Fabrication of Ag-ZnO composite thin films for plasmonic enhanced water splitting

Abstract

Research on plasmonic photoactive materials has resulted in some significant advancements in UV–Vis photo-active catalytic reactions. In this study, pristine ZnO and Ag-ZnO thin films were deposited onto fluorine doped tin oxide (FTO) coated glass substrate from a newly synthesized zinc molecular precursor, {Zn5(TFA)7(OH)2(H2O)4(OAc)}n.2(C4H6O2) [TFA = trifluoroacetate, OAc = acetate], and its homogenous solution with Ag(CH3COO), respectively, via the aerosol assisted chemical vapor deposition (AACVD) technique. The precursor was analyzed by microanalysis, melting point, proton nuclear magnetic resonance (1H NMR), Fourier transformed infra-red (FT-IR), thermogravimetry (TG) and single crystal analysis. Powder X-ray diffraction (PXRD), Raman spectroscopy, field emission scanning electron microscopy (FESEM) coupled with energy dispersive X-ray (EDX), UV–Vis spectroscopic and photoluminescence (PL) analyses were carried out to investigate the phase purity, structural morphology, composition and optical properties of the as-synthesized thin films. Linear scan voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) confirmed that the photo-electrochemical performance of Ag-ZnO for water splitting was much improved compared to ZnO. These results confirm that Ag is an efficient surface plasmon resonance photosensitizer which mediates the interfacial charge transfer process, thus extending the light response of pristine ZnO into the visible region.