Phytogenic‐Assisted Synthesis of ZnO/SnO ₂ Hybrid Catalyst for Photocatalytic Degradation of Malachite Green

Abstract

ABSTRACT Industrial discharge of synthetic dyes like malachite green (MG) poses significant environmental hazards due to their toxicity and persistence. Photocatalytic degradation using semiconductor catalysts offers a sustainable remediation approach, yet efficiency is limited by rapid electron‐hole recombination. Here we report the phytogenic‐assisted synthesis of ZnO/SnO 2 hybrid catalysts using Dovyalis abyssinica ( D. abyssinica) leaf extract, forming stable heterojunctions with enhanced charge separation and an intermediate band gap of 3.25 eV. Notably, this is the first study to employ D. abyssinica leaf extract as a dual reducing and capping agent for the green synthesis of ZnO/SnO 2 heterojunction photocatalysts, enabling controlled interfacial contact and improved charge‐transfer efficiency. Structural, morphological, optical, and thermal properties of the catalysts were characterized by XRD, SEM, FTIR, DRS, BET, and TGA–DSC analyses, confirming improved surface properties and thermal stability. Under visible light, the ZnO/SnO 2 ‐0.05 hybrid achieved 89.12% degradation of MG within 80 min, outperforming individual ZnO and SnO 2 catalysts. Kinetic analysis followed pseudo‐first‐order behavior, and scavenging experiments identified holes and superoxide radicals as primary reactive species. The catalyst maintained over 70% activity after six reuse cycles. These findings demonstrate the potential of green‐synthesized ZnO/SnO 2 hybrids as efficient, stable, and reusable photocatalysts for wastewater treatment applications.