Harnessing Janus structures: enhanced internal electric fields in C3N5 for improved H2 photocatalysis

Homojunction engineering holds promise for creating high-performance photocatalysts, yet significant challenges persist in establishing and modulating an effective junction interface. To tackle this, we designed and constructed a novel Janus homojunction photocatalyst by integrating two different forms of triazole-based carbon nitride (C3N5). In this design, super-sized, ultrathin nanosheets of carbon-rich C3N5 grow epitaxially on a nitrogen-rich honeycomb network of C3N5, creating a tightly bound and extensive interfacial contact area. This arrangement enhances the built-in internal electric field (IEF) between the two forms of C3N5, facilitating faster directional transfer of photogenerated electrons and improved visible-light harvesting. Consequently, Janus-C3N5 achieves a remarkable H2 evolution rate of 1712.4 μmol h−1 g−1 under simulated sunlight, which is approximately 5.58 times higher than that of bulk C3N5 (306.8 μmol h−1 g−1) and 14.1 times higher than another form of bulk C3N5 (121.2 μmol h−1 g−1). This work offers a new approach to design efficient homojunction-based photocatalysts.