Efficient Photocatalytic CH4 Conversion to C1 Oxygenates on Pd/C-TiO2/g-C3N4 Photocatalyst

Abstract

In this work, a Pd_x/C-TiO₂/g-C₃N₄-y photocatalyst was synthesized by combining g-C₃N₄ with Ti₃C₂ through heat treatment, followed by loading with noble metal Pd. Morphological characterization and XPS before and after reaction revealed the formation of a C-TiO₂/g-C₃N₄ Z-scheme heterojunction system with Pd deposited on top. The optimal catalyst, Pd_0.8/C-TiO₂/g-C₃N₄-5, exhibited significantly enhanced total C1 yields under mild conditions, achieving 6.1 and 2.6 times the yields of g-C₃N₄ and C-TiO₂, respectively. Notably, the HCHO yield was improved to 3854.79 μmol·g^–1·h^–1. Mechanistic studies indicated that the C-TiO₂/g-C₃N₄ heterojunction significantly enhanced the CH₄ conversion performance by effectively suppressing photogenerated charge recombination. Additionally, the loaded Pd promoted CH₄ adsorption and activity, further improving the CH₄ conversion efficiency. Furthermore, Pd contributed to the high C1 yield by accelerating the generation of both and •OH radicals.