Lei Bo, Xu Dandan, Wei Bo, Xie Tengfeng, Xiao Chunyu, Jin Weiliang, Xu Lingling
Key Laboratory of Photonic and Electronic Bandgap Materials, Ministry of Education, School of Physics and Electronic Engineering, Harbin Normal University, Harbin 150025, China.
Department of Chemistry, Harbin Normal University, Harbin 150025, China.
ACS Appl Mater Interfaces. 2021 Jan 27;13(3):4785-4795. doi: 10.1021/acsami.0c19927. Epub 2021 Jan 12.
Hematite (α-FeO) is a promising photoanode material in photoelectrochemical (PEC) water splitting. To further improve the catalytic activity, a reasonable construction of heterojunction and surface engineering can effectively improve the photoanode PEC water-splitting performance via improving bulk carrier transport and interfacial charge-transfer efficiency. As FeO has an excellent conductivity and a suitable energy band position, α-FeO/FeO heterojunction can be an ideal structure to improve the activity of α-FeO. However, only few studies have been reported on α-FeO/FeO heterojunctions as photoanodes. In this work, a holey nanorod FeO/FeO heterojunction photoanode with oxygen vacancies was fabricated using a rapid and facile flame reduction treatment. Compared with pure FeO, the water oxidation performance of the FeO/FeO photoanode is improved by ninefold at 1.23 V. Our study revealed that the porous nanorod structure providing more active sites and oxygen vacancies as the hole transfer medium, together improve the interface charge transfer performance of the photoanode. At the same time, FeO can form a FeO/FeO heterojunction to improve the carrier separation efficiency. More importantly, FeO can serve as active sites, solving the slow water oxidation kinetic problem of hematite to enhance the catalytic activity. Our work shows that when flame acts on precursors containing oxygen or hydroxide, it is easy to form compounds with different microstructures or compositions in situ.
赤铁矿（α-Fe₂O₃）是光电化学（PEC）水分解中一种很有前景的光阳极材料。为了进一步提高催化活性，合理构建异质结和进行表面工程可以通过改善体载流子传输和界面电荷转移效率来有效提高光阳极的PEC水分解性能。由于Fe₃O₄具有优异的导电性和合适的能带位置，α-Fe₂O₃/Fe₃O₄异质结可能是提高α-Fe₂O₃活性的理想结构。然而，关于α-Fe₂O₃/Fe₃O₄异质结作为光阳极的研究报道很少。在这项工作中，通过快速简便的火焰还原处理制备了具有氧空位的多孔纳米棒Fe₂O₃/Fe₃O₄异质结光阳极。与纯α-Fe₂O₃相比，Fe₂O₃/Fe₃O₄光阳极在1.23 V时的水氧化性能提高了九倍。我们的研究表明，多孔纳米棒结构提供了更多的活性位点和氧空位作为空穴传输介质，共同提高了光阳极的界面电荷转移性能。同时，Fe₃O₄可以形成Fe₂O₃/Fe₃O₄异质结以提高载流子分离效率。更重要的是，Fe₃O₄可以作为活性位点，解决赤铁矿水氧化动力学缓慢的问题，从而提高催化活性。我们的工作表明，当火焰作用于含氧或氢氧化物的前驱体时，很容易原位形成具有不同微观结构或组成的化合物。
