Anisotropic ZnO nanostructures and their nanocomposites as an advanced platform for photocatalytic remediation

Abstract In pursuit of advanced heterogeneous photocatalysts, ZnO has emerged as a promising option in various fields of applications including wastewater treatment. Although ZnO is well-known for many advantageous properties (e.g., optical band structure and electronic properties), its efficacy in solar-driven heterogeneous photocatalysis also suffers from a number of demerits (e.g., fast recombination of charge carriers and limited photon absorption). As such, considerable efforts are needed for the effective and practical scale-up of ZnO photocatalysts. This article provides a detailed literature review of the synthesis and modification of ZnO nanostructures with tuned band structures and controllable morphologies for solar light harvesting. The potential of anisotropic ZnO nanostructures is also discussed with respect to the photocatalytic degradation/reduction of organic/inorganic water pollutants. Further, the role of various metal dopants for the enhancement of photocatalytic activity has also been assessed by evaluating their photocatalytic performances under UV-visible or solar irradiation. Finally, our discussions are expanded to describe the prospects of developed ZnO nano-photocatalysts for real-world applications based on improved light-harvesting efficiency and mechanical stability.