Photo-electrochemical properties of p-type AgCoO2 prepared by low temperature method. (1st March 2019)

• Record Type: Journal Article
• Authors: Saib, F.; Özel, F.; Sarılmaz, A.; Mahroua, O.; Bellal, B.; Trari, M.
• Is Part Of: Materials science in semiconductor processing. Volume 91(2019)
• Page Start: 174
• Page End: 180
• Publication Date: 2019-03-01
• Subjects: Nano sized -- Co-precipitation -- Delafossite AgCoO2 -- Photo electrochemistry -- Hydrogen; Semiconductors -- Periodicals; Integrated circuits -- Materials -- Periodicals; Semiconducteurs -- Périodiques; Circuits intégrés -- Matériaux -- Périodiques; Electronic journals; 621.38152
• DOI: 10.1016/j.mssp.2018.11.026
• Languages: English
• ISSNs: 1369-8001

Abstract

Abstract: AgCoO2 prepared by co-precipitation at low temperature (~ 80 °C) is characterized by physical and photo-electrochemical techniques. The X-ray diffraction shows broad peaks with a particle size of ~ 20 nm and a specific surface area of ∼ 28 m 2 g −1 . The forbidden band (1.33 eV) is due to Ag + : d → d transition, further transition at 4.50 eV is assigned to the charge transfer. The transport properties, measured up to 650 K, indicate intrinsic conductivity: σ = σo exp{− 0.24 eV/kT (Ω-cm) −1 }, supporting a phonon assisted conduction mechanism. An exchange current density of 1.27 mA cm −2 in Na2 SO4 (0.1 M) solution is consistent with the electrochemical stability up to 0.8 V SCE . The capacitance measurement (C −2 - E) indicates p type conduction, with a flat band potential (Efb ) of 0.26 V SCE and a holes density (NA ) of 7.38 × 10 19 cm −3 due to the oxygen insertion in the layered lattice. The electrochemical impedance spectroscopy (EIS) data, recorded in the range (1 mHz - Hz), reveals a predominant bulk contribution with a low depletion angle of 3° and a pseudo capacitive behavior. As application, AgCoO2 is tested for the hydrogen production upon visible illumination owing to the potential of its conduction band (−0.83 V SCE ), less cathodic than that of H2 O/H2 (~ −0.5 V SCE ). H2 evolution rate of 79 µmol g −1 min −1 is determined at neutral pH with a quantum yield of 1.92% in presence of NO2 - as hole scavenger; no Ag deposition was observed after photocatalysis.