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摘要:
The direct hydrogen peroxide (H2O2) product from H-2 and O-2 is a promising anthraquinone replacement because it is environmentally friendly and has a high atom efficiency. Experimental and theoretical studies have proven that optimizing the adsorption of the critical intermediate OOH* on the metal site significantly promotes the further protonation of this intermediate and inhibits the O-O bond cleavage, thus enhancing the activity and selectivity. Redistributing the charge density of active sites to tuning the d-band center of the metal could effectively modulate the intermediates adsorption, and thus regulate the catalytic efficiency. Herein, we show that a Lewis acid (ZnCl2 solution) induces abundant oxygen vacancies (Ovs) on the TiO2 surface, which results in a reversal of charge transfer from TiO2-Ov support to the Pd atom, generating an electron-rich Pd configuration. Compared with pristine Pd/TiO2, Pd/TiO2-Ov possesses higher H2O2 selectivity and productivity, with values of 80.7% and 186 mol kg(cat)(-1) h(-1), respectively. In addition, Pd/TiO2-Ov maintains stability during the six cycles reaction due to its high resistance to the leaching of Pd species. Theoretical calculations reveal that the reversed charge transfer downshifts the d-band center of Pd, which promotes O-2 adsorption on the Pd surface and weakens the OOH* intermediates adsorption. Thus, the energy barrier for the hydrogenation of the OOH* intermediate is significantly decreased, and the O-O band cleavage is inhibited. This study reports a reversal of charge transfer tuning the d-band center of the active site for efficient direct H2O2 synthesis, which may provide insight for designing high-performance catalysts.
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来源 :
ACS CATALYSIS
ISSN: 2155-5435
年份: 2024
期: 6
卷: 14
页码: 3955-3965
1 2 . 9 0 0
JCR@2022
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