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.