Effective strategy to coupling Zr-MOF/ZnO: Synthesis, morphology and photoelectrochemical properties evaluation

Highlights: • ZnO/MOF heterostructure were formed by mechanical mixture and heat treatment. • Heterostructure outcome on structural and optical properties were investigated. • Separation of photoinduced charge carries was improved with Zr-MOF addition. Zr-MOF was coupled with ZnO particles by mechanical mixture followed by heat treatment at 400°C. The Zr-MOF influence on the ZnO structure was investigated by means of X-ray diffraction (XRD), surface area analysis (BET), electron microscopy (SEM and TEM), spectroscopy (XPS) and photoelectrochemical experiment. The main phase of the synthesized samples well matched the hexagonal wurtzite structure of ZnO. The XPS analysis confirm the heterostructure formation between ZnO and Zr-MOF materials and shows that the sample with 25wt% Zr-MOF (ZnO/MOF25) has the higher proportion of lattice oxygen compared to the pristine ZnO and the sample with 50wt% Zr-MOF (ZnO/MOF50). The reduction in the oxygen vacancies in the ZnO/MOF25 sample supports the greater effectiveness of heterostructure formation in this sample. The results also indicated that the ZnO/MOF25 sample is a promising photoelectrode for solar cells.