A non-platinum metal catalyst, MnN x /C was synthesized via the high-pressure pyrolysis route. The combination of X-ray photoelectron spectroscopy (XPS) and X-ray absorption fine structure (XAFS) studies indicated the presence of Mn in +2 oxidation state surrounded by four N atoms. The peak-to-peak separation (ΔE p ) of the more negative peak pair observed for I 3 − /I − redox couple over MnN x /C catalyst was 20 mV lower than that of the Pt catalyst, indicating high reversibility of the redox couple over MnN x /C catalyst. The charge transfer resistance of the MnN x /C electrode, as measured by the impedance spectroscopy, is ∼ 2 Ω higher than that of Pt, which resulted slightly lower short circuit current (Jsc) value for MnN x /C over Pt, however the fill factor (FF) and power conversion efficiency (PCE) values of MnN x /C was slightly higher and comparable to that of Pt respectively. Hence; replacing Pt with MnN x /C would decrease the cost of DSSCs. © 2016 Elsevier B.V.

Kothandaraman Ramanujam

Department Of Chemistry

Suman K. Kushwaha

Karthikayini M.p

CATALYSTS

Charge transfer

Dye-sensitized solar cells

Electrodes

Manganese compounds

Platinum

Platinum compounds

Solar cells

X ray absorption

Charge transfer resistance

Counter electrodes

Impedance spectroscopy

MNNX/C

NON-PLATINUM

PEAK-TO-PEAK SEPARATION

Power conversion efficiencies

X RAY ABSORPTION FINE STRUCTURES

X ray photoelectron spectroscopy

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Applied Surface Science

Polymer electrolyte fuel cells exhibit high potentials at the cathode during start-stop cycles in automotive applications, which leads to carbon support corrosion, and concomitant loss of electrocatalytic activity. In this study, carbon nanomaterials (CNM), predominantly composed of nitrogen doped multi-walled carbon nanotubes (N-MWCNTs) with encapsulated cobalt nanoparticles, were synthesized in-situ by the solid-state pyrolysis (SSP) of melamine and cobalt Oxide (Co3O4). The best formulation of the catalyst exhibited an ORR activity of of 2.3 mA cm-2 at 0.75 V vs. RHE (4.6 mA mg-1). The role played by cobalt to complete the active site was demonstrated as follows: Upon complexing the cobalt site with bipyridine, the ORR onset potential decreased by ∼90 mV. The stability of the above non-precious metal (NPM) catalyst was studied through accelerated stress tests (ASTs) designed to mimic load cycling and start-stop cycling protocols, wherein the catalyst was exposed to high anodic potentials (up to 1.5 V vs. RHE) in an acidic medium. In rotating disk electrode mode, the ORR polarization curve shifted to more negative values by about 20 mV and 14 mV, respectively, after the load cycling and start-stop cycling AST protocols, suggesting high stability. Similar stability was observed in fuel cell mode. © 2016 The Electrochemical Society.

Journal of the Electrochemical Society

Highly active and durable non-precious metal catalyst for the oxygen reduction reaction in acidic medium

Non-precious metal electrocatalysts based on pyrolysed metal-nitrogen-carbon (MNC) are viewed as an inexpensive replacement for platinum-based electrocatalysts for the oxygen reduction reaction (ORR) in fuel cells. One of the drawbacks of all the reported procedures to synthesize MNC electrocatalysts is the inability to control the nitrogen content. Since the type of nitrogen present (pyridinic, pyrrolic, quaternary/graphitic) and their proportions both play a seminal role in deciding the ORR activity of the electrocatalyst, it is important to carefully study the effect of nitrogen content on electrocatalyst properties. In this study, selenium was used as a ligand to replace the nitrogen coordinated to the iron atom in the electrocatalyst, thereby imparting control on the nitrogen content. Upon introducing 14 at% of selenium, the Ncontent of the catalyst dropped to 3.7 wt% and the ORR activity reached a maximum of 7.2 mA cm-2 at 0.8 V vs. RHE. We demonstrated the need for iron to complete the active site: upon complexing the iron site with bipyridine, ethylene diammine and oxalic acid in 1N H2SO4, the overpotential toward the ORR increased by ∼60 mV, ∼140 mV and ∼140 mV respectively at 2 mA cm-2. © 2015 The Electrochemical Society.

Controlling the nitrogen content of metal-nitrogen-carbon based non-precious-metal electrocatalysts via selenium addition

ACS Applied Materials & Interfaces

Electrocatalytic Zinc Composites as the Efficient Counter Electrodes of Dye-Sensitized Solar Cells: Study on the Electrochemical Performances and Density Functional Theory Calculations

Journal of Materials Chemistry A

Effect of pyrolysis pressure on activity of Fe–N–C catalysts for oxygen reduction

ACS Nano

Iron Pyrite Thin Film Counter Electrodes for Dye-Sensitized Solar Cells: High Efficiency for Iodine and Cobalt Redox Electrolyte Cells

A non-platinum counter electrode, MnN x /C, for dye-sensitized solar cell applications

Journal	Data powered by TypesetApplied Surface Science
Publisher	Data powered by TypesetElsevier B.V.
ISSN	01694332
Open Access	No