Electrooxidation Of Sodium Borohydride Research Articles

Electrocatalytic performance of Shape-Controlled synthesized PdNi-rGO nano Cube on sodium borohydride and methanol electrooxidation

In recent years, increasing climate change, environmental pollution and water problems have increased the need for sustainable and environmentally friendly solutions in energy production. In this context, renewable energy sources, especially fuel cells, have become an important focus. In this study, the synthesis and characterization of the shape-controlled synthesized PdNi-rGO Cube electrocatalyst was carried out. X-ray diffraction (XRD), scanning electron microscopy with energy dispersive x-ray (SEM-EDX), and transmission electron microscope (TEM) characterization experiments were performed to examine the shape of the particles. TEM analysis revealed the formation of nanostructures with a size of 19.18 nm in the cubic structure of the PdNi-rGO. Furthermore, cyclic voltammetry (CV) measurements evaluated the usability of this electrocatalyst in the electrooxidation of sodium borohydride (NaBH4), and methanol (CH3OH). In this context, the anodic peak current density values were 77.34 mA/cm2 and 13.47 mA/cm2, for electrooxidation of sodium borohydride (NaBH4), and methanol (CH3OH), respectively. This study demonstrates that PdNi-rGO cube contains shape-controlled nanostructure, and these structures can play an important role in future renewable energy sources. It can also be considered an important step forward in the development of nanomaterial-based electrocatalysts capable of efficient energy conversion.

Methanolysis and electrooxidation of sodium borohydride on CNT supported Pd and Au bimetallic catalysts

In this study, carbon nanotube (CNT) supported bimetallic PdAu catalysts are synthesized by sodium borohydride reduction method at different atomic molar ratios. X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy and energy-dispersive X-ray (SEM-EDX) analytical techniques have been applied for characterization of the synthesized catalysts. Sodium borohydride electrooxidation activities of PdAu/CNT catalysts and hydrogen generation performances by sodium borohydride methanolysis are researched. The electrocatalytic activities of the catalysts are assigned by electrochemical methods such as cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS). PdAu(50:50)/CNT catalyst exhibits the highest catalytic activity as 39.624 mA/cm2 with long-term stability and low resistance. The initial hydrogen generation rate of PdAu(50:50)/CNT catalyst is obtained as 61840.0 mL/min.gcat under optimum conditions. As a result, PdAu(50:50)/CNT catalyst is promising both as an anode electrode material and as a catalyst for sodium borohydride methanolysis.

Rational design of a low-cost, simple technology and high-performance CoNi/Co3O4 as a catalyst in sodium borohydride electro-oxidation reaction

We present a simple self-supporting catalyst containing CoNi nanosheets grown on Co3O4 electrodes. In the DBHPFC test, it has a maximum power density of 108.5 mW cm−2, an open circuit potential of 1.8 V, and good operating stability.

Phosphorus-doped cobalt oxide constructs high and low valence Cobalt: Efficient synergistic catalytic electrooxidation of sodium borohydride

Low-cost, high-performance electrode materials for mitigating hydrogen release are urgently needed for anodes of direct borohydride fuel cells (DBFC). Herein, CoP-CoOx with both high (Co2+/3+) and low (Coδ+) valence cobalt is successfully constructed by regulating the Co valence state by P and O and achieves efficient catalysis of NaBH4 electrooxidation. Coδ+ has an extremely strong ability to break B-H bonds, and Co2+/3+ is near the grain boundaries to provide strong adsorption of electronegative reactants and uneven stress on B-H bonds. Benefiting from the synergistic effect of high and low valence cobalt, and the unique inner hole structure of material induced by the phosphorylation process, the direct sodium borohydride-hydrogen peroxide fuel cells (DBHPFC) assembled with CoP-CoOx as anodes can reach a maximum power density of 280 mW cm−2 at room temperature. Meanwhile, high phosphorus doping is effective in improving fuel utilization. This work provides a cost-effective, highly-active anode engineering strategy for DBFC and attracts attention to the valence state of cobalt-based materials in the field of catalytic NaBH4 electrooxidation.

A novel hazelnutt bagasse based activated carbon as sodium borohydride methanolysis and electrooxidation catalyst

In this study, activated carbon is produced from defatted hazelnut bagasse at different activation conditions. The catalytic activities of activated carbons are evaluated for NaBH4 methanolysis and electrooxidation. These materials are characterized by N2 adsorption-desorption, FTIR, SEM-EDS and XPS and results show that these materials are prepared successfully. N2 adsorption-desorption results reveal that activated carbon (FH3-500) has the highest BET surface area as 548 m2/g, total pore volume as 0.367 cm3/g and micropore volume as 0.205 cm3/g. On the orher hand, as a result of hydrogen production studies, FH3-500 activated carbon catalyst has the highest initial hydrogen production rate compared to other materials. At 50 °C, this metal-free activated carbon catalyst has a high initial hydrogen production rate of 13591.20 mL/min.gcat, which is higher than literature values. Sodium borohydride electrooxidation measurements reveal that FH2-500 also has the highest electrocatalytic activity and stability. Hazelnut pulp-based activated carbons are firstly used as a metal-free catalyst in the methanolysis and electrooxidation of sodium borohydride, and its catalytic activity is good as a metal-free catalyst. The results show that the hazelnut pulp-based activated carbon catalyst is promising as a metal-free catalyst for the methanolysis and electrooxidation of sodium borohydride.

Performance improvement strategies of a cobalt-based electrode for the electrooxidation of sodium borohydride

The NaBH4 electrooxidation performance of Co is improved by adjusting the component and structure of the electrode material, and a novel device (CRB) is applied for the reaction.

Au-Pt bimetallic nanoparticles anchored on conducting polymer: An effective electrocatalyst for direct electrooxidation of sodium borohydride in alkaline solution

This work proposes Au-Pt nanoparticles decorated poly(p-aminophenol) (PAP) film on a glassy carbon electrode for direct electrochemical oxidation of sodium borohydride. The Au-Pt bimetallic surfaces were prepared with two electrodeposition procedures which are the simultaneous electro-deposition (1-Au-Pt/PAP/GCE) and the successive electro-deposition (2-Au-Pt/PAP/GCE) procedures. The catalysts were used for the investigation of borohydride electrochemical oxidation and compared catalytic activities by CV, RDEs and chronoamperometric techniques. AFM, SEM, XPS, XRD and CV were used to identify of the structural and morphological properties of the developed modified surfaces. The results of electrochemical measurements indicated that simultaneous electro-deposition of Au-Pt to the polymer structure significantly shifted negative oxidation potential and increases the current density of borohydride electrochemical oxidation.The exchange electron number of 1-Au-Pt/PAP/GC and 2-Au-Pt/PAP/GC electrodes were calculated as 7.8 and 6.7, respectively. This approves the strong tendency of the 1-Au-Pt/PAP catalyst toward effective direct electrochemical oxidation of NaBH4 in an alkaline medium.

3D Structured Pt(Cu-Ni)/Ti Catalysts for the Oxidation of Sodium Borohydride

Currently, one of the renewable energy sources is fuel cells, namely chemical energy is directly converted into electricity. Designing new or enhancing the existing fuel cells, much attention is devoted to the search of new effective catalysts, which would allow increasing the effectiveness of fuel cells and creating the background for designing new technologies for catalysts formation.The aim of the work is to form efficient and inexpensive nanostructured catalysts by electroplating 3D structure metal copper-nickel (Cu-Ni) foams on titanium (Ti) surface and decorating them with low amounts of platinum nanoparticles (PtNP) for the electrooxidation of sodium borohydride (NaBH4). The Cu-Ni foam was prepared by electrochemical deposition (I deposition=1.5 Acm-2, t deposition= 3,6 and 9 min) on Ti surface. The electrolyte contained 0.5 M Ni2+ ions, and the concentrations of Cu2+ ions ranged from 0.01 to 0.02 M.PtNP particles were deposited on Cu-Ni foam (noted (Pt(Cu-Ni)/Ti)) by immersion of Cu-Ni foam into 1 mM H2PtCl6 solution at 25 °C for 1 minute. The morphology and composition of the prepared catalysts were investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), and inductively coupled plasma optical emission spectroscopy (ICP-OES). The electrocatalytic activity of the 3D catalysts was evaluated towards the oxidation of borohydride by cyclic voltammetry method in 0.05 M NaBH4 solution in an alkaline media in the potential range from -1.2 to 0.6 V (vs. Ag/AgCl) and with an electrode potential scan rate of 10 mVs-1.The study showed that the prepared 3D Cu-Ni foam and Pt(Cu-Ni)/Ti have good electrochemical stability in alkaline NaBH4 solution. It was also observed that immersion of Cu-Ni foam in a platinum-containing solution for 1 min increased the electrocatalytic activity of the prepared Pt(Cu-Ni)/Ti catalysts for NaBH4 oxidation compared to Cu-Ni foam. Acknowledgment This project has received funding from European Social Fund (project No 09.3.3-LMT-K-712-19-0138) under a grant agreement with the Research Council of Lithuania (LMTLT).

Au-Pt Bimetallic Nanoparticles Anchored on Conducting Polymer: An Effective Electrocatalyst for Direct Electrooxidation of Sodium Borohydride in Alkaline Solution

Au-Pt Bimetallic Nanoparticles Anchored on Conducting Polymer: An Effective Electrocatalyst for Direct Electrooxidation of Sodium Borohydride in Alkaline Solution

The characterization and sodium borohydride electrooxidation of novel carbon nanotube supported copromoted Pd as anode catalyst for fuel cell

AbstractIn the present study, the effect of Co addition on Pd is investigated. Pd/CNT and PdCo/CNT catalysts are prepared via the sodium borohydride (SBH, NaBH4) reduction method. The X‐ray diffraction, transmission electron microscope, and inductively coupled plasma‐mass spectrometry analyses are performed to characterize the PdCo(70‐30)/CNT catalyst. These characterization results reveal that Pd/CNT and PdCo/CNT catalysts are prepared successfully. NaBH4 electrooxidation activities of PdCo/CNT catalysts are examined with electrochemical methods such as cyclic voltammetry, chronoamperometry, and electrochemical impedance spectroscopy. PdCo(70‐30)/CNT catalyst has 11.52 mA/cm2 specific activity, 477.18 m2/g electrochemical active surface area, and the best electrochemical stability. Pd is a promising catalyst for NaBH4 electrooxidation reaction.

Highly Active RuPd Bimetallic Catalysts for Sodium Borohydride Electrooxidation and Hydrolysis

Highly Active RuPd Bimetallic Catalysts for Sodium Borohydride Electrooxidation and Hydrolysis

Disentangling the enhanced catalytic activity on Ga modified Ru surfaces for sodium borohydride electrooxidation

Herein, multi walled carbon nanotube (MWCNT) supported RuGa nanocatalysts (RuGa/MWCNTs) are synthesized at varying atomic molar ratio via sodium borohydride (SBH) reduction method toward SBH electrooxidation (SBHE) and SBH hydrolysis (RSBH). From the X-ray diffraction (XRD) results, Ru and Ga metals are found to be in the alloy form and the average crystal size is determined as 2.77 nm. The distribution of RuGa particles on MWCNT is confirmed using SEM-EDX. These nanocatalysts were employed for RSBH and further measurements were performed to investigate their SBHE activity. For RSBH for RuGa/MWCNT nanocatalysts, one could note that Ga addition to Ru enhanced the initial rate, H2 generation rate, and turnover frequency values and Ru99Ga1/MWCNT has the highest initial rate, H2 generation rate, and turnover frequency value. According to the cyclic voltammetry (CV) results of the prepared RuGa/MWCNT nanocatalysts, Ru99Ga1/MWCNT show the highest electrocatalytic activity for SBHE and this result is in line with the results of electrochemical impedance spectroscopy (EIS). In addition, chronoamperometric curves indicate that Ru99Ga1/MWCNT possesses long term stability compared to these of other nanocatalysts. Catalytic RSBH results of Ru99Ga1/MWCNT show that this nanocatalyst is more active than others. As a result, it is clear that RuGa/MWCNT is a promising nanocatalyst for fuel cells.

MnOOH nanoparticles integrated nitrogen doped porous nanosheet-like carbon network as a non-noble catalyst for electro-oxidation of sodium borohydride

Nitrogen doped carbon-supported with various ratio of electro-active manganite nanoparticles (MnO–NPCs) as a facile, low-cost, and non-noble electrocatalyst is synthesized for electro-oxidation of borohydride. Transmission electron micrographs show the size of MnO nanoparticles in NPC is about 3.8 ± 0.2 nm with a definite lattice parameter and randomly distributed into the entire nanosheet-like porous carbon network. Survey X-ray photoelectron spectrum (XPS) of MnO–NPCs sample reveals the presence of Mn element; and Mn–O–Mn and Mn–O–H peaks from O 1s, indicating the effective insertion of MnO nanoparticles onto the NPC surface. Electrochemically transformed MnOOH–NPCs are further explored as effective catalysts toward the electro-oxidation of borohydride in 1.0 M alkaline NaOH solution. Among the catalysts with different ratios, MnOOH–NPC-2 displays higher catalytic performance (~19.9 mA ⋅ cm−2) with low-onset polarization potential (−0.65 V) towards borohydride electro-oxidation. The obtained results are mainly owing to (i) the unique nanosheet-like structure of nitrogen doped carbon network access large amount of MnOOH nanoparticles (without any aggregation) through their numerous porous-structure with high-specific surface area (821 m2 g−1), (ii), the presence of intrinsic synergetic activity between porous carbon nanosheets and MnOOH nanoparticles, and (iii) the effective interaction of Mn2+ ions with OH− ions to form Mn(OH)2, which mediates improved catalytic activity of borohydride electro-oxidation.

Graphene Supported Pd–Sn–Co Nanocatalysts for the Electrooxidation of Sodium Borohydride in Membraneless Fuel Cells

Graphene Supported Pd–Sn–Co Nanocatalysts for the Electrooxidation of Sodium Borohydride in Membraneless Fuel Cells

Porous nickel electrodes with controlled texture for the hydrogen evolution reaction and sodium borohydride electrooxidation

Porous Ni electrodes with different textures were successfully fabricated by electrodeposition in the presence of NH4Cl and (NH4)2SO4. Moreover, we studied the effect of texture on porous nickel electrodes for HER and NaBH4 electrooxidation.

Hydrolysis and electrooxidation of sodium borohydride on novel CNT supported CoBi fuel cell catalyst

At present, Co, Bi, CoBi, and CoBi/CNT catalysts are prepared via co-precipitation method and sodium borohydride (NaBH4) reduction method for NaBH4 electrooxidation and hydrolysis. These Co, Bi, and CoBi catalysts are characterized by X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM), N2 adsorption-desorption, Inductively Coupled Plasma Mass Spectrometry (ICP-MS), and Temperature Programmed Reduction (TPR). These catalysts are employed for NaBH4 hydrolysis and further measurements are performed to investigate their NaBH4 electrooxidation activity. For NaBH4 hydrolysis, NaOH concentration, reaction temperature, NaBH4 concentration, and catalyst amount are optimized for CoBi and CoBi/CNT catalysts. Furthermore, the rate constants (k) are found between 20 and 50 °C and the activation energy is calculated from the Arrhenius equation. The hydrogen generation rates on CoBi (95–5) and % 10 CoBi (95–5)/CNT catalysts are found as 2605.6 ml H2 g−1cat min−1 and 12996 ml H2 g−1cat min−1, respectively. NaBH4 electrooxidation is investigated with cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS) measurements. Maximum mass activities are obtained as 5.86 mA mg−1 Co for CoBi and 25.7 mA mg−1 Co for CoBi/CNT catalysts. EIS and CA results are also in a good agreement with CV results in terms of stability and electrocatalytic activity of CoBi/CNT catalyst. The CoBi/CNT catalyst is believed to be a promising anode catalyst for the direct borohydride fuel cell (DBFC).

A three-dimensional porous Co-P alloy supported on a copper foam as a new catalyst for sodium borohydride electrooxidation.

Cobalt has been extensively studied as an effective catalyst for the electrooxidation of sodium borohydride. However, there is still the problem of the low catalytic activity of cobalt catalysts. The improvement in the catalytic activity of cobalt for the electrooxidation of sodium borohydride has become a challenge. In this paper, a novel catalyst Co-P alloy was supported on a copper foam (CF) substrate by a one-step electrodeposition method. In the electrodeposition process, a Co-P/CF electrode with a three-dimensional (3D) porous structure was successfully prepared using hydrogen bubbles as a dynamic template. Through the physical characterization of Co-P/CF, it was proven that the doping of P element produced more Co clusters on the surface of the electrode, which resulted in more active sites. These characteristics were very beneficial for NaBH4 electrooxidation. The electrochemical characterization confirmed that the electrocatalytic activity of Co-P/CF for NaBH4 was better than that of Co/CF. At room temperature, for the Co-P/CF in 2.0 mol dm-3 NaOH + 0.20 mol dm-3 NaBH4 solution, the oxidation current density reached 1795 mA cm-2 at -0.20 V (vs. Ag/AgCl), which was higher than that previously reported the literature.

3D Metallic Foams as Catalysts for Hydrolysis and Electrooxidation of Sodium Borohydride

Environmental and social challenges that result from the burning of fossil fuels demand clean energy for the world future sustainability. Fuel cells are devices that convert a fuel source into electricity, providing a clean energy solution for both portable and stationary (e.g., electricity production and heating) applications more than any other currently available power source [1]. Amongst low temperature fuel cells, polymer electrolyte fuel cells (with a typical operation temperature of 80 ºC) are receiving great attention due to their characteristically high power density. However, its large-scale development has been hindered by cost competitiveness, engineering design and safety concerns for hydrogen-fueled devices. These drawbacks can be minimized by the use of high specific energy liquid fuels, such as methanol or sodium borohydride (NaBH4) solutions. NaBH4 is of high interest as it can be a direct or indirect fuel to power a direct borohydride fuel cell (DBFC) or a typical proton exchange membrane fuel cell (PEMFC), respectively [1]. In fact, International Energy Agency supports NaBH4 as a sustainable route for fuel cell systems. NaBH4 is a non-fossil derivative and nonflammable compound with high gravimetric hydrogen storage capacity (10.8 wt.%) [2]. As an indirect fuel, NaBH4 produces clean hydrogen through hydrolysis in alkaline medium and ambient conditions, after which the hydrogen (H2) fuel is channeled to a PEMFC where it is oxidized to generate electricity [3]. As a direct fuel, NaBH4 is oxidized in the DBFC anode at ambient conditions, releasing eight electrons at quite negative electrode potentials [3]. In addition, no CO2 is produced, unlike hydrocarbon fuels, which turns the overall NaBH4 route a green approach suitable for portable applications [3]. A catalyst is always required, either to accelerate the hydrogen release or for the borohydride direct electrooxidation, so that the fuel cell can generate sufficient power [3,4]. Precious metals, such as Pt, Ru and their related alloys, can generate high hydrogen rates toward NaBH4 hydrolysis. In the case of borohydride electrooxidation, most catalysts are built from precious metals, such as Au or Ag. Since these materials are expensive, there has been much focus on the use of transition metals [3]. Moreover, transition metals in the alloy form can be beneficial as they can enhance catalytic activity due to synergetic effects [4]. Recently, three-dimensional catalysts with very high porosity and surface areas based on Co have demonstrated high catalytic activity for borohydride hydrolysis [5], while those based on Ni have shown electroactivity for borohydride electrooxidation [6]. The main goal of this work is to develop low-cost catalysts, based on Ni, Co, Cu, and Fe, to be applied both on borohydride hydrolysis for H2 generation and on borohydride electrooxidation, in order to find in which system, PEMFC or DBFC, they are more suitable. The catalysts were produced by electrodeposition technique, a simple one-step and fast process, using the dynamic hydrogen bubble template to create foam-like nanostructures. The ternary Ni-Cu-Fe foams presented the best performance towards borohydride oxidation in terms of the current density per unit gram of catalyst. On the other hand, Co-based foams are superior in fast H2 demand applications by borohydride hydrolysis. Figure 1. SEM image of Ni4Cu48Fe30 foam catalyst.

3D Metallic Foams as Catalysts for Hydrolysis and Electrooxidation of Sodium Borohydride

Economical non-noble metal catalysts with high activity are needed for the development of systems that use sodium borohydride (NaBH4) as fuel or hydrogen source. In that way, foam-like nanostructured catalysts incorporating transition metals (Ni, Cu, Co and Fe) are prepared by electrodeposition using a simple one-step and fast process, the dynamic hydrogen bubble template. Influence of different metal content on foams morphology is assessed by SEM. Present NaBH4 electrooxidation and hydrolysis studies have the goal of analyzing the catalysts suitability for DBFC and PEMFC systems, respectively. Ni-Cu and Ni-Co bimetallic foams present higher current densities towards borohydride oxidation reaction (BOR) than ternary foams. Ni14Cu26Fe41 foam stands out as the best NaBH4 hydrolysis catalyst for a PEMFC while Ni36Cu46 foam has demonstrated to be the best choice as a BOR catalyst in DBFCs.

Sodium Borohydride Oxidation on Pt and/or Pd-Based Electrodes in Hydrogen Peroxide Direct Borohydride Fuel Cells (H2O2-DBFCs)

Direct borohydride fuel cells (DBFCs) may offer high energy density due to the potential release of 8 electrons when borohydride (BH4 -) has been fully oxidized (overall reaction: BH4 - + 8OH- à BO2 - + 6H2O + 8e-). However, the borohydride oxidation reaction (BOR) is complex producing several reaction intermediates and solid borates1, and may compete with the heterogeneous hydrolysis of BH4 - to produce H2, which can be lost. In consequence, the full 8-electron oxidation reaction may be practically inaccessible. Incomplete BOR is largely due to transport of intermediate species away from the electrocatalyst before complete oxidation can occur. The escape of incompletely oxidized species leads to BH4 - and intermediate species concentrations (including H2) which vary as the fuel solution progresses through the fuel cell flow field 2. For this reason, the optimal catalyst layer composition and porosity are likely different at the fuel inlet vs outlet, making the catalyst layer and overall cell design a challenge. In this study, the direct electrooxidation of sodium borohydride (NaBH4) is investigated within a liquid flow-through DBFC having a catalyst composition which varies from inlet to outlet. Electrochemical and spray coating deposition are used to form catalyst layers composed of a gradient of both thin-film and carbon-supported catalysts. The efficacy of the fuel cell design is evaluated electrochemically to understand which catalyst layer system maximizes fuel diffusion, minimizes hydroxide and hydrogen adsorption, and facilitates the removal of borate from the catalyst layer. The characteristics of catalyst layer structure/composition before and after testing, and electrochemical efficiency for BOR are observed using several analytical techniques including scanning electron microscopy (SEM), X-Ray energy dispersive spectroscopy (X-EDS), Braunauer-Emmett-Teller sorptometry (BET), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS).(1) Olu, P. Y.; Bonnefont, A.; Rouhet, M.; Bozdech, S.; Job, N.; Chatenet, M.; Savinova, E. Electrochim. Acta 2015, 179, 637. (2) Stroman, R. O.; Jackson, G. S. J. Power Sources 2014, 247, 756.