Controllable fabrication of homogeneous ZnO p-n junction with enhanced charge separation for efficient photocatalysis

• Published in: Catalysis today 2019-09, Vol.335, p.151-159
• Main Authors: Wang, Songbo, Huang, Chen-Yu, Pan, Lun, Chen, Ying, Zhang, Xiangwen, Fazal-e-Aleem, Zou, Ji-Jun
• Format: Article
• Language: English
• Subjects: Metal vacancy; Oxygen vacancy; p-n Homojunction; Photocatalysis; Zinc oxide
• ISSN: 0920-5861; 1873-4308
• DOI: 10.1016/j.cattod.2018.10.059

ZnO p-n homojunctions with tunable p/n ratio was fabricated by decorating n-ZnO nanoparticles on p-ZnO leaves and shows excellent performance in charge separation and photocatalysis. [Display omitted] •ZnO p-n homojunction was fabricated by decorating n-type ZnO NPs on p-type ZnO.•ZnO p-n homojunction is abundant in both Vo and VZn simultaneously.•The p-n homojunction shows high efficiency in charge transfer and separation.•ZPN-5 with suitable p/n ratio shows the highest photocatalytic and PEC performance. Construction of junctions between semiconductors is an effective way to promote charge separation and thus improve the photoelectrochemical and photocatalytic performance. Specifically, p-n homojunctions are more efficient due to the larger driving force and lower transfer barrier over the interface. Herein, we fabricated ZnO p-n homojunctions by depositing n-type ZnO nanoparticles (with oxygen vacancy) on the surface of p-type ZnO (with metal vacancy). The structures of the composite were well characterized by TEM, XRD, TG, XPS and EPR analyses. Meanwhile, both the “V-shaped” Mott-Schottky plots and anodic shift of onset potentials confirmed the existence of p-n homojunction, which exhibits much more efficient charge transfer and separation than pure type ZnO as indicated by PL and EIS measurements. As a result, p-n homojunction exhibited activity of 3.2-fold and 3.3-fold higher than pure p-ZnO in photodegradation of phenol and as photocathode in photoelectrochemical water splitting, respectively. This work provides a new strategy for the design and fabrication of highly efficient photocatalysts with promoted charge separation.