The order of loading affects photocatalytic nitrogen fixation activity of the ternary composites of PdO/Au–TiO2

Abstract

As a promising technology for energy storage and conversion, solar-driven reduction of nitrogen to ammonia has attracted a lot of attention. Thus, ternary nanocomposites of PdO/Au–TiO₂ and Au/PdO–TiO₂ were constructed in order to enhance the photocatalytic activity of TiO₂. Because of the distinctive structure of PdO/Au–TiO₂, the TiO₂ supplies more sites of absorption and reaction; PdO improves whole-light harvesting; and Au is used as an electron transfer medium. All these phenomena facilitate the interfacial charge transfer and efficient separation of photogenerated electrons and holes. Characterization was performed, including XRD, FT-IR, STEM-EDS, and XPS, to confirm the presence of both Au and PdO nanoparticles on the TiO₂ surface and, therefore, the formation of these ternary nanocomposites. The photocatalytic activity of the ternary nanocomposites was tested and, as expected, PdO/Au–TiO₂ exhibits a higher photocatalytic nitrogen fixation performance (198.4 mg L⁻¹) compared to Au/PdO–TiO₂. This is mainly due to the fact that the loading order of Au and PdO on TiO₂ has a significant effect on the pathway of electron transport; moreover, the PdO/Au–TiO₂ composite has lower carrier recombination efficiency and better charge transfer capability, and thus has the best photocatalytic nitrogen fixation performance. These findings are of great significance in the design of effective photocatalytic materials in the field of solar energy conversion.