Pd nanocatalysts engineering for direct oxidation methane-to-methanol with 99.7% selectivity.

Deng, Peilin; Xu, Yueshan; Wu, Daoxiong; Liang, Ying; Zhang, Xue; Wang, Zhitong; Li, Jing; Tian, Xinlong · Nat Commun · 2025

basic_science · Level V

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Abstract

Pd catalysts demonstrate remarkable activity and selectivity for the direct oxidation methane-to-methanol (DOMM) under mild conditions. However, understanding the structure-performance relationship is challenging because Pd catalysts used in existing studies have complex polycrystalline structures. In this work, well-defined Pd nanocrystals with controlled morphologies are synthesized and used as model systems to investigate the origins of the observed structure-activity differences. Our findings indicate that DOMM activity is primarily governed by crystal facet type rather than nanocrystal size. The lower d-band center of the Pd {111} facet weakens the adsorption strength of critical intermediates, including *O<sub>2</sub> and *OH species, promoting H<sub>2</sub>O<sub>2</sub> generation and CH<sub>3</sub>OH formation, respectively. Consequently, {111}-dominated octahedral Pd nanocrystals achieve an exceptional CH<sub>3</sub>OH yield of 201.8 mmol·g<sub>Pd</sub><sup>-1</sup>·h<sup>-1</sup>, three times higher than that of their {100}-dominated hexahedral counterparts. These results provide key insights into the structure-dependent behavior of Pd catalysts and pave the way for designing high-performance catalysts for DOMM.