Nanoscale zinc oxide based heterojunctions as visible light active photocatalysts for hydrogen energy and environmental remediation

In the recent years, zinc oxide has emerged as one of the promising alternate materials to titania for photocatalytic applications due to its several advantages properties. This review recapitulates the ongoing advancement in the field of ZnO-based heterojunctions as visible light responsive photocatalysts for energy conversion (hydrogen evolution) and environmental remediation (pollutants degradation) applications. After a short introduction about zinc oxide materials, the various approaches utilized in the design and development of efficient ZnO-based nanoheterostructures has been discussed in detail. Specifically, strategies such as coupling ZnO with other semiconductors, supporting on carbonaceous materials, decorating with noble metal nanoparticles, doping with heteroatoms and engineering defects in the semiconductor material have been elaborated with a particular emphasis on hydrogen energy and organic pollutants removal. Finally, the future perspective of this material has been highlighted. This comprehensive review not only summarizes the recent literature in this topic, but also provides a detailed insight on the scope of this material for hydrogen energy and environmental remediation applications.