Constructing a visible‐active <scp>MgO/NiWO₄</scp> Z‐scheme heterojunction for efficient photodegradation of malachite green

Abstract Background This study examines the growing environmental problem of water pollution caused by the release of organic dyes, with a specific focus on harmful malachite green (MG) causing severe health concerns. Results A MgO/NiWO 4 heterojunction was synthesized through ultrasonic mixing of MgO and NiWO 4 using the ultrasonication technique. X‐ray diffraction, transmission electron microscopy, field emission scanning electron microscopy, photoluminescence spectroscopy and UV–visible spectroscopy were used to study the material's structure, shape and optical features. Photocatalytic experiments were conducted under a xenon lamp to assess the efficiency of the MgO/NiWO 4 heterojunction for the removal of MG dye. The photocatalyst demonstrated enhanced photocatalytic capabilities when MG dye was exposed to light. The photocatalytic degradation mechanism of the system was explained through free radical scavenging experiments. Furthermore, enhanced charge transfer in the heterojunction was confirmed using photoluminescence and electrochemical investigations. Conclusion A possible Z‐scheme was suggested for the degradation mechanism explaining the charge transport of carriers across the junction. The 1:1 MgO/NiWO 4 catalyst emerged as a promising candidate for photocatalytic degradation of MG dye. © 2025 Society of Chemical Industry (SCI).