Synergistic effect of nitrogen-vacancy generation and S-doping within g-C3N4: S-scheme homojunction photocatalysts for effectual NH3 production upon simulated solar light

Abstract

The photocatalytic production of ammonia from air nitrogen and water is green and sustainable, because the primary resources are available and abundant. In the present research, binary nitrogen-vacancy-rich g-C₃N₄/S-doped g-C₃N₄ (abbreviated as NvrGCN/S-GCN) nanocomposites were synthesized by an easy method and employed for N₂ photofixation reaction. The amount of ammonia produced by the optimum NvrGCN/S-GCN nanocomposite was 31,824 μmol/L.g, which was almost 62, 3.2, and 3.3 times more than GCN, NvrGCN, and S-GCN photocatalysts, respectively. The S-type homojunction formed between NvrGCN and S-GCN counterparts is responsible for the promoted surface area, prolonged life for charge carriers, and less resistance for charge migration, which altogether collaborated in the improvement of nitrogen photofixation reaction toward ammonia production. To gain more insights about the reaction mechanism, the effects of light, water, air, solution pH, electrons, and protons on the ammonia production rate were explored. Furthermore, the amount of nitrate, nitrite, and hydrazine produced in the reaction media was assayed. The results of this research provides a straightforward procedure for fabrication of homojunction photocatalysts for ammonia production from nitrogen gas and water.