Anode Electrocatalyst Research Articles

Evaluation of Co–Au bimetallic nanoparticles as anode electrocatalyst for direct borohydride-hydrogen peroxide fuel cell

Evaluation of Co–Au bimetallic nanoparticles as anode electrocatalyst for direct borohydride-hydrogen peroxide fuel cell

Pt/Ni Catalyst Supported by Composite of Graphene and Polyaniline Microtubes Boosting Methanol Electrochemical Oxidation

The development of durable and efficient anode electrocatalysts is crucial for direct methanol fuel cells. In this paper, polyaniline (PANI) microtubes are firstly prepared by removing the polystylene (PS) core from PANI coated electrospun PS. The catalyst of PtNi/PANI@rGO is built by two steps: graphene oxide (GO) is mixed with PANI microtubes to obtain PANI@GO and then PANI@GO is used as a support material to load PtNi nanoparticles by reductive reaction while GO is reduced into rGO. The morphology, electronic structure and chemical structure of the catalysts are characterized by SEM, TEM, XPS and Raman spectroscopy, respectively. The electrochemical analysis of electrochemical impedance spectroscopy, cyclic voltammetry and chronoamperometric measurement are performed to analyze the electrocatalytic performance. The electrochemical results indicate that as-synthesized PtNi/PANI@rGO has the high activity toward methanol oxidation, and its mass activity is 1.7, 1.3 and 4.1 times higher than that of PtNi/PANI, PtNi/rGO and commercial Pt/C catalysts, respectively. The PANI microtubes not only improve the electron transfer kinetic but also help avoid the accumulation of graphene layers. The doping of Ni into Pt changes the surface electronic structure to elevate the catalytic activity and helps effectively improve the resistance to CO poisoning.

PdAuAg Alloy Nanoparticles on Nickel Foam as Anode for Passive Air-Breathing Formate Fuel Cell

A passive air-breathing formate fuel cell with PdAuAg alloy nanoparticles supported on the carbon nanotube (CNT) pasted on nickel foam (NF) as anode is reported in this work. With optimization, a maximum power density of 16 mW cm−2 with PdAuAg/CNT on NF as anode is achieved, which is 2.2 time of that achieved by using commercial Pd/C on NF (7.3 mW cm−2). Furthermore, the cell with PdAuAg/CNT on NF as anode can steadily discharge at 5 mA cm−2 for more than 28 h continuously. This is, to our knowledge, the best performance of passive air-breathing formate fuel cells reported so far and PdAuAg/CNT on NF as anode can be considered as the state-of-the-art for the passive air-breathing formate fuel cell. These results suggested that the PdAuAg/CNT catalyst probably provides an alternative avenue for developing the anode electrocatalysts for passive air-breathing formate fuel cell applications.

A novel electrodeposited poly(melamine)-palladium nanohybrid catalyst on GCE: Prosperous multi-functional electrode towards methanol and ethanol oxidation

Herein, a novel Poly (melamine) have been successively electrodeposited on glassy carbon electrode and decorated by Pd nanoparticles (Pd NPs) subsequently to fabricate Poly (melamine) – Pd nanocomposite. Structural geometry, morphological view, and elemental composition analysis were ensured by X-ray diffractogram, scanning electron microscope, and X-ray photoelectron spectroscopy. The electrodeposited Poly (melamine) (PME) material depicts an interconnected nano rod (50 nm) morphology leads to a nano exploder (~150 nm) arrangement. Spherical shaped Pd decorated PME morphology was obtained for GC\\PME-Pd NPs composite (150 nm). The electrocatalytic activity of the fabricated anode electrocatalyst was examined by cyclic voltammetry, electrochemical impedance spectroscopy and chronoamperometry methods. The modified GC\\PME-Pd NPs composite electrode validates superior electrocatalytic behaviour towards methanol and ethanol oxidation in alkaline background. Besides, the electrochemical surface area and electrocatalytic behaviour make it a greater anode catalyst towards methanol and ethanol oxidation. The synergic effects amid the Poly (melamine)-Pd NPs composite enhances the catalytic activity, mechanical stability on the electrocatalysis of methanol and ethanol oxidation reaction superior than modified Poly (melamine) electrode. Hence, the fabricated anode electrocatalyst is proficient to get realistic approach towards the progression in the direct alcohol (methanol and ethanol) oxidation reaction in direct alcohol fuel cells (DAFCs) applications.

Ionic Liquid-Derived Carbon-Supported Metal Electrocatalysts as Anodes in Direct Borohydride-Peroxide Fuel Cells

Three different carbon-supported metal (gold, platinum, nickel) nanoparticle (M/c-IL) electrocatalysts are prepared by template-free carbonization of the corresponding ionic liquids, namely [Hmim][AuCl4], [Hmim]2[PtCl4], and [C16mim]2[NiCl4], as confirmed by X-ray diffraction analysis, scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy and Raman spectroscopy. The electrochemical investigation of borohydride oxidation reaction (BOR) at the three electrocatalysts by cyclic voltammetry reveals different behavior for each material. BOR is found to be a first-order reaction at the three electrocatalysts, with an apparent activation energy of 10.6 and 13.8 kJ mol−1 for Pt/c-IL and Au/c-IL electrocatalysts, respectively. A number of exchanged electrons of 5.0, 2.4, and 2.0 is obtained for BOR at Pt/c-IL, Au/c-IL, and Ni/c-IL electrodes, respectively. Direct borohydride-peroxide fuel cell (DBPFC) tests done at temperatures in the 25–65 °C range show ca. four times higher power density when using a Pt/c-IL anode than with an Au/c-IL anode. Peak power densities of 40.6 and 120.5 mW cm−2 are achieved at 25 and 65 °C, respectively, for DBPFC with a Pt/c-IL anode electrocatalyst.

Divergent Paths, Same Goal: A Pair-Electrosynthesis Tactic for Cost-Efficient and Exclusive Formate Production by Metal-Organic-Framework-Derived 2D Electrocatalysts.

Electrosynthesis of formic acid/formate is a promising alternative protocol to industrial processes. Herein, a pioneering pair-electrosynthesis tactic is reported for exclusively producing formate via coupling selectively electrocatalytic methanol oxidation reaction (MOR) and CO2 reduction reaction (CO2 RR), in which the electrode derived from Ni-based metal-organic framework (Ni-MOF) nanosheet arrays (Ni-NF-Af), as well as the Bi-MOF-derived ultrathin bismuthenes (Bi-enes), both obtained through an in situ electrochemical conversion process, are used as efficient anodic and cathodic electrocatalysts, respectively, achieving concurrent yielding of the same high-value product at both electrodes with greatly reduced energy input. The as-prepared Ni-NF-Af only needs quite low potentials to reach large current densities (e.g., 100mAcm-2 @1.345V)with ≈100% selectivity for anodic methanol-to-formate conversion. Meanwhile, for CO2 RR in the cathode, the as-prepared Bi-enes can simultaneously exhibit near-unity selectivity, large current densities, and good stability in a wide potential window toward formate production. Consequently, the coupled MOR//CO2 RR system based on the distinctive MOF-derived catalysts displays excellent performance for pair-electrosynthesis of formate, delivering high current densities and nearly 100% selectivity for formate production in both the anode and the cathode. This work provides a novel way to design advanced MOF-derived electrocatalysts and innovative electrolytic systems for electrochemical production of value-added feedstocks.

High-Performance Ru 2 P Anodic Catalyst for Alkaline Polymer Electrolyte Fuel Cells

High-Performance Ru ₂ P Anodic Catalyst for Alkaline Polymer Electrolyte Fuel Cells

Hierarchically nanostructured (Ni,Co)phosphides for hydrazine electrooxidation

Transition metal phosphides are intriguing but less well investigated electrocatalytic materials for potential application in the direct hydrazine fuel cell (DHFC). Herein, we present a systematic study of hierarchically nanostructured (Ni,Co)phosphides for hydrazine electrooxidation reaction (HzOR). A series of nickel foam (NF) supported (Ni,Co)phosphides featured with an urchin-like structure were fabricated using a hydrothermal method followed by reductive calcination and phosphatization treatments. Our study revealed the composition dependences of phase structure and catalytic properties of (Ni,Co)phosphides for HzOR. In general, incorporation of Co into NixP catalyst leads to improvement of HzOR activity, but causes an aggravation of non-faradaic hydrazine decomposition. Among the examined series, NiCoP/NF exhibits the highest activity for HzOR via the 4-electron pathway, outperforming the top-notch HzOR electrocatalysts hitherto reported. But its performance in suppressing non-faradaic hydrazine decomposition was inferior to that of NixP catalyst. Our study demonstrated the great potential as well as the challenge in developing (Ni,Co)phosphides as high-performance anode electrocatalysts of DHFC.

Stable Bimetallene Hydride Boosts Anodic CO Tolerance of Fuel Cells

Active and durable anode electrocatalysts are of vital importance for practical implementation of fuel cells. However, the surface-adsorbed reaction intermediates, especially CO, easily poison and ...

Molybdenum carbide-nitrogen doped carbon composites as effective non-precious electrocatalyst for direct hydrazine fuel cell

Highly efficient, abundant and stable, non-noble metal electrocatalysts are of critical importance to the development of direct hydrazine fuel cells technology. Herein, molybdenum carbide composite with nitrogen doped carbon (MoCx-NC) is prepared by fast pyrolysis. Among as-prepared electrocatalysts, the optimal MoCx-NC electrocatalyst (900°C, 5 %) presents higher electrocatalytic performance (3.56 mA cm−2) and better cycling stability (86.13 %) for anode hydrazine oxidation reaction. Importantly, the optimal electrocatalyst-driven direct hydrazine fuel cell demonstrates an open circuit voltage of 0.96 V (80°C) with a maximum power density of 158.26 mW cm−2, which also possesses a good long-term operating stability for 12 h. Furthermore, a series of physical characterizations of transmission electron microscopy, X-ray photoelectron spectroscopy and Raman is also performed on the optimal MoCx-NC, which proving that the MoCx-NC is a composite of molybdenum carbide and nitrogen doped carbon. This target catalyst is an effective and ideal noble-metal-free anode electrocatalyst, would have a great potential to be applied in direct hydrazine fuel cells in the future.

Study on the effect of calcium hypochlorite and air as mixed oxidant and a synthesized low cost Pd‐Ni/C anode electrocatalyst for electrooxidation of glycerol in an air breathing microfluidic fuel cell

AbstractIn the present work, glycerol‐based air breathing microfluidic fuel cell (μFC) is investigated. The noble metal Pd and non‐noble metal Ni‐based bimetallic synthesized electrocatalyst (Pd‐Ni/C) were used for glycerol electrooxidation and commercial Pt/CHSA was used as cathode electrocatalyst. The anolyte is glycerol mixed with KOH electrolyte. The atmospheric air and calcium hypochlorite mixture are used as oxidant in cathode and catholyte, respectively. Acetylene black carbon is used as electrocatalyst support with low metal loading of 20 wt% Pd and Ni at their different weight ratios (Pd/Ni) of 16:4, 10:10, and 4:16 to synthesize bimetallic Pd‐Ni/C anode electrocatalysts. The crystal structure of the synthesized electrocatalyst was determined by X‐ray diffraction (XRD) analysis. The surface morphology and surface concentration of synthesized electrocatalyst were determined by scanning electron microscopy (SEM) and energy dispersive X‐ray spectroscopy (EDX), respectively. The particle size of synthesized electrocatalyst was determined by transmission electron microscopy (TEM) analysis. The electrochemical activity of Pd‐Ni/C was investigated by cyclic voltammetry analysis. The electrocatalyst Pd‐Ni (10:10)/C gives higher electrocatalytic activity for glycerol electrooxidation compared to other ratios of electrocatalyst. A single air breathing μFC is investigated using various key parameters where air alone as oxidant gives open circuit voltage (OCV) of 0.42 V and maximum power density of 1.27 mW/cm2. While using calcium hypochlorite and air as mixed oxidant, the OCV was increased to 0.72 V and maximum power density increased to 3.43 mW/cm2, which are 1.71 and 2.7 times, respectively, more than that of air as oxidant only.

On the limitations in assessing stability of oxygen evolution catalysts using aqueous model electrochemical cells

Recent research indicates a severe discrepancy between oxygen evolution reaction catalysts dissolution in aqueous model systems and membrane electrode assemblies. This questions the relevance of the widespread aqueous testing for real world application. In this study, we aim to determine the processes responsible for the dissolution discrepancy. Experimental parameters known to diverge in both systems are individually tested for their influence on dissolution of an Ir-based catalyst. Ir dissolution is studied in an aqueous model system, a scanning flow cell coupled to an inductively coupled plasma mass spectrometer. Real dissolution rates of the Ir OER catalyst in membrane electrode assemblies are measured with a specifically developed, dedicated setup. Overestimated acidity in the anode catalyst layer and stabilization over time in real devices are proposed as main contributors to the dissolution discrepancy. The results shown here lead to clear guidelines for anode electrocatalyst testing parameters to resemble realistic electrolyzer operating conditions.

Hydrogen Separation and Purification from Various Gas Mixtures by Means of Electrochemical Membrane Technology in the Temperature Range 100-160 °C.

This paper reports on an experimental evaluation of the hydrogen separation performance in a proton exchange membrane system with Pt-Co/C as the anode electrocatalyst. The recovery of hydrogen from H2/CO2, H2/CH4, and H2/NH3 gas mixtures were determined in the temperature range of 100–160 °C. The effects of both the impurity concentration and cell temperature on the separation performance of the cell and membrane were further examined. The electrochemical properties and performance of the cell were determined by means of polarization curves, limiting current density, open-circuit voltage, hydrogen permeability, hydrogen selectivity, hydrogen purity, and cell efficiencies (current, voltage, and power efficiencies) as performance parameters. High purity hydrogen (>99.9%) was obtained from a low purity feed (20% H2) after hydrogen was separated from H2/CH4 mixtures. Hydrogen purities of 98–99.5% and 96–99.5% were achieved for 10% and 50% CO2 in the feed, respectively. Moreover, the use of proton exchange membranes for electrochemical hydrogen separation was unsuccessful in separating hydrogen-rich streams containing NH3; the membrane underwent irreversible damage.

The in-situ construction of NiFe sulfide with nanoarray structure on nickel foam as efficient bifunctional electrocatalysts for overall water splitting

Developing high-efficiency, stable and cost-effective non-noble metal-based bifunctional electrocatalysts is crucial for the overall water splitting to produce clean hydrogen energy. Nanoarray structures electrocatalysts have attracted increasing research interests due to its structural advantages. Herein, Ni3S2/Fe9S10 with two dimensions (2D) nanosheet arrays in-situ growth on three dimensions (3D) nickel foam (Ni3S2/Fe9S10@NF) was prepared by step-wise hydrothermal method. Ni3S2/Fe9S10@NF was derived from NiFe layered double hydroxides, and the as-prepared Ni3S2/Fe9S10@NF electrode was directly served as a bifunctional catalyst for electrolysis of water. Benefiting from the directly contact with conductive Ni foam substrate, the positive synergy effect between Ni and Fe in the Ni3S2/Fe9S10@NF catalyst and its open 3D porous structure, the binder-free and integrated Ni3S2/Fe9S10@NF electrode displayed excellent catalytic activities towards hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), the overpotential for HER and OER are only 56 and 147 mV at 10 mA cm−2, respectively. Particularly, when the prepared Ni3S2/Fe9S10@NF further employed as both the cathode and anode electrocatalysts a symmetric cell Ni3S2/Fe9S10@NF|| Ni3S2/Fe9S10@NF, a low cell voltage of 1.43 V was achieved at 10 mA cm−2, with good stability. This work not only illustrated that non-noble metal-based electrocatalysts have tremendous potential applications for electrocatalytic electrolysis of water but also provided a feasible strategy to prepare high-efficiency and stable non- precious metal catalysts.

Synthesis and Characterization of Platinum and Platinum based Alloy Nanoparticles Anchored on Various Carbon Materials for Methanol Oxidation in a DMFC – A Short Review

In the fabrication of direct methanol fuel cells (DMFCs) having high performance the essential conditions are (i) the design and construction of a suitable anode electrocatalyst comprising of Pt or a Pt based alloy nanoparticles methanol oxidation reaction (MOR) efficiently and effectively (ii) nature of support materials onto which these nanoparticles are anchored. In MOR one of the major problems is the adsorption of poisoneous carbonmoxide and other similar intermediates near the active surface of Pt active leading to its deactivation and also the crossover of methanol solution towards the cathodic side. All these factors, therefore, lower the overall electrochemical performance of the electro-catalysts. In the present review paper we report some of our important results of the synthesis of different Pt and Pt based anode electro-catalysts (Pt, PtCo alloys, PtCu alloys) anchored on different support materials such as reduced graphene oxide (rGO), Nitrogen doped rGO and a hybrid of rGO/CNTs for MOR and compared with few of those already reported recently. A detailed characterization of raw materials and the electro-catalysts synthesized in this work is also discussed using XRD, FT-IR, SEM, TEM etc. The electrochemical measurements were made using cyclic voltammetry in acidic medium at room temperature.

NiMo Nanoparticles Anchored on N-Doped Carbon Rods for High-Efficiency Hydrogen Electrooxidation in Alkaline Media.

Anion-exchange membrane fuel cells (AEMFCs) are promising clean energy devices of high efficiency; however, their large-scale applications suffer from high cost and/or poor activity of electrocatalysts, especially at the anode. Herein, an electrocatalyst composed of NiMo nanoparticles (≈50 nm) in situ anchored on N-doped carbon rods (denoted as NMNC) has been synthesized by a facile calcination method. The as-prepared NMNC catalyst shows an especially high hydrogen oxidation reaction (HOR) activity (3.23 mA cm-2 at 0.10 V vs reversible hydrogen electrode (RHE)), excellent stability during 10,000 cycles within -0.10 to 0.50 V vs RHE, and extraordinarily high CO tolerance in a 0.1 M KOH electrolyte. Particularly, the doping of Mo atoms into Ni lattices of the electrocatalyst results in Ni lattice distortion and well-regulated graphitization degree of the carbon matrix, contributing to the enhanced reducibility and accelerated HOR reaction kinetics. This facilely synthesized NMNC electrocatalyst of enhanced HOR activity is expected to serve as a promising anodic electrocatalyst for AEMFCs.

Stabilizer-free bismuth nanoparticles for selective polyol electrooxidation

SummaryBismuth is the least toxic element among heavy metals, an outstanding advantage for environmental and health considerations. Yet, utilizing bismuth as anodic electrocatalyst is hindered by the formation of a spreading Bi(OH)3 inhibitor layer during the anodic process. Herein, we report that bismuth nanoparticles, produced using laser ablation, can avoid such drawbacks. The production of Bi(V) species assists polyol electrooxidation. For glucose, instead of the commonly reported gluconic acid as the product, the Bi(V) species enables highly selective oxidation and C–C bond cleavage to produce arabinonic acid, erythronic acid, and eventually glyceric acid. We not only generate high-valent Bi(V) species for catalytic applications, especially for bioelectrocatalysis where the less toxic bismuth is highly appreciated, but also present Bi nanoparticle as a highly selective electrocatalyst that can break C–C bond. We believe that Bi electrocatalyst can find broader applications in electrochemical biomass conversion and electrosynthesis.

Synthesis of Iron Phosphide Nanoclusters by an Electroless Plating Method for Enhanced Oxygen Evolution Reaction

The oxygen evolution reaction is a significant component of water splitting, and the design of anode electrocatalysts is the key to achieving efficient electrochemical water oxidization. However, the high price of anode electrocatalysts like RuO2 or IrO2 limits their wide application. Herein, we introduce the employment of FePx grown on C as a catalyst with high activity and low cost, containing a special nanocluster structure formed by a simple chemical reduction combined with an electroless plating method. The performance of FePx/C shows a low overpotential of 273 mV at 10 mA cm−2, a Tafel slope of 56 mV dec−1 and a long continuous oxygen evolution for 5 h in 1.0 M potassium hydroxide. Such superior performance can be attributed to the porous structure of the iron phosphide nanoclusters. Our work not only shows excellent performance, but also provides a workable design for non-noble catalysts.

Molybdenum compound cocatalyzed Ni‐based anode electrocatalysts for EOR in alkaline media

In this study, Mo2C and MoS2 were used as cocatalyst for a non-noble metal for the first time for ethanol electro-oxidation reaction (EOR) in alkaline media. Anode electrocatalysts containing Nickel, Mo compound, and carbon support were synthesized at different weight ratios of Ni and Mo2C (or MoS2) while keeping the carbon support weight constant in each catalyst combination to investigate the best weight ratio among our range. Physical characterizations of the electrocatalysts were investigated by XRD, XPS, SEM-EDS, EDAX, and TEM techniques. Electrochemical performance of the catalysts was studied via cyclic voltammetry (CV), linear sweep voltammetry (LSV), and chronoamperometry (CA) by using a home-made electrochemical cell test system exhibiting similar alkaline direct ethanol fuel cell (ADEFC) architecture by giving the opportunity of using an anion exchange membrane. All of the Ni-Mo2C/C and Ni-MoS2/C at different weight ratios were shown better performance than pristine Ni and Ni/C. The highest current density was measured with Ni-Mo2C/C-2 (11.4 mA cm−2) anode catalyst, which exhibits the highest electrochemical reaction rate. The diffusion coefficient of the catalysts was calculated by using the data from linear LSV. CA experiment results showed that the tolerance for catalytic poisoning and durability of Ni-Mo2C/C-2 was better among all the electrocatalysts. Highlights Literature survey showed that Mo2C and MoS2 are promising co-catalysts for EOR. However, there is a lack of study on the use of Mo2C or MoS2 as co-catalyst with a non-noble metal. Molybdenum compound containing transition metal-based anode electro-catalysts were synthesized for EOR in alkaline media. A home-made electrochemical cell is designed to make the system more similar to an ADEFC system. The results of the electrochemical characterizations are showed that the Mo compound addition increased the catalytic activity and stability.

Boosting bioelectricity generation in microbial fuel cells using metal@metal oxides/nitrogen-doped carbon quantum dots

Microbial fuel cells have recently received significant consideration from researchers worldwide as sustainable and futuristic energy due to their potential in converting energy from decomposition of natural organisms in waste to green electricity. Unfortunately, the difficulty of achieving high power due to poor extracellular electron transfer (EET) efficiency between microorganisms and the solid substrate, besides low bacterial loading capacity has limited their applications to date. Herein, iron/iron oxide (Fe@Fe2O3) nanoparticles incorporated with nitrogen-doped carbon quantum dots (NCQDs) are synthesized via using an effective and simple electrodeposition technique. Fe@Fe2O3/NCQDs anode provides not only a high effective surface area for the adhesion of microbe’s cells but also promotes favored electrical conductivity to facilitate EET from bacteria to the anode in the mixed culture-based MFCs. Considerably, at a steady-state of the electricity production, the MFC equipped with Fe@Fe2O3/NCQDs as activated anode delivers a maximum power density of 836 ± 8 mW/m2, which is 87% higher compared to instances when NCQDs (446 ± 11 mW/m2) is applied as anode electrocatalyst. This work opens a door toward an effective route to microbial anode electrode to produce sustainable green energy.