Atomic layer deposition of a submonolayer catalyst for the enhanced photoelectrochemical performance of water oxidation with hematite.

Riha, Shannon C; Klahr, Benjamin M; Tyo, Eric C; Seifert, Sönke; Vajda, Stefan; Pellin, Michael J; Hamann, Thomas W; Martinson, Alex B F · ACS Nano · 2013

basic_science · Level V

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Abstract

Hematite photoanodes were coated with an ultrathin cobalt oxide layer by atomic layer deposition (ALD). The optimal coating-1 ALD cycle, which amounts to <1 monolayer of Co(OH)2/Co3O4-resulted in significantly enhanced photoelectrochemical water oxidation performance. A stable, 100-200 mV cathodic shift in the photocurrent onset potential was observed that is correlated to an order of magnitude reduction in the resistance to charge transfer at the Fe2O3/H2O interface. Furthermore, the optical transparency of the ultrathin Co(OH)2/Co3O4 coating establishes it as a particularly advantageous treatment for nanostructured water oxidation photoanodes. The photocurrent of catalyst-coated nanostructured inverse opal scaffold hematite photoanodes reached 0.81 and 2.1 mA/cm(2) at 1.23 and 1.53 V, respectively.