show that Au NBs transfer energy to TpBD-COF within 100 fs through a plasmonic resonance energy transfer mechanism, inducing the formation of a charge-separated state, which facilitates exciton dissociation. Furthermore, photocurrent and electrochemical impedance spectroscopy further confirm that the carrier separation efficiency of the composite material is significantly improved, and the interfacial transport resistance is reduced.
Figure 2 shows the characteristics of TpBD-COF (a, b) and 2% AuNBs/TpBD-COF (c, d). (e) Schematic diagram of the exciton formation mechanism of 2% AuNBs/TpBD-COF.
3. Photocatalytic Performance and Stability
Under visible light irradiation, the hydrogen evolution rate of 2% AuNBs/TpBD-COF reached 6.27 mmol·g⁻¹·h⁻¹, and remained stable after multiple cycles, with no significant structural changes, demonstrating excellent catalytic stability.
Figure 3 (a) Hydrogen yield over 4 hours and (b) Average hydrogen generation rate of the TpBD-COF and AuNBs/TpBD-COF composite material. (c) Schematic diagram of the cyclic test of 2% AuNBs/TpBD-COF.
This study successfully constructed an AuNBs/TpBD-COF composite material with a strong local electric field, and systematically elucidated the physical essence of its enhanced photocatalytic hydrogen evolution performance through the PMRET mechanism. This work provides new ideas for the precise design of plasma/semiconductor composite photocatalysts, and also provides experimental and theoretical basis for understanding the mechanism by which a local electric field promotes charge separation.
Author Introduction
Corresponding Author:
Xu Quanlong, Associate Professor, Wenzhou University. His main research interests are photocatalysis, selective oxidation of organic molecules, and new energy technologies.
First Author:
Deng Yujin, Chen Yishuang, Master's Students, Wenzhou University. Their main research interests are enhancing the photocatalytic hydrogen evolution performance of covalent organic framework-based composite materials.
Deng, Y.; Chen, Y.; Zhang, L.; Jin, H.; Yang, Y.; Xu, Q.; Wang, S. Plasmonic Au Nanobipyramid Assembly Covalent Organic Framework for Boosting Photocatalytic Hydrogen Evolution through Strong Local Electric Field. Acta Phys. Chim. Sin. 2025, 100193.
https://doi.org/10.1016/j.actphy.2025.100193
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