期刊
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
卷 141, 期 16, 页码 6592-6600出版社
AMER CHEMICAL SOC
DOI: 10.1021/jacs.8b13858
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资金
- National Natural Science Foundation of China [21673073, 21677048, 5171101651]
- Science and Technology Commission of Shanghai Municipality [18520710200, 16JC1401400, 17520711500]
- Shanghai Pujiang Program [18PJD012]
- PetroChina Innovation Foundation [2015D-5006-0402]
- Fundamental Research Funds for the Central Universities [222201717003, 22221818014]
Photodriven nonoxidative coupling of CH4 (NOCM) is a potential alternative approach to clean hydrogen and hydrocarbon production. Herein, a Mott-Schottky photocatalyst for NOCM is fabricated by loading Pt nanoclusters on a Ga-doped hierarchical porous TiO2-SiO2 microarray with an anatase framework, which exhibits a CH4 conversion rate of 3.48 mu mol g(-1) h(-1) with 90% selectivity toward C2H6. This activity is 13 times higher than those from microarrays without Pt and Ga. Moreover, a continuous H-2 production (36 mu mol g(-1)) with a high CH4 conversion rate of similar to 28% can be achieved through a longtime irradiation (32 h). The influence of Ga on the chemical state of a surface oxygen vacancy (Vo) and deposited Pt is investigated through a combination of experimental analysis and first-principles density functional theory calculations. Ga substitutes for the five-coordinated Ti next to Vo, which tends to stabilize the single-electron trapped Vo and reduce the electron transfer from Vo to the adsorbed Pt, resulting in the formation of a higher amount of cationic Pt. The cationic Pt and electron-enriched metallic Pt form a cationic-anionic active pair, which is more efficient for the dissociation of C-H bonds. However, the presence of too much cationic Pt results in more C2+ product with a decrease in the CH4 conversion rate due to the reduced charge-carrier separation efficiency. This study provides deep insight into the effect of the doping/loading strategy on the photocatalytic NOCM reaction and is expected to shed substantial light on future structural design and modulation.
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