Photoelectrochemical Properties of α-PbO Films Prepared by Spray Pyrolysis

Abstract

Thin films of photoactive α-PbO have been prepared on fluorine doped tin oxide substrates using spray pyrolysis in the range of 380°C to 470°C. SEM showed the formation of interconnected PbO grains with increase in grain size at elevated temperature. The Raman peak at 147 cm−1 shows the formation of phase pure α-PbO. XPS indicates the phase purity of α-PbO as well as its stoichiometric nature. Photoelectrochemical studies of as-deposited α-PbO in 0.1 M potassium ferrocyanide (K4Fe(CN)6) or potassium iodide (KI) at pH 9.2 under visible light irradiation showed photoanodic and photocathodic current, indicating nearly intrinsic behavior. Photocurrent spectra showed the presence of a semiconductor with an indirect bandgap of 1.9 eV. Doping by inducing oxygen deficiency through annealing in hydrogen and addition of 2 at. % In, shifted the onset potential to more negative values (down to −0.5 vs. Hg/HgO) in KI, indicating successful conversion into n-type semiconducting material. The In doped hydrogen annealed α-PbO shows a flatband potential of −0.58 V vs. Hg/HgO. The IPCE (incident photon to current conversion efficiency) in KI electrolyte was found to be 0.016 in the plateau region (0.6 V vs. Hg/HgO) at an incident wavelength of 532 nm.