催化学报

催化学报

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氰氧共功能化氮化碳中的协同能带和电子工程用于高效光催化合成H2O2

陈榕兴a, 权永康a, 蔡伟龙a,b, 吴永豪c,d, 黄剑莹a,*, 赖跃坤a,b,*   

  1. a福州大学化工院,福建福州 350116, 中国;
    b清源创新实验室,福建泉州 362801, 中国;
    c香港城市大学能源与环境学院, 香港 999077, 中国;
    d阿卜杜拉国王科学技术大学物理科学与工程部, 图沃, 沙特
  • 收稿日期:2025-08-30 接受日期:2025-09-27
  • 通讯作者: *电子信箱: jyhuang@fzu.edu.cn (黄剑莹), yklai@fzu.edu.cn (赖跃坤).
  • 作者简介:1共同第一作者.
  • 基金资助:
    国家自然科学基金国际(地区)合作与交流项目(22361162607); 国家自然科学基金(22375047, 22075046); 国家重点研发计划 (2022YFB3804905, 2022YFB3804900).

Synergistic band and electronic engineering in cyano-oxygen co-functionalized carbon nitride for efficient photocatalytic H2O2 synthesis

Rongxing Chena, Yongkang Quana, Weilong Caia,b, Yun Hau Ngc,d, Jianying Huanga,*, Yuekun Laia,b,*   

  1. aCollege of Chemical Engineering, Fuzhou University, Fuzhou 350116, Fujian, China;
    bQingyuan Innovation Laboratory, Quanzhou 362801, Fujian, China;
    cSchool of Energy and Environment, City University of Hong Kong, Kowloon Tong 999077, Hong Kong, China;
    dCenter for Renewable Energy and Storage Technologies (CREST), Physical Science and Engineering (PSE) Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
  • Received:2025-08-30 Accepted:2025-09-27
  • Contact: *E-mail: jyhuang@fzu.edu.cn (J. Huang), yklai@fzu.edu.cn (Y. Lai).
  • About author:1 Contributed equally to this work.
  • Supported by:
    International Cooperation and Exchanges NSFC (22361162607), National Natural Science Foundation of China (22375047, 22075046), and the National Key Research and Development Program of China (2022YFB3804905, 2022YFB3804900).

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摘要： 过氧化氢(H2O2)是一种多用途的化学和环境友好的氧化剂. 在不同条件下, H2O2表现出氧化和还原特性, 氧化和还原产物分别为H2O和O2, 它广泛应用于化工、环保及能源等领域. 目前工业H2O2制法(蒽醌法、H2和O2直接合成法等)普遍存在能耗高、污染重等问题. 相比之下, 光催化合成H2O2以太阳光为驱动力, 仅需H2O和O2为原料, 反应温和且无污染, 被认为是最具前景的绿色合成途径之一. 石墨相氮化碳(g-C3N4)虽然是一种理想的候选材料, 但传统方法制备的g-C3N4存在比表面积低、可见光吸收不足、电荷分离效率低、对双电子氧还原反应(2e- ORR)选择性差等问题. 针对上述挑战, 本文提出了一种前驱体-熔盐协同策略, 为高效光催化产H2O2提供了新的思路.
氧掺杂是增强氮化碳对可见光的捕获和载流子分离的有效策略, 然而传统方法通常依赖草酸盐等外来源含氧物质, 在引入氧的同时不可避免地引入其他杂原子. 这些杂原子可能成为新的电荷复合中心, 降低光生载流子的分离效率, 从而限制氮化碳光催化性能的提升. 另一方面, 传统熔盐(如NaCl)虽然有效引入缺陷和氰基官能团, 但往往导致氮化碳导带位置下移, 削弱其氧还原能力, 不利于光催化合成H2O2. 针对以上问题, 本文通过富含氧元素的氰尿酸三聚氰胺为前驱体, 在氩气气氛中通过一步热诱导缩合, 实现了氧的自掺杂; 进一步通过过硫酸钠熔盐辅助成功构建了兼具氧掺杂和氰基功能化氮化碳(MCN-N15). 实验结果表明: 在可见光下, MCN-N15在乙醇中生成H2O2的速率达到950.14 μmol·g-1·h-1, 分别是MCN和CN的2.22倍和23.61倍. 表征结果显示, 紫外-可见吸收光谱中氧掺杂诱导了n→π*电子跃迁, 拓宽了氮化碳对可见光吸收范围. 同时, 熔盐辅助引入的氰基(-C≡N)不仅促进了光生电荷的分离, 也提高了MCN-N15对2e- ORR的选择性. 更重要的是, 该方法在实现氧自掺杂的同时, 还克服了传统熔盐修饰后导致的导带下移问题, 使MCN-N15形成了更负的导带电位(ECB = -0.84 V vs. NHE), 为2e- ORR提供了强大的热力学驱动力. 通过旋转圆盘电极、电子顺磁共振(EPR)和原位红外光谱等表征手段, 证明了MCN-N15主要是通过两步单电子氧还原反应生成H2O2, 且对氧还原反应的选择性显著高于CN和MCN. 进一步通过密度泛函理论计算比较了CN, MCN和MCN-N15在两步单电子ORR过程中各阶段的吉布斯自由能变化; 结果表明, 氧掺杂和氰基修饰协同降低了反应能垒, 而较低的能垒促进了中间产物的形成和转化, 从而显著提升了H2O2生成的选择性和反应速率.
综上, 本研究通过氧掺杂和氰基修饰的协同策略, 有效调控了氮化碳的电子和能带结构, 实现了高效的光催化生产H2O2. 结合系统的表征分析, 明确了H2O2经由两步单电子氧还原路径的反应机制. 本工作为设计高性能的光催化生产H2O2系统提供了一种新颖的“能带工程-表面功能化”协同调控策略.

关键词: 氮化碳, 氧掺杂, 氰基, 光催化, H2O2

Abstract: Photocatalytic hydrogen peroxide (H2O2) synthesis via the two-electron oxygen reduction reaction (2e- ORR) offers a sustainable alternative to industrial methods. However, conventional carbon nitride photocatalysts suffer from rapid charge recombination, limited visible-light utilization, and insufficient 2e- ORR selectivity. Herein, we report a novel precursor-molten salt synergistic strategy. Using the oxygen-containing precursor itself, the spontaneous oxygen doping of the carbon nitride skeleton was initiated by a one-step heat-induced condensation process, and the O-doped cyano-functionalized carbon nitride (MCN-N15) was further synthesized by molten salt-assisted synthesis. Under visible light, MCN-N15 achieves an exceptional H2O2 production rate of 950.14 μmol·g-1·h-1 in ethanol. O-doping induces n → π* electronic transitions, broadening the visible-light absorption range. Simultaneously, the introduced cyano groups (-C≡N) facilitate charge separation and enhance 2e- ORR selectivity. Crucially, this approach not only realizes the self-doping of O, but also mitigates the conduction band downshifting typically caused by conventional molten salts, yielding a more negative conduction band potential (ECB = -0.84 V vs. NHE) that provides a strong thermodynamic driving force for 2e- ORR. The results of density functional theory calculations show that the synergistic modification strategy of oxygen doping and cyano modification effectively reduces the Gibbs free energy change (∆G) of the rate-determining step (* + O2 → *O2) and promotes the formation of intermediate *OOH, thereby significantly improving the selectivity and reaction rate of H2O2 synthesis. The synergistic modification optimizes the electronic and band structure of carbon nitride, providing a novel "energy band engineering-surface functionalization" co-regulation strategy for designing efficient photocatalytic H2O2 generation systems.

Key words: Carbon nitride, O-doping, Cyano group, Photocatalytic, H2O2