实际光催化反应中的半导体-助催化剂界面电子转移

doi:10.1016/S1872-2067(24)60178-6

催化学报 ›› 2025, Vol. 68: 213-222.DOI: 10.1016/S1872-2067(24)60178-6

实际光催化反应中的半导体-助催化剂界面电子转移

陈加藏^a^,^b^,^*()

^a杭州师范大学工学院, 浙江杭州 310018
^b中国科学院山西煤炭化学研究所, 煤炭高效低碳利用全国重点实验室, 山西太原 030001

收稿日期:2024-06-27 接受日期:2024-08-16 出版日期:2025-01-18 发布日期:2025-01-02
通讯作者: * 电子信箱: chenjiazang@hznu.edu.cn (陈加藏).
基金资助:
国家自然科学基金(22172185);杭州师范大学科研启动费

Semiconductor-cocatalyst interfacial electron transfer in actual photocatalytic reaction

Jiazang Chen^a^,^b^,^*()

^aSchool of Engineering, Hangzhou Normal University, Hangzhou 310018, Zhejiang, China
^bState Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001, Shanxi, China

Received:2024-06-27 Accepted:2024-08-16 Online:2025-01-18 Published:2025-01-02
Contact: * E-mail: chenjiazang@hznu.edu.cn (J. Chen).
About author:Jiazang Chen (School of Engineering, Hangzhou Normal University) obtained his PhD from Institute of Coal Chemistry, Chinese Academy of Sciences (CAS) in 2011. He was a research assistant in Prof. Jing Sun’s group in Shanghai Institute of Ceramics, CAS and a research fellow in Prof. Bin Liu’s group at Nanyang Technological University. Prior to joining Hangzhou Normal University, he was a full professor and a group leader in Institute of Coal Chemistry, CAS (2016-2023). His research focuses on interfacial charge transfer (fundamental understanding, numerical modeling, and method development), and the pilot development of photocatalytic reaction (wastewater treatment, waste acid recycling, and hydrogen purification).
Supported by:
National Natural Science Foundation of China(22172185);Start-Up Grant of Hangzhou Normal University

摘要/Abstract

摘要：

光催化反应不仅包含化学反应步骤, 还涉及到若干光致电子过程. 若将光催化剂视为一个整体, 被半导体吸收的光子不仅能通过引发光致电子过程来降低反应活化能、提高催化活性, 同时也是产生光生电荷的“反应参与物”. 决定半导体光生电荷密度的入射光通量对电子过程动力学参数具有深远的影响. 因此, 即使在排除了反应物传质影响的高浓度体系, 光催化反应的光子利用率仍然表现为显著依赖于入射光强的应变量. 目前普遍采用的激光脉冲光谱技术, 其光通量比实际光催化反应的入射光大4-10个数量级, 所获取信息显示目标反应的光致电子过程是发生在皮秒-微秒时间尺度的快速步骤. 这些事实激励着研究者们不断探索新的实验技术和方法, 以期摆脱对产生可分辨光信号之超高光通量脉冲激光的依赖，从而能够更精确地观测并认知光致电子过程, 为光催化研究的进一步发展开辟新途径.
半导体与助催化剂接触后因发生能带弯曲而形成的高势垒可使相关界面电子转移成为光催化反应的速控步骤. 随着入射光增强, 光生电子浓度提高可降低半导体-助催化剂界面电子转移势垒. 在此过程中, 主导界面电子转移的方式由弱光下的势阱态辅助电荷复合演变为强光下的热电子发射. 相应地, 光致界面电子转移速率对入射光强的幂指数由0.5增加到2, 并随着光强的进一步增大, 二者间又呈线性关系. 通过选取合理的参数进行模拟发现, 半导体-助催化剂界面电子转移速率随入射光强的变化与光催化反应速率对入射光通量的依赖性一致. 界面电子转移速率与光催化反应速率之间的差值则是由助催化剂上的电子利用率决定, 因而二者在光强变化中保持相对固定的比例. 理论模拟和实验结果一致, 不仅明确了半导体-助催化剂界面电子转移是光催化反应的速控步骤, 而且还可以通过调变表面态密度等参数来阐释光子利用率随入射光增强而降低等现象. 为了获取实际光催化反应中相应的动力学信息, 我们提出了多通道电子转移模型, 并采用(光)电化学方法获取半导体-助催化剂界面电子转移的时间常数. 该方法可以采用与实际光催化反应相同或相近的入射光强或偏置电势进行测试, 并通过操控半导体-溶液电荷泄露、目标还原反应以及副反应的半导体-助催化剂-溶液界面电子转移三个通道, 映射出实际工况下的电子过程动力学信息. 结果表明, 在实际光催化反应中, 半导体-助催化剂界面电子转移发生在亚秒-秒级别的时间尺度. 基于这些认知, 我们提出了以下策略: 在半导体浅层表面构筑惰性媒介点以促进势阱态辅助的电荷复合、引入桥接金属以降低热电子发射的势垒、纳米构筑引发限域效应来降低势垒宽度以促进电子隧穿等, 由此降低半导体-助催化剂界面电子转移的活化能.
综上, 光催化反应的高效性深受界面电子转移过程的影响. 有幸的是, 这一复杂依赖关系可借助于光致界面电子转移模型进行预测. 本文综合理论与实验结果, 提出了能够映射实际光催化反应半导体-助催化剂界面电子转移时间常数的测试方法以及促进该界面电子转移过程的策略, 以期提升光催化效率, 为未来更精准地调控光催化过程、推动光催化技术的广泛应用提供参考.

关键词: 半导体-助催化剂界面电子转移, 势阱态辅助的电荷复合, 热电子发射, 光催化光子利用率, 实际光催化反应

Abstract:

Semiconductor-cocatalyst interfacial electron transfer has widely been considered as a fast step occurring on picosecond-microsecond timescale in photocatalytic reaction. However, the formed potential barriers severely slow this interfacial electronic process by thermionic emission. Although trap-assisted charge recombination can transfer electrons from semiconductor to cocatalyst and can even be evident under weak illumination, the parallel connection with thermionic emission makes the photocatalytic photon utilization encounter a minimum along the variation of light intensity. By this cognition, the light-intensity-dependent photocatalytic behaviors can be predicted by simulating the photoinduced semiconductor-cocatalyst interfacial electron transfer that mainly determines the reaction rate. We then propose a (photo)electrochemical method to evaluate the time constants for occurring this interfacial electronic process in actual photocatalytic reaction without relying on extremely high photon flux that is required to generate discernible optical signal in common instrumental methods based on ultrafast pulse laser. The evaluated decisecond-second timescale can accurately guide us to develop certain strategies to facilitate this rate-determining step to improve photon utilization.

Key words: Semiconductor-cocatalyst interfacial, electron transfer, Trap-assisted charge recombination, Thermionic emission, Photocatalytic photon utilization, Actual photocatalytic reaction

陈加藏. 实际光催化反应中的半导体-助催化剂界面电子转移[J]. 催化学报, 2025, 68: 213-222.

Jiazang Chen. Semiconductor-cocatalyst interfacial electron transfer in actual photocatalytic reaction[J]. Chinese Journal of Catalysis, 2025, 68: 213-222.

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图/表 8

Fig. 1. Schematic diagram for the general electronic processes occurring in photocatalytic reaction. The electronic processes occurring for forward reaction are shown by green arrows; while the red arrows show the electronic processes related to the back reaction.

Fig. 2. Light-intensity-dependent SC band alignment and interfacial electron transfer (a-c) and the related photocatalytic behaviors (d,e). The photocatalytic hydrogen evolution (HE, squares) rates (d) generally match the simulated SC interfacial electron transfer (Jiet, solid lines) after correction (dash lines) with electron utilization (η = 0.294). Under weak illumination (a), the potential barrier (qVB) is high and the interfacial transfer of electrons to cocatalyst (cat) is dominated by trap-assisted charge recombination (CR). By intensifying irradiation (b), thermionic emission (TE) emerges to dominate SC interfacial electron transfer, making the photocatalytic reaction rate grows quadratically with the light intensity (d). Under very intense irradiation (c), qVB can be very low and photocatalytic photon utilization can be nearly constant (e). Adapted with permission from Ref. [5] (a-c) and Ref. [30] (d,e). Copyright 2023, American Chemical Society.

Fig. 3. Light-intensity-dependent HE rates (a) and the related gross quantum yields (b) for CdS-based photocatalysts with influence of manganese dopant concentration. Surface doping with manganese can be realized by hydrothermal treatment of CdS nanorods in Mn2+-containing solution. Mn-0, Mn-0.5, Mn-1, and Mn-3 respectively represent the molar ratios of 0, 0.5%, 1%, and 3% of manganese to cadmium of CdS in the hydrothermal dispersion. Reprinted with permission from Ref. [24]. Copyright 2022, Royal Society of Chemistry.

Fig. 4. Schematic diagrams for the three-channel electron transfer (a) and the shrinking of dispersed semiconductor (b) and photocatalyst (c) into porous films for OCP measurements. Adapted with permission from Ref. [5] (a). Copyright 2023, American Chemical Society. Adapted with permission from Ref. [13] (b,c). Copyright 2021, American Chemical Society.

Fig. 5. The OCP decay from the biased potential in dark or the photoinduced potential for TiO2 and Pt/TiO2 electrodes. By taking the derivation of OCP with respect to time (a), we can obtain the time constants (b) for transfer of electrons from semiconductor to solution with one channel (τ1C), two channels (τ2C), and three channels (τ3C). The time constant for SCS interfacial electron (τSCS) and side/back reaction (τSCS-SB) can be calculated from τ1C, τ2C, and τ3C (c). By these parameters, we can estimate photogenerated electron utilization (c), which is very close to photon utilization (~38%) of the photocatalytic reaction under very intense irradiation. The abscissa values for GQY (c) can refer the equilibrium potential of the photocatalyst (Pt/TiO2) under irradiation (d). Adapted with permission from Ref. [5]. Copyright 2023, the American Chemical Society.

Fig. 6. Schematic diagrams (a) and time constants (b,c) for interfacial transfer of electrons from semiconductor to the argon (b) and oxygen (c) saturated solution via catalytic sites. For the conventional construction loaded with metallic cocatalyst like Pt/CdS (left panel, a), SC interfacial electron transfer can be realized by the combination of trap-assisted charge recombination (CR) and thermionic emission (TE). For cocatalyst-free photocatalyst like W-CdS (right panel, a), in addition to transport/transfer of electron to the catalytic sites by conduction band affected by trapping/detrapping events, the levels in the bandgap can also transport charges. When the required bias is less negative (e.g.: oxygen reduction, c), the trap states in the deeper levels sensitively affects the electron transport in the levels in the bandgap (c). Reprinted with permission from Ref. [41]. Copyright 2022, the American Chemical Society.

Fig. 7. Influence of bridging metal on band alignment and interfacial electron transfer of SC contacts. For the semiconductor loaded with cocatalysts (cat) typically like platinum with large work function, the very high potential barrier (qVbi0) severely slows SC interfacial electron transfer by thermionic emission (TE, shown by the thin blue arrow, a). Although some electrons can be transferred to the cocatalyst by trap-assisted charge recombination (CR), the utilization of incident photons will be undesirably reduced as the light becomes intense. By introducing intermediate metal (mim) with small work function (b), the lowering of potential barrier (qVbi) can facilitate the interfacial transfer of electrons to the cocatalysts by thermionic emission (shown by the green thick arrow, b). Reprinted with permission from Ref. [50]. Copyright 2022, Elsevier.

Fig. 8. Schematic diagrams for common (bulk) metal-semiconductor contact (a), nanostructuring induced band bending confinement for the semiconductor nanostructures without (b) and with (c) ultrathin interlayers and the related interfacial electron transfer. The band structures for contacts and semiconductor-metal (SC) interfacial electron transfer (bottom panels of (a)-(c)) are sensitively influenced by the size of the semiconductor (upper panels of (a)-(c)). Reprinted with permission from Ref. [34]. Copyright 2020, the American Chemical Society.

参考文献

[1]	R. Li, C. Li, Adv. Catal., 2017, 60, 1-57.
[2]	J. Schneider, M. Curti, Photochem. Photobio. Sci., 2023, 22, 195-217.
[3]	C. Wu, K. Lv, X. Li, Q. Li, Chin. J. Catal., 2023, 54, 137-160.
[4]	Y. Qi, J. Zhang, Y. Kong, Y. Zhao, S. Chen, D. Li, W. Liu, Y. Chen, T. Xie, J. Cui, C. Li, K. Domen, F. Zhang, Nat. Commun., 2022, 13, 484.
[5]	X. Wei, S. Gao, H. Liu, Y. Fang, J. Chen, J. Phys. Chem. Lett., 2023, 14, 3721-3726.
[6]	T. Ge, J. Chen, J. Phys. Chem. Lett., 2024, 15, 1241-1245.
[7]	X. Wei, H. Xiang, Y. Xu, Z. Wang, J. Chen, AIChE J., 2023, 69, e17985.
[8]	Z. Jiang, B. Cheng, L. Zhang, Z. Zhang, C. Bie, Chin. J. Catal., 2023, 52, 32-49.
[9]	L. Wang, Y. Li, C. Wu, X. Li, G. Shao, P. Zhang, Chin. J. Catal., 2022, 43, 507-518.
[10]	Z. Wang, N. Xue, J. Chen, J. Phys. Chem. C, 2019, 123, 24404-24408.
[11]	Z. Wang, W. Qiao, M. Yuan, N. Li, J. Chen, J. Phys. Chem. Lett., 2020, 11, 2369-2373.
[12]	T. Ge, J. Chen, J. Phys. Chem. Lett., 2023, 14, 7477-7482.
[13]	H. Xiang, Z. Wang, J. Chen, J. Phys. Chem. Lett., 2021, 12, 7665-7670.
[14]	Y. Qi, B. Zhang, G. Zhang, Z. Zheng, T. Xie, S. Chen, G. Ma, C. Li, K. Domen, F. Zhang, Joule, 2024, 8, 193-203.
[15]	S. Chen, Y. Qi, T. Hisatomi, Q. Ding, T. Asai, Z. Li, S. S. K. Ma, F. Zhang, K. Domen, C. Li, Angew. Chem. Int. Ed., 2015, 54, 8498-8501.
[16]	J. Ma, T. J. Miao, J. Tang, Chem. Soc. Rev., 2022, 51, 5777-5794.
[17]	J. Schneider, M. Matsuoka, M. Takeuchi, J. Zhang, Y. Horiuchi, M. Anpo, D. W. Bahnemann, Chem. Rev., 2014, 114, 9919-9986.
[18]	M. R. Hoffmann, S. T. Martin, W. Choi, D. W. Bahnemann, Chem. Rev., 1995, 95, 69-96.
[19]	H. Zhang, Z. Wang, J. Zhang, K. Dai, Chin. J. Catal., 2023, 49, 42-67.
[20]	J. Zhang, B. Zhu, L. Zhang, J. Yu, Chem. Commun., 2023, 59, 688-699.
[21]	X. Deng, J. Zhang, K. Qi, G. Liang, F. Xu, J. Yu, Nat. Commun., 2024, 15, 4807.
[22]	J. Yan, J. Zhang, J. Mater. Sci. Technol., 2024, 193, 18-21.
[23]	E. H. Rhoderick, Metal-Semiconductor Contacts, Clarendon Press, Oxford, 1978.
[24]	D. Yang, Z. Wang, J. Chen, Catal. Sci. Technol., 2022, 12, 3634-3638.
[25]	J. Wang, D. N. Tafen, J. P. Lewis, Z. Hong, A. Manivannan, M. Zhi, M. Li, N. Wu, J. Am. Chem. Soc., 2009, 131, 12290-12297.
[26]	Y. Nam, L. Q. Li, J. Y. Lee, O. V. Prezhdo'a, J. Phys. Chem. Lett., 2019, 10, 2676-2683.
[27]	J. Chen, H. B. Tao, B. Liu, Adv. Energy Mater., 2017, 7, 1700886.
[28]	J. Zhang, G. Yang, B. He, B. Cheng, Y. Li, G. Liang, L. Wang, Chin. J. Catal., 2022, 43, 2530-2538.
[29]	X. Zhang, D. Gao, B. Zhu, B. Cheng, J. Yu, H. Yu, Nat. Commun., 2024, 15, 3212.
[30]	X. Wei, J. Chen, J. Phys. Chem. Lett., 2023, 14, 5386-5389.
[31]	J. Chen, L. Zhang, Z. Lam, H. B. Tao, Z. Zeng, H. B. Yang, J. Luo, L. Ma, B. Li, J. Zheng, S. Jia, Z. Wang, Z. Zhu, B. Liu, J. Am. Chem. Soc., 2016, 138, 3183-3189.
[32]	H. Xiang, Z. Wang, J. Chen, J. Chem. Phys., 2021, 154, 221102.
[33]	J. Bisquert, A. Zaban, M. Greenshtein, I. Mora-Sero, J. Am. Chem. Soc., 2004, 126, 13550-13559.
[34]	Z. Wang, W. Qiao, M. Yuan, N. Li, J. Chen, J. Phys. Chem. Lett., 2020, 11, 4644-4648.
[35]	S. Tabata, H. Ohnishi, E. Yagasaki, M. Ippommatsu, K. Domen, Catal. Lett., 1994, 28, 417-422.
[36]	W. Yang, R. Godin, H. Kasap, B. Moss, Y. Dong, S. A. J. Hillman, L. Steier, E. Reisner, J. R. Durrant, J. Am. Chem. Soc., 2019, 141, 11219-11229.
[37]	L. Megatif, R. Dillert, D. W. Bahnemann, Catal. Today, 2020, 355, 698-703.
[38]	C. Shao, Q. He, M. Zhang, L. Jia, Y. Ji, Y. Hu, Y. Li, W. Huang, Y. Li,, Chin. J. Catal., 2023, 46, 28-35.
[39]	A. Zaban, M. Greenshtein, J. Bisquert, ChemPhysChem, 2003, 4, 859-864.
[40]	X. Wei, H. Liu, S. Gao, K. Jia, Z. Wang, J. Chen, J. Phys. Chem. Lett., 2022, 13, 9642-9648.
[41]	Y. Xu, Z. Wang, H. Xiang, D. Yang, J. Wang, J. Chen, J. Phys. Chem. Lett., 2022, 13, 2039-2045.
[42]	H. Xiang, Z. Wang, J. Chen, Chin. J. Struct. Chem., 2022, 41, 2209069-2209073.
[43]	S. Gao, X. Wei, H. Liu, Y. Fang, K. Jia, H. Xiang, J. Chen, J. Fuel Chem. Technol., 2024, 52, 87-96.
[44]	H. Liu, X. Huang, J. Chen, Chin. J. Catal., 2023, 51, 49-54.
[45]	T. Luo, Z. Wang, X. Wei, X. Huang, S. Bai, J. Chen, Catal. Sci. Technol., 2022, 12, 2340-2345.
[46]	S. Gao, T. Ge, B. Li, J. Chen, Catal. Sci. Technol., 2023, 13, 6631-6634.
[47]	Y. Xu, M. A. A. Schoonen, Am. Mineral., 2000, 85, 543-556.
[48]	S. M. Sze, K. K. Ng, Physics of Semiconductor Devices, 3rd ed., John Wiley & Sons, Hoboken, 2006.
[49]	J. Chen, B. Li, J. Zheng, J. Zhao, Z. Zhu, J. Phys. Chem. C, 2012, 116, 14848-14856.
[50]	Z. Wang, B. Mei, J. Chen, J. Catal., 2022, 408, 270-278.
[51]	C. Hu, Modern Semiconductor Devices for Integrated Circuits, Prentice Hall, New Jersey, 2009.
[52]	S. Chen, S. Shen, G. Liu, Y. Qi, F. Zhang, C. Li, Angew. Chem. Int. Ed., 2015, 54, 3047-3051.
[53]	H. S. Ahn, A. J. Bard, Angew. Chem. Int. Ed., 2015, 54, 13753-13757.
[54]	C. M. Hill, J. Kim, N. Bodappa, A. J. Bard, J. Am. Chem. Soc., 2017, 139, 6114-6119.
[55]	W. Qiao, H. B. Tao, B. Liu, J. Chen, Small, 2019, 15, 1804391.
[56]	S. Ruhle, D. Cahen, J. Phys. Chem. B, 2004, 108, 17946-17951.

实际光催化反应中的半导体-助催化剂界面电子转移

Semiconductor-cocatalyst interfacial electron transfer in actual photocatalytic reaction

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