In-Situ Construction of Atomic-Level Fe–O Bond Bridges within Fe2N/g-C3N4 Heterojunction for Efficient Visible-Light-Driven Photocatalytic H2 Production

The limited active sites and faster photogenerated electron–hole pair recombination rate of g-C3N4 restrict its application in photocatalytic H2 production. Constructing heterojunctions has been shown to improve the spatial (directional) separation of photogenerated electrons and holes. However, due to interface mismatch in traditional heterojunction structures and a lack of precise electron transport channels, the photocatalytic efficiency is limited. Here, we developed a two-step calcination approach to create an Fe2N/g-C3N4 heterojunction linked by Fe–O bonds (named as Fe-OCN). The newly formed Fe–O bonds within the heterojunction can act as atomic-level interface electron transfer channels, directly transferring the photogenerated electrons of g-C3N4 to the reactive center Fe2N, significantly improving the charge transfer rate and utilization, thus promoting visible-light-driven photocatalytic H2 production. The optimal Fe-OCN achieved a H2 production rate of 5986.29 μmol g–1 h–1 under visible light, 13.44 times higher than that of the OCN due to efficient charge separation and transfer capabilities. This work provides a constructive reference for the design and synthesis of organic–inorganic heterojunction with chemically bonded interfaces, establishing quick electron transfer channels, and achieving targeted electron transfer.