Studies on Nanostructured Bilayered Semiconductor System in PEC Water Splitting for Hydrogen Production

摘要

Performance of photo-electrodes in photoelectrochemical (PEC) water splitting forhydrogen production is expected to improve by fabricating bilayered electrodes consisting of twosemiconductors possessing different energy levels for their corresponding conduction and valenceband. The small/mid band gap semiconductor is primarily responsible for visible light absorption andsensitizing the large band gap semiconductor through electron and/or hole injection. The energylayers in the bilayered semiconductors can cover visible spectrum thereby offering synergistic effectand better output is achieved. In the present study, an attempt has been made to synthesize bilayeredSrTiO_3 (～3.4 eV) / WO_3 (～2.8eV) thin films by sol-gel spin-coating process on conducting glasssubstrate to explore its application in PEC cell. Maximum photocurrent density 0.091 mA/cm~2 at0 V/SCE was observed for bilayered SrTiO_3/WO_3 thin film photoelectrode which was two foldshigher than offered by SrTiO_3 (0.046 mA/cm~2) and much higher than that for WO_3 thin films. Theenhanced photoelectrochemical behaviour of bilayered photoelectrodes can be attributed to: (a) theextended absorption towards visible region, (b) formation of mixed oxide at the interface and ?enhanced charge separation of both the materials resulting in decrease of recombination of chargecarriers.