Current perspective of nano-engineered metal oxide based photocatalysts in advanced oxidation processes for degradation of organic pollutants in wastewater

Metal oxides have attracted considerable attention as an emerging group of visible-light-driven photocatalysts due to their cleaner processes, outstanding photo-oxidation ability and high performance in degradation of organic contaminants via advanced oxidation processes. However, metal oxides are not attractive when it came to faster recombination rates, the ability to make full use of light and the migration of photogenerated electrons. In this paper, a review of different nano-engineered metal oxides on the synthesis, modifications and efficiencies for degradation of organic pollutants is discussed. Some major categories of nano-engineered metal oxides include titanium oxides, zinc oxides, copper oxides, iron oxides, silver oxides, tungsten oxides, platinum oxides, bismuth oxides and other metal oxides. The complex mechanism of various nano-engineered metal oxide based photocatalyst with their limitations is critically narrated. Also, for improvement, doping with metals, non-metals, and metalloids has been discussed to enhance the photocatalytic performance of metal oxide photocatalysts. Finally, comments on current obstacles, research directions, and future perspectives are offered to aid in the nano-engineered design and configuration of highly efficient solar-light-driven photocatalysts for environmental cleaning and energy conversion.