第一作者：孙鑫海
通讯作者：郭峰, 施伟龙
通讯单位：江苏科技大学
DOI:10.1016/j.jcis.2023.08.133
具有快速电荷转移和提高光谱利用率的光热纳米反应器是光催化研究的一个重点。江苏科技大学郭峰/施伟龙副教授团队采用简单的煅烧方法，将硫化银量子点（Ag2S QDs）涂覆在多孔囊泡状石墨相氮化碳表面（PCNNVs），形成Ag2S/PCNNVs纳米反应器，在模拟/真实阳光照射下获得高效的光热辅助光催化产氢。其中，制备的最佳 3% Ag2S/PCNNVs 样品的产氢率为 34.8 mmol h-1 g-1，是纯相PCNNVs 的 3.5 倍。Ag2S/PCNNVs 复合体系光热辅助活性的增强主要归功于Ag2S QDs等离子耦合与 PCNNVs 光热纳米反应器保温性能。这项研究为开发高效光热辅助光催化剂提供了一种前景广阔的策略。
江苏科技大学郭峰/施伟龙副教授团队首先设计并开发在多孔g-C3N4囊泡上涂覆 Ag2S QDs 构建光热辅助光催化纳米反应器，用于高效光催化制氢。在该纳米反应器系统中，首次探索了 Ag2S 的光热效应和PCNNVs 的保温性能的共同作用。利用各种分析技术对合成复合材料的物理和化学性质进行了全面研究。此外，还通过控制实验温度研究了提高反应溶液温度对光催化剂活性的影响。同时，应用红外热成像和数值模拟探讨了 Ag2S/PCNNVs 纳米反应器内外的温度变化，分析了结构的独特作用和光热辅助光催化机理。最后，对 Ag2S/PCNNVs 进行了室外光催化 H2 性能测试，以探索其实际应用的潜力。
Scheme.1 Schematic illustration for the synthesis process of Ag2S/PCNNVs nanoreactor for photocatalysis.
Fig.1 SEM (a, c) and TEM (b, d) images of PCNNVs and 3% Ag2S/PCNNVs, respectively. (e) HAADF-STEM and elemental mapping images of 3% Ag2S/PCNNVs.
Fig.2 (a) XRD patterns and (b) FT-IR spectra of Ag2S, PCNNVs and Ag2S/PCNNVs composites. XPS high-resolution spectra of (c) Ag 3d, (d) S 2p, (e) C1s and (f) N 1s for 3% Ag2S /PCNNVs composite.
Fig.3 (a) Photocatalytic HER performance (b) H2 production rates of PCNNVs and Ag2S/PCNNVs composites under light irradiation. (c) Wavelength dependence of AQE of photocatalytic H2 efficiency over 3% Ag2S/PCNNVs. (d) H2 evolution performance for 3% Ag2S/PCNNVs in comparison with other recent reported g-C3N4-based photocatalysts. (e) Cycling measurements of photocatalytic HER over 3% Ag2S/PCNNVs. (f) XRD patterns of fresh and used 3% Ag2S/PCNNVs. (g) TEM image of 3% Ag2S/PCNNVs after photocatalysis.
Fig.4 (a) UV-vis absorption spectrum for Ag2S QDs. (b) Temperature curves of Ag2S QDs within 480 s irradiation. (c) UV-Vis absorption spectra for PCNNVs and Ag2S/PCNNVs composites. (d) Temperature curves of BCN, PCNNVs, 3% Ag2S/BCN and 3% Ag2S/PCNNVs within 480 s irradiation.
Fig.5 (a, b) Photocatalytic H2 production curves of BCN, 3% Ag2S/BCN, PCNNVs and 3% Ag2S/PCNNVs at different reaction temperatures. Photothermal IR images of (c) BCN, (d) 3% Ag2S/BCN, (e) PCNNVs and (f) 3% Ag2S/PCNNVs during the reaction process.
Fig.6 (a) Photocurrent response curves and (b) EIS plots of 3% Ag2S/PCNNVs under different temperature conditions. (c) Mott-Schottky plots of PCNNVs and 3% Ag2S/PCNNVs under light and darkness. (d) PL spectra of 3% Ag2S/PCNNVs under different excitation.
Fig.7 (a) Infrared thermal images and (b) temperature curves of BCN (A), 3% Ag2S/BCN (B), PCNNVs (C) and 3% Ag2S/PCNNVs (D) under light on/off conditions. Numerical simulations of the surrounding temperature distribution and velocity vector of 3% Ag2S/PCNNVs nanoreactor at illumination times of (c) 0 s and (d) 720 s. (e) Photothermal cycle curves (3 cycles) of 3% Ag2S/PCNNVs nanoreactor. (f) Measurement and calculation of the photothermal conversion efficiency over 3% Ag2S/PCNNVs.
Fig.8 Schematic diagram for photothermal-assisted photocatalytic H2 production mechanism over Ag2S/PCNNVs nanoreactor.
综上所述，通过简单的煅烧方法制备了PCNNVs表面装饰Ag2S量子点的Ag2S/PCNNVs纳米反应器，在模拟/真实阳光照射下实现高效的光热辅助光催化产氢。性能测试结果表明，制备的3% Ag2S/PCNNVs具有较高的光催化活性，H2产量高达34.8 mmol h-1 g-1，比之前研究的纯相PCNNVs高3.5倍。制氢性能的提高主要是由于以下原因：(i) PCNNVs纳米反应器的比表面积增加了负载Ag2S量子点的活性位点，通过光激发下独特的LSPR效应有效地提高了复合材料的光热辅助光催化性能；（ii）PCNNVs纳米反应器的多孔腔结构形成多个反射，提高光利用也有光热约束的热收集效应，可以收集热的光热效应，抑制内部热的快速逃逸，实现保温，大大促进光催化H2的进化；（iii）Ag2S/PCNNVs纳米反应器具有极强的亲水性，在高温Ag2S/PCNNVs纳米反应器周围的水分子移动得更快，通过促进局部传质动力学提高了光催化反应速率。本文为高效光热辅助光催化剂的设计和开发提供了设计思路和参考。此外，Ag2S/PCNNVs纳米反应器光催化剂可以在没有额外能量输入的情况下，在真实的室外阳光下高效生产H2，证明了g-C3N4基光催化剂具有实用和有前景的潜力。
X. Sun, Z. Chen, Y. Shen, J. Lu, Y. Shi, Y. Cui, F. Guo, W. Shi, Plasmonic coupling-boosted photothermal nanoreactor for efficient solar light-driven photocatalytic water splitting, Journal of Colloid and Interface Science, 652 (2023) 1016-1027. https://doi.org/10.1016/j.jcis.2023.08.133
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