Fabrication of S, N co-doped alpha-Fe2O3 nanostructures: effect of doping, OH radical formation, surface area, [110] plane and particle size on the photocatalytic activity

A highly efficient S, N co-doped alpha-Fe2O3 has been synthesized by a simple co-precipitation technique using thiourea as the precipitating agent, as well as the source for sulphur and nitrogen. Detailed characterizations are performed for establishing the structural, morphological, optical and electronic property of the synthesized materials. Sulphur doping induces a strong diffraction along the [110] plane which is a determining factor for the enhancement in photocatalytic activity. The presence of both sulphur and nitrogen has remarkable enhancement of the degradation of Rhodamine B (RB) compared to the bulk material, as well as the single non-metal doped hematite. A comparison has been made between the adsorption, Fenton, photo-Fenton and photocatalytic degradation of RB. A maximum degradation of 95% was obtained in just 4 h under natural sunlight illumination. The difference in catalytic activity has been discussed in terms of their (1) particle size, (2) surface area, (3) [110] plane in the sulphur doped material, (4) formation of OH radicals and (5) co-doping of sulphur and nitrogen creating the trap state, etc.