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 (K 4 Fe(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.

Photoelectrochemical Methods for the Determination of the Flat-Band Potential in Semiconducting Photocatalysts: A Comparison Study

“…Another method is the photocurrent onset potential (POP). − Equation shows that the photocurrent decreases to zero value as the applied potential achieves the level of E FB . Therefore, the potential when the photocurrent achieves zero value (i.e., photocurrent onset potential) can be attributed to the flat-band potential in the photocatalyst.…”