Electrocatalysis of Perovskites: The Influence of Carbon on the Oxygen Evolution Activity

Abstract

Single and double perovskite oxides have been reported to be amongst the most active electrocatalysts for the oxygen evolution reaction (OER) in alkaline electrolyte. Although a detailed study of the bulk electronic structure-activity relationship towards oxygen evolution on these oxides has been reported, the influence of carbon on the behavior of these oxides as OER catalysts is not yet clearly understood. In the present work we study the influence of functionalized acetylene black (AB f ) carbon in the electrode composition on the OER activity for perovskite oxides using the thin-film rotating disk electrode technique. It was found that the addition of AB f significantly enhances the OER activity of the single perovskite oxides, namely Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3-δ , (BSCF) and La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ (LSCF). The activity of the double perovskite oxide, (Pr 0.5 Ba 0.5 )CoO 3-δ (PBCO), was relatively unaffected by the addition of AB f in the electrode. Ex situ impedance spectroscopy measurements at room temperature showed that BSCF powder displayed a lower resistivity compared to PBCO with LSCF displaying the highest resistivity of the three materials. These results therefore suggest that the AB f present can more than simply improve the conductive pathway in the perovskite/carbon composite electrodes but can also significantly enhance the electrocatalytic activity of selected perovskites towards the OER. The oxygen evolution reaction (OER), the process of generating molecular oxygen through the electrochemical oxidation of water, is a key reaction in energy storage processes involving hydrogen and central to addressing the impending global energy crisis. This reaction, occurring at the anode of the water splitting reaction, is primarily governed by slow kinetics 1 and has therefore been extensively studied to improve the performance of devices such as water electrolyzers. 2,3,4 Significant overpotential losses remain a hurdle which requires the need for rare and expensive noble-metal based electrocatalysts for efficient operation. The development and application of new materials able to compete with expensive state-of-the-art current electrocatalysts for hydrogen generating devices therefore yields a great challenge.Various electrocatalytic materials have been studied in the past towards improving the OER, where the oxides of Ir and Ru have been conventionally identified as the most active, often in mixtures with other transition metal oxides. 5,6,7 From the numerous metal oxides studied, perovskite oxides emerged as promising electrocatalysts for both the OER and ORR (oxygen reduction reaction) in alkaline media where a number of these oxides have been reported to be sufficiently stable for practical applications. 8,9 The perovskite-type oxide family, has the general formula ABO 3 , where the A-site is occupied by an alkaline earth element, such as Ca, Ba and Sr and rare earth elements (lanthanides) such as La or Pr. The B-site is occupied by a transition metal element in 6-fold coordination to...

The Comprehensive Understanding of as an Evaluation Parameter for Electrochemical Water Splitting

“…This is consistent with a benchmark study where the catalyst‐loading dependence of η@ is demonstrated by OER measurement for commercial IrO 2 particles (Premetek) with various loading masses (Figure c) . The same trend is also reported at La 0.7 Ba 0.15 Sr 0.15 Co 0.8 Fe 0.2 O 3−δ ‐50 nm perovskite, where a higher loading mass gives an earlier onset of OER in terms of current density normalized to geometric area of electrode; and a series of perovskite catalysts . Second, η@ is based on the current density normalized to the geometric area of electrode, which neglects that the electrocatalysis reaction (such as the HER and the OER) is a surface process, where only the surface atoms participate .…”

“…[9] The same trend is also reported at La 0.7 Ba 0.15 Sr 0.15 Co 0.8 Fe 0.2 O 3−δ -50 nm perovskite, where a higher loading mass gives an earlier onset of OER in terms of current density normalized to geometric area of electrode; [10] and a series of perovskite catalysts. [11] Second, η@ 10 mA cm geo 2 − is based on the current density normalized to the geometric area of electrode, which neglects that the electrocatalysis reaction (such as the HER and the OER) is a surface process, where only the surface atoms participate. [1,12] To reflect the intrinsic electrocatalytic activity, the current density should be normalized to a quantified parameter about the catalyst surface, such as the number of active sites, [1,7] or alternatively the surface area of the catalyst.…”

Electrodeposited Ni‐P Alloy Nanoparticle Films for Efficiently Catalyzing Hydrogen‐ and Oxygen‐Evolution Reactions

“…All currents presented are corrected against the ohmic potential drop and all LSV curves subtracted the capacitance current (average of anodic and cathodic scans). [36,37] Keywords: bifunctionalc atalysts · electrodeposition · hydrogen energy · nickel · water splitting…”

Electrodeposition of cobalt-sulfide nanosheets film as an efficient electrocatalyst for oxygen evolution reaction

“…E (RHE) = E (SCE) + 1.068 V, η = E (RHE) -1.23 V. The onset potential was read from the Tafel plot for OER and determined based on the beginning of linear regime in the Tafel plot and no activationprocess was involved in all electrochemical tests. All LSV curves subtracted the capacitance current (average of anodic and cathodic scans)[23].…”