A scalable approach for functionalization of TiO2 nanotube arrays with g-C3N4 for enhanced photo-electrochemical performance

Graphitic carbon nitride (g-C3N4) has manifested itself as an effective counterpart of titanium di-oxide (TiO2) to extend its photoactivity in the visible range. In this work, g-C3N4 functionalized TiO2 nanotubes were synthesized by electrodeposition of g-C3N4 in bulk on TiO2 nanotubes from a continuously rotating organic suspension at a moderate voltage (similar to 90 V). Additionally, samples with varying time durations were also synthesized to examine the effect of electrodeposition time on the performance of g-C3N4 functionalized TiO2 nanotubes. Photo-electrochemical measurements demonstrated strong light induced activity, with a photocurrent density of 0.14 mA/cm(2) at 1 V vs Ag/AgCl in 1 M Na2SO4 electrolyte. Maximum photoresponse for g-C3N4 functionalized TiO2 nanotubes was upto 4 factors higher than bare TiO2 nanotubes. The crystallinity, morphology and chemical compositions were investigated by XRD, FESEM and XPS respectively. Further, the optical absorption edge, chemical bonds and defects states were evaluated by UV-visible, Raman, FTIR, PL and EPR spectroscopy. The properties of g-C3N4/TiO2 system were correlated with the photocurrent behaviour and a mechanism of the probable role of vacancies and defects in their photo induced activity has been proposed. The study has established a simple and scalable scheme for the functionalization of TiO2 nanotube with g-C3N4 to achieve enhanced photoelectrochemical properties. (C) 2020 Elsevier B.V. All rights reserved.