Direct photocatalytic methane oxidation to produce liquid oxygenates offers a promising approach for the upgrading of abundant methane under mild conditions, yet it remains a formidable challenge in achieving high reaction rates while maintaining high selectivity. Herein, we report the highly dispersed CuOx and Pd nanodots decorated TiO2 for photocatalytic oxidation of CH4 with O2 at room temperature, which exhibits a remarkable C1 oxygenates production rate of 39.5 mmol·g−1·h−1 with a nearly 100 % selectivity, outperforming most of the state-of-the-art photocatalysts. Both experimental and theoretical studies suggest that the impressive photocatalytic performance is attributed to the synergy of Cu+ species and Pd nanodots. Cu+ species not only promote the interfacial electrons transfer from TiO2 to Pd, but also mediate CH4 oxidation reaction to avoid overoxidation of oxygenates to CO2, while the resulting electron-rich Pd sites boost the production of primary products (CH3OOH and CH3OH) by lowering the reaction energy. This work provides a new pathway for developing highly efficient photocatalysts for the selective conversion of methane to value-added chemicals by designing bimetallic cocatalysts.

中文翻译：

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CuOx 和 Pd 纳米点在 TiO2 上的协同作用，用于 CH4 高效、高选择性的光催化氧化，以 O2 为氧合物


直接光催化甲烷氧化生产液态含氧化合物为在温和条件下提纯丰富的甲烷提供了一种很有前途的方法，但在保持高选择性的同时实现高反应速率仍然是一项艰巨的挑战。在此，我们报道了在室温下用 O2 光催化氧化 CH4 的高分散性 CuOx 和 Pd 纳米点修饰的 TiO2，其表现出 39.5 mmol·g-1·h-1 的显着 C1 氧化物产生速率，选择性接近 100%，优于大多数最先进的光催化剂。实验和理论研究表明，令人印象深刻的光催化性能归因于 Cu+ 物种和 Pd 纳米点的协同作用。Cu+ 物质不仅促进界面电子从 TiO2 转移到 Pd，而且还介导 CH4 氧化反应以避免含氧化合物过度氧化成 CO2，而由此产生的富电子 Pd 位点通过降低反应能促进初级产物（CH3OOH 和 CH3OH）的产生。这项工作为开发高效光催化剂提供了一条新途径，通过设计双金属助催化剂将甲烷选择性地转化为增值化学品。