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A g-C3N4/TiO2 (CN/TiO2) nanocomposite was fabricated by depositing proton-functionalized g-C3N4 nanosheets onto the TiO2 nanotube array films with oxygen vacancies. Proton-functionalized g-C3N4 (p-CN) nanosheets was prepared by sonicationexfoliation of bulk g-C3N4 in the presence of hydrochloric acid. Protonation pretreatment of g-C3N4 reduce the size of g-C3N4 and increase the interfacial contact area of g-C3N4 nanosheets with TiO2 nanotube arrays. TiO2 nanotube arrays containing oxygen vacancy (OV-TiO2) was obtained by NaBH4 reduction, which results in the enhanced visible light absorption. As a result, the best photocurrent density of p-CN/OV-TiO2 nanocomposite is 5.3 times higher than that of CN/TiO2 samples. As further confirmed by photocatalytic degradation of methyl orange (MO), p-CN/OV-TiO2 heterostructure exhibit the highest photocatalytic activity among all the prepared samples. This improved photoelectrochemical (PEC) and photocatalytic performance can be attributed to the formation of a direct Z-Scheme heterostructure between protonated g-C3N4 and TiO2 containing oxygen vacanc [ABSTRACT FROM AUTHOR]

A novel and sensitive electrochemical method was proposed for the determination of Sunset yellow (SY) using an expanded graphite paste electrode (EGPE). The EGPE was prepared by mixing expanded graphite (EG) with solid paraffin. EG was characterized with scanning electron microscopy. Compared with flake graphite paste and carbon paste electrode, the EGPE showed a higher electrocatalytic activity toward the oxidation of SY. The EGPE exhibited wide linear response of 5.0 x 10-8 x 10-6 mol/L with a detection limit down to 5.0 nmol/L (S/N = 3) and good accuracy, precision, reproducibility. The proposed method was successfully applied in the determination of SY in jelly and fruit juice. [ABSTRACT FROM AUTHOR]