You Jiakang, Baktash Ardeshir, Yao Dazhi, Zhang Yanzhao, Ding Shanshan, Hou Jingwei, Zhao Guangyu, Jin Yonggang, Wang Zhiliang, Wang Lianzhou
Nanomaterials Centre, School of Chemical Engineering and Australian Institute for Bioengineering and Nanotechnology, The University of Queensland St Lucia Queensland 4072 Australia
CSIRO Mineral Resources 1 Technology Court, Pullenvale QLD 4069 Australia.
Chem Sci. 2025 May 8. doi: 10.1039/d5sc00888c.
Identifying the rate-determining step is crucial for designing an effective photocatalytic system. The surface adsorption/desorption behaviour of reactants has received much less attention in photocatalyst design because the charge separation and transfer in the bulk is commonly regarded as a more sluggish process. In this work, we investigate photocatalytic methane (CH) conversion (PMC) on various titanium oxide (TiO) surfaces, including rutile and anatase, and reveal that the influence of surface CH adsorption can outweigh the photogenerated charge separation and transfer. Specifically, the rutile TiO surface is totally inert for CH activation. Further theoretical calculations reveal the significance of the hydrogen-adsorption/desorption process during the initial C-H bond cleavage on the TiO surface. A reversible hydrogen adsorption/desorption process with a small Gibbs free energy not only enables the activation of the first C-H bond in CH but also ensures a timely clearance of surface-adsorbed species, leading to a continuous PMC process. The findings of the phase effect study on the interaction between the photocatalyst surface and hydrogen atoms provide new insights into the rational design of efficient photocatalysts towards PMC. It also highlights the gap in transferring the knowledge of photocatalytic water splitting into PMC.
确定速率决定步骤对于设计有效的光催化系统至关重要。在光催化剂设计中，反应物的表面吸附/解吸行为受到的关注要少得多，因为通常认为体相中的电荷分离和转移是一个更为缓慢的过程。在这项工作中，我们研究了各种氧化钛（TiO）表面（包括金红石型和锐钛矿型）上的光催化甲烷（CH）转化（PMC），并揭示了表面CH吸附的影响可能超过光生电荷的分离和转移。具体而言，金红石型TiO表面对CH活化完全惰性。进一步的理论计算揭示了TiO表面上初始C-H键断裂过程中氢吸附/解吸过程的重要性。具有小吉布斯自由能的可逆氢吸附/解吸过程不仅能够活化CH中的第一个C-H键，还能确保及时清除表面吸附物种，从而实现连续的PMC过程。光催化剂表面与氢原子相互作用的相效应研究结果为合理设计高效的PMC光催化剂提供了新的见解。这也凸显了将光催化水分解知识转移到PMC中的差距。
