Highly Conductive Cable‐Like Bicomponent Titania Photoanode Approaching Limitation of Electron and Hole Collection

Abstract

TiO₂‐based materials are cheap and stable choices for photoelectrochemical devices. However, the activity is still limited by the inefficient charge extraction. Here a highly conductive cable‐like bicomponent titania photoanode, consisting of reduced anatase‐coated TiO₂‐B nanowires, is proposed to simultaneously establish effective electron and hole transport channels separately, which meets the requirements of electronic dynamics for efficient water splitting. A synergistic effect of charge separation from the built‐in electric field is demonstrated with this 1D TiO₂‐B/anatase heterojunction, in which a high electron collection efficiency of up to 97.1% at 0.6 V versus reversible hydrogen electrode is achieved. The efficient electron collection approaching the limitation is also attributed to the large electron conducting region in the photoanode. Moreover, the O‐deficient amorphous layer is found to be more catalytic toward the oxygen evolution reaction through quantifying rate constants for charge recombination and charge transfer. It can reduce onset potential and suppress charge‐carrier recombination simultaneously, prompting surface hole collection efficiency up to 95% at 0.6 V versus reversible hydrogen electrode.