Harnessing Janus structures: enhanced internal electric fields in CN for improved H 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 (CN). In this design, super-sized, ultrathin nanosheets of carbon-rich CN grow epitaxially on a nitrogen-rich honeycomb network of CN, creating a tightly bound and extensive interfacial contact area. This arrangement enhances the built-in internal electric field (IEF) between the two forms of CN, facilitating faster directional transfer of photogenerated electrons and improved visible-light harvesting. Consequently, Janus-CN achieves a remarkable H evolution rate of 1712.4 μmol h g under simulated sunlight, which is approximately 5.58 times higher than that of bulk CN (306.8 μmol h g) and 14.1 times higher than another form of bulk CN (121.2 μmol h g). This work offers a new approach to design efficient homojunction-based photocatalysts.