In situ observation of carrier transfer in the Mn-oxide/Nb:SrTiO3 photoelectrode by X-ray absorption spectroscopy

Abstract

The Mn-oxide/Nb:SrTiO3 photoelectrode for oxygen evolution reaction was investigated by in situ Mn K-edge XAFS spectroscopy under UV irradiation. The oxidization of the Mn oxide was observed via photoexcited carrier transfer, which results in the positive potential shift of the Mn oxide cocatalyst toward oxygen evolution reaction.

In Situ Observation of Model Catalysts under Reaction Conditions Using X‐ray Core‐Level Spectroscopy

“…In our case, we combined a Teflon‐based electrochemical XAFS cell with a xenon lamp for UV irradiation to investigate a photoelectrode for water splitting, as shown in Figure . The Teflon electrochemical cell was sealed with a polyethylene thin film as an X‐ray and UV light window and equipped with a Pt wire counter electrode and a Ag/AgCl (saturated KCl) reference electrode in 0.1 M Na 2 SO 4 aqueous solution with Ar bubbling.…”

“…In this situation, we thought that the valence change of the MnO x deposited on semiconductor photoelectrodes during the photoelectrochemical reaction could be estimated by XAFS measurements. Therefore, we applied the in situ electrochemical Mn K‐edge XAFS spectroscopy technique for the observation of photoinduced carrier transfer from a SrTiO 3 photoelectrode to MnO x cocatalysts under controlled potential conditions during UV irradiation (Figure ) …”

“… Observation of the photoinduced carrier transfer from the SrTiO 3 photoelectrode to the MnO x cocatalyst by in situ electrochemical XAFS measurements. Adapted from reference with permission from the Royal Society of Chemistry. …”

“…Thirdly, an in situ electrochemical XAFS system was fabricated for in situ observation of catalytic reactions at liquid/solid interfaces under electrochemical control. In particular, this technique has been applied to observe photoinduced carrier transfer from a photoelectrode to a cocatalyst in water with applied voltages and under UV irradiation . In the following sections, we describe these three synchrotron‐based X‐ray core‐level spectroscopies for in situ observations and their applications to prototypical catalytic reactions.…”

Valence state heterojunction Mn3O4/MnCO3: Photo and thermal synergistic catalyst

“…Most of Mn compounds have excellent capacity for harvesting visible light. And, a major portion of researches reported Mn as one of visible light sensitized elements in photocatalysis field [12][13][14][15] …”