Improving the Efficiency of Hematite Nanorods for Photoelectrochemical Water Splitting by Doping with Manganese

Abstract

Here, we report a significant improvement of the photoelectrochemical (PEC) properties of hematite (α-Fe2O3) to oxidize water by doping with manganese. Hematite nanorods were grown on a fluorine-treated tin oxide (FTO) substrate by a hydrothermal method in the presence on Mn. Systematic physical analyses were performed to investigate the presence of Mn in the samples. Fe2O3 nanorods with 5 mol % Mn treatment showed a photocurrent density of 1.6 mA cm(-2) (75% higher than that of pristine Fe2O3) at 1.23 V versus RHE and a plateau photocurrent density of 3.2 mA cm(-2) at 1.8 V versus RHE in a 1 M NaOH electrolyte solution (pH 13.6). We attribute the increase in the photocurrent density, and thus in the oxygen evolving capacity, to the increased donor density resulting from Mn doping of the Fe2O3 nanorods, as confirmed by Mott-Schottky measurement, as well as the suppression of electron-hole recombination and enhancement in hole transport, as detected by chronoamperometry measurements.

Fabrication of superior α-Fe2O3 nanorod photoanodes through ex-situ Sn-doping for solar water splitting

“…To date, hematite nanostructures have been synthesized using a variety of techniques including sol-gel processing [8], electrodeposition [9,10], spray pyrolysis [11], and hydrothermal synthesis [12]. In particular, hydrothermal synthesis is simple, cost effective, and provides good control over the composition and morphology [13,14]. Elemental doping plays a critical role in improving the electrical conductivity and in enhancing the PEC performance of hematite photoanodes [5,15].…”

“…Elemental doping plays a critical role in improving the electrical conductivity and in enhancing the PEC performance of hematite photoanodes [5,15]. Dopants, such as Si [16,17], Ti [17][18][19][20][21], Sn [6,15,17,22], Zr [18], Ge [17,23], Mn [14,17], Al [24], and Pt [9,12,25], have been investigated for use in hematite photoanodes. Sn has an advantage over other dopants because Sn ions have a similar ionic radius and Pauling electronegativity compared to Fe ions.…”

Mn-doping and NiFe layered double hydroxide coating: Effective approaches to enhancing the performance of α-Fe2O3 in photoelectrochemical water oxidation

“…Morphological manipulation [23][24][25], foreign element doping [26][27][28], and constructing heterojunctions [29][30][31][32] have been reported to enhance charge separation efficiency. IrO 2 and RuO 2 are the most active OER catalysts used to improve the oxygen evolution kinetics [3], but the high cost limits their extensive use.…”

Convenient synthesis of Mn-doped Zn (O,S) nanoparticle photocatalyst for 4-nitrophenol reduction

“…In literatures, manganese had been shown as dopant to enhance the catalytic performance. For example, manganese doped hematite (α-Fe 2 O 3 ) nanorods could enhance the efficiency of photoelectrochemical water splitting [9]. Abduhadir also had reported that Mn-doped WO 3 had the higher catalytic activity compared to un-doped WO 3 for methylene blue degradation [10].…”