Nonequilibrium Deposition in Epitaxial BiVO₄ Thin Film Photoanodes for Improving Solar Water Oxidation Performance

다국어 초록 (Multilingual Abstract)

<P>To improve the photoelectrochemical performance of photoelectrodes, various modifications such as the doping of electron donors, morphology control, and adoption of catalysts have been widely implemented, among which the formation of type-II heterojunctions has been recognized as an effective method to significantly improve the charge transport efficiency of photoelectrodes. In this regard, we report on an in situ high-quality epitaxial BiVO<SUB>4</SUB>/Bi<SUB>4</SUB>V<SUB>2</SUB>O<SUB>11</SUB> type-II heterojunction thin-film photoanode fabricated by using pulsed laser deposition on the basis of only one BiVO<SUB>4</SUB> ceramic target using the transition between BiVO<SUB>4</SUB> and Bi<SUB>4</SUB>V<SUB>2</SUB>O<SUB>11</SUB> crystalline phases. Herein, for the first time, we report on the structural and chemical transition between monoclinic BiVO<SUB>4</SUB> (010) and orthorhombic Bi<SUB>4</SUB>V<SUB>2</SUB>O<SUB>11</SUB> (001) crystalline phases by simply controlling the oxygen partial pressure. Subsequently, the growth of epitaxial BiVO<SUB>4</SUB>/Bi<SUB>4</SUB>V<SUB>2</SUB>O<SUB>11</SUB> heterojunction thin film is achieved by controlling only the oxygen partial pressure based on band alignment. At 1.23 <I>V</I><SUB>RHE</SUB>, the photocurrent density of heterojunction BiVO<SUB>4</SUB>/Bi<SUB>4</SUB>V<SUB>2</SUB>O<SUB>11</SUB> structure is also significantly higher than that of the epitaxial BiVO<SUB>4</SUB> thin film owing to the effective charge transfer of the Bi<SUB>4</SUB>V<SUB>2</SUB>O<SUB>11</SUB> thin film. This study strongly suggests that the nonequilibrium deposition of epitaxial BiVO<SUB>4</SUB> thin films can propose a new paradigm in the structural design of photoanodes.</P>
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