Current updates on p-type nickel oxide (NiO) based photocatalysts towards decontamination of organic pollutants from wastewater

Nickel oxide (NiO) semiconductor is an interesting material in photocatalysis applications due to its p-type nature and high hole concentration properties. These properties of NiO promote its effective p-n heterojunctions interfacial charge carriers' separation and transmission efficiency for improved photocatalytic performance. The review discusses the photocatalytic properties of NiO and its heterostructures with application focus in photodegradation removal of various organic wastewater contaminants. The photodegradation mechanism of NiO-based photocatalysts with respect to improvements in charge separation and transfer for their effective redox utilization in the removal of organic pollutants is discussed. The review highlights the knowledge on interplay correlations of NiO photocatalytic properties with electronic and band structure properties of p-type NiO from computational analysis viewpoint via modulation of defects and vacancies are highlighted. Furthermore, the various strategies to optimize the photoactivity properties of NiO-based photocatalysts via structural modifications driven by doping, heterojunction interfaces with metal oxides and hybrid carbon composites are deliberated. Finally, the overview of the potentials and shortcomings of various NiO junctions interfaced photocatalysts in photodegradation removal of aqua organic pollutants is presented to strengthen the foundation knowledge for further design and development of new NiO-based photocatalysts.