An Iron-based Film for Highly Efficient Electrocatalytic Oxygen Evolution from Neutral Aqueous Solution

Abstract

An ultrathin Fe-based film was prepared by electrodeposition from an Fe(II) solution through a fast and simple cyclic voltammetry method. The extremely low Fe loading of 12.3 nmol cm(-2) on indium tin oxide electrodes is crucial for high atom efficiency and transparence of the resulted film. This Fe-based film was shown to be a very efficient electrocatalyst for oxygen evolution from neutral aqueous solution with remarkable activity and stability. In a 34 h controlled potential electrolysis at 1.45 V (vs NHE) and pH 7.0, impressive turnover number of 5.2 × 10(4) and turnover frequency of 1528 h(-1) were obtained. To the best of our knowledge, these values represent one of the highest among electrodeposited catalyst films for water oxidation under comparable conditions. The morphology and the composition of the catalyst film was determined by scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray, and X-ray photoelectron spectroscopy, which all confirmed the deposition of Fe-based materials with Fe(III) oxidation state on the electrode. This study is significant because of the use of iron, the fast and simple cyclic voltammetry electrodeposition, the extremely low catalyst loading and thus the transparency of the catalyst film, the remarkable activity and stability, and the oxygen evolution in neutral aqueous media.

An iron-based thin film as a highly efficient catalyst for electrochemical water oxidation in a carbonate electrolyte

“…9,14,22,23,28 The incorporation of carbonate anions in Fe-Ci is also evidenced by an obvious peak at 288.4 eV for C1s region of XPS spectrum, in line with the contribution from -C(O)O-group ( Figure S9c). 9,14,22,23,28 In brief, the deposited film is composed of carbonate coordinated iron (III) oxyhydroxide with spheroidal morphology; these features make it distinctive from other iron-based water oxidation catalysts. SEM and TEM images revealed that the film with a lower catalyst loading has a rough surface and interconnected tiny particles (Figure 2, S5a, and S7).…”

“…Two satellite peaks at 718.8 and 733.3 eV also suggest the main valence of iron is three. 22,23,31 The resolved subpeaks at 530.0 and 531.4 eV are attributed to O 2and OHspecies, respectively. The relative content of O 2species is higher than that of the iron-based thin film deposited from acetate electrolyte but lower than those of the FeOOH catalysts.…”

“…The relative content of O 2species is higher than that of the iron-based thin film deposited from acetate electrolyte but lower than those of the FeOOH catalysts. [22][23][24]31 The peak at 532.4 eV is attributed to the adsorbed carbonyl groups ( Figure S9b). 9,14,22,23,28 The incorporation of carbonate anions in Fe-Ci is also evidenced by an obvious peak at 288.4 eV for C1s region of XPS spectrum, in line with the contribution from -C(O)O-group ( Figure S9c).…”

“…[22][23][24]31 The peak at 532.4 eV is attributed to the adsorbed carbonyl groups ( Figure S9b). 9,14,22,23,28 The incorporation of carbonate anions in Fe-Ci is also evidenced by an obvious peak at 288.4 eV for C1s region of XPS spectrum, in line with the contribution from -C(O)O-group ( Figure S9c). 9,14,22,23,28 In brief, the deposited film is composed of carbonate coordinated iron (III) oxyhydroxide with spheroidal morphology; these features make it distinctive from other iron-based water oxidation catalysts.…”

X20CoCrWMo10-9//Co3O4: a metal–ceramic composite with unique efficiency values for water-splitting in the neutral regime

“…We determined for the OER upon iron oxide-based layers in 0.1 M phosphate (pH 7) buffer solution η=462 mV at 1 mA/cm 2 current density 25 which is still far below the OER performance of up to date electrocatalysts shown in alkaline regime. 26 Iron based films 27,28 ,Ni-(oxy)hydroxide-borate 29 , cobalt phosphate compounds 30,31 , cobalt borate/graphene 32 …”