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

Photocatalysis can produce NH 3 using N 2 and H 2 O at room temperature and atmospheric pressure, which has been considering as a safe, clean, and sustainable NH 3 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 Bi 4 O 5 Br 2 is deposited on the surface of hydrophobic ZIF-8 to form a novel Bi 4 O 5 Br 2 /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 Bi 4 O 5 Br 2 /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 Bi 4 O 5 Br 2 ). Furthermore, efficient molecular nitrogen activation by Bi 4 O 5 Br 2 /ZIF-8 further brings out an attractive potential to improve other gas-consumption reactions, such as CO 2 reduction, according to this concept of triphase direct contact.