Methanol Oxidation In Alkaline Media Research Articles

New type nanocomposite based on metal-organic frameworks decorated with nickel nanoparticles as a potent electrocatalyst for methanol oxidation in alkaline media

Methanol oxidation reaction (MOR) is used to provide electrical energy via direct methanol fuel cell (DMFC), which requires a practical design of electrocatalysts to accelerate the sluggish MOR. In this study, we successfully fabricated the carbon black nanoparticles/graphite ceramic electrode (CBNPs/GCE) supported metal-organic frameworks (MOFs) and decorated with nickel nanoparticles (NiNPs) as a new type nanocomposite modified electrode (NiNPs/MOFs/CBNPs/GCE) via a chemical and an electrochemical process, respectively. The surface morphology and structure of the synthesized nanocomposite materials and modified electrodes were characterized using field emission scanning electron microscopy, energy dispersive X-ray analysis, Fourier transform infrared spectroscopy, X-ray diffraction and thermogravimetric analysis. Then, the NiNPs/MOFs/CBNPs/GCE was used as a non-platinum electrocatalyst for electrocatalytic oxidation of methanol in alkaline media. The obtained results show the efficient electrocatalytic activity of the NiNPs/MOFs/CBNPs/GCE toward the MOR with high anodic peak current density (Jpa = 34.8 mA cm−2) compared with the other prepared electrocatalysts; MOFs/CCE, NiNPs/CCE, MOFs/CBNPs/GCE, NiNPs/CBNPs/GCE, and NiNPs/MOFs/CCE, due to the synergistic effect of nanocomposite components; NiNPs, MOFs and CBNPs. The prepared electrocatalyst; NiNPs/MOFs/CBNPs/GCE, not only shows a high electrochemically active surface area (ECSA = 2.15 cm2) but also has long-term durability in MOR. In general, it can be said the NiNPs/MOFs/CBNPs/GCE is a promising candidate for application in DMFC.

Controlled synthesis of efficient novel Cr0.2Co2.8O4–MoO3 nanocomposites for high-performance O2-evolution and methanol oxidation in alkaline medium

The world of electrochemical devices is constantly pushing the boundaries to what's possible, and nanocomposites are becoming crucial electrocatalysts for enhancing electrochemical performance. In this study, the affect in electrochemical behaviour on altering constituent amount in the electrocatalysts has been discussed. For this we synthesized a novel Cr0.2Co2.8O4–MoO3 nanocomposites with varying constituent proportional amount using simple low-temperature route. The formation and the physicochemical properties have been investigated by Fourier-transform infrared spectroscopy (FTIR), X-Ray diffraction analysis (XRD), X-ray photoelectron spectroscopy (XPS), Raman, Scanning electron microscopy (SEM)/energy dispersive X-ray spectroscopy (EDS) and Brunauer-Emmett-Teller (BET) techniques. The XRD and XPS patterns confirms the nano crystalline structures and compositional difference in metal cations distribution respectively. Results from Cyclic Voltammetry (CV), Tafel experiments, Chronoamperometry and Electrochemical impedance Spectroscopy (EIS) shows the ratio of Cr0.2Co2.8O4 to MoO3 strongly affects the catalytic performance in both oxygen evolution and methanol oxidation reactions. The observed enhancement in electrocatalytic activity can be ascribed to the combined impact of the two materials facilitating the electron transfer process by increasing the number of active sites and thereby. Amongst different synthesized electrocatalysts the one with 1:4 composition exhibited not only the highest Specific activity of 2.5 × 103 mA cm−2/g at 700 mV towards OER but also retains maximum current showing their highest stability.

Electrochemical properties of NiO–Ni electrocatalyst synthesized via solution combustion for methanol oxidation in alkaline media

Transition metal oxides have been recently considered as the anode catalyst in direct methanol fuel cells to reduce the anodic overpotential of methanol electrooxidation in alkaline media. In this work, the NiO–Ni catalyst is synthesized via solution combustion synthesis process to reach an appropriate nanomorphology with high effective surface area and electrocatalytic activity. The influence of the fuel type (glycine and urea) and the fuel to oxidizer (F/O) ratio are investigated. The composition and phase analysis, crystallite size, particle size, specific surface area, and morphology of the nanoparticles are assessed. Moreover, electrochemical characteristics of the products are evaluated. The catalytic activity of the product towards methanol oxidation is found to vary with the fuel type and F/O ratio. The dependence of the oxidation current on the adiabatic temperature and morphological characteristics of the product is discussed. It is found that solution combustion synthesis is a confident technique that provides a considerable improvement in catalytic performance. Moreover, it is concluded that samples with dominant NiO show lower onset potential and higher current density. Synthesis by glycine in the most explosive condition (i.e., F/O = 0.83) results in more desirable catalytic activity.

Electrodeposited Pd nanoparticles on polypyrole/nickel foam for efficient methanol oxidation

The present work describes the Ni foam (Ni–F)/polypyrrole (PPy)/palladium (Pd) (Ni–F/PPy/Pd) multilayered catalysts via a facile electrochemical technique. Potentiostatic deposition of PPy on the surface of Ni–F is followed by galvanostatic deposition of Pd nanoparticles on Ni–F/PPy acted as supports for electrochemical deposition of Pd nanoparticles. The produced catalysts are utilized for electrocatalytic methanol oxidation in alkaline media. Chronoamperometry (CA), cyclic voltammetry (CVs), and electrochemical impedance spectroscopy (EIS) techniques are used to examine the electrocatalytic performance of Ni–F/PPy/Pd based electrodes for methanol oxidation. The polypyrrole modification on Ni–F leads to an improvement in the electrocatalytic activity of the Ni-F/PPY-Pd catalysts toward methanol oxidation. As an open-pored, porous metal with high electrical conductivity, nickel foam produces a substantial amount of active area during the modification of Pd and polypyrrole, which results in significant catalytic activity and a rapid rate charge transfer reaction kinetics on methanol oxidation. The Ni–F/PPy/Pd10 catalyst exhibits enhanced specific activity than its counterparts and a reduced onset potential for methanol oxidation, as well as a low Tafel slope. Based on these results, Ni–F/PPy/Pd10 is suggested as a good material for the anode in the electrocatalytic oxidation of methanol.

The extended Stӧber method for synthesizing nitrogen-doped porous carbon nanospheres supported Pt nanoparticles towards methanol oxidation in alkaline media

• N -doped porous carbon nanospheres were prepared via the extended Stӧber method. • The NPCs have a high surface area and abundant nitrogen content. • The Pt nanoparticles supported on NPCs showed superior MOR activity and stability. Heteroatom-doped porous carbon materials have emerged as attractive catalyst supports of Pt nanoparticles in the direct methanol fuel cells (DMFCs). Herein, the simple extended Stӧber method towards nitrogen-doped porous carbon nanospheres (NPCs) is reported by polymerizing of 3-aminophenol-formaldehyde (APF) resin spheres. The synthesized NPCs were applied as a carrier for Pt nanoparticles to fabricate the Pt@NPCs catalyst for methanol oxidation. Compared with the commercial Pt/C catalyst, Pt@NPCs showed the larger electrochemically active area (93.6 m 2 g −1 ), higher peak current density (95.91 mA·cm −2 ) and better stability in alkaline media. This improved performance can be attributed to the porous structure of NPCs and nitrogen atoms doped in the carbon matrix increasing the dispersion of the Pt particles on the NPCs catalyst.

Pulse-electrodeposition of PtNi nanoparticles on a novel substrate of multi-walled carbon nanotubes/poly(eriochrome blue-black B) as an active and durable catalyst for the electrocatalytic oxidation of methanol

• A facile producer is developed for deposition of Pt-Ni nanoparticles by improving the size, dispersion, and promoting the catalyst utilization on a polymeric substrate. • Electropolymerization of eriochrome blue-black B is reported for the first time. • The pulsed electrodeposition of the metal ions has more catalytic properties with higher current density and lower onset potential than chronoamprometric method. • PtNi@p-EBB is an effective electrocatalyst with long-time stability for methanol oxidation in alkaline media. Herein, a simple and novel methodology for fabricating a high-methanol-tolerant electrocatalyst based on poly(eriochrome blue-black B)/multi-walled carbon nanotubes, coated with nickel and platinum nanoparticles is described. The polymer thin film was prepared using cyclic voltammetry and pulsed electrodeposition technique was used to decorate the polymer layer with nickel and platinum nanoparticles. The energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscope (TEM), and inductively coupled plasma analyses were performed to characterize the prepared catalyst. The morphological studies reveal that the PtNi-nanoparticles were distributed without accumulation throughout the polymer layer. The development of pulse electrodeposition technique for immobilization of PtNi-nanoparticles on the polymeric substrate significantly improves the size, dispersion, and promotes the catalyst utilization. The PtNi@p-EBB/MWNT catalyst show high stability and high current density (1550 mA.mg -1 Pt).

(Digital Presentation) Facile Fabrication of Graphene Quantum Dot- Doped Polyaniline Embedded Cu Metal-Organic Frameworks Composite Electrode As Improved Anode Electrocatalyst for Methanol Oxidation

Nonrenewable energy sources accounted for roughly 80% of total energy consumption [1]. Solar energy, wind energy, geothermal energy, hydropower, and fuel cells (FCs) have all recently been described as renewable energy sources. In commercial uses, renewable energy has experienced meteorological and logistical obstacles. Because of advantages such as simple fabrication/operation conditions, eco-friendly, high energy conversion efficiency, and long-term durability, FCs technologies are considered one of the most important renewable energy sources for many applications such as portable devices, cars, and electricity plants [2–5]. Methanol can be utilized in direct methanol fuel cells (DMFC) to produce clean energy that can be used in smart electronic gadgets or small automobiles in this regard [6]. However, before DMFC can be used commercially, the slow oxidation kinetics and catalyst toxicity [7] must be resolved. Therefore, the development of direct methanol fuel cells (DMFCs) is one of the most promising technologies for the applications of these devices in stationary power supplies and electric vehicles [8]. Apart from the future of mobile devices such as mobile chargers, phones, computers, and many other applications, this energy is environmentally benign because no gases are emitted and the waste is simply clean water. The biggest issue that this technique may encounter is its high cost due to the usage of noble metal catalysts (platinum (Pt) and ruthenium (Ru)) [9]. Methanol is oxidized via a multi-electron process and several products and/or intermediates can be formed, depending on the electrolyte and the nature of the electrode. Electrode materials are important parameters in the electrochemical oxidation of methanol, where high efficient electrocatalysts are needed. Several metal oxides such as Fe2O3, CeO2, MoOx, Co3O4, NiO, and CuO has been used in various applications, such as catalysis, water splitting photocatalysis, solar cells and gas sensing, besides their uses to enhance the electrocatalytic activity for methanol oxidation [10-11].This paper describes the preparation of graphene quantum dot-doped polyaniline embedded copper metal-organic frameworks composite catalysts for investigating methanol oxidation in alkaline solutions. The electrode surface was characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and electrochemical impedance spectroscopy (EIS). After physicochemical characterizations of graphene quantum dot-doped polyaniline embedded copper metal-organic frameworks composite modified carbon ceramic electrode (Cu- MOF/GQDs-PAN/CCE), its electrocatalytic and stability characterizations toward methanol oxidation in alkaline media were investigated in detail by cyclic voltammetry and chronoamperometry. Results showed that, the electrocatalytic activity of the Cu- MOF/GQDs-PAN/CCE electrode is much higher than those of unmodified electrode under similar experimental conditions, showing the possibility of attaining good electrocatalytic anodes for fuel cells. Kinetic parameters such as the electron transfer coefficient (α) and the number of electrons involved in the rate determining step (nα) for the oxidation of methanol were determined utilizing cyclic voltammetry (CV). Keywords: Graphene quantum dot, Polyaniline, Metal-organic frameworks, electrocatalyst, MethanolReferences[1] S.K. Kamarudin, F. Ahmad, W.R.W. Daud, Overview on application of direct methanol fuel cell (DMFC) for portable electronic devices, Int. J. Hydrog. Energy 34 (2009) 6902–6916.[2] L. Carrette, K.A. Friedrich, U. Stimming, Fuel cells: principles, types, fuels and applications, ChemPhysChem 1 (2000) 162–193.[3] A.B. Stambouli, Fuel cells: The expectations for an environmental-friendly and sustainable source of energy, Renew. Sustain. Energy Rev. 15 (9) (2011) 4507– 4520.[4] P. Joghee, J.N. Malik, S. Pylypenko, R. O’Hayre, A review on direct methanol fuel cells – In the perspective of energy and sustainability, MRS Energy Sustain. 2 (2015), https://doi.org/10.1557/mre.2015.4.[5] D. Hassen, M.A. Shenashen, S.A. El-Safty, M.M. Selim, H. Isago, A. Elmarakbi, H. Yamaguchi, Nitrogen-doped carbon-embedded TiO2 nanofibers as promising oxygen reduction reaction electrocatalysts, J. Power Sources 330 (2016) 292– 303.[6] M. Mansor, S.N. Timmiati, K.L. Lim, W.Y. Wong, S.K. Kamarudin, N.H. Nazirah Kamarudin, Recent progress of anode catalysts and their support materials for methanol electrooxidation reaction, Int. J. Hydrogen Energy 44 (29) (2019) 14744–14769, https://doi.org/10.1016/j.ijhydene.2019.04.100.[7] Z. Mousavi, A. Benvidi, S. Jahanbani, M. Mazloum-Ardakani, R. Vafazadeh, H. R. Zare, Investigation of electrochemical oxidation of methanol at a carbon paste electrode modified with Ni(II)-BS complex and reduced graphene oxide nano sheets, Electroanalysis 28 (12) (2016) 2985–2992, https://doi.org/10.1002/ elan.201501183.[8] S. Wasmus, A. Küver, Methanol oxidation and direct methanol fuel cells: a selective review, J. Electroanal. Chem. 461 (1-2) (1999) 14–31.[9] M. Liu, R. Zhang, W. Chen, Graphene-Supported Nanoelectrocatalysts for Fuel Cells: Synthesis, Properties, and Applications, Chem. Rev. 114 (2014) 5117– 5160.[10] N. Spinner, W.E. Mustain, Electrochim. Acta 56 (2011) 5656.[11] M.S. Risbud, S. Baxter, M. Skyllas-Kazacos, Open Fuels Energy Sci. 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Facile Preparation of Porous Carbon Flake-Supported Nickel Nanoplates as Effective Catalysts for Methanol Electrooxidation

Herein, we report a facile and efficient method for fabricating porous carbon flakes (PCFs)-supported nickel nanoplates (Ni NPs) as electrocatalysts for methanol oxidation in alkaline media. The catalyst was fabricated in one step using molten salt synthesis. Various techniques were used to characterize the morphology and composition of the Ni NPs@PCFs catalyst, and these revealed that the Ni NPs were dispersed finely across the PCFs with a highly crystalline structure. The Ni NPs@PCFs catalyst demonstrated high electrocatalytic activity for methanol oxidation (121 mA/cm2 vs. Ag/AgCl), and it had an onset potential of 0.35 V. It also exhibited high stability in an alkaline electrolyte for the duration of the experiment (up to 2000 s).

Ir Single Atoms Doped Cuboctahedral Pd for Boosted Methanol Oxidation Reaction

AbstractThe construction of binary metal Pd‐based catalysts is an effective strategy to enhance the activity of methanol oxidation reaction. Herein, atomically dispersed Ir single atoms doped to cuboctahedral Pd nanoparticles (Ir‐SAs/Pd) as efficient catalysts for alkaline methanol oxidation are prepared via a simple chemical reduction method. The synthetic Ir‐SAs/Pd catalysts exhibit the outstanding mass activity of about 1717.3 mA mgPd−1 compared with pure Pd and commercial Pd/C in electrooxidation for methanol. Meanwhile, the introduction of Ir single atoms enhances the CO tolerance of Pd nanoparticles to a large extent. On the basis of density functional theory results, the enhanced catalytic performance and CO tolerance rely on the effective improvement of the electron dominance near Fermi level and the negative shift of the d‐band center for Pd as a result of the electron redistribution between Pd and Ir atoms. This article will provide new insight into the design of high‐performance binary metal catalysts for methanol oxidation in alkaline media.

Bio-Based Graphene Sheet/Copolymer Composite as Supporting Material for Nanocatalysts towards Electrochemical Studies and Direct Alkaline Alcohol Fuel Cells

In this work, graphene carbon sheets (BGS) were prepared from writing paper and lemon peel, and its polymer composite has a higher surface area compared with the existing Vulcan carbon. Further, the use of lead as a promoter for the oxidation of alcohol and CO on platinum-supported poly(amine-terminated cyclophosphazene-co-cyclophosphazene)-biobased graphene sheet (Poly(AFCP-co-CP)-BGS) composite was demonstrated. The size, phase morphology, and distribution of metal nanoparticles on Poly(AFCP-co-CP)-BGS composite as well as the formation of composite based catalysts were confirmed from TEM, XRD, and FTIR studies. The catalytic activity and stability of the prepared catalysts were tested and compared to methanol, ethylene glycol, glycerol, and CO in 0.5 M KOH solution. The results conclude that the lead-doped Pt/Poly(AFCP-co-CP)-BGS catalyst shows higher oxidation current with respect to onset potential and lower I f / I r ratio for alcohol as well as CO oxidation. In addition, Pt-Pb/Poly(AFCP-co-CP)-BGS catalyst was checked for direct alkaline fuel cells and proved as a potent anode catalyst in alkaline medium for real-time fuel battery applications. In addition, Poly(AFCP-co-CP)-BGS composite also promotes the catalytic reaction compared to Poly(AFCP-co-CP) and BGS supports as noticed from methanol oxidation in alkaline medium. The surface area of the prepared supporting material is 750.72 m2g-1, which is higher than the activated carbon (250.12m2g-1). So, the prepared Poly(AFCP-co-CP)-BGS composite is a potent support for metal deposition, electrooxidation, and single stack fuel cell constructions.

Investigation of palladium-mesostructured silica nanoparticles (Pd-MSN) as anode electrocatalyst for alkaline direct methanol fuel cell

The commercialization of fuel cells is hindered by the high cost of noble metal electrocatalysts, such as platinum. Mesostructured silica nanoparticles (MSNs), as a novel catalyst support, are added to active palladium nanoparticles to create a Pd-MSN electrocatalyst with low Pd content to improve catalytic efficacy and decrease costs. Wet impregnation method was used to prepare catalysts that comprise palladium nanoparticles supported on MSNs (i.e. 5 wt% Pd-MSN, 10 wt% Pd-MSN, 15 wt% Pd-MSN, 20 wt% Pd-MSN and 20 wt% Pd-C) to enhance electrocatalytic activity for methanol oxidation. The structures of the catalysts were characterized by X-ray diffraction (XRD), Fourier transform infrared spectrometry (FTIR), field-emission scanning electron microscopy (FESEM), energy-dispersive X-ray (EDX) and Brunauer–Emmet–Teller (BET) surface area analysis, and their electrocatalytic performance towards methanol oxidation was investigated by cyclic voltammetry (CV) and chronoamperometry (CA). Amongst the catalysts, 20 wt% Pd-MSN has the highest electrocatalytic activity (14.3 mA cm−2) and stability (3600 s) for methanol oxidation in alkaline medium at the constant potential of −0.2 V. This result indicates that 20 wt% Pd-MSN may be a promising anode material for direct methanol fuel cells. The improved electrocatalytic activity and stability of the electrocatalyst are attributed to the high specific surface area of MSN and the effective surface structure of Pd nanoparticles. Furthermore, MSN increases catalyst dispersion by producing new active sites, which results in the promotion of Pd utilization.

Effective Methanol Oxidation with Platinum Nanoparticles-Decorated Poly(2-bromomethyl-2-methyl-3,4-propylenedioxythiophene)-Coated Glassy Carbon Electrode

Here, we developed a porous network of bromomethyl-substituted 3,4-propylenedioxythiophene polymer using a simple and efficient technique of electrochemical deposition used as conductive support for methanol oxidation. Platinum nanoparticles (PtNPs) are well dispersed and decorated on a high surface area of electrochemically deposited Poly(2-bromomethyl-2-methyl-3,4-propylenedioxythiophene (PProDOT-Br) on a glassy carbon electrode (GCE). A thin film of PProDOT-Br acts as a supporting matrix for deposition of PtNPs and improves the interfacial properties between electrode and electrolyte. The PtNPs-decorated PProDOT-Br (Pt/PProDOT-Br) samples were characterized by X-ray diffraction, Fourier transform infrared attenuated total reflectance spectroscopy, atomic force microscopy, and scanning electron microscopy. Furthermore, the electrocatalytic performance of Pt/PProDOT-Br on GCE for methanol oxidation was assessed by cyclic voltammetry, chronoamperometry, and electrochemical impedance spectroscopy measurements. The findings suggest that the use of Pt/PProDOT-Br/GCE assemblies for efficient methanol oxidation in alkaline media with a small intermediate poisoning is promising for applications as anode material in DMFCs, which should be attributed to the PProDOT-Br support providing a larger surface area with porous nature and enabling the adsorption of more CH3OH for further oxidation. The developed porous network PProDOT-Br with high capacitance may also have large potential in supercapacitor applications.

Remarkable electrocatalytic activity of Ni-nanoparticles on MOF-derived ZrO2-porous carbon/reduced graphene oxide towards methanol oxidation

In the present work, a porous carbonaceous platform containing zirconium oxide was used for spreading Ni nanoparticles, and applied to methanol oxidation. The platform was obtained by calcination of a metal-organic framework (MOF) attached to graphene oxide. Nickel nanoparticles were then deposited on the nanocomposite by chemical reduction from a Ni2+ solution. The obtained electrocatalyst was characterized by different methods. An excellent electrocatalytic behavior was observed towards methanol oxidation in alkaline medium (j ~ 240 mA cm−2 or ~ 626 mA mg−1 in 1.0 M methanol). The results of methanol oxidation by various electrochemical studies (cyclic voltammetry, electrochemical impedance spectroscopy, chronoamperometry and chronopotentiometry) revealed the effective synergy between reduced graphene oxide, porous carbon material, ZrO2 metal oxide and Ni nanoparticles. Good durability and stability of the proposed electrocatalyst and significantly increased current density of methanol oxidation suggest it as a potential alternative for Pt-based electrocatalysts in direct methanol fuel cells.

Electrocatalytic performance of inorganic nanoflakes nickel phosphates under adjusted synthetic parameters towards urea and methanol oxidation in alkaline media

Inorganic nanoflakes nickel phosphates (Ni-P) were introduced to enhance the activity of the working electrode for the electrooxidation of small organic molecules: methanol and urea. The urea proportions during the synthesis of the Ni-P material were evaluated and its impact on Ni-P morphology and structure was determined. The as-fabricated Ni-P material was studied in terms of Fourier-transform infrared spectroscopy (FTIR), Field emission scanning electron microscope/ energy-dispersive X-ray spectroscopy (FESEM/EDX), Transmission electron microscopy (TEM), X-ray diffraction (XRD), and Brunauer–Emmett–Teller (BET) surface area analyses. These techniques indicate the synthesized material is Ni-P with nanoflakes morphology. Cyclic voltammetry (CV), as well as impedance spectroscopy (EIS) techniques, were investigated in the reference/working/counter electrodes system to study the electrocatalytic performance of the introduced nanoflakes phosphate material for both methanol and urea oxidation in presence of KOH aqueous medium. 0.8 M of urea was the optimum proportion found for the electrocatalytic oxidation of methanol. The synthesized phosphates showed enhanced electrocatalytic oxidation of methanol and urea at different scan rates. Besides, the EIS approves the ability of the synthesized nanoflakes phosphate to electrochemically oxidize methanol and urea. This study presents cheap electrocatalysts to help in the commercial process of fuel cells as well as water treatment from organics like urea.

Low-platinum catalyst based on sulfur doped graphene for methanol oxidation in alkaline media

A novel two-step, low-temperature method was employed for the synthesis of a catalyst with small platinum content (2 wt%) based on sulfur doped reduced graphene oxide (S-RGO-Pt). Morphology and chemical composition of the hybrid material were investigated by several methods: X-ray powder diffraction (XRD), transmission and scanning electrode microscopy (TEM, SEM), elemental analysis, X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The electrocatalytic performance of the prepared hybrid material was investigated in 1M CH3OH/1M NaOH using a modified glassy carbon electrode (GC_S-RGO-Pt). The results showed excellent electrocatalytic activity and stability toward methanol oxidation in alkaline media (50.4% activity retained after 500 cycles and 8.4% after 1000 cycles) compared to commercial platinum 10 wt% on carbon (Pt/C) material (8.09% activity retained after 500 cycles). The catalyst tolerance to CO poisoning intermediates was evaluated using CO stripping voltammetry and the ratio of forward and backward peak current density (If/Ib). The If/Ib ratio calculated for S-RGO-Pt is 15, while for Pt/C is 9.6, which clearly demonstrates that the prepared hybrid material is significantly more efficient than commercial Pt/C, even if the platinum content is only 2 wt%. The rotating disk electrode (RDE) technique was employed to study the kinetic aspects of methanol oxidation reaction in alkaline media. To follow the transformations occurred at the electrodes' surfaces after the electrochemical treatment, the Raman spectroscopy and Machine Learning (ML) algorithms were used; the results also indicated a greater stability of the S-RGO-Pt composite for Methanol oxidation reaction (MOR) in alkaline media.

Plasmon-Driven Electrochemical Methanol Oxidation on Gold Nanohole Electrodes.

Direct methanol oxidation is expected to play a central role in low-polluting future power sources. However, the sluggish and complex electro-oxidation of methanol is one of the limiting factors for any practical application. To solve this issue, the use of plasmonic is considered as a promising way to accelerate the methanol oxidation reaction. In this study, we report on a novel approach for achieving enhanced methanol oxidation currents. Perforated gold thin film anodes were decorated with Pt/Ru via electrochemical deposition and investigated for their ability for plasmon-enhanced electrocatalytic methanol oxidation in alkaline media. The novel methanol oxidation anode (AuNHs/PtRu), combining the strong light absorption properties of a gold nanoholes array-based electrode (AuNHs) with surface-anchored bimetallic Pt/Ru nanostructures, known for their high activity toward methanol oxidation, proved to be highly efficient in converting methanol via the hot holes generated in the plasmonic electrode. Without light illumination, AuNHs/PtRu displayed a maximal current density of 13.7 mA/cm2 at -0.11 V vs Ag/AgCl. Enhancement to 17.2 mA/cm2 was achieved under 980 nm laser light illumination at a power density of 2 W/cm2. The thermal effect was negligible in this system, underlining a dominant plasmon process. Fast generation and injection of charge carriers were also evidenced by the abrupt change in the current density upon laser irradiation. The good stability of the interface over several cycles makes this system interesting for methanol electro-oxidation.

A sponge like Pd arrays on Ni foam substrate: Highly active non-platinum electrocatalyst for methanol oxidation in alkaline media

In order to commercialize direct methanol fuel cells (DMFCs), the selection of the appropriate catalysts for the replacement of platinum is a basic factor. Herein, we report a sponge like Pd arrays on Ni foam (NF) substrate which is successfully synthesized by a template method. The surface of NF is covered with patterned mesoporous silica (NF-PMS) through electro-assisted self-assembly (EASA) method and Pd nanoparticles are deposited on NF-PMS via the galvanic replacement reaction. After template removal, the synthesized catalyst viz. Pd2/NF-PMS is used for electrocatalytic oxidation of methanol in the alkaline media. The efficiency of template method is proved with the comparison between electrocatalytic activity of Pd2/NF-PMS and Pd2/NF. The synthesized catalyst show more than 5 times higher mass activity and significantly lower onset potential for methanol oxidation as compared with the state-of-the-art Pt/C as well as high antipoisoning property. The excellent results propose Pd2/NF-PMS as an excellent candidate anode for electrocatalytic oxidation of methanol.

Green synthesis of Au@N-CQDs@Pd core-shell nanoparticles for enhanced methanol electrooxidation

Abstract A strategy for the synthesis of Au@N-CQDs@Pd three-layer core-shell nanoparticles without the use of any surfactant is proposed in this work. Herein, N-doped carbon quantum dots (N-CQDs) are used as the reducing agent, stabilizing agent, and shape-directing agent. The morphology and structure of the final product were characterized by Transmission electron microscopy (TEM), high-resolution TEM (HRTEM), and X-ray powder diffraction (XRD). The electrocatalytic test indicates the as-synthesized Au@N-CQDs@Pd 20 exhibites excellent activity for methanol oxidation in alkaline media, which is approximately 6 times higher than commercial Pd/C. And its resistance to CO and stability are also greatly improved. This work provides a simple and straightforward approach to prepare bimetallic core-shell electrocatalyst by using CQDs with high catalytic activity for alkaline fuel cells.

Electrocatalysis of Pd–Er bimetallic catalysts for methanol oxidation in alkaline media

The Pd–Er/C catalysts with different Pd/Er ratios were synthesized through a simple simultaneous reduction reaction with sodium borohydride in aqueous solution. The structural and morphological features were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM), respectively. The electrocatalytic performance of those catalysts for methanol oxidation in alkaline media was tested using cyclic voltammetry (CV) and linear sweep voltammetry (LSV). It is found that the Pd-4Er/C catalyst has a higher catalytic activity than the Pd/C catalyst. CO stripping experiments show its good resistance to CO poisoning, which can be explained by a bifunctional mechanism. According to the results from the X-ray photoelectron spectroscopy (XPS), the higher content of metallic Pd caused by the doping of metal Er also accounts for the improvement of catalytic performance. This work provides a highly efficient catalyst for methanol electrooxidation in alkaline media.

Nickel boride and cobalt boride coated stainless steel gauze for enhanced electrochemical oxidation of methanol

Ni-Co-B catalyst consisting of different ratios of Ni and Co was successfully synthesized via a simple electroless deposition method on stainless steel (SS) gauze substrate. Among various ratios, the Ni-Co-B of the ratio (0.09 M/0.01 M, designated as Ni-Co-B-MR1) exhibited higher electrochemical response towards methanol oxidation in alkaline medium with a highest current density about 11.3 mA/cm2 at a potential of − 0.65 V. The electrode exhibited improved CO tolerance for methanol oxidation reaction (MOR) in alkaline medium. The surface morphology and composition of the SS gauze coated with Ni-Co-B-MR1 catalyst was analysed using SEM and energy dispersive X-ray analysis. XRD confirms the presence of orthorhombic nickel boride and cobalt boride structure. The XPS analysis confirms the active presence of nickel boride and cobalt boride on SS gauze coated with Ni-Co-B-MR1 catalyst. The BET surface area of SS gauze coated with Ni-Co-B-MR1 catalyst was 1.21 m2 g−1. The single direct methanol fuel cell with SS gauze coated with Ni-Co-B-MR1 electrode produces a current density of about 0.1 mA/cm2 and power density about 10 mW/cm2, respectively.