Multifunctional ZnO–g‐C ₃ N ₄ Heterojunctions as Efficient Photocatalysts for Dye Degradation and Sensors for Ethanol Vapor

ABSTRACT

Semiconductor heterojunctions are known to exhibit multifunctional properties. Herein, we report the synthesis of a ZnO–g‐C ₃ N ₄ (Zinc oxide‐graphitic carbon nitride) heterojunction via a wet‐chemical route. The formation of the ZnO–g‐C ₃ N ₄ heterojunction was confirmed by XRD, FTIR, BET, SEM, UV–vis, PL, and XPS spectroscopy analyses. The synergistic interaction between ZnO and g‐C ₃ N ₄ of the ZnO–g‐C ₃ N ₄ heterojunction leads to improvements in the photocatalytic and sensing response against ethanol vapor. Upon exposure to white light, the ZnO–g‐C ₃ N ₄ photocatalyst exhibited a degradation efficiency of ∼92% against Rhodamine B (RhB), a common organic pollutant frequently released in water bodies by textile industries. The ZnO–g‐C ₃ N ₄ composite also demonstrated its gas sensing property as it exhibited a good response of ∼24.5 against exposure to ethanol vapor of low concentration (50 ppm) at room temperature. As a sensor, it also showed relatively fast response/recovery times of 21/6 s and good selectivity. The enhanced multifunctional performance of the composite is attributed to the increased specific surface area and the efficient separation and transfer of photo‐induced electron–hole pairs. Thus, we demonstrate that the synthesized ZnO–g‐C ₃ N ₄ heterojunctions have the versatile potential for both as a good photocatalyst for water pollution mitigation and air‐quality monitoring.