国家纳米中心唐智勇团队报道了通过控制自由基类型实现特定光催化甲烷氧化。相关研究成果发表在2023年1月17日出版的《美国化学会杂志》。

在温和条件下，用O₂在H₂O中选择性地将CH₄氧化成CH₃OH或HCHO，为合成商品化学品提供了一条理想的可持续途径。然而，在保持高生产率的同时操纵反应选择性仍然是一个巨大的挑战，因为难以对所需含氧化合物的形成进行动力学控制以防止其过度氧化。

该文中，研究人员提出了一种高效的策略，该策略基于通过合理设计光催化剂来精确控制生成的自由基的类型，从而首次在CH₄光氧化过程中实现CH₃OH和HCHO的高选择性和高生产率。通过调整Au/In₂O₃催化剂中的能带结构和活性位点（即单原子或纳米颗粒）的大小，研究人员发现了两个重要自由基OOH和OH的交替形成，这分别导致了CH₃OH和HCHO形成的明显不同的反应路径。在室温下光催化CH₄氧化3小时后，该方法在In₂O₃负载的Au单原子（Au1/In₂O₃）上产生了97.62%的显著HCHO选择性和6.09 mmol g^–1的产率，在In₂O₃负载的Au纳米颗粒（AuNPs/In₂O₃）中产生了89.42%的优异CH₃OH选择性和5.95 mmol g^-1的产率。

该项工作为通过精细设计复合光催化剂实现高效选择性CH₄氧化开辟了一条新途径。

附：英文原文

Title: Enabling Specific Photocatalytic Methane Oxidation by Controlling Free Radical Type

Author: Yuheng Jiang, Siyang Li, Shikun Wang, Yin Zhang, Chang Long, Jun Xie, Xiaoyu Fan, Wenshi Zhao, Peng Xu, Yingying Fan, Chunhua Cui, Zhiyong Tang

Issue&Volume: January 17, 2023

Abstract: Selective CH4 oxidation to CH3OH or HCHO with O2 in H2O under mild conditions provides a desired sustainable pathway for synthesis of commodity chemicals. However, manipulating reaction selectivity while maintaining high productivity remains a huge challenge due to the difficulty in the kinetic control of the formation of a desired oxygenate against its overoxidation. Here, we propose a highly efficient strategy, based on the precise control of the type of as-formed radicals by rational design on photocatalysts, to achieve both high selectivity and high productivity of CH3OH and HCHO in CH4 photooxidation for the first time. Through tuning the band structure and the size of active sites (i.e., single atoms or nanoparticles) in our Au/In2O3 catalyst, we show alternative formation of two important radicals, OOH and OH, which leads to distinctly different reaction paths to the formation of CH3OH and HCHO, respectively. This approach gives rise to a remarkable HCHO selectivity and yield of 97.62% and 6.09 mmol g–1 on In2O3-supported Au single atoms (Au1/In2O3) and an exceptional CH3OH selectivity and yield of 89.42% and 5.95 mmol g–1 on In2O3-supported Au nanoparticles (AuNPs/In2O3), respectively, upon photocatalytic CH4 oxidation for 3 h at room temperature. This work opens a new avenue toward efficient and selective CH4 oxidation by delicate design of composite photocatalysts.

DOI: 10.1021/jacs.2c13313

Source: https://pubs.acs.org/doi/10.1021/jacs.2c13313