Transition Metal Oxides as Photocatalysis Environmental Remediation for Organic Dyes: A Systematic Review

Nanotechnology has enabled transition metal oxide (TMO) synthesis technologies that have led to the development of photocatalytic nanostructure materials. This review concisely highlights the synthetic approaches of TMOs and their application in the breakdown of organic dyes, using both traditional and response surface methodology (RSM). TMOs, including titanium dioxide (TiO 2 ), iron oxide (Fe 3 O 4 ), and zinc oxide (ZnO), have received much interest because of their photocatalytic activity, thermal stability, and environmental friendliness, making them potential materials for organic dyes removal from wastewater. By employing various synthetic approaches such as sol‐gel, hydrothermal, co‐precipitation, and thermal decomposition, this work aimed to explore the impact of various synthesis parameters on the physicochemical properties and the performance of TMO as a photocatalyst. A chosen method between the conventional and RSM approaches for dye degradation is presented, permitting an insight into the strengths and limitations of each of them. The criterion of the RSM method is to find the interconnections between multiple factors, allowing us to eliminate the need to carry out multiple experiments. It is proposed that RSM be incorporated in future research projects because it will open up the ability to have water treatment products that are sustainable and more efficient. Therefore, the nanosized TMOs pose as the potential materials for addressing environmental issues, reminiscent of the organic dye degradation in wastewater treatment.