The high activation barrier of the C-H bond in methane, combined with the high propensity of methanol and other liquid oxygenates toward overoxidation to CO2, have historically posed significant scientific and industrial challenges to converting methane directly and selectively to energy-dense fuels and chemical feedstocks. Here, we report a unique photocatalyst architecture, silica encapsulated titania decorated with AuPd nanoparticles (TiO2@SiO2-AuPd), that prevents methanol overoxidation on its surface and possesses high selectivity and yield of oxygenates even at high UV intensity. This room-temperature approach achieves high selectivity for oxygenates (94.5%) with oxygenate yield of 15.4 mmol/gcat·h at 9.65 bar total pressure of CH4 and O2. The underlying working principles of the photocatalyst system were further elucidated by tracking the photogenerated radicals and systematically varying the reaction conditions. The catalyst design principle was demonstrated to be generalizable for selective oxidation of other alkanes.

中文翻译：

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用于将甲烷选择性转化为甲醇和其他氧化物的传输介导光催化剂

甲烷中 CH 键的高活化势垒，再加上甲醇和其他液态含氧化合物极易过度氧化为 CO2，在历史上对将甲烷直接和选择性地转化为能量密集型燃料和化学原料提出了重大的科学和工业挑战。在这里，我们报告了一种独特的光催化剂结构，即用 AuPd 纳米粒子 (TiO2@SiO2-AuPd) 装饰的二氧化硅封装的二氧化钛，它可以防止甲醇在其表面过度氧化，并且即使在高 UV 强度下也具有高选择性和高氧化物产率。这种室温方法实现了对含氧化合物的高选择性 (94.5%)，在 CH4 和 O2 的总压力为 9.65 bar 时，含氧化合物的产率为 15.4 mmol/gcat·h。通过跟踪光生自由基和系统地改变反应条件，进一步阐明了光催化剂系统的基本工作原理。催化剂设计原理被证明可推广用于其他烷烃的选择性氧化。