Visible light induced HCl splitting over the hetero-system p-CuCrO2/n-WO3

The chloride oxidation is successfully carried out on CuCrO2/WO3 (1/1) dispersed in air-equilibrated KCl solution. The delafossite CuCrO2 is p type semiconductor characterized by an optical gap of 1.28 eV, properly matched to the sun spectrum, and a chemical stability over the whole pH range. By contrast, WO3 is stable only in neutral solution and has a valence band with a potential of 2.30 V-SCE. The present hetero-system is twofold, the Cl- oxidation and the hydrogen production respectively on WO3 and CuCrO2 connected in a short circuited configuration via the electrolytic solution. A chloride elimination of 60% is achieved and the oxidation obeys to a first order kinetic with a rate constant of 0.17 h(-1) and a quantum yield of 1.1%. The reaction is followed by amperometry at a rotating disk electrode. The water reduction takes place by photoelectrons located in CuCrO2-CB (-1.13 V-SCE) with a rate liberation of 6.5 mu mol/mg (catalyst)/min and a quantum yield of 0.2%. The system is evaluated for the chemical storage through the HCl photo-splitting (2H(2)O + 2 KCl -> 2KOH + Cl-2 + H-2, Delta G degrees = 422.2 kJ mol(-1)). (C) 2014 Elsevier Ltd. All rights reserved.