Photocatalytic conversion of CO2 using ZnO semiconductor is an effective, simple, economical
and attractive way of combating energy problems resulting from anthropogenic emissions of CO2
i.e. greenhouse gases to the atmosphere. This article focuses on current advances in CO2
photoreduction by hydrothermal method. The fundamental photocatalytic CO2 reduction system
by photocatalysts especially ZnO has been explicated. The synthetic protocol of ZnO and its
growth mechanism in alkaline solution is elaborated with specific illustration of defect chemistry
and its influence on CO2 reduction activity and selectivity. Conclusively, brief challenges of its
current state and future prospects were also discussed.