Hematene Nanoplatelets with Enhanced Visible Light Absorption; the Role of Aromatic Molecules

Hematite has been considered an important candidate for the development of an efficient photoelectrocatalytic water-splitting system. One of the most serious obstacles that limits the efficiency of hematite is low absorption capacity in visible light. Herein, we report the production of hematene nanoplatelets from hematite ore with yields of up to 60%, using a low-cost, sustainable method that is based on the ultrasonic treatment of hematite ore in a water solution of a series of organic aromatic compounds. We show that the chemisorption of molecules with increased aromaticity on the surface of hematene resulted in the significant improvement of its visible light absorptivity, with an increase of up to 200%. As a result, using a water solution of terephthalaldehyde as a liquid medium, hematite ore was exfoliated to hematene nanoplatelets with a yield of 40% and remarkable stability in water. Due to this, hematene was easily drop-casted on glass forming homogenous thin films with strong absorptivity in the visible region.