Photoelectrochemical properties of bare fluorine doped tin oxide and its electrocatalysis and photoelectrocatalysis toward cysteine oxidation

• Published in: Electrochimica acta 2016-03, Vol.195, p.59-67
• Main Authors: Mu, Shaolin, Shi, Qiaofang
• Format: Article
• Language: English
• Subjects: Bare FTO; Charge; Cysteine oxidation; Electrocatalysis; Electrodes; Fluorine; Oxidation; Photocatalysis; Photoelectrocatalysis; Photoelectrochemical response; Semiconductors; Tin oxides
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2016.02.139

CVs of 0.30M Na2SO4 solution containing 2.0mM cysteine, curves: (1) glassy carbon electrode, (2) FTO electrode in the dark, (3) FTO electrode in the light illumination, and (4) Pt electrode; pH 10.0, at a scan rate of 60mVs−1. [Display omitted] •First revelation of photoelectrochemical properties of bare fluorine doped tin oxide.•Determination of band gap of energy of FTO in the solution without a redox couple.•Electrochemical and photoelectrochemical catalysis of bare FTO toward cysteine oxidation.•Determination and recognition of cysteine with electrocatalytic and photocatalytic methods.•Rate-determining step of cysteine oxidation at the FTO electrode. We first revealed that the bare fluorine doped tin oxide (FTO) under the cathodic polarization over −0.7V (vs.SCE) shows very sensitive to the irradiating light in a wide wavelength region 850–400nm in the aqueous solution free of a redox couple, and its band gap of energy Eg is determined to be 1.38eV via the photoelectrochemical method. The bare FTO can effectively catalyze electrochemically L-cysteine (CySH) oxidation and especially shows the photocatalytic ability toward CySH oxidation. Thus the bare FTO electrode can be directly used for determination of CySH concentration using cyclic voltammetry in both the dark and light illumination and it can be used to recognize CySH among 20 α-amino acids found in proteins, based on the low oxidation peak potential and unique photoelectric response. The rate-determining step for the photocatalytic oxidation of CySH on the bare FTO electrode is controlled by supply of charge inside the FTO film to the electrode surface, which exhibits the typical characteristics of semiconductors.