化学
光催化
纳米团簇
阳离子聚合
离解(化学)
锐钛矿
兴奋剂
密度泛函理论
催化作用
光化学
选择性
无机化学
物理化学
计算化学
材料科学
有机化学
光电子学
作者
Shiqun Wu,Xianjun Tan,Juying Lei,Haijun Chen,Lingzhi Wang,Jinlong Zhang
摘要
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 μmol 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 H2 production (36 μmol g–1) with a high CH4 conversion rate of ∼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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