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Influence of g-C₃N₄ Precursors in g-C₃N₄/NiTiO₃ Composites on Photocatalytic Behavior and the Interconnection between g-C₃N₄ and NiTiO₃

Pham, Thanh-Truc, Shin, Eun Woo
Langmuir 2018 v.34 no.44 pp. 13144-13154
carbon nitride, chemical bonding, dicyandiamide, irradiation, melamine, models, nitrogen, photocatalysis, photocatalysts, thiourea, urea
In this study, composite photocatalysts were produced from NiTiO₃ and N₂-rich precursors (dicyandiamide, melamine, urea, and thiourea) under N₂ flow conditions. The goal of the study was to investigate the interaction between NiTiO₃ and the synthesized g-C₃N₄. The properties of the g-C₃N₄/NiTiO₃ (CNT) composites were different depending on the starting materials. Dicyandiamide and thiourea created strong connections with NiTiO₃ and resulted in the generation of Ti–N and Ti–O–S bonds. Urea and melamine, however, had difficulty forming g-C₃N₄ structures or interconnections with NiTiO₃. The Ti–N and Ti–O–S bridges in the composite photocatalysts led to increased photocatalytic activity as well as inhibition of the recombination rate. Additionally, the band diagrams of g-C₃N₄ prepared from dicyandiamide and thiourea exhibited positions suitable for the Z-scheme charge-transfer model with NiTiO₃, implying that the composite photocatalysts were applicable for photocatalytic degradation of organic contaminants under the visible-light irradiation. Higher reaction rate constants for the composites prepared with dicyandiamide and thiourea confirmed the significant role of the Ti–N/Ti–O–S bridge between g-C₃N₄ and NiTiO₃.