Doping of Pt into Anodic TiO2 Nanotubes for Water Oxidation: Underpotential Shock Method in Cl– Solution

Abstract

For the preparation of a highly stable and active electrode for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), Pt was doped into TiO2 nanotubes by means of an underpotential shock method, in which positively biased voltage lower than the anodizing voltage was applied to anodic TiO2 for short seconds immediately after anodization, to reduce the overpotential of the catalyzed hydrogen and oxygen evolution reactions of water splitting. Because aqueous acidic H2PtCl6 solution was used as a doping precursor, Cl– ions were generated during imposing high positive voltage (so-called potential shock), which would aggressively damage the anodic oxide if a normal potential shock were applied. Instead, the novel underpotential shock method allowed Pt to be homogeneously doped into TiO2 films without destroying the structures. Pt could not thoroughly penetrate the barrier oxide into the interface between the oxide and Ti metal because the voltage of the potential shock was lower than the anodiz...