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

Photocatalysis can produce NH3 using N2 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 N2 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 N2 from gas phase to the photocatalytic reaction interface replaced the diffusion of N2 through the liquid phase. This rapid supply of N2 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 μmol·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.