Trimetallic CdTiZr oxide anchored on rGO: Heterojunction-driven charge separation for improved photocatalytic and antibacterial efficacy

Abstract

The problem with the efficient mineralisation process still persists with the existing dye impurities in the wastewater samples, and it has been attributed to the quick recombination of the charge carriers and the inability to absorb the light with metal oxide-based catalysts. Despite the large amount of investigation that has been conducted on the photocatalytic properties of rGO/metal oxide composites, the trimetallic heterojunction systems that can facilitate directional charge carriers are still underdeveloped. In this study, a trimetallic Cd-Ti-Zr oxide photocatalyst supported on rGO, denoted as CdTiZrO 2 /rGO, was successfully synthesised via the sol-gel method, which can facilitate the charge separation network at the interface. This can, in turn, boost the photocatalytic and antibacterial activities. From the results, it was confirmed that the CdTiZrO 2 /rGO composite has better degradation efficiency compared with the pure CdTiZrO 2 system, with 87.08% for Alizarin Red and 86.96% for Nile Blue, with 60 minutes of exposure time under UV light illumination. This shows that the apparent rate constant increased up to 0.0338 and 0.0337 min⁻¹, which means that the kinetics of the reaction has been accelerated. The reduction of the band gap to 2.11 eV and the enhancement of the movement of electrons across the interface indicate that the charge transport mediated by rGO slows the rate of the combination of electrons and holes. It also demonstrated stable photocatalytic activity after several cycles. It exhibited excellent antibacterial activity towards both Gram-positive and Gram-negative bacteria. These results demonstrate the impact of heterojunction engineering and the integration of charge carriers with a conductive carbon 2 substrate. It facilitates the synthesis of a multifunctional material for environmental remediation on a large scale.