Bioinspired TriPhase Interfacial Design Promotes Mass Transfer for Enhanced Photocatalytic Nitrogen Fixation

Photocatalytic Nitrogen Reduction Reaction (PNRR) offers a sustainable alternative to the energy-intensive Haber-Bosch process, yet its efficiency is often constrained by sluggish mass transfer of nitrogen and water. Herein, we report a novel gas-liquid interfacial photocatalytic system composed of 3D printing clay network (CN) and its supported g-C 3 N 4 /Bi 2 MoO 6 heterojunction, which largely overcomes current limitation of mass transfer. The engineered 3D network offers a high surface area for efficient catalyst loading, facilitates repeated internal light scattering and enhances photon harvesting. By positioning the photocatalyst at the air-water interface, the interaction of light with the active sites is no longer constrained by water depth or volume, thereby significantly improving light utilization efficiency. As a result, the CN@g-C 3 N 4 /Bi 2 MoO 6 system achieves a remarkable ammonia production rate of 69.7 μmol . g cat −1 h −1 , representing a 4.4-fold enhancement over conventional powder-based systems. This study not only strongly advances the performance of PNRR, but also provides a universal strategy for enhancing reduction of carbon dioxide through interfacial and structural engineering. CN@ g-C 3 N 4 /Bi 2 MoO 6 is a photocatalytic system at the air-water interface to enable concurrent gas and water mass transfer that inspired by aquatic plants. It forms a N 2 -H 2 O- g-C 3 N 4 /Bi 2 MoO 6 triphase interface to transfer nitrogen and water concurrently, resulting in better nitrogen fixation performance. • g-C 3 N 4 /Bi 2 MoO 6 anchored on a 3D-printed bionic clay network forms a tailored catalytic system. • The microreactor at gas-liquid interface creates a triphase zone for optimized mass transfer. • The thin water film reduces optical loss, enhancing light harvesting at the interface. • CN@g-C 3 N 4 /Bi 2 MoO 6 achieves high nitrogen fixation performance of 64 μmol g cat −1 h −1 .