Boosting the visible-light photoelectrochemical performance of C3N4 by coupling with TiO2 and carbon nanotubes: An organic/inorganic hybrid photocatalyst nanocomposite for photoelectrochemical water spitting

Developing photoanode with proficient sunlight harvesting, stability as well as enhancing the electron injection across the interface remains a major challenge in the photoelectrochemical water splitting strategy to generate hydrogen. Herein, we design and fabricate an organic/inorganic TiO2/C3N4/CNT photoanode by a hydrothermal technique which exhibits much enhanced photoelectrochemical properties. The TiO2/C3N4/CNT photoanode exhibits a photocurrent density of 2.94 mA/cm(2), which is similar to 6.4 time higher than pristine graphitic carbon nitride (C3N4) at an applied bias potential of 0.6 V vs. Ag/AgCl. The excellent photoelectrochemical performance benefits from the impactful migration of photo-induced electrons at the TiO2/C3N4 interface from C3N4 to TiO2 and their intimate interface contact with CNT. Kelvin probe force microscopy result shows a smaller interface barrier height (similar to 10 meV) between TiO2 and C3N4, suggesting that electrons transport is favored through TiO2/C3N4 interfaces in a ternary photoanode. The TiO2/C3N4/CNT photoanode exhibited an onset potential of 0.25 V vs. Ag/AgCl which is much lower compared to pristine C3N4. The electrochemical impedance spectroscopy results also confirmed the enhanced electron injection across the interface in a ternary photoanode. These results demonstrate a promising approach to develop a highly proficient and visible light active photoanode with excellent stability for renewable energy applications. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.