Recent progress on heterostructures of photocatalysts for environmental remediation

Abstract

In the recent years, global energy supply demand and environmental pollution have been regarded as one of serious concern. Due to industrial revolution around the globe, million tons of organic/metal ions wastes have been dumped in the water system. In this context, various research groups put numerous efforts for effectual removal/degradation of organic wastes. In particular advanced oxidation processes widely explored for degrading dyes. Metal oxide nanostructures have been one of the most explored nanoparticles class as photocatalysts to apply environmental remediation. In spite of heavy use of metal oxide nanostructure for photocatalysis, yet the wide band gap results in the utilization of ultra violet radiation for degradation. In this context, hetero structures of various visible light active nanomaterials prove to be advantageous over the metal oxide nanostructures. The modification of various metal oxide nanostructures has been reported with various dopants to increase their visible light activity and to inhibit the electron hole pair recombination. Recent advances in the carbonaceous quantum dots, due to their non-toxic, affordable, and extremely proficient nature, high quantum yield, finds application in various fields of science particularly for the photo degradation via. composites formation with metal oxides improves the efficiency of photocatalytic degradation to a greater extent. Therefore, the present review article compiles the recent advancement in improving the efficacy of photocatalysis using various routes like doing and formation of heterostructures. In this review, attempts have been made to classify numerous approaches to operate metal oxide nanostructures as visible light region photocatalyst. Here a comparative study is performed for utilization of dopant included non-metal, transition metal, rare earth metals in metal oxide nanocrystals for visible light response. In addition, composites of metal oxide with carbonaceous quantum dots are reviewed thoroughly and systematically.