Surface Engineering of Defective Hematite Nanostructures Coupled by Graphene Sheets with Enhanced Photoelectrochemical Performance

The major challenge in improving the photoelectrochemical performance of Fe2O3 lies on increasing the photon absorption capability and the charge transfer efficiency. In this work, we facilely maneuvered the morphology of Fe2O3 nanomaterials by a combination of electrospinning and hydrothermal approach. Through controlling the type, the concentration of inorganic species, and the consequent ionic strength of hydrothermal solution, the hematite with four different nanostructures (i.e., nanoflowers, nanocubes, irregular nanoparticles, and flat nanoflakes) were engineered. The narrow bandgap of 1.85 eV and the unique structure of flower-Fe2O3 allowed an enhanced photon absorption and thus a small charge transfer resistance (R-ct) of 32.2 Omega. After coupling with RGO sheets, Fe2O3 nanostructures experienced decreased size and enriched defects, facilitating enhanced photoelectrochemical performance. Taking the flower-Fe2O3/RGO as an example, the R-ct declined to 21.8 Omega and the steady state photocurrent density increased up to 220.2 mu A/cm(2) (3. folds of that of pristine flower-Fe2O3). Moreover, this improvement should also be ascribed to RGO sheets that act as a bridge to enhance the charge transfer efficiency and further retard the undesirable recombination of electrons and holes. The present work will deepen the understanding of precise control over the morphology of inorganic nanocrystals as well as their structure-related performance.