Photoelectrochemical Hydrogen Evolution: Single-Layer, Conjugated Polymer Films Bearing Surface-Deposited Pt Nanoparticles

In this report, we examine the origin of photocurrent produced by irradiating single layer poly(3-hexylthiophene) (P3HT) films deposited on ITO-coated glass, in aqueous solutions. The photocurrent is found to be largely due to reduction of trace molecular oxygen, which decreases significantly in the presence of an oxygen scavenger. Residual current, <1 mu A cm(-2), is observed in acidic media that may be attributed to proton reduction. The addition of a catalyst to aid proton reduction is achieved through photoelectrochemical deposition of Pt nanoparticles from K2PtCl6. Photocurrents at single layer films in aqueous solution increase significantly and bubble formation is observed on the P3HT film that is confirmed to be hydrogen gas. While the photocurrents produced are smaller than those devices employing sophisticated multilayer architectures, the results hold promise that, with further studies, H-2 can be evolved at technologically-simple single layer systems with substantially higher rates. (C) 2015 The Electrochemical Society. All rights reserved.