Abundant hydroxyl groups decorated on nitrogen vacancy-embedded g-C3N4 with efficient photocatalytic hydrogen evolution performance

Abstract

Regulation of the properties of photocatalytic materials that are targeted at maximizing their superiorities in photocatalytic H₂ evolution are essential for full utilization of solar energy but still face enormous challenges. In this work, engineering of hydroxyl and nitrogen vacancies on graphitic carbon nitride (g-C₃N₄) was fabricated via a flexible calcination–hydrothermal method. The characterization indicated that loss of N atoms at N_2C resulted in the exposure of lone-pair electrons on the adjacent C atoms, thus stimulating anchoring of abundant hydroxyl on g-C₃N₄. Meanwhile, hydroxyl and N vacancies could capture the holes and electrons separately, which mitigated the recombination of photogenerated carriers. Furthermore, the improvement in hydrophilicity triggered by hydroxyl and the decreased conduction band caused by the N vacancies were critical for boosting the photocatalytic activity. As a result, an average H₂ evolution rate of 232.75 μmol h⁻¹ g⁻¹ was achieved, which was about 4.2 times higher than that of pristine g-C₃N₄. This research lays good foundations and provides new insights into engineering highly efficient g-C₃N₄ with modified surface and electronic structures.