The In Situ Electrochemical Stable Promotion of Photoelectrocatalytic Activity of TiO2 by Pulsed Reductive Doping: Application in Photoelectrochemical Water Splitting

The periodic electrochemical promotion of TiO2's photoelectrocatalytic activity, termed pulsed reductive doping (PRD), is a new, facile, costless, in situ method, that enhances even up to fivefold TiO2's photocurrent. This is based on TiO2's self doping upon application of negative reductive voltage on TiO2 photoelectrode. Investigation and optimization of the method's operating parameters is analyzed. The nature of self doping is investigated by means of cyclic voltammetry, HRTEM and XRD and in conjunction to recent surface science literature, is rationalized through the formation of interstitial Ti3+ species and subsequent formation of electronic states within the bandgap that induce a profound enhancement of the photocurrent. The PRD process bypasses the impermanent nature of the self doping process on the photoelectrocatalytic activity, thus resulting in a steady and profoundly enhanced photoelectrochemical performance, as compared to the steady state operation. (C) 2015 The Electrochemical Society. All rights reserved.