Electrocatalytic Activity of Some Cobalt Based Sodium Phosphates in Alkaline Solution

MRS Advances ◽  
2018 ◽  
Vol 3 (22) ◽  
pp. 1215-1220 ◽  
Author(s):  
Debasmita Dwibedi ◽  
Ritambhara Gond ◽  
Krishnakanth Sada ◽  
Baskar Senthilkumar ◽  
Prabeer Barpanda
Keyword(s):  
Oxygen Reduction ◽  
Alkaline Solution ◽  
Water Oxidation ◽  
Electrocatalytic Activity ◽  
Large Scale ◽  
Cost Effective ◽  
Platinum Group Metals ◽  
Rotating Disk Electrode ◽  
Oxidation Catalyst ◽  
Sodium Phosphates

ABSTRACTThe development of efficient water oxidation catalyst is a major path to realize water splitting systems, which could benefit high performance and cost-effective metal-air batteries, fuel cells and solar energy conversion. To date, the rare crustal abundant platinum group metals rule this sector with Pt-alloys being the best for oxygen reduction reaction (ORR) and ruthenium oxides for oxygen evolution reaction (OER) in acidic solution. However, they show poor stability and are too expensive for large scale applications. Moreover, oxygen reduction in basic solutions can otherwise be catalysed by metal oxide with non-precious earth abundant transition metals (e.g. Fe, Co, Ni). Hence, there is a massive demand to explore noble metal free bifunctional electrocatalysts. In this work, we present the electrocatalytic activity of three cobalt based sodium phosphates namely NaCoPO4 (with one phosphate), Na2CoP2O7 (with two phosphate) NaFe2Co(PO4)3 (with three phosphate). Synthesized by solution combustion route, all these phosphates confirmed phase purity. NaCoPO4 and Na2CoP2O7 adopted orthorhombic structure with Pnma and Pna21 space group respectively; whereas NaFe2Co(PO4)3 crystallized in monoclinic (C2/c) framework. Electrocatalytic activity of these cobalt phosphates were inspected by linear sweep voltammetry with rotating disk electrode (RDE). All three showed promising bifunctional activity. In fact, the ORR activities of both orthorhombic cobalt phosphates are comparable to Vulcan carbon and Pt/C. OER activity of Na2CoP2O7 overrode other phosphates. The bifunctional activity and good stability of these sodium cobalt phosphates stem from cobalt ions and stabilization of the catalytic centres by the phosphate frameworks. The present work builds a detail structure-property correlation in these phosphate systems and also demonstrates the possibility of utilizing these sodium cobalt phosphates as alternate cost-effective, novel electrocatalysts for efficient OER/ORR activity in alkaline solution.

scholarly journals Methanol-Tolerant M–N–C Catalysts for Oxygen Reduction Reactions in Acidic Media and Their Application in Direct Methanol Fuel Cells

Catalysts ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 650 ◽  
Author(s):  
Carmelo Lo Vecchio ◽  
David Sebastián ◽  
María Lázaro ◽  
Antonino Aricò ◽  
Vincenzo Baglio
Keyword(s):  
Fuel Cells ◽  
Oxygen Reduction ◽  
Large Scale ◽  
High Efficiency ◽  
Direct Methanol Fuel Cells ◽  
Cell System ◽  
Rotating Disk Electrode ◽  
Capital Costs ◽  
Direct Methanol ◽  
Methanol Fuel Cells

Direct methanol fuel cells (DMFCs) are emerging technologies for the electrochemical conversion of the chemical energy of a fuel (methanol) directly into electrical energy, with a low environmental impact and high efficiency. Yet, before this technology can reach a large-scale diffusion, specific issues must be solved, in particular, the high cost of the cell components. In a direct methanol fuel cell system, high capital costs are mainly derived from the use of noble metal catalysts; therefore, the development of low-cost electro-catalysts, satisfying the target requirements of high performance and durability, represents an important challenge. The research is currently addressed to the development of metal–nitrogen–carbon (M–N–C) materials as cheap and sustainable catalysts for the oxygen reduction reaction (ORR) in an acid environment, for application in polymer electrolyte fuel cells fueled by hydrogen or alcohol. In particular, this mini-review summarizes the recent advancements achieved in DMFCs using M–N–C catalysts. The presented analysis is restricted to M–N–C catalysts mounted at the cathode of a DMFC or investigated in rotating disk electrode (RDE) configuration for the ORR in the presence of methanol in order to study alcohol tolerance. The main synthetic routes and characteristics of the catalysts are also presented.

Tailoring molecular architectures of Fe phthalocyanine on nanocarbon supports for high oxygen reduction performance

2015 ◽  
Vol 3 (18) ◽  
pp. 10013-10019 ◽  
Author(s):  
Shiming Zhang ◽  
Heyou Zhang ◽  
Xing Hua ◽  
Shengli Chen
Keyword(s):  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Alkaline Solution ◽  
Electrocatalytic Activity ◽  
Reduction Reaction ◽  
High Oxygen ◽  
Molecular Architectures

Tailored molecular architectures of FePc on nanocarbon supports from nanorods to uniform shells exhibit excellent electrocatalytic activity for the oxygen reduction reaction in alkaline solution.

scholarly journals In Situ EPR Characterization of a Cobalt Oxide Water Oxidation Catalyst at Neutral pH

Catalysts ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 926 ◽  
Author(s):  
Yury Kutin ◽  
Nicholas Cox ◽  
Wolfgang Lubitz ◽  
Alexander Schnegg ◽  
Olaf Rüdiger
Keyword(s):  
Cobalt Oxide ◽  
Water Oxidation ◽  
Large Scale ◽  
Low Cost ◽  
Operating Conditions ◽  
Oxidation Catalyst ◽  
O2 Evolution ◽  
Ligand Field ◽  
Neutral Ph

Here we report an in situ electron paramagnetic resonance (EPR) study of a low-cost, high-stability cobalt oxide electrodeposited material (Co-Pi) that oxidizes water at neutral pH and low over-potential, representing a promising system for future large-scale water splitting applications. Using CW X-band EPR we can follow the film formation from a Co(NO3)2 solution in phosphate buffer and quantify Co uptake into the catalytic film. As deposited, the film shows predominantly a Co(II) EPR signal, which converts into a Co(IV) signal as the electrode potential is increased. A purpose-built spectroelectrochemical cell allowed us to quantify the extent of Co(II) to Co(IV) conversion as a function of potential bias under operating conditions. Consistent with its role as an intermediate, Co(IV) is formed at potentials commensurate with electrocatalytic O2 evolution (+1.2 V, vs. SHE). The EPR resonance position of the Co(IV) species shifts to higher fields as the potential is increased above 1.2 V. Such a shift of the Co(IV) signal may be assigned to changes in the local Co structure, displaying a more distorted ligand field or more ligand radical character, suggesting it is this subset of sites that represents the catalytically ‘active’ component. The described spectroelectrochemical approach provides new information on catalyst function and reaction pathways of water oxidation.

Concentrated-acid triggered superfast generation of porous amorphous cobalt oxide toward efficient water oxidation catalysis in alkaline solution

2019 ◽  
Vol 55 (12) ◽  
pp. 1797-1800 ◽  
Author(s):  
Xuqiang Ji ◽  
Yujia He ◽  
Jingquan Liu
Keyword(s):  
Cobalt Oxide ◽  
Alkaline Solution ◽  
Water Oxidation ◽  
Oxidation Catalysis ◽  
Oxidation Catalyst ◽  
Carbon Cloth ◽  
Water Oxidation Catalysis

Amorphous cobalt oxide on carbon cloth (AMO-CoO/CC) was prepared as an excellent water-oxidation catalyst with 50 mV less overpotential at 10 mA cm−2 than highly-crystallized Co3O4 in 1.0 M KOH.

A lead–porphyrin metal–organic framework: gas adsorption properties and electrocatalytic activity for water oxidation

2016 ◽  
Vol 45 (1) ◽  
pp. 61-65 ◽  
Author(s):  
Fangna Dai ◽  
Weidong Fan ◽  
Jiahui Bi ◽  
Peng Jiang ◽  
Dandan Liu ◽  
...  
Keyword(s):  
Alkaline Solution ◽  
Water Oxidation ◽  
Electrocatalytic Activity ◽  
Gas Adsorption ◽  
Metal Organic Framework ◽  
Porous Metal ◽  
Adsorption Properties ◽  
Metal Organic ◽  
Organic Framework

A 3D non-interpenetrating porous metal–organic framework shows electrocatalytic activity for water oxidation in alkaline solution.

scholarly journals Oxygen Reduction Reaction of Carbon Nanotubes Supported Polypyrrole Doped Toluene Sulfonic Acid in Alkaline Medium

2019 ◽  
Vol 7 (4.14) ◽  
pp. 473
Author(s):  
Rika Sri Utami ◽  
Wai Yin Wong ◽  
Edy Herianto Majlan ◽  
Kee Shyuan Loh
Keyword(s):  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Electrocatalytic Activity ◽  
Sulfonic Acid ◽  
Oxidative Polymerization ◽  
Reduction Reaction ◽  
Rotating Disk Electrode ◽  
Alkaline Condition ◽  
X Ray ◽  
Toluene Sulfonic Acid

In this study, polypyrrole/toluene sulfonic acid-based nitrogen doped carbon nanotube (NCNT) is synthesized via chemical oxidative polymerization followed by high-temperature heat treatment under N2 atmosphere. The structure, morphology and composition of the NCNT catalyst are investigated with X-ray diffraction (XRD), scanning electron microscopy (SEM) and Raman spectroscopy. Different N species including pyridinic, pyrrolic, graphitic, and oxidized-N are quantitatively determined by X-ray photoelectron spectroscopy (XPS). The electrocatalytic activity of NCNT towards oxygen reduction reaction (ORR) in alkaline condition is evaluated with cyclic voltammetry (CV) and rotating disk electrode (RDE). The globular and tubular structure of NCNT can be clearly seen from SEM images. The typical Raman spectrum for NCNT showed two prominent bands around 1348 cm-1 (D band) and 1568 cm-1 (G band). High-resolution XPS spectrum of N 1s for NCNT showed that graphitic-N has the highest percentage (39.36%), whereas the pyridinic-N (26.54%), pyrrolic-N (18.88%) and oxidized-N (15.22%). The ORR electrocatalytic activity of the NCNT in 0.1 M KOH has the onset potential of -0.154 V vs. Ag/AgCl, the current density 0.455 mA/cm2, and electron transfer number of n ≈ 4.  

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