(Invited) Insight into Polyoxometalate-Induced Catalysis at Semiconducting Oxides

Abstract

One of the major limitations in photoelectrochemical water splitting with use of semiconducting oxide is their sluggish surface water oxidation kinetics. Identification of a molecular oxygen evolution catalysts active especially in highly corrosive media is not a trivial case. N-type mesoporous tungsten trioxide, WO3, is one of few stable semiconductor materials able to photo-electrochemically split water under solar light irradiation but it’s operational acidic environment restricts use of any catalyst to the precious metals. In an attempt to overcome this limitation, Keggin‐type polyoxometalate, [PW12O40]3− and [PMo12O40]3−, anions have been employed to act as highly effective oxygen evolution reaction molecular catalysts in photoelectrochemical water splitting devices. This the first example of oxidatively stable in acid media non noble metal water splitting catalyst. Combined with semitransparent Na‐doped nanoporous WO3 film photoanode, they allow achieving under simulated AM 1.5G sunlight exceptionally high water oxidation photocurrent of 4.5 mA cm−2 at 1.1 V versus reversible hydrogen electrode. The surface and structure modifications of a WO3 photoanode which led to this performance, in parallel with the mechanism of the enhancement will be presented and discussed in details. M. Sarnowska, K. Bienkowski, R. Solarska, P. Barczuk, J.Augustynski; Highly Efficient and Stable Solar Water Splitting at (Na)WO3 Photoanodes in Acidic Electrolyte Assisted by Non-noble Metal Oxygen Evolution Catalyst; Advanced Energy Materials 10.1002/aenm201600526