Photocatalytic hydrogen evolution on new mesoporous material Bi2S3/Y-zeolite

The novel semi conducting configuration n-Bi2S3/Y-zeolite is elaborated by exchange reaction between H/Y-zeolite and Bi3+. The precipitation of Bi2S3 is achieved with thiourea, and activated by ultra sound probe at a frequency of 20 kHz for 60 min. X-ray diffraction and Raman spectroscopy confirm the formation of Bi2S3 which crystallizes in an orthorhombic symmetry. The scanning electron microscopy (SEM) shows uniform and rough surface with fine Bi2S3 crystallites. The specific surface area (S-BET = 87.82 m(2) g(-1)) is similar to seven times greater than that of Bi2S3 (9.57 m(2) g(-1)) prepared under the same conditions. The Mott-Schotticy characteristic gives a flat band potential of 0.465 V-NHE. The electrical conductivity of Bi2S3 is correlated to the optical gap (E-g = 1.40 eV) and photo-electrochemical characterization to establish the energetic diagram of the hetero-system Bi2S3/Y-zeolite/KOH solution. The latter predicts a spontaneous hydrogen evolution upon visible light. An enhancement of twice with respect to Bi2S3 is obtained in presence of S2O32- as holes scavenger. The best performance (292 mu mol H-2 (g catalyst)(-1) h(-1)) occurs at pH similar to 13.1 with a light-to-chemical energy yield of 0.12%. Copyright (C) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.