Photocatalytic conversion of nitrogen to ammonia with water on triphase interfaces of hydrophilic-hydrophobic composite Bi4O5Br2/ZIF-8

Photocatalysis can produce NH3 using N-2 and H2O at room temperature and atmospheric pressure, which has been considering as a safe, clean, and sustainable NH3 synthesis. However, the poor solubility and slow diffusion rate of N-2 in water severely limited the nitrogen activation efficiency. Herein, we solve this problem by developing a hydrophilic-hydrophobic structure photocatalyst with gas-liquid-solid triphase reaction interface, where hydrophilic Bi4O5Br2 is deposited on the surface of hydrophobic ZIF-8 to form a novel Bi4O5Br2/ZIF-8 composite photocatalyst. Such triphase interface architecture allows the direct delivery of N-2 from gas phase to the photocatalytic reaction interface replaced the diffusion of N-2 through the liquid phase. This rapid supply of N-2 can efficiently capture photoinduced electrons, thereby promoting the utilization efficiency of photo-induced electrons and the nitrogen fixation activation. This novel Bi4O5Br2/ZIF-8(30%) composite photocatalyst with good triphase contact performance shows obviously improved photocatalytic nitrogen fixation activity 327.338 mu mol.L-1.h(-1).g(-1) (3.6 times than that of Bi4O5Br2). Furthermore, efficient molecular nitrogen activation by Bi4O5Br2/ZIF-8 further brings out an attractive potential to improve other gas-consumption reactions, such as CO2 reduction, according to this concept of triphase direct contact.