Bismuth Oxysulfide Photoelectrodes with Giant Incident Photon‐to‐Current Conversion Efficiency: Chemical Stability in Aqueous Solutions

Abstract

Bismuth oxysulfide (BOS) films demonstrate giant incident photon-to-current conversion efficiency (IPCE @ 100 %) under cathodic polarization. Their photoelectrochemical behavior and corrosion stability in aqueous solutions containing different redox systems ([Fe(CN) 6 ] 3À /[Fe(CN) 6 ] 4À , Fe 3 + /Fe 2 + , I 2 /I À , S n 2À /S 2À ) has been investigated. We established that the chemical stability of the BOS is controlled mainly by three factors: i) potentials of cathodic and anodic destruction of the BOS (Bi 3 + reduction and S 2À oxidation)L ii) protolytic reactions leading to the dissolution of the semiconductor in acidic solutions at pH < 3; iii) presence in solutions of anions, capable to participate in ion exchange reactions with the semiconductor forming poorly soluble compounds (K[BiFe(CN) 6 ] · 3H 2 O, BiOI and Bi 2 S 3 ). The enrichment of the BOS surface with sulfur atoms (formation of S-terminated surface) gives rise to the substantial increase in the electrocatalytic activity of [Fe(CN) 6 ] 3À cathodic reduction, which is accompanied by up to order increase of IPCE.includes such subsequent stages as photogeneration of charge carriers, transfer of electrons in the BOS film, electrochemical discharge, delivery and removal of reagents and reaction products from the surface, etc.The enrichment of the BOS surface by sulfur atoms increases the rate of the cathodic reduction of [Fe(CN) 6 ] 3À and, correspondingly, allows one to control the IPCE value. 4 5 6 7 8

Bismuth oxysulfide thin films for light and humidity sensing

“…Recently, a new semiconductor materialbismuth oxysulfide (BOS) Bi10O6S9 has been synthesized [22][23][24]. Photoelectrochemical properties of BOS were investigated in details, and in particular a great photoconductivity under electrochemical polarization in various aqueous electrolytes was discovered [22].…”