物理化学学报 >> 2026, Vol. 42 >> Issue (2): 100173.doi: 10.1016/j.actphy.2025.100173

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Ir调控中间体生成类型抑制光催化甲烷转化中产物过氧化

张宇航1,2, 李意1,2, 曹玥晗2,*(), 帅英杰1,2, 周宇1,2, 周莹1,2,*()   

  1. 1 西南石油大学油气藏地质及开发工程全国重点实验室, 四川 成都 610500
    2 西南石油大学新能源与材料学院, 四川 成都 610500
  • 收稿日期:2025-07-25 修回日期:2025-08-22 录用日期:2025-08-24 发布日期:2025-12-03
  • 通讯作者: Email: yzhou@swpu.edu.cn; Tel.: +86-28-83032202 (周莹)yhcao419@163.com (曹玥晗)

Regulating the formation type by Ir of intermediates to suppress product overoxidation in photocatalytic methane conversion

Yuhang Zhang1,2, Yi Li1,2, Yuehan Cao2,*(), Yingjie Shuai1,2, Yu Zhou1,2, Ying Zhou1,2,*()   

  1. 1 State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu 610500, Sichuan Province, China
    2 School of New Energy and Materials, Southwest Petroleum University, Chengdu 610500, Sichuan Province, China
  • Received:2025-07-25 Revised:2025-08-22 Accepted:2025-08-24 Published:2025-12-03
  • Contact: Email: yzhou@swpu.edu.cn; Tel.: +86-28-83032202 (Ying Zhou)yhcao419@163.com (Yuehan Cao)

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摘要：

储量丰富的甲烷不仅是优质化石燃料，而且是合成高附加值化工产品的核心原料。太阳能推动的甲烷转化过程，为温和环境下直接制取甲醇(CH3OH)、甲醛(HCHO)等高价值化学品提供了前景十分广阔的途径。然而，该转化过程的核心挑战在于目标产物很容易发生过氧化反应，使得目标产物的选择性处于较低水平，这成为该领域迫切需要突破的关键瓶颈。在此，我们构建了Ir修饰的CdS (Irx/CdS)光催化体系，提出通过金属Ir调控关键核心反应中间体的生成种类，是提高目标产物选择性并遏制过氧化的有效策略。通过原位漫反射傅里叶变换红外光谱(in situ DRIFTS)证实，在甲烷活化过程里，关键中间体的生成种类存在差异，这对产物分布发挥决定性影响。在纯CdS表面CH4活化生成*CH3O关键中间体倾向于通过其O原子参与到后续深度氧化反应中，最终生成CO2等过氧化产物；而负载Ir后，关键反应中间体转变为*CH3，Ir位点通过局域电子转移促进*CH3向‧CH3自由基的转化，生成的‧CH3自由基与‧OH自由基快速结合定向生成CH3OH。光催化CH4转化性能评价结果显示，在60 ℃、0.1 MPa及分子氧为氧化剂作用下，0.50 wt% Ir负载的Ir0.50/CdS时表现出最佳性能：其含氧液相产物(CH3OH和HCHO)产率达509.2 μmol g−1 h−1，总选择性提升至88%。结合X射线衍射(XRD)、X射线光电子能谱(XPS)及透射电子显微镜(TEM)等表征技术用于催化材料的表征测试，发现Ir在催化剂表面有两种价态共存(金属态Ir0和氧化态Ir4+)，且以金属态为主导。本工作提出的金属修饰调控中间体生成类型以抑制过氧化的策略，为高效转化甲烷制备高值含氧化学品提供了新思路。

关键词: 甲烷转化, 光催化, 金属负载, 关键中间体生成

Abstract:

Methane, as an abundant resource, serves not only as an excellent fossil fuel but also as a pivotal feedstock for synthesizing high-value-added chemical products. Solar-driven methane conversion offers a highly promising pathway for the direct production of high-value chemicals such as methanol (CH3OH) and formaldehyde (HCHO) under mild conditions. However, the core challenge of this conversion process lies in the tendency of target products to undergo over-oxidation, resulting in low selectivity—a critical bottleneck that urgently requires breakthrough in this field. Herein, we constructed an Ir-modified CdS (Irx/CdS) photocatalytic system and proposed that regulating the generation types of key reaction intermediates via metallic Ir is an effective strategy to enhance the selectivity of target products and suppress over-oxidation. In situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS) confirmed that the types of key intermediates generated during methane activation differ, which decisively influences the product distribution. On pure CdS surfaces, the key intermediate *CH3O tends to participate in subsequent deep oxidation reactions via its O atom, ultimately leading to over-oxidized products like CO2. In contrast, after Ir loading, the key reaction intermediate shifts to *CH3. The Ir sites facilitate the conversion of *CH3 to ‧CH3 radicals through localized electron transfer, and the generated ‧CH3 radicals rapidly combine with ‧OH radicals to selectively form CH3OH. The performance evaluation of photocatalytic methane conversion demonstrated that under conditions of 60 ℃, 0.1 MPa, and molecular oxygen as the oxidant, the 0.50 wt% Ir-loaded Ir0.50/CdS sample exhibited optimal performance: the yield of oxygenated liquid products (CH3OH and HCHO) reached 509.2 μmol g−1 h−1, with overall selectivity enhanced to 88%. Characterization techniques such as X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM) revealed the coexistence of two valence states of Ir on the catalyst surface (metallic Ir0 and oxidized Ir4+), with the metallic state being dominant. The strategy proposed in this work—regulating intermediate species generation via metal modification to inhibit over-oxidation—provides a novel approach for the efficient conversion of methane into high-value oxygenated chemicals.

Key words: Methane conversion, Photocatalysis, Metal loading, Generation of key intermediates