Controlled Growth of Ferrihydrite Branched Nanosheet Arrays and Their Transformation to Hematite Nanosheet Arrays for Photoelectrochemical Water Splitting

Mei Ji, Jinguang Cai, Yurong Ma, Limin Qi

    Research output: Contribution to journalArticle

    34 Citations (Scopus)

    Abstract

    The morphology engineering represents an alternative route toward efficient hematite photoanodes for photoelectrochemical (PEC) water splitting without changing the chemical composition. In this work, a facile and mild solvothermal synthesis of unique ferrihydrite branched nanosheet arrays vertically aligned on FTO substrate was achieved at around 100 °C. The hierarchical branched ferrihydrite nanosheet arrays consisted of tiny branches up to 40 nm in length grown almost vertically on stem nanosheets ∼10 nm in thickness. Moreover, the variation of the morphology of the ferrihydrite nanostructures from bare nanosheet arrays through branched nanosheet arrays to dense branched structures can be readily achieved through the regulation of the reaction time and temperature. The obtained ferrihydrite branched nanosheet arrays can be in situ transformed into α-Fe2O3 nanosheet arrays with small surface protrusions upon annealing at 550 °C. After a simple postgrowth Ti-doping process, the resulting Ti-doped α-Fe2O3 nanosheet arrays showed a good PEC performance for water splitting with a photocurrent density of 1.79 mA/cm2 at 1.6 V vs RHE under AM 1.5G illumination (100 mW/cm2). In contrast, the Ti-doped irregular aggregates of the α-Fe2O3 nanograins transformed from dense ferrihydrite branched structures exhibited a much lower photocurrent density (0.41 mA/cm2 at 1.6 V vs RHE), demonstrating the important influence of the morphology of α-Fe2O3 photoanodes on the PEC performance.

    Original languageEnglish
    Pages (from-to)3651-3660
    Number of pages10
    JournalACS Applied Materials and Interfaces
    Volume8
    Issue number6
    DOIs
    Publication statusPublished - 2016 Feb 24

    Keywords

    • ferrihydrite
    • hematite
    • morphology engineering
    • nanosheet arrays
    • photoelectrochemical water splitting

    ASJC Scopus subject areas

    • Materials Science(all)

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