PANI-modified Pt/Na4Ge9O20 with low Pt loadings: Efficient bifunctional electrocatalyst for oxygen reduction and hydrogen evolution

Exploring cost-effective electrocatalysts for the oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER) have been a goal in the sustainable hydrogen-based society. Although abundant of alternative materials have been developed, Pt/C remains the most efficient electrocatalyst for the ORR and HER. Nevertheless, improving the stability and reducing Pt loading for Pt-based electrocatalysts are still big challenges. Herein, semiconductor crystals Na₄Ge₉O₂₀ with richer topology structure was chosen as electrocatalyst support, subsequently, the conductive polymer polyaniline (PANI) was decorated on semiconductor Na₄Ge₉O₂₀, low-content Pt nanoparticles (Pt NPs) with the size of 1–3 nm were then uniformly anchored on the surface of Na₄Ge₉O₂₀-PANI to obtain the efficient bifunctional electrocatalyst for ORR and HER in the acidic solution. More importantly, the stability and mass activity of the obtained electrocatalyst 5 wt% Pt/Na₄Ge₉O₂₀-PNAI are significantly higher than that of commercial 20 wt% Pt/C for ORR and HER. It was proposed that the PANI could not only promote the electron transfer from Na₄Ge₉O₂₀ to Pt, but also stabilize the Pt NPs, thus, improving the electrocatalytic activity and stability of 5 wt% Pt/Na₄Ge₉O₂₀-PNAI.     

Towards continuous ammonia electro-oxidation reaction on Pt catalysts with weakened adsorption of atomic nitrogen

One of the key challenges for ammonia-fed anion exchange membrane fuel cells is to the ammonia electro-oxidation reaction (AEOR) at anode, which has sluggish kinetics and generates atomic nitrogen (N_ads) poisoning the Pt catalyst. In this study, a comparative study on Pt/Ta₃N₅, Pt/Ta₂O₅, Pt/carbon black, and Pt plate are conducted in order to clarify the promoting effect of the support materials for Pt catalysts. X-ray photoelectron spectroscopy analysis and density functional theory calculations reveal that the support materials significantly affect the electron condition of the Pt, resulting in the tuned adsorption energy of N_ads on Pt surface. The electrochemical analysis demonstrates that the weakened adsorption of N_ads lowers the coverage of N_ads on Pt surface, resulting in the enhanced performance and stability of Pt catalysts for AEOR. In particular, Pt/Ta₃N₅ catalyst exhibits a current density of 5.92 mA cm⁻² of AEOR at −0.34 V vs. SCE, which is higher than that of Pt/Ta₂O₅ (2.56 mA cm⁻², −0.35 V vs. SCE) and Pt/C (4.45 mA cm⁻², −0.26 V vs. SCE). The achievements in this study demonstrate the importance of controlling the type of supports for the development of an active electrocatalyst for continuous AEOR.     

Platinum-decorated three dimensional titanium copper nitride architectures with durable methanol oxidation reaction activity

The development of highly effective and robust electrocatalysts is an imperative requirement for the commercialization of direct methanol fuel cells. In this work, three dimensional, porous and urchin-like titanium copper nitride architectures is explored and implemented as the Pt support. The methanol oxidation reaction (MOR) performance of the obtained electrocatalyst shows a specific and mass activity of 1.46 mAcm⁻² and 0.84 Amg_Pt⁻¹, respectively, which are both more than 3 times higher compared with the commercial Pt/C catalyst. Notably, the novel catalyst also exhibits high stability, and a much slower performance decay compared with the benchmarked Pt/C with the same durability testing procedures. The comprehensive data confirms that the new type catalyst possesses a high charge transfer during the MOR process, and the synergistic effects between anchored Pt and the support mainly contributes to the high stability. This work provides a strategic method for designing effective MOR electrocatalyst with desirable stability.     

Synthesis and characterization of Pt/ZnO@SWCNT/Fe3O4 as a powerful catalyst for anodic part of direct methanol fuel cell reaction

Platinum is a preferred metal in fuel cell applications owing to its superior catalytic activity; Platinum's high cost and CO poisoning in oxidation processes, limit its usage as a standalone catalyst. At this point, it is important to develop new intermediate tolerant electrocatalysts. In this study, Zinc Oxide/Single Wall Carbon Nanotube/Iron oxide (ZnO@SWCNT/Fe₃O₄₎ catalyst was obtained by using ZnO, SWCNT/Fe₃O₄ support material, and Zinc Oxide/Single Platinum/Wall Carbon Nanotube/Iron oxide (Pt/ZnO@SWCNT/Fe₃O₄₎ catalyst was obtained by chemical synthesis method by adding Pt metal. With these catalysts, the efficiency of the use of Pt was examined within the scope of the study, and reducing limiting factors by using a low amount of Pt, at the same time, it is aimed to prepare a high electrocatalyst. The morphological structure of the obtained catalysts was characterized by scanning electron microscope (SEM), and X-ray diffraction (XRD). Methanol oxidation reactions (MOR) were conducted to determine the electrochemical performance of the catalysts. In the results obtained, it was observed that the current value obtained as a result of the Cyclic Voltammetry (CV) of the ZnO@SWCNT/Fe₃O₄ catalyst was 103.36 mA/cm², and the current value obtained as a result of the CV of the Pt/ZnO@SWCNT/Fe₃O₄ catalyst was 362.46 mA/cm². The results showed high stability for both catalysts, and it was seen that Pt increased the conductivity, methanol oxidation performance, and stability in the catalyst. The obtained catalysts showed high potential for methanol oxidation and are promising for fuel cell applications.     

Electrocatalytic activity of Pt–Pd electrocatalysts for the oxygen reduction reaction in proton exchange membrane fuel cells: Effect of supports

Pt–Pd electrocatalysts supported on different types of support including domestic Hicon Black (HB), multi-walled carbon nanotubes (MWCNT) and titania (TiO₂) were prepared by a combined approach of impregnation and seeding, and compared to that prepared using the commercial Vulcan XC-72 (C). Their oxygen reduction reaction (ORR) activities in an acid electrolyte (0.5 M H₂SO₄) and in a single proton exchange membrane (PEM) fuel cell were evaluated. The type of support was found to affect the Pt–Pd electrocatalyst morphology and ORR activity. The Pt–Pd/C electrocatalyst had the smallest Pt particle size, better catalyst dispersion and a higher Pt:Pd M ratio compared to that of other types of supported Pt–Pd electrocatalysts. However, both in the acid solution and in a single PEM fuel cell, the ORR activities of the Pt–Pd/HB and Pt–Pd/CNT electrocatalysts were comparable to that of the Pt–Pd/C one. The ORR pathway of all supported Pt–Pd electrocatalysts were close to the four-electron pathway.     

Hierarchically organized nanostructured TiO2/Pt on microfibrous carbon paper substrate for ethanol fuel cell reaction

Titanium dioxide is emerging as new class of catalyst support for fuel cell reactions. Via pulsed laser deposition, we prepare hierarchically organized and vertically aligned TiO₂/Pt nanostructured films on microfibrous carbon paper (CP) substrate at room temperature. Microstructural analyses reveal a metal-support interaction between TiO₂ and Pt. Namely; (i) the particles size of Pt on TiO₂ is smaller than those of Pt grown onto carbon paper substrate under similar condition of synthesis and (ii) Pt metallic state is transformed to ionized Pt²⁺ and Pt⁴⁺. Compared to CP/Pt electrocatalyst, the CP/TiO₂/Pt electrocatalysts (i) oxidize ethanol at much lower potentials, (ii) display superior current peak densities of more than 2.5 times higher by voltammetry, and (iii) steady state current density during long-term stability up to 8 times greater. For portable electronic applications, the binder-free and hierarchical structures of the CP/TiO₂/Pt electrocatalyst with its planar deposition make it very attractive as anode for direct ethanol fuel cells.     

SEM and XAS characterization at beginning of life of Pd-based cathode electrocatalysts in PEM fuel cells

The fuel cell performance of membrane electrode assemblies with a Pt anode and Pd, PdCu or Pd₅Cu₄Pt cathodes has been tested during 116 h (beginning of life). The incorporation of Cu to Pd increases the fuel cell performance. Incorporation of Pt leads to further improvement. SEM micrographs of the as-prepared and the fuel cell-tested assemblies show the effects of the 116 h of continuous operation. Nafion membranes were characterized by small angle X-ray scattering. The results show a reduction of the size of the lamellar domains in the perfluorinated matrix after fuel cell testing, but no correlation with the cathode electrocatalyst material. The cathode electrocatalysts were characterized by ex-situ synchrotron radiation X-ray diffraction and X-ray absorption spectroscopy at the Pd L₃, Cu K and Pt L₃ edges. Re-organization of Pd₅Cu₄Pt electrocatalyst after fuel cell testing was observed. The Cu in the electrocatalyst can be described as a nano-mixture of metallic Cu, alloyed Cu and CuO. The CuO acts as a promoter of the ORR.     

Pt support of multidimensional active sites and radial channels formed by SnO2 flower-like crystals for methanol and ethanol oxidation

SnO₂ nanoflowers and nanorods have been synthesized by the hydrothermal method without using any capping agent. Both types of SnO₂ nanostructures are selected as a support of Pt catalyst for methanol and ethanol electrooxidation. The synthesized SnO₂ nanostructures and SnO₂ supported platinum (Pt/SnO₂) catalysts are characterized by X-ray diffraction, scanning electron microscope and high resolution transmission electron microscope. The electrocatalytic properties of the Pt/SnO₂ and Pt/C catalysts for methanol and ethanol oxidation have been investigated systematically by typical electrochemical methods. The influence of SnO₂ morphology on its electrocatalytic activity is comparatively investigated. The Pt/SnO₂ flower-shaped catalyst shows higher electrocatalytic activity and better long-term cycle stability compared with other electrocatalysts owing to the multidimensional active sites and radial channels of liquid diffusion.     

Boosting CO tolerance and stability of Pt electrocatalyst supported on sulfonated carbon nanotubes

CO tolerance and stability are of prominent importance for the anodic electrocatalyst utilized in direct methanol fuel cells (DMFCs). Due to the electrochemical instability of Ru atoms, the state-of-the-art DMFC anodic electrocatalyst (PtRu/C) is unable to survive for long time. Here, we report a newly designed Pt electrocatalyst with robust CO tolerance and stability after coating with poly(vinyl pyrrolidone) (PVP). Electrochemically active surface area (ESA) is negligibly affected by the PVP decoration; meanwhile, almost undetectable ESA loss is obtained for the PVP decorated Pt electrocatalyst. However, the ESA degradations for non-decorated and commercial CB/Pt electrocatalysts are found to be 30% and 40%, respectively. The improved stability is ascribed to the strong interaction between PVP and sulfonated carbon nanotubes. Also, the CO tolerance evaluated from the methanol oxidation reaction is ∼3 and 3.5 fold higher compared to non-decorated and commercial CB/Pt electrocatalysts, respectively, which is attributed to the hydrophilic PVP polymer accelerating the water absorption and formation of Pt(OH)_ads species to re-activate nearby CO poisoned Pt nanoparticles. Thus, decoration with PVP polymer can simultaneously promote the stability and CO anti-poisoning of Pt electrocatalyst.     

Pt/C/MnO2 hybrid electrocatalysts for degradation mitigation in polymer electrolyte fuel cells

Pt/C/MnO₂ hybrid catalysts were prepared by a wet chemical method. Pt/C electrocatalysts were treated with manganese sulfate monohydrate (MnSO₄·H₂O) and sodium persulfate (Na₂S₂O₈) to produce MnO₂. The presence of MnO₂ was confirmed by FTIR spectroscopy. Rotating ring–disk electrode (RRDE) experiments were performed on electrodes prepared using the hybrid electrocatalysts to estimate the amount of hydrogen peroxide (H₂O₂) formed during the oxygen reduction reaction (ORR) as a function of MnO₂ content. Pt/C/MnO₂ (5% by weight of MnO₂) hybrid electrocatalysts produced 50% less hydrogen peroxide than the baseline Pt/C electrocatalyst. The hybrid electrocatalysts were used to prepare membrane electrode assemblies that were tested at 90 °C and 50% RH at open circuit with pure hydrogen as fuel and air as the oxidant. The fluoride ion concentration was measured using an ion selective electrode. The concentration of F⁻ in the anode condensate over 24 h was found to be reduced by a factor of 3–4 when Pt/C/MnO₂ replaced Pt/C as the catalyst. Through cyclic voltammetry and RRDE kinetic studies, the lower ORR activity of the acid treated hybrid electrocatalysts was attributed to catalyst treatment with acid during MnO₂ introduction. The activity of the hybrid catalyst was improved by switching to a water-based synthesis.     

Binary CuPt alloy nanoparticles assembled on reduced graphene oxide-carbon black hybrid as efficient and cost-effective electrocatalyst for PEMFC

Addressed herein is the synthesis of binary CuPt alloy nanoparticles (NPs), their assembly on reduced graphene oxide (rGO), Vulcan XC72 (VC) and their hybrid (rGO-VC) to be utilized as electrocatalysts for fuel cell reactions (HOR and ORR) in acidic medium and PEMFC tests. The synthesis of nearly-monodisperse Cu₄₅Pt₅₅ alloy NPs was achieved by using a chemical reduction route comprising the reduction of commercially available metal precursors in a hot surfactant solution. As-synthesized Cu₄₅Pt₅₅ alloy NPs were then assembled on three support materials, namely rGO, VC and rGO-VC) via liquid phase self-assembly method. After the characterization, the electrocatalysts were prepared by mixing the yielded materials with Nafion and their electrocatalysis performance was investigated by studying CV and LSV for HOR and ORR in acidic medium. Among the three electrocatalysts tested, Cu₄₅Pt₅₅/rGO-VC hybrid showed the highest catalytic activity with ECSA of 119 m² g⁻¹ and mass activity of 165 mA mg⁻¹_Pt. After the evaluation of electrochemical performance of the three prepared electrocatalysts, their performance was then evaluated in fuel cell conditions. In similar to electrochemical activities, the Cu₄₅Pt₅₅/rGO-VC hybrid electrocatalyst showed a superior fuel cell performance and power output by providing a maximum power of 480 mW cm⁻² with a relatively low Pt loading (0.28 mg cm⁻²). Additionally, the Cu₄₅Pt₅₅/rGO-VC hybrid electrocatalyst exhibited substantially better activity as compared to Pt/rGO-VC electrocatalyst. Therefore, the present study confirmed that alloying Pt with Cu enhances the catalytic activity of Pt metal along with the help of beneficial features of rGO-VC hybrid support material. It should be noted that this is the first example of studying PEMFC performance of CuPt alloy NPs supported on rGO, VC and rGO-VC hybrid.     

The effect of acetaldehyde and acetic acid on the direct ethanol fuel cell performance using PtSnO2/C electrocatalysts

PtSnO₂/C with Pt:SnO₂ molar ratios of 9:1, 3:1 and 1:1 prepared by an alcohol-reduction process were evaluated as anodicelectrocatalysts for direct ethanol fuel cell (DEFC). Acetaldehyde, acetic acid and mixtures of them with ethanol were also tested as fuels. Single cell tests showed that PtSnO₂/C electrocatalysts have a superior electrical performance for ethanol and acetaldehyde electro-oxidation when compared to commercial Pt₃Sn/C_(alloy) and Pt/C electrocatalysts. For all electrocatalysts, no electrical response was observed when acetic acid was used as a fuel. For ethanol electro-oxidation, the main product was acetaldehyde when Pt₃Sn/C_(alloy) and Pt/C electrocatalysts were employed. Besides, PtSnO₂/C electrocatalysts led to the formation of acetic acid as the major product. CO₂ was formed in small quantities for all electrocatalysts studied. A sharp drop in electrical performance was observed when using a mixture of ethanol and acetaldehyde as a fuel, however, the use of a mixture of ethanol and acetic acid as a fuel did not affect the DEFC performance.     

Experimental investigation on DMFCs using reduced noble metal loading with NiTiO3 as supportive material to enhance cell performances

In this present work, the effect of anode electrocatalyst materials is investigated by adding NiTiO₃ with Pt/C and Pt-Ru/C for the performance enhancement of direct methanol fuel cells (DMFCs). The supportive material NiTiO₃/C has been synthesized first by wet chemical method followed by incorporation of Pt and Pt-Ru separately. Experiments are conducted with the combination of four different electrocatalyst materials on the anode side (Pt/C, Pt-NiTiO₃/C, PtRu/C, Pt-Ru-NiTiO₃/C) and with commercial 20 wt % Pt/C on the cathode side; 0.5 mg_pt/cm² loading is maintained on both sides. The performance tests of the above catalysts are conducted on 5 cm² active area with various operating conditions like cell operating temperatures, methanol/water molar concentrations and reactant flow rates. Best performing operating conditions have been optimized. The maximum peak power densities attained are 13.30 mW/cm² (26.6 mW/mg_pt) and 14.60 mW/cm² (29.2 mW/mg_pt) for Pt-NiTiO₃/C and Pt-Ru-NiTiO₃/C at 80 °C, respectively, with 0.5 M concentration of methanol and fuel flow rate of 3 ml/min (anode) and oxygen flow rate of 100 ml/min (cathode). Besides, 5 h short term stability tests have been conducted for PtRu/C and Pt-NiTiO₃/C. The overall results suggest that the incorporation of NiTiO₃/C supportive material to Pt and Pt-Ru appears to make a promising anode electrocatalysts for the enhanced DMFC performances.     

An effective electrocatalyst based on platinum nanoparticles supported with graphene nanoplatelets and carbon black hybrid for PEM fuel cells

A facile synthesis at room temperature and at solid-state directly on the support yielded small, homogeneous and well-dispersed Pt nanoparticles (NPs) on CB-carbon black, GNP-graphene nanoplatelets, and CB-GNP-50:50 hybrid support. Synthesized Pt/CB, Pt/GNP and Pt/CB:GNP NPs were used as electrocatalysts for polymer electrolyte membrane fuel cell (PEMFC) reactions. HRTEM results displayed very small, homogeneous and well-dispersed NPs with 1.7, 2.0 and 4.2 nm mean-diameters for the Pt/CB-GNP, Pt/GNP and Pt/CB electrocatalysts, respectively. Electrocatalysts were also characterized by RAMAN, XRD, BET and CV techniques. ECSA values indicated better activity for graphene-based supports with 19 m² g⁻¹_Pt for Pt/GNP and 55 m² g⁻¹_Pt for Pt/CB-GNP compared to 10 m² g⁻¹_Pt for Pt/CB. Oxygen reduction reaction (ORR) studies and fuel cell tests were in parallel with these results where highest maximum power density of 377 mW cm⁻² was achieved with Pt/CB-GNP hybrid electrocatalyst. Both fuel cell and ORR studies for Pt/CB-GNP indicated better dispersion of NPs on the support and efficient fuel cell performance that is believed to be due to the prevention of restacking of GNP by CB. To the best of our knowledge, Pt/GNP and Pt/CB-GNP electrocatalysts are the first in literature to be synthesized with the organometallic mild synthesis method using Pt(dba)₃ precursor for the PEMFC applications.     

Bimetallic platinum–ruthenium nanoparticles immobilized on reduced graphene oxide-TiO2 (RGO-TiO2) support for ethanol electro oxidation in acidic media

The present work addresses the potentialities of Pt–Ru nanoparticles deposited on a graphene oxide (RGO) and TiO₂ composite support towards electrochemical oxidation of ethanol in acidic media relevant for fuel cell applications. To immobilize platinum–ruthenium bimetallic nanoparticles on to an RGO-TiO₂ nanohybrid support a simple solution-phase chemical reduction method is utilized. An examination using electron microscopy and energy dispersive X-ray spectroscopy (EDS) indicated that Pt–Ru particles of 4–8 nm in diameter are dispersed on RGO-TiO₂ composite support. The corresponding Pt–Ru/RGO-TiO₂ nanocomposite electrocatalyst was studied for the electrochemical oxidation of ethanol in acidic media. Compared to the commercial Pt–Ru/C and Pt/C catalysts, Pt–Ru/RGO-TiO₂ nanocomposite yields higher mass-specific activity of about 1.4 and 3.2 times, respectively towards ethanol oxidation reaction (EOR). The synergistic boosting provided by RGO-TiO₂ composite support and Pt–Ru ensemble together contributed to the observed higher EOR activity and stability to Pt–Ru/RGO-TiO₂ nanocomposite compared with other in-house synthesized Pt–Ru/RGO, Pt/RGO and commercial Pt–Ru/C and Pt/C electrocatalysts. Further optimization of RGO-TiO₂ composite support provides opportunity to deposit many other types of metallic nanoparticles onto it for fuel cell electrocatalysis applications.     

PdBi/C electrocatalysts for ethanol electro-oxidation in alkaline medium

PdBi/C electrocatalysts (Pd:Bi atomic ratios of 95:05, 90:10, 80:20 and 70:30) were prepared by borohydride reduction using Pd(NO₃)₂.2H₂O and Bi(NO₃)₃.5H₂O as metal sources and Vulcan XC72 as support. The electrocatalysts were characterized by energy-dispersive X-ray analysis, X-ray diffraction, transmission electron microscopy and cyclic voltammetry. The activity for the ethanol electro-oxidation in alkaline medium was investigated at room temperature by chronoamperometry and the results were compared with Pt/C and PtBi/C electrocatalysts. PdBi/C (95:05) electrocatalyst showed a significant increase of performance for ethanol electro-oxidation compared to Pd/C and others PdBi/C electrocatalysts. The final current value after holding the cell at −0.4 V versus Ag/AgCl electrode for 30 min in alkaline medium for PdBi/C (95:05) electrocatalyst was about eleven times higher than the current value of the Pt/C electrocatalyst and 1.5 times higher than PtBi/C (50:50).     

Electrochemical behaviour of carbon supported Pt electrocatalysts for H2O2 reduction

Carbon supported bimetallic Pt-alloys (Pt_0.75M_0.25/C, with M = Ni or Co) are investigated as novel electrode materials for H₂O₂ reduction in acid solution. The alloy electrocatalysts, Pt_0.75Ni_0.25/C and Pt_0.75Co_0.25/C, as well as carbon supported Pt (Pt/C) are characterised using cyclic voltammetry. The electrocatalytic activity of the materials is studied using a rotating disc electrode system with a combination of linear scan voltammetry and chronoamperometry. It is found that the activity of Pt_0.75M_0.25/C electrocatalysts for H₂O₂ reduction is comparable to the activity of Pt/C electrocatalyst, with Pt_0.75Co_0.25/C exhibiting the best performance.     

A durable and robust Fe–N–C electrocatalyst for oxygen reduction reactions by introducing Ti3C2–TiO2 as radical scavengers

Modern Fe–N–C electrocatalysts are promising as alternatives to expensive Pt-based catalysts for oxygen reduction reactions (ORR). Although the activity of this type of electrocatalyst have been improved over the years, their durability and longevity need critical enhancements for practical applications in fuel cells. Typically, the incomplete oxygen reduction inevitably generates reactive oxygen species, including ·OH and HO₂· radicals, which will fiercely attack the carbon support and directly damage active sites in Fe–N–C electrocatalysts. Herein, a durable and robust Fe–N–C@Ti₃C₂–TiO₂ electrocatalyst for high-efficiency ORR is synthesized, in which Ti₃C₂–TiO₂ could effectively scavenge ·OH radicals or decompose H₂O₂ molecules, and synergistically work with Fe–N–C catalysts to improve the durability. Consequently, the Fe–N–C@Ti₃C₂–TiO₂ electrocatalyst shows prominent ORR performance in both alkaline and acidic electrolytes, low H₂O₂ yield, and long-term stability. This work provides great prospects for the design of highly stable ORR electrocatalysts by introducing radical scavengers as an active defense to proactively eliminate H₂O₂ and its radicals.     

Highly stable RuO2/SnO2 nanocomposites as anode electrocatalysts in a PEM water electrolysis cell

This work explores the opportunity to reduce the cost and enhance the stability of RuO₂ as an oxygen evolution reaction catalyst by coating RuO₂ on chemically stable SnO₂ support. Nano‐sized RuO₂/SnO₂ composites of different mass ratios of RuO₂ to SnO₂ (0.45:1, 0.67:1, and 1.07:1) were synthesized using solution‐based hydrothermal method. The physicochemical properties of the RuO₂/SnO₂ were studied by scanning electron microscopy, X‐ray diffraction, transmission electron microscopy, and N₂ adsorption–desorption isotherms. The electrochemical activity of RuO₂/SnO₂ as anode electrocatalyst was investigated in a proton exchange membrane (PEM) water electrolysis cell of Pt/C cathode and Nafion membrane. Experimental results showed that RuO₂/SnO₂ of ratio (1.07:1) exhibit higher electrochemical activity compared to pure RuO₂, resulting ~50% reduction of noble metal content. The extended life test of electrocatalysts for 240 h implied that RuO₂/SnO₂ (1.07:1) significantly improved the stability of electrode in comparison to pure RuO₂ in oxygen evolution processes. Copyright © 2013 John Wiley & Sons, Ltd.     

An efficient Fe2O3/FeS heterostructures water oxidation catalyst

Slow kinetics and insufficient understanding of the perceptual design of oxygen evolution reaction (OER) electrocatalysts are major obstacles. Overcoming these challenges, heterostructures have recently attracted attention because they encourage alternative OER electrocatalysts with active structural features. In this study, synthesis, characterization and electrochemical evaluation of the heterostructure of iron oxide/iron sulfide (Fe₂O₃/FeS) and its counterparts, iron oxide (Fe₂O₃) and iron sulfide (FeS) are reported. The structural features of as-synthesized electrocatalysts have been evaluated by infrared spectroscopy, powder X-ray diffraction study and scanning electron microscopy. Fe₂O₃/FeS was found to be a stable electrocatalyst for efficient water splitting, which initiates OER at a surprisingly low potential of 1.49 V (vs RHE) in 1 M potassium hydroxide. The Fe₂O₃/FeS electrocatalyst drives OER with a current density of 40 mA cm^?2 at overpotential of 370 mV and a Tafel slope of 90 mV dec^?1. Its performance is better than its counterparts (Fe₂O₃ and FeS) under similar electrochemical conditions. At an applied potential of 1.65 V (vs RHE), continuous oxygen production for several hours revealed the long-term stability and effective activity of the Fe₂O₃/FeS electrocatalyst for OER. The as-developed Fe₂O₃/FeS heterostructure provides an effective alternative low-cost metal-based electrocatalysts for OER.