Solvothermal synthesis of various C3N4 films on FTO substrates and their photocatalytic and sensing applications

This paper reports solvothermal syntheses of pristine and KOH-NaCl-modified melon and melon-rGO composite films without post annealing and their applications in photocatalysis and Cu2+ sensing. Melon seed-layer coating enhanced film adhesion to fluorine-doped tin oxide substrates. X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, and Raman spectroscopy were used to verify melon film structures. Assorted complex agents were studied to tailor film morphologies. (001)-Oriented nanorods were observed in KOH-NaCl-modified melon films. Constituent elements were determined based on their binding energies using X-ray photoelectron spectroscopy. Ultraviolet-visible and ultraviolet photoelectron spectroscopy were employed to confirm band gaps and valence band positions, respectively, of melon films. Associated energy-band diagrams were then constructed. The melon-rGO composite films exhibited superior photodegradation of methylene blue (degradation rate constant [k] congruent to 6.4 x 10(-3)/min) and rhodamine B (k congruent to 2.5 x 10(-3)/min) under visible-light irradiation. The performance was confirmed by nanorod structures, low photoluminescence emission, and high electrochemical surface areas. Furthermore, a reliable photoelectrochemical current density (similar to 0.5 mA/cm(2)) at a 0.6-V bias was obtained for KOH-NaCl-modified melon and melon-rGO composite films. The KOH-NaCl-modified melon films demonstrated excellent selectivity between Cu2+ and Cr6+, indicating promising applications in Cu2+ sensing.

Automated summary

This study reported the solvothermal syntheses of pristine and KOH-NaCl-modified melon films, which showed enhanced adhesion to substrates. Various analytical techniques were used to verify film structures, revealing the presence of (001)-oriented nanorods in KOH-NaCl-modified melon films. These films exhibited superior performance in terms of photodegradation and sensing, making them promising for practical applications.