Defective titanium dioxide nanobamboo arrays architecture for photocatalytic nitrogen fixation up to 780 nm

Solar-driven nitrogen fixation is a potential solution to satisfying industrial and agricultural demand, but is severely hampered by the difficulties in capturing, activating and cleaving the dinitrogen (N-2). Here, the defect TiO2 nanobamboo arrays (DTiO2 NBAs) is designed with an electro-reduction strategy, which, for the first time, successfully converted N-2 to ammonia (NH3) in the visible and near infrared light range under ambient conditions, without any sacrificial agent or noble-metal co-catalysts. A highly selective NH3 yield of 48.3 mg m(-2) h(-1) (178 mu mol g(-1) h(-1), no N2H4 formation) is obtained on the DTiO2 NBAs haired titanium foil. The apparent quantum efficiency (AQE) was measured to be 0.39% at 365 nm, 0.12% at 405 nm, 0.11% at 450 nm, 0.15% at 532 nm, 0.24% at 650 nm, and 0.07% at 780 nm. It is found that the electro-reduction process creates amorphous surface layer with modest oxygen vacancy (O-vac) density so as to greatly enhance light harvesting, charge carrier, photo-thermal effect, as well as nitrogen adsorption and hydrogenation activity. The alternating photo-fixation pathway is also confirmed by density functional theory (DFT) calculations. This novel nanobamboo TiOx architecture shows a potential as a new artificial nitrogen fixation for environmentally friendly NH3 production.