Sn doped α-Fe2O3 (Sn=0,10,20,30 wt%) photoanodes for photoelectrochemical water splitting applications

Abstract

Abstract One pot hydrothermal route was adapted to synthesis pristine and Sn doped α-Fe2O3 nanospheres successfully. Sharp high intense diffraction peaks obtained from XRD confirmed crystalline nature of rhombohedral hematite. The secondary SnO2 face formation was due to increasing Sn dopant concentration. Raman spectra confirmed intrinsic phonon vibration modes [Eg(1)+Eg(2)+Eu] of hematite nanospheres. 2P3/2(1) → 2P1/2 transition by emission peak at 549 nm confirmed hematite phase formation. Metal oxygen vibration (Fe O stretching) was confirmed by absorption band situated at 539 cm−1. The noticeable variation in band gap of pristine hematite nanospheres was due to tetravalent Sn4+ dopant concentration. The lowest band gap energy 1.90 eV was found for 10 wt% Sn4+ doped hematite. Highest photocurrent 2.34 mA/cm2 at 0.098 V V RHE was obtained for 10% Sn doped hematite nanospheres. The EIS exposed the charge transferring mechanism of synthesized pristine and Sn doped α-Fe2O3 nanospheres. M-S plot evidenced that the lower shift of flat band potential for 10 wt% Sn4+ doped hematite was as −0.35 V. CA study proved the good stability over 4 h of the best performed photoanodes. Sn4+ doping and its dopant concentration on pristine hematite had dominant effect on photocatalytic activity of hematite nanospheres.