Ni(OH)2 clusters decorated NiTiO3 Z-scheme heterojunctions with strong O2 activation and robust interfacial built-in electric field for efficient NO photo-oxidation

Abstract

Photocatalytic oxidation offers a viable method for removing low-concentration NO from the atmosphere. However, poor oxygen adsorption-activation capacity and high re-combination rate of electrons and holes limit the photocatalytic NO oxidation activity. To over-come these problems, Ni(OH)2 clusters decorated NiTiO3 Z-scheme heterojunctions are constructed by a precipitation method. The tight interfacial contacts and built-in electric field between the (002) crystal facet of Ni(OH)2 and (012) crystal facet of NiTiO3 promote a Z-scheme charge transfer mechanism. This Z-scheme mechanism will enhance the charge-transfer driving force and result in high separation efficiency of the charges, thus leading to an enhanced photocatalytic performance. Importantly, introducing Ni(OH)2 is considered a promising strategy to enhance the adsorption ability of the O2, NO and NO2. This might help to increase O2 activation efficiency and speed up NO deep oxidation, leading to high NO removal efficiency and low NO2 selectivity. Benefiting from the above excellent properties, the photocatalytic NO oxidation efficiency of Ni(OH)2/NiTiO3 composites is enhanced and the formation of more toxic NO2 is inhibited compared with that of NiTiO3. This work offers a promising and effective route to design efficient NiTiO3-based photocatalysts in the application of environmental remediation.