Toggle Main Menu Toggle Search

Open Access padlockePrints

Browsing publications by Professor Paul Christensen.

Newcastle AuthorsTitleYearFull text
Dr Wojciech Mrozik
Dr Mohammad Rajaeifar
Dr Oliver Heidrich
Professor Paul Christensen
Environmental impacts, pollution sources and pathways of spent lithium-ion batteries2021
Dr Wojciech Mrozik
Professor Paul Christensen
Dr Zoran Milojevic
Dr Mohamed Ahmeid
malcolm Wise
et al.
Hazards and Pollution Released from Abused and Burnt Industrial Lithium-Ion Batteries2021
Professor Paul Christensen
Dr Simon Lambert
Dr Wojciech Mrozik
Dr Mohammad Rajaeifar
malcolm Wise
et al.
Risk management over the life cycle of lithium-ion batteries in electric vehicles2021
Professor Paul Christensen
Synthesis and electrochemical characterization of Si/TiO2/Au composite anode: Efficient oxygen evolution and hydroxyl radicals generation2021
Professor Paul Christensen
Dr Zoran Milojevic
malcolm Wise
Dr Mohamed Ahmeid
Dr Pierrot Attidekou
et al.
Thermal and mechanical abuse of electric vehicle pouch cell modules2021
Professor Paul Christensen
Zeinab Mashhadani
Mohd Md Ahid
Professor David Manning
Dr Michael Carroll
et al.
An in situ FTIR study of the plasma- and thermally-driven reaction of isopropyl alcohol at CeO2: Evidence for a loose transition state involving Ce3+?2019
Professor Paul Christensen
Dr Oliver Heidrich
Dr Simon Lambert
Recycling lithium-ion batteries from electric vehicles2019
Professor Paul Christensen
Zeinab Mashhadani
In situ FTIR studies on the oxidation of isopropyl alcohol over SnO2 as a function of temperature up to 600 oC and a comparison to the analogous plasma-driven process2018
Professor Paul Christensen
Zeinab Mashhadani
A Direct Fourier Transform Infrared Spectroscopic Comparison of the Plasma- and Thermally-Driven Reaction of CO2 at Macor2018
Professor Paul Christensen
Halim Bin Md Ali
Zeinab Mashhadani
Dr Michael Carroll
The Production of Ketene and C5O2 from CO2, N2 and CH4 in a Non-thermal Plasma Catalysed by Earth-Abundant Elements: An In-Situ FTIR Study2018
Professor Paul Christensen
Zeinab Mashhadani
Dr Michael Carroll
The Production of Methane, Acetone, “Cold” CO and Oxygenated Species from Isopropyl Alcohol in a Non-Thermal Plasma: An In-Situ FTIR Study2018
Dr Pierrot Attidekou
Chen Wang
Dr Matthew Armstrong
Dr Simon Lambert
Professor Paul Christensen
et al.
A new time constant approach to online capacity monitoring and lifetime prediction of lithium ion batteries for Electric Vehicles (EV)2017
Dr Simon Lambert
Dr Matthew Armstrong
Chen Wang
Dr Pierrot Attidekou
Professor Paul Christensen
et al.
A rapid non-destructive-testing technique for in-line quality control of Li-ion batteries2017
Professor Paul Christensen
Dr Pierrot Attidekou
Professor Russ Egdell
Supandee Maneelok
Professor David Manning
et al.
The identification of the mechanism of electrocatalytic ozone generation on Ni/Sb-SnO22017
Professor Paul Christensen
Dr Pierrot Attidekou
Professor Russ Egdell
Supandee Maneelok
Professor David Manning
et al.
An in-situ FTIR spectroscopic and thermogravimetric analysis study of the dehydration and dehydoxylation of SnO2: the contribution of the (100), (110) and (111) facets2016
Abdullah Al-Abduly
Professor Paul Christensen
An in situ and downstream study of non-thermal plasma chemistry in an air fed dielectric barrier discharge (DBD)2015
Dr Pierrot Attidekou
Dr Simon Lambert
Dr Matthew Armstrong
Dr James Widmer
Emeritus Professor Keith Scott
et al.
A study of 40 Ah lithium ion batteries at zero percent state of charge as a function of temperature2014
Professor Paul Christensen
Steven Jones
An in Situ FTIR Study of Ethanol Oxidation at Polycrystalline Platinum in 0.1 M KOH at 25 and 50 degrees C2014
Professor Paul Christensen
Steven Jones
An in situ FTIR study of undoped PolyBenzoImadazole as a function of relative humidity2014
Abdullah Al-Abduly
Professor Paul Christensen
Professor Adam Harvey
Dr Kui Zhang
Characterization and optimization of an oscillatory baffled reactor (OBR) for ozone-water mass transfer2014
Dr Khalid Zakaria
Professor Paul Christensen
The Use of Ni/Sb-SnO2-based Membrane Electrode Assembly for Electrochemical Generation of Ozone and the Decolourisation of Reactive Blue 50 Dye Solutions2014
Professor Paul Christensen
Steven Jones
Dr Andrew Hamnett
An in situ FTIR spectroscopic study of the electrochemical oxidation of ethanol at a Pb-modified polycrystalline Pt electrode immersed in aqueous KOH2013
Professor Wen-Feng Lin
Professor Paul Christensen
Effect of methanol concentration on oxygen reduction reaction activity of Pt/C catalysts2013
Professor Paul Christensen
Dr Khalid Zakaria
Dr Henriette Christensen
Dr Taner Yonar
The Effect of Ni and Sb Oxide Precursors, and of Ni Composition, Synthesis Conditions and Operating Parameters on the Activity, Selectivity and Durability of Sb-Doped SnO2 Anodes Modified with Ni2013
Professor Paul Christensen
Dr Taner Yonar
Dr Khalid Zakaria
The Electrochemical Generation of Ozone: A Review2013
Professor Paul Christensen
Steven Jones
Dr Andrew Hamnett
In Situ FTIR Studies of Ethanol Oxidation at Polycrystalline Pt in Alkaline Solution2012
Professor Paul Christensen
Dr Khalid Zakaria
Professor Thomas Curtis
Structure and Activity of Ni- and Sb-doped SnO2 Ozone Anodes2012
Professor Paul Christensen
The influence of Ir and Pt1Ir1 structure in metallic multilayers nanoarchitectured electrodes towards ethylene glycol electro-oxidation2012
Professor Paul Christensen
Dr Michael Carroll
Douglas Linares Moya
David Molyneux
A Novel Composite Anode: The Electrooxidation of Organic Molecules via Formation of Highly Energetic Holes2011
Professor Paul Christensen
Dr Andrew Hamnett
Douglas Linares Moya
Oxygen reduction and fuel oxidation in alkaline solution2011
Dr Rui Yang
Professor Paul Christensen
Dr Terry Egerton
Emeritus Professor Jim White
Spectroscopic Studies of Photodegradation of Polyethylene Films Containing TiO2 Nanoparticles2011
Professor Paul Christensen
Dr Andrew Hamnett
Douglas Linares Moya
The electro-oxidation of formate ions at a polycrystalline Pt electrode in alkaline solution: an in situ FTIR study2011
Professor Paul Christensen
Ajchara Imkum
The Inhibition of Ozone Generation at Ni/Sb-SnO2 Electrodes in High Concentrations of Dissolved O-32011
Professor Paul Christensen
The selective oxidation of ethanol to CO2 at Pt-pc/Ir/Pt metallic multilayer nanostructured electrodes2011
Dr Rui Yang
Professor Paul Christensen
Dr Terry Egerton
Emeritus Professor Jim White
Degradation products formed during UV exposure of polyethylene-ZnO nano-composites2010
Dr Fei Li
Professor Paul Christensen
Preparation and cell performance of special-shaped Ti electrode for direct ethanol fuel cell2010
Professor Paul Christensen
Douglas Linares Moya
The Role of Adsorbed Formate and Oxygen in the Oxidation of Methanol at a Polycrystalline Pt Electrode in 0.1 M KOH: An In Situ Fourier Transform Infrared Study2010
Professor Paul Christensen
Dr Terry Egerton
Carbon dioxide formation during initial stages of photodegradation of poly(ethyleneterephthalate) (PET) films2009
Professor Paul Christensen
Dr Terry Egerton
Evaluation of poly(ethylene terephthalate) photostabilisation using FTIR spectrometry of evolved carbon dioxide2009
Professor Paul Christensen
Dr Terry Egerton
Fourier Transfer Infrared Measurement of CO2 Photogeneration from Polyethylene, Polypropylene, and Polyesters2009
Sudesh Fernando
Professor Paul Christensen
Dr Terry Egerton
Humidity dependence of carbon dioxide generation during photodegradation of biaxially oriented polypropylene in oxygen2009
Professor Paul Christensen
Dr Terry Egerton
Photogeneration of carbon dioxide from polypropylene film stabilized by hindered amines2009
Dr Fei Li
Xu Wang
Dr Weilu Lin
Professor Paul Christensen
Preparation and cell performance of tubular cathode for direct methanol fuel cell2009
Professor Paul Christensen
Professor Wen-Feng Lin
Dr Henriette Christensen
Ajchara Imkum
Jia Jin
et al.
Room Temperature, Electrochemical Generation of Ozone with 50% Current Efficiency in 0.5M Sulfuric Acid at Cell Voltages2009
Professor Javier Marugan
Professor Paul Christensen
Dr Terry Egerton
Herry Purnama
Synthesis, characterization and activity of photocatalytic sol-gel TiO2 powders and electrodes2009
Professor Paul Christensen
Dr Terry Egerton
Herry Purnama
Influence of the synthesis pH on the properties and activity of sol-gel TiO2 photocatalysts2008
Professor Wen-Feng Lin
Jia Jin
Professor Paul Christensen
Fuyun Zhu
In-situ FT-IR spectroscopic studies of fuel cell electro-catalysis: From single-crystal to nanoparticle surfaces2008
Professor Paul Christensen
Dr Terry Egerton
Changqing Jin
Photodegradation of polycaprolactone/poly(vinyl chloride) blend2008
Jia Jin
Professor Wen-Feng Lin
Professor Paul Christensen
The effects of the specific adsorption of anion on the reactivity of the Ru(0001) surface towards CO adsorption and oxidation: in situ FTIRS studies2008
Sudesh Fernando
Professor Paul Christensen
Dr Terry Egerton
Emeritus Professor Jim White
Carbon dioxide evolution and carbonyl group development during photodegradation of polyethylene and polypropylene2007
Dr Terry Egerton
Professor Paul Christensen
Emeritus Professor Jim White
FTIR measurement of CO2 photogeneration from polyethylene, polypropylene and polyester films2007
Professor Wen-Feng Lin
Professor Paul Christensen
Jia Jin
In-situ FTIR spectroscopic studies of the adsorption and oxidation of small organic molecules at the Ru(0001) electrode under various conditions2007
Professor Paul Christensen
In-Situ Spectroscopic Studies of Adsorption at the Electrode and Electrocatalysis2007
Sudesh Fernando
Chunyu JIN
Professor Paul Christensen
Dr Terry Egerton
Emeritus Professor Jim White
et al.
Use of Dynamic CO2 Monitoring to Study the Early Stages of Photo-Oxidation2007
Professor Paul Christensen
Dr Terry Egerton
Professor Wen-Feng Lin
Dr Paola Meynet
Professor Nick Wright
et al.
A novel electrochemical device for the disinfection of fluids by OH radicals2006
Professor Wen-Feng Lin
Fuyun Zhu
Professor Paul Christensen
A tubular direct methanol fuel cell with Ti mesh anode2006
Professor Paul Christensen
Professor Wen-Feng Lin
Electrode, method of manufacture and use thereof2006
Professor Paul Christensen
Emeritus Professor Keith Scott
Dr Hua Cheng
Electrolysis cell and method2006
Professor Wen-Feng Lin
Fuyun Zhu
Professor Paul Christensen
Dr Minquaing Li
Dr Honglin Zhang
et al.
Novel electrode structure for DMFC operated with liquid methanol2006
Dr Terry Egerton
Professor Paul Christensen
Samia Kosa
John Harper
Dr James Tinlin
et al.
Photoelectrocatalysis by titanium dioxide for water treatment2006
Dr Terry Egerton
Samia Kosa
Professor Paul Christensen
Photoelectrocatalytic disinfection of E. coli suspensions by iron doped TiO22006
Fujun Zhu
Professor Wen-Feng Lin
Professor Paul Christensen
Dr Honglin Zhang
Preparation and characterization of new anodes based on Ti mesh for direct methanol fuel cells2006
Fuyun Zhu
Professor Wen-Feng Lin
Professor Paul Christensen
Dr Honglin Zhang
PtRu/Ti anodes with varying Pt:Ru ratio prepared by electrodeposition for the direct methanol fuel cell2006
Fujun Zhu
Professor Wen-Feng Lin
Professor Paul Christensen
Huqui Zhang
PtRuO2/Ti anodes with a varying Pt:Ru ratio for direct methanol fuel cells2006
Changqing Jin
Professor Paul Christensen
Dr Terry Egerton
Emeritus Professor Jim White
Rapid measurement of photocatalytic oxidation of poly(vinyl chloride) by in situ FTIR spectrometry of evolved CO22006
Changqing Jin
Professor Paul Christensen
Dr Terry Egerton
John Lawson
Emeritus Professor Jim White
et al.
Rapid measurement of polymer photo-degradation by FTIR spectrometry of evolved carbon dioxide2006
Professor Wen-Feng Lin
Professor Paul Christensen
Ti mesh anodes prepared by electrochemical deposition for the direct methanol fuel cell2006
Professor Wen-Feng Lin
Fuyun Zhu
Professor Paul Christensen
Tubular cathode prepared by a dip-coating method for low temperature DMFC2006
Emeritus Professor Keith Scott
Professor Paul Christensen
Professor Sudipta Roy
A study of PtRuO2 catalysts thermally formed on titanium mesh for methanol oxidation2005
Dr Hua Cheng
Emeritus Professor Keith Scott
Professor Paul Christensen
Application of a solid polymer electrolyte reactor to remove nitrate ions from wastewater2005
Dr Hua Cheng
Emeritus Professor Keith Scott
Professor Paul Christensen
Paired electrolysis in a solid polymer electrolyte reactor - Simultaneously reduction of nitrate and oxidation of ammonia2005
Dr Terry Egerton
Professor Paul Christensen
Robert Harrison
Jiasong Wang
The effect of UV absorption on the photocatalytic oxidation of 2-nitrophenol and 4-nitrophenol2005
Professor Paul Christensen
Dr Terry Egerton
Samia Kosa
Dr James Tinlin
Emeritus Professor Keith Scott
et al.
The photoelectrocatalytic oxidation of aqueous nitrophenol using a novel reactor2005
Dr Lianxi Yang
Ruth Allen
Emeritus Professor Keith Scott
Professor Paul Christensen
Professor Sudipta Roy
et al.
A comparative study of ptru and ptrusn thermally formed on titanium mesh for methanol electro-oxidation2004
Dr Hua Cheng
Emeritus Professor Keith Scott
Professor Paul Christensen
Design and operation of a solid polymer electrolyte reactor for electrochemical hydrodehalogenation2004
Dr Hua Cheng
Emeritus Professor Keith Scott
Professor Paul Christensen
Electrochemical Hydrodehalogenation of 2,4-Dibromophenolin Paraffin Oil Using a Solid Polymer Electrolyte Reactor2004
Dr Hua Cheng
Emeritus Professor Keith Scott
Professor Paul Christensen
Electrochemical hydrodehalogenation of 2,4-dichlorophenol in paraffin oil and comparison with aqueous systems2004
Dr Hua Cheng
Emeritus Professor Keith Scott
Professor Paul Christensen
Engineering aspects of electrochemical hydrodehalogenation of 2,4-dichlorophenol in a solid polymer electrolyte reactor2004
Dr Hua Cheng
Emeritus Professor Keith Scott
Professor Paul Christensen
Feasibility study of electrochemical hydrodehalogenation of 2,4-dibromophenol in a paraffin oil2004
Dr Raghuram Chetty
Professor Paul Christensen
Professor Bernard Golding
Emeritus Professor Keith Scott
Fundamental and applied studies on the electrochemical hydrodehalogenation of halogenated phenols at a palladised titanium electrode2004
Professor Paul Christensen
Jia Jin
Professor Wen-Feng Lin
Dr Andrew Hamnett
Identification of CO adsorbed at Ru and Pt sites on a polycrystalline Pt/Ru electrode and the observation of their oxidation and free interchange under open circuit conditions2004
Professor Paul Christensen
Jia Jin
Professor Wen-Feng Lin
Dr Andrew Hamnett
Identification of CO Adsorbed at Ru and Pt Sites on a Polycrystalline Pt/Ru Electrode and the Observation of Their Oxidation and Free Interchange under Open Circuit Conditions2004
Jia Jin
Professor Wen-Feng Lin
Professor Paul Christensen
In situ FTIR spectroscopic studies of the oxidation of CO adsorbates on Ru(0 0 0 1) electrodes under open circuit conditions2004
Emeritus Professor Jim White
Dr Terry Egerton
Professor Paul Christensen
Chunyu JIN
Photomechanical oxidation of anisotropic polyethylene2004
Dr Terry Egerton
Professor Paul Christensen
Emeritus Professor Keith Scott
Robert Harrison
Dr James Tinlin
et al.
UV absorption by nitrophenols:Implications for design of photocatalytic and photoelectrocatalytic reactors.2004
Dr Terry Egerton
Professor Paul Christensen
Water treatment by Photoelectrocatalysis2004
Changqing Jin
Professor Paul Christensen
Dr Terry Egerton
Emeritus Professor Jim White
Effect of anisotropy on photo-mechanical oxidation of polyethylene2003
Dr Hua Cheng
Emeritus Professor Keith Scott
Professor Paul Christensen
Electrochemical hydrodehalogenation of chlorinated phenols in aqueous solutions I. Material aspects2003
Dr Hua Cheng
Emeritus Professor Keith Scott
Professor Paul Christensen
Electrochemical hydrodehalogenation of chlorinated phenols in aqueous solutions: II. Effect of operating parameters2003
Dr Hua Cheng
Emeritus Professor Keith Scott
Professor Paul Christensen
Hydrodehalogenation of 2,4-dibromophenol by electrochemical reduction2003
Dr Raghuram Chetty
Professor Paul Christensen
Professor Bernard Golding
In situ FTIR studies on the electrochemical reduction of halogenated phenols2003
Professor Paul Christensen
Infrared Spectroscopy of Electrode Surfaces2003
Professor Paul Christensen
Professor Thomas Curtis
Dr Terry Egerton
Samia Kosa
Dr James Tinlin
et al.
Photoelectrocatalytic and photocatalytic disinfection of E. coli suspensions by titanium dioxide2003
Changqing Jin
Dr Terry Egerton
Professor Paul Christensen
Rapid method to assess effect of pigments on photodegradability of polymers2003
Changqing Jin
Dr Terry Egerton
Professor Paul Christensen
Rapid Method to assess the effect of pigments on photo-degradability of polymers2003
Professor Wen-Feng Lin
Jia Jin
Professor Paul Christensen
Emeritus Professor Keith Scott
Structure and reactivity of the Ru(0 0 0 1) electrode towards fuel cell electrocatalysis2003
Professor Wen-Feng Lin
Jia Jin
Professor Paul Christensen
Effects of thermal activation on the electrocatalysis of the Ru(0001) surface2002
Professor Thomas Curtis
Professor Paul Christensen
Fate of Cryptosporidium oocysts in an immobilised titanium dioxide reactor with electric field enhancement2002
Dr Hua Cheng
Emeritus Professor Keith Scott
Professor Paul Christensen
Hydrodehylogenation of 2, 4-dibromophenol by electrochemical reduction2002
Professor Wen-Feng Lin
Professor Paul Christensen
In situ FTIR studies on the effect of temperature on the electro-oxidation of small organic molecules at the Ru(0001) electrode2002
Professor Paul Christensen
Dr Terry Egerton
John Lawson
Measurements of carbon dioxide evolution from alkyd paint films - Part I - Oxidative scission during film ageing2002
Professor Paul Christensen
Dr Terry Egerton
John Lawson
Measurements of carbon dioxide evolution from alkyd paint films: Part I Oxidative scission during film ageing2002
Professor Paul Christensen
Dr Terry Egerton
John Lawson
Photocatalytic oxidation of alkyd paint films measured by FTIR analysis of UV generated carbon dioxide2002
Professor Paul Christensen
Professor Thomas Curtis
Dr Terry Egerton
John Harper
Samia Kosa
et al.
Photoelectrochemical detoxification and disinfection of water using a novel bubble column reactor2002
Dr Clare Jones
Professor Paul Christensen
Some in situ reflectance Fourier transform infrared studies of electrochemically prepared polybenzo[c]thiophene and poly-5-fluorobenzo[c]thiophene films2002
John Harper
Professor Paul Christensen
Dr Terry Egerton
Professor Thomas Curtis
Effect of catalyst type on the kinetics of the photoelectrochemical disinfection of water inoculated with E. coli2001
Dr Hua Cheng
Emeritus Professor Keith Scott
Professor Paul Christensen
Electrochemical Recycling of Halogenated Phenols2001
Emeritus Professor Keith Scott
Dr Hua Cheng
Professor Paul Christensen
Electrochemical Treatment of Chlorinated Organics2001
John Harper
Professor Paul Christensen
Dr Terry Egerton
Emeritus Professor Keith Scott
Mass transport characterization of a novel gas sparged photoelectrochemical reactor2001
Professor Paul Christensen
Dr Andrew Hamnett
Professor Wen-Feng Lin
Observation of an optical phonon band in situ in TiO2 electrochemistry: A possible indicator of strongly trapped intermediates in the O2 evolution reaction2001
Professor Paul Christensen
Spectroelectrochemical characterisation of poly[Ni(saltMe)]-modified electrodes2001
Professor Paul Christensen
Syntheses and electro(co)polymerization of novel thiophene- and 2,2 ': 5 ',2 ''-terthiophene-functionalized metal-tetraazamacrocycle complexes, and electrochemical and spectroelectrochemical characterization of the resulting polythiophenes2001
Professor Wen-Feng Lin
Professor Paul Christensen
Dr Andrew Hamnett
The electro-oxidations of methanol and formic acid at the Ru(0001) electrode as a function of temperature: In-situ FTIR studies2001
Professor Wen-Feng Lin
Professor Paul Christensen
Professor Andrew Hamnett
Electro-oxidation of CO at the Ru(0001) single-crystal electrode surface2000
Professor Wen-Feng Lin
Professor Paul Christensen
Professor Andrew Hamnett
In situ FTIR studies of the effect of temperature on the adsorption and electrooxidation of CO at the Ru(0001) electrode surface2000
Professor Paul Christensen
Dr Terry Egerton
Infrared spectroscopic evaluation of the photodegradation of paint Part II: The effect of UV intensity and wavelength on the degradation of acrylic films pigmented with titanium dioxide2000
Professor Paul Christensen
Dr Terry Egerton
Infrared spectroscopic evaluation of the photodegradation of paint: Part II: The effect of UV intensity & wavelength on the degradation of acrylic films pigmented with titanium dioxide2000
Professor Paul Christensen
Professor Andrew Hamnett
In-situ techniques in electrochemistry - Ellipsometry and FTIR2000
Dr Robert Reeve
Professor Paul Christensen
Professor Andrew Hamnett
Emeritus Professor Keith Scott
Methanol-tolerant oxygen reduction catalysts based on transition metal sulfides and their application to the study of methanol permeation2000
Professor Andrew Hamnett
Professor Paul Christensen
A study of the polymerisation and electrochemical cycling of Pd methoxy- Salen derivatives using fast ellipsometry and FT-infrared spectroscopy1999
Professor Paul Christensen
Professor Ronald Armstrong
Electrochemical oxidation of a carbon black loaded polymer electrode in aqueous electrolytes1999
Professor Andrew Hamnett
Professor Paul Christensen
Fast ellipsometric studies of surface processes1999
Professor Paul Christensen
Dr Andrew Hamnett
In situ FTIR studies of the photo-electrochemical behaviour of thermal TiO2 films as a function of temperature1999
Dr Terry Egerton
Professor Paul Christensen
Infrared Spectroscopic Evaluation of Photodegradation of Paint’ Part 11999
Professor Paul Christensen
Dr Terry Egerton
Infrared spectroscopic evaluation of the photodegradation of paint - Part I - The UV degradation of acrylic films pigmented with titanium dioxide1999
Professor Paul Christensen
Dr Terry Egerton
John Harper
Dr James Tinlin
Photoelectrochemical oxidation of organics on thermal film TiO2,Topical Issues in Glasses ‘ Photons Glasses and Coatings1999
Professor Paul Christensen
Professor Thomas Curtis
Water disinfection using an immobilised titanium dioxide film in a photochemical reactor with electric field enhancement1997
Professor Paul Christensen
Dr Andrew Hamnett
Emeritus Professor Mark Thomas
Direct methanol fuel cell cathodes with sulfur and nitrogen-based carbon functionality1996