Photoelectrochemical Properties of Particulate CuGaSe2 and CuIn0.7Ga0.3Se2 Photocathodes in Nonaqueous Electrolyte

Abstract

The photoelectrochemical (PEC) properties of particulate CuGaSe2 (CGSe) and CuIn0.7Ga0.3Se2 (CIGS) photocathodes were evaluated in an acetonitrile electrolyte containing iron(III) acetylacetonate (Fe(acac)3) under simulated sunlight illumination, and compared to that in a typical aqueous electrolyte. The particulate CGSe and CIGS photocathodes can generate higher photovoltages, which is a more positive onset potential than the hydrogen evolution in an aqueous electrolyte possibly due to the facile one-electron reduction of Fe(acac)3, while the cathodic photocurrent decreased due to light shielding by the colored nonaqueous electrolyte. Indeed, the incident-photon-to-current conversion efficiencies (IPCEs) of the photocathode evidently decreased in the wavelength region of 400–600 nm, where the Fe(acac)3 acetonitrile electrolyte shows an intense light absorption. The CIGS photocathode generates a higher cathodic photocurrent than the CGSe during hydrogen evolution from the aqueous electrolyte, while the CGSe exhibits superior PEC performances to CIGS in the nonaqueous electrolyte, which can be explained by the energy level of the conduction band minimum (CBM) of CGSe and CIGS compared to the reduction potential for Fe(acac)3. Finally, the two-electrode PEC-voltaic (PECV) cell consisting of the CGSe photocathode and Pt anode demonstrated a stable generated photovoltage by a one-step photoexcitation process.

Z-Scheme Overall Water Splitting Using ZnxCd1–xSe Particles Coated with Metal Cyanoferrates as Hydrogen Evolution Photocatalysts

“…The VBM energy levels of the Zn x Cd 1– x Se particles were determined by photoelectron spectroscopy in air (PESA; Riken Keiki, AC-3). Prior to these analyses, the Zn x Cd 1– x Se particles were fixed on Ti foil via the particle transfer (PT) method to avoid charging-up of the semiconductor particles . The flat-band potentials of the Zn 0.75 Cd 0.25 Se as synthesized and after being coated with metal cyanoferrates were estimated from Mott–Schottky plots obtained while applying a frequency of 10 kHz at an amplitude of 10 mV.…”

“…The elemental compositions of the Zn x Cd 1−x Se particles were also analyzed by inductively coupled plasma-optical emission spectrometry (ICP-OES; SII NanoTechnology, SPS5510) after dissolution in an aqueous solution containing 0.1 M nitric acid and 60 mM hydrochloric acid, as well as by X-ray photoelectron spectroscopy (XPS; Ulvac-Phi, PHI Quantera Prior to these analyses, the Zn x Cd 1−x Se particles were fixed on Ti foil via the particle transfer (PT) method to avoid chargingup of the semiconductor particles. 54 The flat-band potentials of the Zn 0.75 Cd 0.25 Se as synthesized and after being coated with metal cyanoferrates were estimated from Mott−Schottky plots obtained while applying a frequency of 10 kHz at an amplitude of 10 mV. Aqueous borate buffer solutions (0.3 M H 3 BO 3 , adjusted to a pH of 5−9) with and without 5 mM K 4 [Fe(CN) 6 ] were used as the electrolyte.…”

Dominant Processing Factors in Two-Step Fabrication of Pure Sulfide CIGS Absorbers

“…Group I-III-VI chalcopyrite alloys are one of the promising materials for energy-based applications in the fields of photovoltaics and photo electrochemistry [1][2][3]. Among the family, copper indium gallium di selenide/sulfide (CIGS) are specifically interesting as candidates for standalone or tandem photovoltaics, due to, i.e., their tunable direct bandgap (~1-2.6 eV), decent efficiencies and their stability [4][5][6].…”