江苏科技大学施伟龙/郭峰课题组JCIS：阳光和空气的可持续H2O2光合作用

双氧水（H₂O₂）因其绿色、无污染的氧化特性，广泛应用于环境治理、医药和电子等领域。然而，目前工业上仍以蒽醌法为主进行集中式高浓度生产，该方法存在工艺复杂、能耗高、副产物多以及储运成本高、安全风险大的问题。近年来，光催化技术因可在常温常压下以水和氧为原料、可见光为能源直接生成H₂O₂，被视为一种具有前景的可持续替代方案。在该研究领域，课题组前期报道的均相催化剂如氮、硫掺杂碳点（N, S-CDs, Journal of Catalysis 435 (2024) 115579，Chemical Engineering Journal 499 (2024) 156239）虽具有高活性，但因难以回收和稳定性差等问题限制了实际应用，而传统异相催化剂虽可分离，却面临活性下降等挑战。因此，构建兼具高活性与良好回收性的光催化体系成为关键。为此，本文提出一种从“均相”向“异相”转化的新策略，利用废弃羽毛合成的N, S-CDs，结合氢氧化钾刻蚀构建的含氰基缺陷g-C₃N₄（CCN）形成S型异质结体系，在实现碳点锚定与高效电子传输的同时，大幅提升了光催化纯水的H₂O₂生成效率与循环稳定性，为绿色双氧水合成设计提供了新思路。

基于此，江苏科技大学施伟龙/郭峰课题组在期刊Journal of Colloid And Interface Science上发表题为“Efficient hydrogen peroxide generation via biomass-derived carbon dots/graphitic carbon nitride S-scheme Heterostructures under visible light in pure water systems”的文章（Journal of Colloid and Interface Science, 699 (2025) 138282.）。

本文围绕低成本、高效可见光驱动双氧水合成的目标，提出了一种由生物质来源的氮硫共掺杂碳点（N, S-CDs）与含氰缺陷的石墨相氮化碳（CCN）构成的S型异质结光催化体系。通过构建该结构，不仅实现了对原本均相碳点的有效锚定与异相化转化，解决了其难以分离回收的问题，还显著提升了电子-空穴对的分离效率和光催化活性。在可见光照射下，该材料在纯水体系中实现了139.78 μM 的H₂O₂产率，且具有优异的循环稳定性与选择性。此外，作者通过电化学测试、EPR分析、KPFM和原位红外等手段系统揭示了其增强型电子转移机制与活性氧物种路径，验证了该异质结构在促进H₂O₂选择性生成中的协同效应。该研究不仅展示了生物质碳点的高价值应用潜力，也为绿色双氧水分布式制造提供了新材料体系与理论支撑。

1. 在纯水体系中高效合成H₂O₂

本研究构建的N, S-CDs/CCN光催化体系可在无牺牲剂条件下，于纯水中实现可见光驱动的H₂O₂合成，最佳产率达到139.78 μM，远高于单独使用N, S-CDs或CCN（分别为其的1/1.4和1/8）。该体系在7次循环使用后仍保持超过120 μM的产氢过氧化物能力，展现出优异的催化稳定性与可回收性，具有良好的实际应用前景。

Fig.1 (a) Photocatalytic H₂O₂ production curves and (b) H₂O₂ production rates of as-prepared photocatalysts, including 7% N, S-CDs/CCN, N, S-CDs, CCN, 7% N, S-CDs/CN, and CN, compared with pure water. Photocatalytic H₂O₂ production over N, S-CDs/CCN under (c) different pH values from 1-7 and (d) atmospheres including N₂, air and O₂. (e) Photocatalytic decomposition of H₂O₂ when exposed to light and coexisting with the N, S-CDs/CCN. (f) H₂O₂ formation (Kf) and decomposition (Kd) rate constant of without/with N, S-CDs/CCN photocatalyst. (g) Assessment of the photocatalytic stability of N, S-CDs/CCN in H₂O₂ production with 7 cycles. (h) Comparison of H₂O₂ production of CN-based photocatalysts reported in previous studies. (All errors were estimated for 3 replicate experiments.)

2. S-scheme异质结协同机制增强电子分离效率

N, S-CDs与含氰缺陷的g-C₃N₄形成紧密界面，构建S-scheme异质结，有效调控能带结构，实现光生载流子的定向迁移与快速分离。光电流响应、阻抗谱（EIS）、PL/TRPL结果显示，该异质结体系具有更强的光响应能力和电子传导性能。KPFM测试进一步验证了光照下电子从N, S-CDs流向CCN、空穴相反积聚的异质结行为。

Fig.2 (a) Transient photocurrent-response curves in 200s and (b) EIS plots of N, S-CDs, CCN and N, S-CDs/CCN. (c) PL spectra and (d) TRPL spectra of CCN and N, S-CDs/CCN. (e) UV-vis DRS and (f) corresponding plots of (αhv)2 versus photon energy (hv) for the band gap energies of N, S-CDs, CCN and N, S-CDs/CCN composite. (g) Mott-Schottky plots and (h) corresponding band structure diagrams of N, S-CDs and CCN. (i) Active species capturing tests of N, S-CDs/CCN composite during the synthesis of H₂O₂ with ethanol, AgNO₃, and VC used as scavengers in comparison to the condition without any scavenger.

3. 明确活性氧物种的反应路径，探明光催化机制

自由基捕获实验和EPR测试表明，H₂O₂生成主要依赖于光生电子驱动的双电子氧还原反应（ORR）路径，生成中间物•O₂^-。原位FT-IR测试捕捉到O–O和C=N活性峰，揭示关键中间体参与；TPD-O2和RRDE测试进一步验证其优异的氧吸附与电子转移性能，最终实现约80%的H₂O₂选择性（明显优于CCN的50–60%）。

Fig.3 (a) TPD-O₂ profiles of CCN and N, S-CDs/CCN in the temperature range of 50–500 ℃. (b) Number (n) of electro transfer and (c) calculated H₂O₂ selectivity of CCN and N, S-CDs/CCN. (d) In-situ FT-IR spectra of N, S-CDs/CCN with a periodic light irradiation, including overall spectral changes (500–4000 cm^-1) during a 20-minute reaction and detailed variations (800–2000 cm-1) caused by reactive functional groups. The reaction process consists of the initial 2 min in the dark, 16 min under illumination, and 2 min in the dark. (e) Photocatalytic mechanism of N, S-CDs/CCN heterogeneous photocatalytic system for H₂O₂ production.

S.Zou, H. Qin, Y. Tang, K. Sun, L. Sun, B. Xiong, L. Wang, W. Shi,* C. Li,* F. Guo,* Efficient Hydrogen Peroxide Generation via Biomass-Derived Carbon Dots/Graphitic Carbon Nitride S-Scheme Heterostructures Under Visible Light in Pure Water Systems, Journal of Colloid and Interface Science, 699 (2025) 138282.

https://doi.org/10.1016/j.jcis.2025.138282

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