Photothermal‐Assisted Photocatalytic Nitrogen Oxidation to Nitric Acid on Palladium‐Decorated Titanium Oxide

Abstract Industrial nitric acid production involves multistep processes operating at high temperatures and pressures. Photocatalysis offers an alternative approach for directly transforming nitrogen molecules into nitrogen‐containing compounds under ambient conditions but still faces visible light utilization and product selectivity restrictions. Herein, a tandem photothermal‐assisted photocatalytic nitrogen oxidation system based on palladium‐decorated hydrogenated titanium oxide is fabricated, in which nitric acid is produced as the only nitrogen fixation product. The yield of nitric acid increases from 0.56 µmol g −1 h −1 at room temperature to 4.58 µmol g −1 h −1 (1.42 ppm) at 200 °C, accompanied by an enhanced quantum yield from 0.24% to 0.99% at 350 nm. The photothermal effect of palladium nanoparticles promotes the generation of superoxide radicals and nitrogen oxide intermediates in the gas–solid phase nitrogen oxidation process and contributes to improved nitric acid productivity. Therefore, the photothermal‐assisted photocatalytic nitrogen oxidation strategy opens new avenues toward developing clean and energy‐saving nitric acid production.