Ce-Doped W₁₈O₄₉ Nanowires for Tuning N₂ Activation toward Direct Nitrate Photosynthesis

Abstract

Nitrate acts as a fundamental raw material in modern industrial and agricultural fields. Recently, photocatalytic nitrogen oxidation into nitrate has been expected to be an alternative method to replace the industrial nitrate synthesis process, which encounters many challenges, i.e., huge energy consumption and greenhouse gas emission. We synthesized Ce-doped W₁₈O₄₉ nanowires (Ce-W₁₈O₄₉) to realize photocatalytic nitrogen oxidation into nitrate under mild conditions. The defect state generated by coupling of Ce³⁺ introduction and surface plasma state acts as an "electron trap" to restrain photogenerated electrons, so as to facilitate the separation of photogenerated electron-hole pairs and prolong their lifetime. W₁₈O₄₉ doped with 5 mol % Ce exhibited the highest yield of nitrate (319.97 μg g^-1 h^-1) without any sacrificial agent, which is about 5 times higher than that of pristine W₁₈O₄₉. This work provides new insight into achieving high-efficiency photocatalytic nitrate evolution activity from direct N₂ oxidation by controlling the energy band structure of photocatalysts.