Performance of CoNiO spinel oxide coating on AISI 430 stainless steel as interconnect for intermediate temperature solid oxide fuel cell

In order to decrease oxide growth kinetics, maintain suitable conductivity and prevent Cr-volatilization of AISI 430 stainless steels (430 SS) as the interconnect for intermediate temperature solid oxide fuel cells (SOFCs), a CoNiO spinel oxide protective coating has been successfully fabricated on the 430 SS specimen using a simple and cheap process with two steps: 1) electroplation of CoNi alloy layer and 2) pre-oxidation treatment to convert the CoNi alloy into spinel oxide. The CoNiO spinel layer on the 430 SS (CoNiO 430 SS) is dense and uniform with 8–10 μm thickness. And the CoNiO spinel oxide protective coating consists of a main face-centered-cubic (fcc) NiCo₂O₄ spinel phase and a minor fcc NiO phase. Compared with bare 430 SS, the oxidation resistance and the conductivity of the CoNiO 430 SS have been improved remarkably under simulated typical SOFC operating cathode conditions (at 800 °C in air). After an isothermal oxidation test at 800 °C, the area specific resistance (ASR) of CoNiO 430 SS is much lower and stable (0.1 Ω cm² for 100 h and 0.9 Ω cm² for 600 h) than that of bare 430 SS (1.2 Ω cm² for 100 h and 2.4 Ω cm² for 600 h). These performances of CoNiO 430 SS imply that it can be a promising candidate interconnect for solid oxide fuel cell.     

In situ preparation of N doped orthorhombic Nb2O5 nanoplates /rGO composites for photocatalytic hydrogen generation under sunlight

The synthesis of nitrogen doped orthorhombic niobium oxide nanoplates/reduced graphene oxide composites (NNb₂O₅/rGO) and their photocatalytic activity towards hydrogen generation from water and H₂S under natural sunlight has been demonstrated, uniquely. Nanostructured NNb₂O₅/rGO is synthesized by in situ wet chemical method using urea as a source of nitrogen and optimized by varying percentage of graphene oxide (GO). X?ray diffraction (XRD) study reveals that NNb₂O₅ have orthorhombic crystal structure with crystalline size, 35 nm. Further, X?ray photoelectron spectroscopy (XPS) confirm the presence of nitrogen and rGO in NNb₂O₅/rGO nanocomposite. Morphological features of (NNb₂O₅/rGO) were examined by FE?SEM and FE?TEM showed Nb₂O₅ nanoplates of diameter 25–40 nm anchored on 2D rGO. Diffuse reflectance spectra depicts the extended absorbance in the visible region with band gap of 2.2 eV. Considering the band gap in the visible region, the photocatalytic hydrogen generation from water and H₂S has been performed. The 1 wt % rGO hybridized NNb₂O₅ (S2) exhibited superior photocatalytic hydrogen generation (537 μmol/h) from water and (1385 μmol/h) from H₂S under sunlight. The improved photocatalytic activity is attributed due to an extended absorbance in the visible region, modified electronic structure upon doping and formation of well defined NNb₂O₅/rGO interface, provides large surface area, accelerates the supression of electron and hole pairs recombination rate. In our opinion, this works may provides facile route for energy efficient and economic approach for fabrication of NNb₂O₅/rGO nanocomposites as a visible light active photocatalyst.     

Hydrogen production by low-temperature oxidation of coal: Exploration of the relationship between aliphatic CH conversion and molecular hydrogen release

Molecular hydrogen, released by coal combustion, is closely related to mine safety. In this study, the evaluation of emission characteristics of hydrogen in the low-temperature (T ≤ 200 °C) oxidation process of coal was first introduced in the use of batch reactors. The effects of coal rank, coal temperature, and particle size on hydrogen release were systematically investigated. Results showed that the release of hydrogen at low temperature was linearly related to oxygen consumption and did not really depend on the mass of coal. Coal samples with higher rank and under the condition of higher temperature produced more amount of hydrogen. When the particle size was large, the rate of hydrogen release exhibited a dependence on particle size, while for the coal samples with very fine particles (less than 0.12 mm in diameter), it was much more difficult to release hydrogen and the rate of hydrogen release was independent of the particle size. Moreover, in-situ fourier transform infrared spectroscopy was employed to analyze aliphatic CH stretching vibration from 2800 to 3000 cm^?1. The conversion rates of three types of CH groups during coal oxidation were analyzed and calculated. The results indicated that methylene group exhibited the highest conversion rate; however, hydrogen release was more likely to involve the conversion of hydrogen radicals from functional group containing methane bond. Finally, the intrinsic relationship between the conversion of aliphatic CH and the release of hydrogen was quantified based on theory of oxidation kinetics.     

PtRh alloys on hybrid TiO2 – Carbon support as high efficiency catalyst for ethanol oxidation

High cost and poor stability of catalysts remain major obstacles for the commercialization of direct ethanol fuel cells (DEFCs). In this work, a Pt₉Rh/TiO₂C nanostructured catalyst is synthesized via an impregnation-reduction method followed by thermal annealing in N₂ at ambient pressure. X-ray powder diffraction (XRD) and scanning transmission electron microscopy (STEM) are used to characterize the corresponding physico-chemical properties of the as-prepared catalysts. The results reveal that PtRh nanoparticles are uniformly distributed on the TiO₂C hybrid support material. Cyclic voltammetry, linear scan voltammetry, CO-stripping voltammograms, chronoamperometry and chronopotentiometry methods are employed to investigate their catalytic performance for ethanol oxidation. The results show that the Pt₉Rh/TiO₂C produced a current density of 1039.5 mA mg_Pt^?1, which are 3.98, 8.31 and 2.43 times higher than Pt/TiO₂C, Pt/C and Pt₉Rh/C, respectively. Furthermore, the Pt₉Rh/TiO₂C also has greater resistance to CO-poisoning and displays better stability for ethanol oxidation than other catalysts. Pt₉Rh/TiO₂C therefore provides a promising material for ethanol oxidation in direct ethanol fuel cells.     

Facile synthesis of Ti3+ doped Ag/AgITiO2 nanoparticles with efficient visible-light photocatalytic activity

We successfully synthesized novel Ti³⁺ doped TiO₂ and Ti³⁺ doped Ag/AgITiO₂ nanoparticles with efficient visible-light photocatalytic activity for hydrogen production by facile one-step solvothermal method. The as-prepared Ti³⁺ doped TiO₂ nanoparticles displayed excellent visible-light absorption and visible-light driven hydrogen production activity (115.3 μmol g^?1 h^?1), while the commercial TiO₂ had no visible-light response. Moreover, the as-prepared Ti³⁺ doped Ag/AgITiO₂ nanoparticles in this experiment showed highly enhanced visible-light absorption and efficient visible-light driven activity for hydrogen (571.0 μmol g^?1 h^?1), which was 4.95 times as high as that of the as-prepared TiO₂ nanoparticles. And the surface areas of the as-prepared TiO₂ and Ti³⁺ doped Ag/AgITiO₂ catalysts were up to 138.829 m² g^?1 and 102.988 m² g^?1, much higher than that of the commercial TiO₂ (55.516 m² g^?1). Finally, the visible-light photocatalytic mechanism of the Ti³⁺ doped Ag/AgITiO₂ nanoparticles for hydrogen generation was also proposed in detail.     

Bimetallic Pt-M electrocatalysts supported on single-wall carbon nanotubes for hydrogen and methanol electrooxidation in fuel cells applications

A series of PtRu and PtMo bimetallic catalysts were prepared via a chemical reduction method by bubbling CO to form carbonyl compounds as metal precursors. In both cases the PtRu and PtMo bimetallic electrocatalysts achieved the maximum activity when the amount of Ru and Mo in the material was 50%wt. The physicochemical characterization of the electrocatalytic materials through X-ray diffraction (XRD) and transmission electron microscopy (TEM) has determined the presence of bimetallic structures. The electrochemical characterization using cyclic voltammetry, electrochemical impedance spectroscopy (EIS) and polarization curves in Proton Exchange Membrane Fuel Cells (PEMFC) and Direct Methanol Fuel Cell (DMFC) allowed to systematically investigate the electrocatalytic activity of the synthesized materials for the electrooxidation of hydrogen and methanol. The PtRu/SWCNT electrocatalysts showed a higher current density at least 7-fold and 3-fold compared with Pt/SWCNT and PtMo/SWCNT electrocatalysts, respectively. Besides, the Pt50%–Ru50%/SWCNT exhibited a shifting to negative values in the onset potential reaction for the electrooxidation of methanol of 200 mV in comparison with Pt100%/SWCNT and Pt50%–Mo50%/SWCNT electrocatalysts. The experimental and simulated polarization curves obtained from DMFC show that PtRu/SWCNT and PtMo/SWCNT electrocatalysts exhibited higher power and current densities values compared with the Pt/SWCNT electrocatalyst. The membrane-electrode assembly (MEA) with Nafion^® and the PtRu/SWCNT electrocatalysts showed an open-circuit voltage value of 0.730 V, significantly higher than that the values for the MEAs with Pt/SWCNT (0.663 V) and PtMo/SWCNT (0.633 V), respectively.     

Catalytic transformation of H2S for H2 production

Hydrogen sulfide (H₂S) gas is a by-product from natural gas refining, hydrodesulfurization of various fossil fuels, and syngas cleaning from pyrolysis and gasification. Catalytic pyrolysis of H₂S provides an alternative and effective pathway to recover both H₂ and sulfur. Catalysts from hydrotalcite of ZnAl, ZnNiAl, and ZnFeAl were employed for H₂S pyrolysis and compared with TiO₂ and MoS₂ at atmospheric pressure and temperatures in the range of 923–1123 K. Kinetic analysis was carried out in a packed bed reactor which revealed the effect of H₂S partial pressures to be of the order of 0.8–1 with respect to H₂S. The developed novel catalysts showed improved performance with significantly reduced activation energy compared to TiO₂ by 30 kJ/mol as well as higher H₂S conversion during pyrolysis (17% at 1173 K) than with MoS₂ catalyst, even at high H₂S partial pressure which is necessary for viable hydrogen production. The new approach showed an alternate economical and efficient pathway of catalyst design to obtain high activity and stability for simultaneous H₂ energy and pure sulfur recovery from unwanted H₂S resources.     

Study on steam reforming of coal tar over NiCo/ceramic foam catalyst for hydrogen production: Effect of Ni/Co ratio

The effect of Ni/Co ratio on the catalytic performance of NiCo/ceramic foam catalyst for hydrogen production by steam reforming of real coal tar was studied. The NiCo/ceramic foam catalyst was synthesized by deposition-precipitation (DP) method and characterized with different methods. The experiments were conducted in a two-stage fixed-bed reactor. The results showed that the reducibility of the metallic oxides in bimetallic NiCo/ceramic foam catalysts was influenced obviously by the Ni/Co ratio.Both gas and hydrogen yield increased first and then decreased with the decline of Ni/Co ratio, and the highest hydrogen yield of 31.46 mmol g^?1 was obtained when the Ni/Co ratio was 5/5. The lowest coke deposition of 0.34 wt% was generated at the same Ni/Co ratio. The lifetime test showed the catalyst maintained catalytic activity after 14 cycles (28 h), indicating the coal tar steam reforming on NiCo/ceramic foam catalyst is a promising method for hydrogen production.     

Effects of silicon concentration in SOFC alloy interconnects on the formation of oxide scales in hydrocarbon fuels

Oxide scale formations on FeCr alloy interconnects were investigated in anode gas (mixtures of CH₄ and H₂O) atmospheres for solid oxide fuel cells. The silicon concentration in FeCr alloy changed the microstructures of oxide scales, elemental distribution and oxide scale growth rates. Oxide scale is composed of the following phases from surface to inner oxides: FeMn spinel, Cr₂O₃, oxide scale/alloy interface and internal oxides of Si and Al. With decreasing the Si concentration from 0.4 to 0.01 mass%, formation of thin Si and Mn layer was observed inside the FeCr alloy. Oxide scale growth rate constants decreased by lowering the Si concentration in FeCr alloy from 4.2 × 10⁻¹⁸ to 2.1 × 10⁻¹⁸ m² s⁻¹ at 1073 K. Diffusivity of Fe and Cr was changed by the concentration of Si in FeCr alloy, which affects the growth rates of oxide scale. The electrical conductivity of oxidized FeCr alloy shows almost same level regardless the Si concentration (in the orders of 10 S cm⁻² at 1073 K).     

Pulsed electrodeposition of reduced graphene oxide on NiNiO foam electrode for high-performance supercapacitor

Through electrodeposition, controlling hydrogen evolution reaction and selective electrochemical dealloying of copper from NiCu porous foam, highly nanoporous nickel and nickel oxide is fabricated on the copper surface. Electrochemically reduced graphene oxide (ERGO) is loaded on the NiNiO foam as high-performance electrodes for supercapacitors through pulsed galvanostatic reduction of drop casted graphene oxide nanosheets at different duty cycles and frequencies. Surface morphology and composition of fabricated ERGO/NiNiO foam composite electrodes are characterized using scanning electron microscopy (SEM), powder X-ray diffraction (XRD), X-ray photoelectron spectra (XPS), Raman Spectroscopy. Electrochemical impedance spectroscopy (EIS) measurements, galvanostatic charge/discharge (GCD) and cyclic voltammetry (CV) are carried out to study the electrochemical behavior of ERGO/NiNiO foam electrodes. From structural and electrochemical characterizations, optimized parameters for pulse duty cycle and frequency were found to be 10% and 1000 Hz, respectively. As a result, the ERGO/NiNiO foam film (i_c = ?10 mA/cm², f = 1000 Hz and DC = 10%) provides a specific capacitance of 2298 F/g in 1 M KOH at a current density of 1 A/g. Stability study of fabricated film represents a long cycling life up to 4000 cycles with 0.7% decay in specific capacitance at the high current density of 20 A/g in the potential range of 0–0.6 V vs. saturated calomel electrode (SCE).     

Rare earth metal Gd influenced defect sites in N doped TiO2: Defect mediated improved charge transfer for enhanced photocatalytic hydrogen production

In this experimental studies, we report the synthesis of TiO₂ co-doped by both cationic and anionic sites by simple sol-gel based method. All the prepared samples exhibit the anatase crystalline morphology however, showed lattice distortion caused by the displacement of Ti⁴⁺ sites by Gd³⁺. The improved visible absorption is witnessed by the Gd and N co-doping with an assured redshift in the absorption edge. The N and Gd displacement inside TiO₂ lattice accompanied by the creation of OTiN and GdOTi bonds are characterized by the X-ray photoelectron spectra. The strong resonance signal by Gd4f electrons in the electron paramagnetic resonance spectroscopy further substantiate the displacement of lattice cites of TiO₂ by Gd³⁺ ions. The longevity of the photo produced charges observed in fluorescence spectra of Gd and N co-doped TiO₂ is because of the effective transfer of charges to the defect sites. The aforementioned catalysts are tested for their capacity for the H₂ production from water splitting. The 2 wt% gadolinium and nitrogen co-doped TiO₂ has shown 10764 μmol g^?1 H₂ production which is 26 times higher than the commercial Degussa P-25 catalyst. The enhanced activity for hydrogen production can be attributed to factors such as increased absorptivity under visible light and effective charge carrier separation.     

Tailoring a Pt–Ru catalyst for enhanced methanol electro-oxidation

A carbon-supported (1:1) Pt–Ru (Pt–Ru/C) alloy catalyst has been prepared in-house by the sulfito-complex route, and has been tailored to achieve enhanced activity towards methanol electro-oxidation by annealing it at varying temperatures in air. The catalyst samples annealed between 250 and 300 °C in air for 30 min exhibit superior catalytic activity towards methanol electro-oxidation in a solid-polymer-electrolyte direct methanol fuel cell (SPE-DMFCs) operating at 90 °C. Both the as-prepared and annealed Pt–Ru/C catalysts have been characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), extended X-ray absorption fine structure (EXAFS), and cyclic voltammetry. It is conjectured that while annealing the Pt–Ru/C catalysts, both PtPt and PtRu bonds increase whereas the PtO bond shrinks. This is accompanied with a positive variation in Ru/Pt metal ratio suggesting the diffusion of Ru metal from the bulk catalyst to surface with an increase in oxidic ruthenium content. Such a treatment appears seminal for enhancing the electrochemical activity of Pt–Ru catalysts towards methanol oxidation.     

Trimetallic NiFeCo selenides nanoparticles supported on carbon fiber cloth as efficient electrocatalyst for oxygen evolution reaction

Trimetallic NiFeCo selenides (NiFeCoSe_x) anchored on carbon fiber cloth (CFC) as efficient electrocatalyst for oxygen evolution reaction (OER) in alkaline medium have been synthesized via a facile two-step method. Firstly, trimetallic NiFeCo (oxy) hydroxides have been electrodeposited on CFC support (NiFeCo/CFC). Secondly, a solvothermal selenization process has been used to convert NiFeCo/CFC into NiFeCoSe_x/CFC using N, N-dimethylformamide (DMF) as solvent. The composition and homogeneous distribution of NiFeCoSe_x/CFC nanoparticles are determined by XRD, XPS, SEM elemental mapping and EDX images. Furthermore, SEM images reveal that NiFeCoSe_x/CFC has volcano-shaped morphology with rough surface and homogenously distributed on the surface of CFC, which may provide more active sites for OER. The electrochemical measurements show that trimetallic NiFeCoSe_x/CFC possesses the better electrocatalytic activity with the lower overpotential (150 mV at 10 mA cm^?2), Tafel slope (85 mV dec^?1), larger double-layer capacitance (200 mF cm^?2) and long-term stability than unary or binary metal selenides. The enhanced activity of NiFeCoSe_x/CFC may be attributed to the trimetallic NiFeCo selenides and selenides-CFC synergistic interaction. It may offer a promising way to design transition multimetallic selenides supported on conductive support as electrocatalysts for OER.     

Formation of Mg2Cu at low temperature in Mg/Cu super-laminate composites during initial hydrogenation

The formation mechanism of microstructures in Mg/Cu super-laminates composites (SLCs) fabricated by accumulative roll-bonding (ARB) during initial activation was investigated. It is revealed that Mg₂Cu can grow with sufficient growth rate at low temperatures (<453 K) in Mg/Cu SLCs. The growth of Mg₂Cu layers for short growth length is diffusion-controlled. The activation energies for layer growth process of Mg₂Cu layers in Mg/Cu SLCs are 107 ± 8 kJmol^?1 with acid cleaning prior to ARB and 103 ± 12 kJmol^?1 without acid cleaning prior to ARB, respectively, which are about 2/3 of those in MgCu diffusion couples. It is considered that the high density of lattice defects in Mg/Cu SLCs fabricated by ARB contributes the much lower activation energies for layer growth process of Mg₂Cu layers in Mg/Cu SLCs than in MgCu diffusion couples.     

Hydrogen storage properties of nanocrystalline Mg2Ni prepared from compressed 2MgH2Ni powder

In the present work, nanocrystalline Mg₂Ni with an average size of 20–50 nm was prepared via ball milling of a 2MgH₂Ni powder followed by compression under a pressure of 280 MPa. The phase component, microstructure, and hydrogen sorption properties were characterized by using X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), pressure-composition-temperature (PCT) and synchronous thermal analyses (DSC/TG). Compared to the non-compressed 2MgH₂Ni powder, the compressed 2MgH₂Ni pellet shows lower dehydrogenation temperature (290 °C) and a single-phase Mg₂Ni is obtained after hydrogen desorption. PCT measurements show that the nanocrystalline Mg₂Ni obtained from dehydrogenated 2MgH₂Ni pellet has a single step hydrogen absorption and desorption with fairly low absorption (?57.47 kJ/mol H₂) and desorption (61.26 kJ/mol H₂) enthalpies. It has very fast hydrogen absorption kinetics at 375 °C with about 3.44 wt% hydrogen absorbed in less than 5 min. The results gathered in this study show that ball milling followed by compression is an efficient method to produce Mg-based ternary hydrides.     

Production and electrochemical characterization of MgNi alloys by molten salt electrolysis for Ni–MH batteries

MgNi alloys are produced by molten salt electrolysis and diffusion method on a nickel plate in KClNaCl based melts. Structure, alloy composition and electrochemical properties of these alloys are evaluated. Electrolyte composition and applied current density parameters are studied for the characterization of the alloys. It is found that MgNi alloys with 45 wt% to 49 wt% Ni content which can be defined as MgNi–type alloys, have both higher discharge capacity and good retaining rate (72%). These alloys are mainly composed of Mg₂Ni phases and displayed a maximum discharge capacity of 384 mAhg^?1. Increased Ni content is advantageous for the enhancement of the cycle life. At the same time, the discharge capacity of MgNi alloy electrode is found to be decreasing. The highest capacity retaining (85%) rate is observed in the highest Ni content alloys (72 wt% Ni).Electrochemical impedance spectroscopy and potentiodynamic polarization measurements show that the controlling–step of the discharge process changed from a mixed rate–determining process at lower depth of discharge to a mass transfer controlled process at higher depth of discharge. The charge transfer resistance increases from 0.5 Ω to 23 Ω with increasing depth of discharge.     

Aqueous phase reforming of polyols for hydrogen production using supported PtFe bimetallic catalysts

3-D cubic ordered mesoporous carbon (CMK-9) supported PtFe bimetallic catalysts with a range of PtFe compositions were applied to the aqueous phase reforming (APR) of polyols for hydrogen production. The catalytic performance with respect to the polyol and support used was also studied. The catalysts and supports were characterized via X-ray powder diffraction (XRD), transmission electron microscopy (TEM), N₂ sorption, temperature programmed reduction (TPR), and CO chemisorption techniques. The polyols investigated include ethylene glycol (EG), glycerol, xylitol, and sorbitol. It was found that the addition of Fe to the Pt/CMK-9 catalyst significantly improved catalytic performance, with the optimum Pt:Fe ratio for APR activity being 1:3. It was also observed that, in the PtFe (1:3) system, the CMK-9 support demonstrated better catalytic performance than commercially available activated carbon or alumina. In addition, the catalytic activity of the PtFe/CMK-9 catalyst was successfully increased by both the effect of the water-gas shift reaction, promoted by Fe addition to Pt, and by the structural properties and nature of the CMK-9 support. Moreover, the PtFe (1:3)/CMK-9 catalyst showed efficient catalytic activity for different biomass derivatives (EG, glycerol, xylitol, and sorbitol), with the activity decreasing with increase in the number of carbon atoms.     

Platinum-palladium nanoparticles-loaded on N-doped graphene oxide/polypyrrole framework as a high performance electrode in ethanol oxidation reaction

Existing catalysts for ethanol oxidation in direct ethanol fuel cells (DEFC) are faced to significant challenges due to their poor performance and CO like intermediates poisoning tolerance at anode surface. Hence researchers are looking for new electrocatalysts in the ethanol oxidation. In this study, polypyrrole/N-doped graphene oxide (PPy/NGO) nanocomposite was prepared using in-situ polymerization method. Next the platinum-palladium (PtPd) was electrochemically decorated on PPy/NGO nanocomposite surface. In order to ensure the correct preparation of nanocomposite, fourier transform infrared spectroscopy (FT-IR) analysis was carried out to peruse the chemical structure of the nanocomposite and also to investigate their morphology, field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD) were used. The morphology of nanocomposite shows that PPy has penetrated into the space between NGO plates. Disparate electrochemical techniques like cyclic voltammetry (CV), linear sweep voltammetry (LSV) and chronoamperometry (CA) were employed to evaluate the oxidation of ethanol. Results showed that PtPd/PPy/NGO exhibits improved electrocatalytic activity and stability for ethanol oxidation. Enhanced active surface area of the PtPd/PPy/NGO electrode (35.1 m² g^?1) contributes to increase in current density and decrease in over potential values in the ethanol oxidation as compared to PtPd electrocatalyst.     

Synthetic fuels from 3-φ Fischer-Tropsch synthesis using syngas feed and novel nanometric catalysts synthesised by plasma

Nanometric carbon-supported catalysts based on cobalt and iron (Co/C, Fe/C and CoFe/C) were synthesised by plasma method for application in Fischer-Tropsch synthesis (FTS). FTS tests were conducted at reaction conditions (ca 533 K, 2 MPa) over the catalyst, in a feed stream of 60% mol fraction H₂ and 30% mol fraction CO at 1.0 cm³s⁻¹g⁻¹ of catalyst for 24 h. Prior to this, the catalysts were pre-treated at 673 K either in pure H₂ or CO flowing at 250 cm³ min⁻¹ for 24 h. Results showed that higher temperature promoted better CO conversion; up to 100% for the Co/C catalyst at 533 K. However, lower temperatures were more conducive for the selectivity of Co/C catalyst towards gasoline (C₄C₁₂) and diesel (C₁₃C₂₀) fractions, since production of undesired products such as CO₂ and CH₄ was prevalent at higher temperatures. At 493 K, the CoFe/C bimetallics were almost inert, but at 533 K, they showed improved CO conversion. When compared to the Co/C catalyst, Fe-containing catalysts suppressed both CO₂ and CH₄ production. Moderated H₂O production was witnessed in the CO-reduced catalysts, contrasting with catalysts pre-treated in H₂ gas. Catalyst characterisation by BET surface area, XRD analysis and microscopy (SEM & TEM) showed that plasma synthesis produces catalysts with consistency, having highly dispersed nanoparticle metal moieties, interspersed with various forms of metallic, carbidic and intermetallic CoFe species in the carbon matrix support.     

Dimensionally stable NiFe@Co/Ti nanoporous electrodes by reactive deposition for water electrolysis

The development of efficient and dimensionally stable electrode plates is of a significant challenge for the oxygen evolution reaction in the industrial water electrolysis process. In this work, structurally stable electrode plates are developed based on the nanostructured NiFe catalysts on highly porous and dimensionally stable Co reactive deposited on Ti substrates, NiFe@Co/Ti. SEM analysis shows the hierarchically structured micro- and nano-porous structure of the Co electrode on Ti substrates by reactive deposition route. The surface area of the reactive deposited Co is 3 times larger than that of the conventional electrodeposited Co electrode, providing highly porous and stable base for the subsequent deposition of NiFe electrocatalysts. The as-prepared NiFe@Co/Ti electrode exhibits high catalytic activity towards oxygen evolution in alkaline solutions, achieving an onset potential of as low as 1.44 V (η = 210 mV) and delivering a current of 10 mA cm^?2 at an overpotential of 0.26 V. Most importantly, the electrode shows excellent stability with negligible degradation under the discharge current density at 100 mA cm^?2 for 100 h, demonstrating the practical applicability of the NiFe@Co/Ti nanostructured electrodes for industrial scale water electrolysis.