Photocatalytic and Photoelectrocatalytic Water Splitting by Porous g-C₃N₄ Nanosheets for Hydrogen Generation

Semiconductor-based photocatalytic and photoelectrochemical water splitting is an ultimate source of hydrogen generation for tackling the ongoing fuel crisis. In this context, we have synthesized a highly porous N-rich g-C3N4 metal-free, nontoxic semiconductor through the polycondensation method. In the present work, we have discussed the major changes in the morphology of g-C3N4 after acidic exfoliation thoroughly by using transmission electron microscopy (TEM) and scanning electron microscopy (SEM) studies. The chemical purity of the as-synthesized materials was analyzed by using powder X-ray diffraction (PXRD). The specific surface area and porosity of the materials were obtained through Brunner–Emmet–Teller (BET) surface area studies. Besides this, the electronic structure of g-C3N4 was discussed through X-ray absorption near-edge spectroscopy (XANES), and the elemental composition was determined by using X-ray photoelectron spectroscopy (XPS). Moreover, the dependency of the sacrificial agents of g-C3N4 was discussed in detail by using sodium sulfide/sodium sulfite (Na2S/Na2SO3) and triethanolamine (TEOA). It was observed that exfoliated g-C3N4 shows remarkable hydrogen evolution in the presence of TEOA and an efficient quantum yield up to 12%, which is 1.7-fold higher than in the presence of Na2S/Na2SO3 (7%). Furthermore, to harness most of the solar light spectrum, a high current density and improved Faradaic efficiency during the photoelectrocatalysis have been reported.