Tuning p-Band Center of Carbon Nitride Homojunction Photocatalysts through Strain Effect for Solar-Driven H2 Production

The arduous kinetic behaviors of charge carrier transfer from generation sites to surface redox sites as well as their reaction barrier with H2O have not been resolved, which seriously hinder the improvement of solar-to-H2 conversion (STH). Herein, a g-C3N4 microtube homojunction ((t-C3N4)um) evolving from urea ((t-C3N4)u) and melamine ((t-C3N4)m) was designed for unlocking the above kinetic constraints by optimizing the p-band center within the strain effect. Photoexcited electrons and holes are driven to the reductive (t-C3N4)m and oxidative (t-C3N4)u by localized electric field to dehydrogenate *–OH and couple *–O for H2 and O2 evolution, respectively, with a noticeable STH of 2.69% at 65 °C under AM 1.5 G irradiation, which has been revealed by in situ diffuse reflectance infrared Fourier transform spectroscopy, femtosecond transient absorption spectroscopy, and Hall effect tests. The strategy provides unique insights into expanding the types of homojunctions and even heterojunction photocatalysts and further improving their STH.