Single source precursor derived ZnO–PbO composite thin films for enhanced photocatalytic activity

Abstract

Bimetallic oxide composite has emerged as an effective stratagem to enhance the performance of metal oxide photoanodes. ZnO–PbO composite thin films were deposited onto fluorine doped tin oxide (FTO) coated glass substrates from a newly synthesized polymeric Zn–Pb based single source precursor {ZnPb(OAc)(TFA)3(THF)2}n via aerosol-assisted chemical vapor deposition (AACVD) technique. The precursor was synthesized by the reaction of zinc acetate dihydrate (Zn(CH3CO2)2⋅2H2O), and lead acetate trihydrate (Pb(CH3CO2)2⋅3H2O) in the presence of triflouroacetic acid using THF as a solvent. The prepared complex {ZnPb(OAc)(TFA)3(THF)2}n, was characterized by FTIR, NMR, and single crystal X-ray analysis. The polymeric precursor had melting point of 72 ᴼC and decomposed at 450 ᴼC with 36.6% residue as obtained via thermogravimetry (TG/DTG). X-ray diffraction and energy-dispersive X-ray spectroscopy studies of thin films predicted a prominent growth of ZnO–PbO crystallites onto FTO substrate. FESEM analysis illustrated a homogenous and smooth surface with evenly distributed microspheres. The direct band gap of ZnO–PbO composite, estimated by UV–Vis spectroscopy is 2.40 ​eV that proves the narrowing of band gap in composite form of ZnO with PbO. Photoelectrochemical properties of the as-synthesized ZnO–PbO composite thin films investigated in the presence of 0.5 ​M aqueous NaOH solution shows photocurrent density of 705 ​μA ​cm−2 at an applied potential of +0.8 VSCE. The charge transfer dynamics of thin films were also examined using an electrochemical impedance spectroscopy (EIS) technique.