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[Display omitted] • Operando NMR combined with gas-probe method was used to study active sites transfer under the metal-support interaction. • The photocatalytic conversion efficiency of pure TiO 2 decreased, while that of Pt/TiO 2 was unaffected in gas conditions. • After loading metal-Pt, active sites changed from TiO 2 surface to Pt/TiO 2 interface. Recently metal-support interaction (MSI) has attracted considerable attention in photocatalysis. Some studies emphasize the importance of active sites on photocatalysts; however, there are no reports on site changes under MSI in real reactive conditions. Herein, an operando nuclear magnetic resonance technique was proposed to study such site changes on anatase TiO 2 and Pt/TiO 2 , through a gas-probe method, in CH 3 OH reforming. The photocatalytic oxidation efficiency of CH 3 OH by pure TiO 2 decreased immensely under extra-gas conditions, while that by Pt/TiO 2 was unaffected. The surface of pure TiO 2 were occupied by injected gas molecules, making CH 3 OH inaccessible to active sites. However, in Pt/TiO 2 , CH 3 OH adsorption sites changed from TiO 2 surface to metal-Pt/TiO 2 interface as confirmed by H 2 gas-probe experiments. This study provides a deeper understanding of active sites transfer by MSI and leverages the gas-probe method for its detection to guide the development of technology to test active-site positions in heterogeneous catalysts. [ABSTRACT FROM AUTHOR]

The development of low-Pt catalysts is important for the large-scale application of Pt-based catalysts. Catalytic reactions mainly occur on the surface or interface of a material, and thus the surface properties of the catalyst will strongly affect their catalytic activity; this phenomenon has attracted widespread attention. Here, a series of Pt NPs with different chemical states and particle sizes were obtained by changing the light source wavelength, light time, and other conditions of light deposition synthesis. The Pt-TiO 2 catalyst has excellent potential in both photocatalytic hydrogen evolution (4.5 mmol·g−1·h−1) and electrocatalytic hydrogen evolution (26 mV@10 mA cm−2). We also found that the photocatalytic activity is more sensitive to the chemical state of Pt and that reducing the catalyst size can improve the electrocatalytic activity. This work not only provides a green and effective method to adjust the chemical state of precious metals on metal oxides but also helps to understand the impact of surface states on the catalytic process. A series of Pt NPs with different chemical states and sizes were embedded in TiO 2 (B) via a modified photochemical reduction method. The optimized Pt-TiO 2 (B) bifunctional catalyst exhibited excellent p-HER and e-HER catalytic activity. [Display omitted] • A series of Pt NPs with different chemical states and particle sizes were obtained by a photochemical strategy. • The optimized Pt-TiO 2 catalyst has excellent potential in both p-HER (4.5 mmol g−1 h−1) and e-HER (26 mV@10 mA cm−2). • The p-HER is more sensitive to the chemical state of Pt, and reducing the catalyst size improves the e-HER. • This work provides a new idea to promote catalytic activity by adjusting the catalyst's state and size. [ABSTRACT FROM AUTHOR]