Catalytic Electrode Research Articles

Synthesis of rGO/NiFe2O4 nanocomposite as an alternative counter electrode material to fabricate Pt-free efficient dye sensitized solar cells

Reduced graphene oxide/nickel ferrite (rNiF) nanocomposites via one pot hydrothermal procedure were synthesised. The synthesised rNiF composite was used as a catalytic counter electrode (CE) material for dye-sensitized solar cell (DSSC). HR-TEM results demonstrates that rNiF composites were firmly enfolded on rGO network, allowing easy electron transfer across the CE-electrolyte interface. The XPS survey scan spectrum of samples demonstrates that the presence of Ni, Fe, C and O in the composite structure. The large amount of porosity and specific surface area was achieved 241.71 (m2/g) and 0.521 (cc/g) by rNiF-25 sample. When rNiF-25 nanocomposite was employed as the CE catalyst in iodine electrolytes, the DSSCs achieved a power conversion efficiency (PCE) of η = 8.41 %, corresponding to 98 % of that of Pt CEs under the illumination. Also, the device maintains 88 % efficiency up to 40 days under ambient conditions without encapsulation. The IPCE of DSSCs for the Pt-based and rNiF-25 based CEs achieves maximum absorption of 81 % and 78 % at 520 nm respectively. The high catalytic activities of rNiF-25 nanocomposite are attributed to synergetic effects from the combination of active NiF structure and conductive graphene which provides efficient charge transport. These findings suggest that rNiF-25 CE can be considered as a promising alternative material to replace Pt counter electrode in DSSCs.

Chem-bio interface design for rapid conversion of CO2 to bioplastics in an integrated system

Chem-bio interface design for rapid conversion of CO2 to bioplastics in an integrated system

Catalytic membrane electrode with Co3O4 nanoarrays for simultaneous recovery of water and generation of hydrogen from wastewater

Tremendous research efforts have been devoted to new methods of water decontamination and water splitting at low cost and less energy consumption. Herein, we developed a robust electrochemical strategy with an efficient membrane electrode to remove refractory organic pollutants and simultaneously produce pure hydrogen in wastewater. Firstly, the membrane anode was constructed with a three-dimensional (3D) nanoneedle array of Co3O4 and Ti membrane, exhibiting superior degradation of phenol and dye with Na2SO4 as the electrolyte in a conventional electrocatalytic membrane reactor (ECMR). For the phenol degradation, ≥99% removal efficiency of phenol, 99.5% chemical oxygen demand (COD) removal rate, 92.5% total organic carbon (TOC) removal rate, 88.7% current efficiency and 0.061 kW h (g COD)−1 energy consumption can be obtained. For the dye degradation, ≥99% decolor efficiency and 95.2% COD removal rate, 87.6% TOC removal rate, 82.1% current efficiency and 0.12 kW h (g COD)−1 energy consumption can be achieved. The obtained membrane electrode can provide more active CoOOH sites, dramatically increase the electric fields and overcome mass transfer limitation in a flow-through configuration, thereby significantly enhance the catalytic performance. Finally, we designed a H-type ECMR with the proton exchange membrane (PEM) as the separator for pure H2 production, i.e., PEM-ECMR, demonstrating superior degradation performance of phenol and dye, stable production of high-purity hydrogen (11–15 mL h−1), and excellent long-term stability (100 days) and low voltage input (below 3.0 V). This work demonstrates a promising pathway towards reducing cost and energy consumption for water decontamination and simultaneous hydrogen production.

Sheet-like units of ferrocene-based coordination compounds for oxygen evolution

Metal-organic frameworks represent an emerging class of effective pre-electrocatalysts with low cost and high activity for oxygen evolution, which is a critical process involved in water splitting and metal-air batteries. In this study, a new electrode with ferrocene-based coordination compounds supported by nickel foam was designed and prepared, in which the coordination compounds are assembled by cobalt chloride and 1, 1'-ferrocenedicarboxylic acid. The as-obtained pre-catalytic electrode shows remarkable electrocatalytic activity and stability towards oxygen evolution. In 1 M KOH, the electrode can provide a current density of 50 mA cm−2 at an overpotential of 268 mV with Tafel slope of 109 mV dec−1. During the catalytic process, the metal-organic framework surface shows an obvious phase evolution behavior. The synergetic effect between Co and Fe sites, and the unique microstructure of the in situ derived active species are believed to be responsible for the excellent electrocatalytic performance. The catalytic electrode was also investigated as a cathode in a Zn-air battery, which presents an energy density of 572 mW h gZn−1, a peak power density of 60 mW cm−2, and an excellent cyclability of over 50 h. This work presents a new type pre-catalytic electrode for oxygen evolution and would provide some hints for the development of advanced catalytic electrodes.

Low Platinum-Content Electrocatalysts for Highly Sensitive Detection of Endogenously Released H2O2.

The commercial viability of electrochemical sensors requires high catalytic efficiency electrode materials. A sluggish reaction of the sensor’s primary target species will require a high overpotential and, consequently, an excessive load of catalyst material to be used. Therefore, it is essential to understand nanocatalysts’ fundamental structures and typical catalytic properties to choose the most efficient material according to the biosensor target species. Catalytic activities of Pt-based catalysts have been significantly improved over the decades. Thus, electrodes using platinum nanocatalysts have demonstrated high power densities, with Pt loading considerably reduced on the electrodes. The high surface-to-volume ratio, higher electron transfer rate, and the simple functionalisation process are the main reasons that transition metal NPs have gained much attention in constructing high-sensitivity sensors. This study has designed to describe and highlight the performances of the different Pt-based bimetallic nanoparticles and alloys as an enzyme-free catalytic material for the sensitive electrochemical detection of H2O2. The current analysis may provide a promising platform for the prospective construction of Pt-based electrodes and their affinity matrix.

Electrodeposited PEDOT/Nafion as Catalytic Counter Electrodes for Cobalt and Copper Bipyridyl Redox Mediators in Dye-Sensitized Solar Cells.

PEDOT-based counter electrodes for dye-sensitized solar cells (DSSCs) are generally prepared by electrodeposition, which produces polymer films endowed with the best electrocatalytic properties. This translates in fast regeneration of the redox mediator, which allows the solar cell to sustain efficient photoconversion. The sustainable fabrication of DSSCs must consider the scaling up of the entire process, and when possible, it should avoid the use of large amounts of hazardous and/or inflammable chemicals, such as organic solvents for instance. This is why electrodeposition of PEDOT-based counter electrodes should preferably be carried out in aqueous media. In this study, PEDOT/Nafion was electrodeposited on FTO and comparatively evaluated as a catalytic material in DSSCs based on either cobalt or copper electrolytes. Our results show that the electrochemical response of PEDOT/Nafion toward Co(II/III-) or Cu(I/II)-based redox shuttles was comparable to that of PEDOT/ClO4 and significantly superior to that of PEDOT/PSS. In addition, when tested for adhesion, PEDOT/Nafion films were more stable for delamination if compared to PEDOT/ClO4, a feature that may prove beneficial in view of the long-term stability of solar devices.

Self-supported cobalt/cobalt selenide heterojunction for highly efficient overall water splitting

Electrocatalytic water splitting is a vastly reliable method for hydrogen production. Nonetheless, its wide practical application urgently requires the development of highly active and stable bifunctional electrocatalysts with self-supported structures. This paper reports on a novel, simple way to fabricate an efficient cobalt/cobalt selenide (CS) catalytic electrode with a unique 3-D finger-like structure. More specifically, porous Co substrate was fabricated by a phase-inversion tape-casting and sintering method, followed by one-step selenization in Ar atmosphere. The resultant CS electrode manifested superior catalytic performance in both HER and OER (hydrogen and oxygen evolution reaction, respectively) that took place in an alkaline medium, with low overpotential and high long-term stability. Furthermore, the electrolysis test for overall water splitting was successfully performed by assembling the CS electrodes as both anode and cathode. The excellent electrocatalytic performance is ascribed to the high conductivity of the Co substrate, the distinctive finger-like structure, and the numerous in-situ developed heterojunctions, which suitably adjust the electronic structure and decrease the energy barrier of water splitting. Moreover, the density function theory (DFT) calculations revealed that the heterojunction enhances the density of the state near the Fermi level and optimize the kinetics of HER and OER processes. As a result, the hydrogen adsorption free energy (ΔGH*) is close to zero, and the energy barrier of the rate-determining step of OER is low due to the heterojunction formed.

Heterogeneous electro-Fenton using three-dimension Fe-Co-Bi/kaolin particle electrodes for degradation of quinoline in wastewater.

Wastewater containing quinoline has become a common pollutant in water and soil environments, which poses a threat to human health due to its carcinogenicity, teratogenicity, and mutagenicity. Quinoline's stability and toxicity hinders its degradation by conventional physicochemical and biological methods. In this contribution, Fe-Co-Bi/kaolin particle electrodes were prepared for the efficient degradation of quinoline in wastewater, and characterized by using scanning electron microscope, X-ray diffraction, pyridine-IR, Brunauer-Emmett-Teller, X-ray photoelectron spectroscopy, and four-probe resistivity test. Parameters affecting the degradation efficiency were optimized to be the particle electrode dosage of 40g/L, pH 3.5, H2O2 addition of 67.6mmol/L, electrical conductivity of 12.7ms/cm, and voltage of 20V. The constructed three-dimensional catalytic particle electrode system (3D-CPE) achieved 92.1% removal rate of chemical oxygen demand (COD) under the optimal conditions. Hydroxyl radicals (•OH) generated in the 3D-CPE process were identified by radical scavenging tests and electron spin response analysis. To unravel the degradation mechanism, the intermediate products were identified by using high performance liquid chromatography-mass spectrometry. The degradation mechanism was discussed with the help of theoretical calculation.

A Transparent to Dark Non‐Complementary Electrochromic Device Based on Al3+ Guest Ions with TMTU/TMFDS2+ Redox Couple for Robust Stability

AbstractAl3+‐based electrochromic devices (ECDs) are expected to substitute Li+‐based ECDs as the next‐generation smart windows options. Compared to Li+, Al3+ possess large quantities in the earth and safety, while the smaller ionic radius and three‐electron redox mechanism can break the capacity bottleneck of inorganic electrochromic materials (ECM). However, limited by the strong electrostatic interaction between Al3+ with ECM and the lack of matching counter electrodes, the research on Al3+ is still focused on three‐electrode system without applications in ECDs. Different from conventional complementary structure, the ECM/redox/CCE (catalytic counter electrode) structure is introduced to enhance the kinetics (from 1.56 × 10−11 to 9.45 × 10−11 cm2 s−1) of the Al3+ intercalation/extraction process. Based on this structure, Al3+‐based ECDs achieve a series of excellent properties: a) almost total absorption of visible and near‐infrared waveband (T500–1500 nm ≈0%) under −1.0 V; b) ultra‐low driving voltage (53% transmittance modulation under −0.1 V); c) excellent memory effect with the presence of redox couple; d) wide range of color modulation capability (yellow, green, blue, and black); e) outstanding energy efficiency. Moreover, the possibility of Na+ as an alternative to Li+ is also verified and Na+‐based ECDs exhibit comparable electrochromic properties to Li+‐based ECDs.

Electrocatalytic Self‐Supported‐Electrode Based on CoxNi1‐xP/TiC0.5N0.5 for Enhancing pH‐Universal Hydrogen Evolution Electrocatalysis

AbstractThe industrial application of powder‐based catalytic electrodes is heavily restricted by powder shedding, inhibition of active sites, and poor long‐term stability. Herein, a porous titanium carbonitride (TiC0.5N0.5) ceramic substrate with open straight finger‐like holes is first made by a simple approach of phase‐inversion tape‐casting and pressureless sintering, and then a CoxNi1‐xP active layer is in situ formed by a hydrothermal technique and phosphorization to achieve integrated CoxNi1‐xP/TiC0.5N0.5 self‐supported ceramic electrodes. Electrochemical tests reveal that the optimized Co0.9Ni0.1P/TiC0.5N0.5 electrode exhibits overpotentials of 76.5 and 79.8 mV at 10 mA cm−2, Tafel slopes of 47.3 and 40.5 mV dec−1, in 0.5 m H2SO4 and 1 m KOH, respectively. Furthermore, its superior long‐term stability and resistance to corrosion can be achieved for more than 20 h in both media at 100 mA cm−2. In addition, the Co0.9Ni0.1P/TiC0.5N0.5 electrode has much better performance than Pt/C at high current density in neutral media. Density functional theory calculations confirm that the Ni substitution of 1/10 Co in CoP leads to the more optimal |ΔGH*| among the CoxNi1‐xP catalysts. Compared with other CoP or NiP‐based electrodes, the Co0.9Ni0.1P/TiC0.5N0.5 electrode benefits from high strength, unique pore structure, tight and compatible bonding, and high hydrophilicity.

2D Nanomaterial—Based Electrocatalyst for Water Soluble Hydroperoxide Reduction

Hydroperoxides generated on lipid peroxidation are highly reactive compounds, tend to form free radicals, and their elevated levels indicate the deterioration of lipid samples. A good alternative to the classical methods for hydroperoxide monitoring are the electroanalytical methods (e.g., a catalytic electrode for their redox-transformation). For this purpose, a series of metal oxides—doped graphitic carbon nitride 2D nanomaterials—have been examined under mild conditions (pH = 7, room temperature) as catalysts for the electrochemical reduction of two water-soluble hydroperoxides: hydrogen peroxide and tert-butyl hydroperoxide. Composition of the electrode modifying phase has been optimized with respect to the catalyst load and binding polymer concentration. The resulting catalytic electrode has been characterized by impedance studies, cyclic voltammetry and chronoamperometry. Electrocatalytic effect of the Co-g-C3N4/Nafion modified electrode on the electrochemical reduction of both hydroperoxides has been proved by comparative studies. An optimal range of operating potentials from −0.215 V to −0.415 V (vs. RHE) was selected with the highest sensitivity achieved at −0.415 V (vs. RHE). At this operating potential, a linear dynamic range from 0.4 to 14 mM has been established by means of constant-potential chronoamperometry with a sensitivity, which is two orders of magnitude higher than that obtained with polymer-covered electrode.

Synthesis of ruthenium sulfide nanoparticles decorated on reduced graphene oxide/multi-walled carbon nanotubes as a catalytic counter electrode for dye-sensitized solar cells exceeding 13 % efficiency

The luxury price, shortage, and instability of platinum (Pt) markedly hamper its commercialization in dye-sensitized solar cells (DSSCs). Consequently, developing an efficient alternative catalyst in lieu of noble Pt is imperative issue for the promotion of DSSCs. In this paper, a robust and electrochemically stable 3D nanocomposite comprised of amorphous ruthenium sulfide nanoparticles (RuS2 NPs), reduced graphene oxide (RGO), and functionalized multi-walled carbon nanotubes (MWCNTs) was prepared by the facile hydrothermal method and explored as a counter electrode (CE) in DSSCs. The RuS2 NPs uniformly decorated on the surfaces of the RGO/MWCNTs to form the RuS2/RGO/MWCNTs composite, which adequately inhibited aggregation of the RuS2 NPs to fully exploit its impressive electrochemical activity. Benefiting from the unexceptionable catalytic activity of RuS2 NPs in the RuS2/RGO/MWCNTs as well as superior electronic transmission channels provided by the conductive RGO/MWCNTs network, the designed DSSC with RuS2/RGO/MWCNTs exhibited a remarkable power conversion efficiency (PCE) of 13.24 % exceeding that of Pt CE (PCE: 9.53 %). Consequently, this research opens a new avenue to fabricate advanced cathode catalysts based on metallic sulfides and carbon-based materials with excellent performance for their potential application in next-generation energy storage and conversion devices such as DSSCs, water splitting, and other electrochemical applications.

Carbon-Doped Copper (hydro)Oxides on Copper Wires as Self-supported Bifunctional Catalytic Electrode for Full Water Splitting

Carbon-Doped Copper (hydro)Oxides on Copper Wires as Self-supported Bifunctional Catalytic Electrode for Full Water Splitting

A laser-scribed wearable strain sensing system powered by an integrated rechargeable thin-film zinc-air battery for a long-time continuous healthcare monitoring

Wearable sensors with long cruising times without the need for an external wire-connected power supply are urgently required for a continuous physiological signal monitoring. Herein, we report the design and fabrication of a wearable all-in-one sensing system that integrates a sensitive strain sensor and a rechargeable zinc-air battery on the same laser-induced graphene (LIG) platform. The sensing electrode of the strain sensor, the catalytic air electrode of the zinc-air battery and the interconnection lines between the two are simultaneously fabricated through the same laser-scribing process on polyimide (PI) followed by pattern transfer to a flexible and stretchable polydimethylsiloxane (PDMS) substrate. In the sensor, the conductive porous LIG exhibits a high gauge factor (~2710.95), a wide detection range (~40%), and a well cyclic loading-unloading stability (>20,000 cycles). In the zinc-air battery, Co3O4 nanoparticles are in-situ laser-sintered on LIG to form an excellent electrode/electrolyte/air three-phased interfacing structure for a high catalytic performance, and a moisturized tetraethyl ammonium hydroxide (TEAOH)-KOH/polyvinyl alcohol (PVA) gel electrolyte tightly binds the Co3O4/LIG air electrode and zinc foil electrode together into an integrate thin-film energy device, which provides a high open-circuit voltage (~1.39 V) and a high specific capacity (712 mAh g−1 at 0.2 mA cm−2). For a proof-of-concept, an intelligent wristband based on the sensing system was fabricated and worn on the wearer’s wrist for a long-time continuous pulse monitoring of up to 10 h. The health state of the wearer can be depicted upon the acquired pulse waveforms. The developed LIG-based sensing system with a high internal powering capability will be promising in wearable sensing applications.

Catalytic electrodes for the oxygen reduction reaction based on co-doped (B-N, Si-N, S-N) carbon quantum dots and anion exchange ionomer

B-N-, Si-N, and S-N-co-doped carbon quantum dots (CQD) were prepared by hydrothermal synthesis from inexpensive and non-toxic precursors. They were analysed by Raman, FTIR, and XPS spectroscopies and used as oxygen reduction reaction (ORR) electrocatalysts. The electrodes were prepared by drop-casting a slurry containing poly(sulfone trimethylammonium) hydroxide (PSU-TMA) to enhance the hydroxide-ion transport near the catalytically active centers. Furthermore, polyaniline (PANI), reported to be catalytically active for the ORR, was added to some electrodes. A similar trend was observed for the electrode capacitance measured by cyclovoltammetry in the non-Faradaic region and impedance spectroscopy. The ORR kinetics studied by linear sweep voltammetry showed the lowest onset and half-wave potentials and the lowest Tafel slopes for the B-N-co-doped samples, although the B concentration is low (0.5%). Data with and without PANI are quite similar. The S-N- and Si-N co-doped samples are slightly less efficient. The stability test demonstrated a decrease by about 10% of the diffusion-limited current after 500 cycles, indicating a microstructural change impacting the mass transport conditions, but the onset potential is not modified. Altogether, the good electrocatalytic activity of B-N-co-doped CQD with a low boron concentration in presence of PSU-TMA indicated the high potential of these electrodes. The inexpensive synthesis of co-doped CQD from non-toxic precursors is an important advantage of these materials vs other carbon-doped electrocatalysts.

Construction of Pd nanoparticles/two-dimensional Co-MOF nanosheets heterojunction for enhanced electrocatalytic hydrodechlorination

To simultaneously enhance the catalytic activity of Pd and lower its dosage, we report a Pd/Co-MOF nanosheets/Ni foam electrode (Pd/Co-MNSs/Ni foam) with conductive 2D MOF nanosheets as interlayer for electrocatalytic hydrodechlorination (ECH). Such electrode delivers high ECH activity for nearly complete dechlorination (~97%) of chloramphenicol (CAP) with an apparent rate constant of 0.11 min−1, outcompeting the well-reported and the commercial electrode materials. Pd/Co-MNSs/Ni foam maintains its activity after 9 consecutive runs and 5-day exposure to air, and shows rapid degradation kinetics for other priority contaminants. The formation of Pd/Co-MNSs heterojunction interface increases the electron density of metallic Pd and brings the d states closer to Fermi level than Pd alone, thus optimizing the binding of ECH intermediates. This support construction-based strategy tunes the interface of catalytic electrode to expose active sites and modulate the electronic states of catalyst to promote intrinsic activity, boosting electroreductive remediation of organic halides.

Electrochemical Impedance Spectroscopic Investigations of Nanocomposite Thin-Film Formation at an Electrified Micro Liquid-Liquid Interface

Herein, the interface between two immiscible electrolyte solutions (ITIES) has been exploited as a pristine platform for electropolymerization of the 2D and 3D nanocomposite materials, i.e., metal nanoparticles (NPs) embedded within a conductive polymer matrix that are electrogenerated/electropolymerized simultaneously The free-standing conductive thin film can be prepared with an adjustable loading of metallic NPs, to be tailored for a variety of applications, including as catalytic electrodes in fuel cells, or act as a bioreceptor in a biosensor. Electrochemical impedance spectroscopy (EIS) has been used to investigate mechanistic aspects of film growth through two types of charge transfer processes, ion and electron transfer, that occur during electropolymerization. The thermodynamics of a heterogeneous electron transfer (HET) between redox centers, KAuCl4(aq) and terthiophene (TT, org), across the interface governs the electropolymerization reaction, including the rate, which is itself affected by the rate of diffusion of reactants toward the interface, ohmic resistance of the two electrolyte solutions, distance between reactants due to arrangement of ions at the interface, and reorganization energy of the involved species in the reaction. Electropolymerization is controlled through application of an applied external potential difference and monitored voltammetrically as well as by EIS. Curve fitting of EIS data was performed using an equivalent circuit incorporating a phase constant element (CPE) parallel to a resistor for non-ideal interfacial capacitance, and HET resistance across the film as it forms at the ITIES. Next, those elements are parallel to a resistor (R), and a Warburg element (W) to approximate ion transfer across the ITIES/porous thin-film as it grows (Fig. 1). Data suggest that the films electronic conductivity improves with increasing the [TT]:[KAuCl4] ratio. Increased capacitance was hypothesized to be linked to an increase in the effective surface area of the polymer film during its growth phase versus the molecularly smooth ITIES. Higher [TT]:[KAuCl4] ratios elicited higher capacitance as well as diffusion resistance which can be attributed to formation of a more compact film structure. Cyclic voltammetric and potential step methods are compared and discussed, highlighting the formed films final properties, including film thickness and conductivity. Figure 1

Galvanically Displaced Noble Metal Nanoparticles Onto Electrosprayed Graphene-CNT Electrodes for Lithium-Ion and Fuel Cell Applications

Advanced lithium-ion batteries (LIB) and Fuel Cells demonstrate promise as the next generation energy storage and conversion (ESC) technology especially as it pertains to wearable technology and electric vehicles. Although LIB dominate the battery market (>90%) due its reliability, long cycle life, and market maturity, different and more innovative ways to improve the chemistry of the electrode structure must be discovered in order to reduce the cost of materials, dendritic issues at the solid-electrolyte interphase (SEI) layer, and improve upon the limited anode capacity (graphite theoretical capacity 372 mAh g-1). Fuel cells are also promising renewable energy sources due to their high energy densities and scalability. However, both LIB and Fuel Cells are limited by the 3D materials that enable their enhanced electrochemical and catalytic performance. We propose a platform methodology for the synthesis of 3D electrodes with carbon nanomaterials and noble metals. The enhanced electrical, thermal, chemical, and mechanical stability of graphene and carbon nanotubes (CNTs) offer an ideal platform for electrode design for energy storage applications. Here we utilize spontaneous galvanic displacement driven by reduction potential difference to produce three-dimensional (3D) graphene-CNT-noble metal nanoparticle 3D electrode without the use of any harsh chemical reducing agents. A graphene-CNT slurry with a poly(acrylic acid) (PAA) binder is air-controlled electrosprayed onto copper foil to create 3D composite thin film electrodes. Although noble metals are expensive materials to be used in LIB, we propose a new approach for synthesizing conductive electrochemically stable electrodes. We demonstrate a spontaneous technique to reduce the noble metal salts by galvanically displacement with the copper substrate to deposit noble metal nanoparticles onto the graphene-CNT electrode. The noble metal salt solutions (HAuCl4, K2PtCl4, and Na2PdCl4) are drop casted onto the resulting copper supported graphene-CNT electrodes to enable electroless noble metal nanoparticle deposition. Scanning electron microscopy (SEM) imaging confirms that the carbon nanomaterials are integrated with noble metal nanoparticles forming an overall 3D electrode structure. Raman spectroscopy verifies the characteristic D-band, G-band, and 2D-band peaks from the graphitic structure within the 3D carbon and noble metal nanostructure. Cyclic voltammetry and electrochemical impedance spectroscopy (EIS) are used to characterize the electrochemical properties of the electrodes. We demonstrate that the use of an energy-free and spontaneous process based on the difference in thermodynamic reduction potentials as the driving force for producing carbon nanomaterial/noble metal nanostructured electrodes for batteries and fuel cells. This process is a more simple, scalable, and cost-efficient alternative to current methods for developing lightweight and catalytic electrodes for energy storage applications, such as lithium-ion batteries, lithium-air batteries, and fuel cells. Raman Spectroscopy is used to confirm the presence defects on the oxidized carbon nanotube and graphene oxide surface. Scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDX), and x-ray diffraction (XRD) were used to characterize the morphology of the 3D carbon-noble metal structure and the surface elemental composition. Electrochemical characterization techniques such as electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), performance testing for oxygen reduction reaction (ORR), hydrogen evolution reaction (HER), and potentiostatic measurements are used to characterize the areal specific resistance (ASR), areal capacitance, electrochemical surface area, initial Coulombic efficiency (ICE), rate capability and cycling performance, and electrochemical stability, respectively.

(Digital Presentation) In-Situ Growth of Core@Shell Ni@Fe Doped Ni(Oxy)Hydroxide Nanoarrays on Commercial Nickel Mesh to Promote Oxygen Evolution Reaction

Oxygen evolution reaction (OER) is a rate-determining step in water electrolysis. Herein, we report a novel one-step oxidation-electrodeposition (OSOE) approach to generate core@shell (CS) Ni@Fe doped Ni(Oxy)Hydroxide nanoarrays based alkaline water electrolysis electrode with an outstanding OER performance that is, an overpotential of 245 mV is obtained reaching 10 mA cm– 2. The corresponding Tafel slope is 36.8 mV dec– 1. Strikingly, it delivers a Ni-based mass activity of 1336 A g– 1 and a high turnover frequency of 0.285 s– 1, over 7-fold higher than state-of-the-art IrO2. Moreover, the electrode can also survive at 500 mA cm–2 for over 500 h without apparent degradation under industrial conditions. The proficient catalysis was driven by the Fe doped Ni(Oxy)Hydroxide shell that serves as the intrinsically active site over an equally important electrically conductive metallic Ni core array. This is the first report by using OSOE to construct high performance practical catalytic electrode for alkaline water electrolysis.

An effective pre-catalytic electrode based on iron/nickel hydroxyquinoline for water oxidation

Oxygen evolution reaction is related in various energy-related devices including water splitting and metal-air batteries. Herein, the reaction between Fe3+, Ni2+, and 8-hydroxyquinoline was used to generate iron/nickel hydroxyquinoline salts (FeNi-HQ), which were loaded on a nickel framework for water oxidation. The formed coordination compound contains iron/nickel bimetal sites that show strong interaction between them, and so presents excellent electrocatalytic activity for oxygen evolution after an electrochemical activation process. Driven by a small overpotential of 293 mV, the activated catalytic electrode can provide 50 mA cm−2 of current density with higher stability. Investigation on the catalyst after long time catalytic operation confirms that the surface layer is activated with the formation of metal oxyhydroxides. This study provides a new and effective pre-catalytic electrode for oxygen evolution.