Synergistic interplay of CuOx and Pd nanodots on TiO2 for efficient and highly selective photocatalytic oxidation of CH4 to oxygenates with O2

Abstract

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 CuO_x 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.