Facet-Controlling Agents Free Synthesis of Hematite Crystals with High-Index Planes: Excellent Photodegradation Performance and Mechanism Insight

Abstract

Hematite (α-Fe<inf>2</inf>O<inf>3</inf>) crystals with uniform size and structure are synthesized through very facile one-pot hydrothermal methods without any additive. The as-synthesized sub-micrometer-sized α-Fe<inf>2</inf>O<inf>3</inf> crystals with small surface areas perform superb visible light photodegradation activities, even much better than most other α-Fe<inf>2</inf>O<inf>3</inf> nanostructures with large surface areas. Profound mechanism analyses reveal that the microwave-assisted hydrothermal (Mic-H) synthesized α-Fe<inf>2</inf>O<inf>3</inf> is enclosed by 12 high-index {2-15} facets. The structure and the low unoccupied molecular orbital (LUMO) of the high-index planes result in the excellent photocatalytic activity. This is the first report on the formation of {2-15} plane group of hematite, and the synthesis of the hematite particles with the {2-15} planes is very simple and no any facet-controlling agent is used. This study may pave the way to further performance enhancement and practical applications of the cheap hematite materials.