“Catalysts for Alcohol-Fuelled Direct Oxidation FuelCells” is aimed at a general audience with an interestin low power fuel cells, as well as experts in the area.The book is edited by Zhen-Xing Liang, Lecturer atthe South China University of Technology, and TimS. Zhao, Professor of Mechanical Engineering at theHong Kong University of Science and Technology(HKUST) and director of the HKUST Energy Institute.The book contains seven chapters in 264 pages andreviews the catalysis of alcohol electrooxidationin low-temperature fuel cells. The reader will fi nda general overview of the catalysis involved in theoxidation of alcohols such as methanol and ethanol.More unusually the oxidation of ethylene glycol andglycerol are also described in detail. Although thetitle for this book is specifi c to alcohol fuel cells italso contains individual chapters describing theoxidation of other fuels of interest such as formic acid,borohydride and sugars. The book concludes with achapter on the challenges that alcohol fuel cells needto overcome.Role of the Platinum Group MetalsMany of the book’s chapters are easy to read even forpeople with little experience in the area. Chapter 1,‘Electrocatalysis of Alcohol Oxidation Reactions atPlatinum Group Metals’, by Claude Lamy (Universityof Montpellier, France) and Christophe Coutanceau(Université de Poitiers, France), starts with a good ifsimplistic overview about what constitutes fuel celleffi ciency. This is an important subject and the authors’general description can easily be followed by studentsin chemistry or related subjects. The authors highlightthat the theoretical effi ciencies for methanol/airand ethanol/air fuel cells are actually higher thanhydrogen/oxygen fuel cells. This is a great foundationfor the book because it really justifi es the need forresearch in this area. The chapter continues with avery simplistic description of the methods used forthe synthesis and characterisation of fuel cell catalysts,from well-known chemical and electrochemicalapproaches to more exotic methods such as plasmaenhancedtechniques. The content fl ows in a logicalorder with this introduction followed by dedicatedsections describing in detail the oxidation of differentfuels. The oxidation of methanol or ethanol isdescribed in acidic environments, mainly for the wellknownplatinum-based binary catalysts PtM/C (M =ruthenium or tin), at different atomic ratios.The authors describe the differences in reactivitywhen using different atomic ratios such as Pt0.5Ru0.5,Pt0.8Ru0.2, Pt3Sn and Pt9Sn. These binaries are knownto be active because of the effi cient removal ofadsorbed carbon monoxide (via the bifunctionalmechanism), a common intermediate in the oxidationof primary alcohols. In contrast, the oxidation ofethylene glycol and glycerol is described mainly inalkaline media with the authors focusing on the useof carbon supported platinum, platinum-palladiumand platinum-palladium-bismuth for the oxidationof ethylene glycol and platinum, palladium and goldcatalysts and their binaries and ternaries such asPtPd, PtBi, PdBi and PtPdBi for the oxidation of glycerol.The chapter offers a good introduction, although itlacks references to the use of commercial catalysts formethanol oxidation (1, 2).Catalyst PreparationChapter 2, ‘Nanoalloy Electrocatalysts for AlcoholOxidation Reactions’, by Jun Yin (Cornell University,New York, USA) et al. describes the use of PtAucatalysts for alcohol oxidation. The synthesis of PtAucatalysts is a very interesting topic with challengingnanoscale catalyst preparation. Nanoscale gold hasbeen shown to produce surface oxygenated speciessuch as gold(III) oxide, adsorbed gold hydroxide orgold(III) hydroxide which are highly active for theM1M2PrecursorsCappingagentReduction ordecompositionWet chemicalsynthesisAssemblyon supportThermaltreatmentSupportedcatalystAssemblyActivation(a)(b)30 nm(c)30 nmM1mM2100–m+Fig. 1. (a) A general scheme showing the molecularly engineered synthesis of bimetallic nanoparticles cappedwith a monolayer shell of oleic acid/oleylamine and the preparation of bimetallic nanoparticles supported oncarbon powders or carbon nanotubes by assembly and activation. Transmission electron microscopy imagesshowing: (b) Au22Pt78 nanoparticles supported on carbon black; and (c) Au nanoparticles supported on carbonnanotubes (Reproduced by permission of The Royal Society of Chemistry)removal of adsorbed CO, especially in alkaline media.Traditional methods for PtAu catalyst preparation arementioned such as co-precipitation, impregnationwith subsequent reduction, and calcination. Moreinterestingly, the synthesis of Au and PtAu supportednanoparticles via the molecular encapsulationsynthesis is described (Figure 1). This approachinvolves three steps: (a) chemical synthesis of metalnanocrystal cores with molecular encapsulation;(b) assembly of the encapsulated nanoparticleson support materials; and (c) thermal treatmentof the supported nanoparticles. A brief mention ofcore–shell type PtAu nanoparticles is also includedalthough no characterisation data is shown. PtAunanoparticles with different atomic compositions arepresented for the oxidation of methanol in alkalineand acidic media. An iron(II,III) oxide Fe3O4@Au@Ptternary is presented as a more active catalyst than Ptin acidic media. The chapter fi nishes with a sectiondedicated to the characterisation of PtAu particles andincludes experimental data from different techniquessuch as X-ray diffraction (XRD), Fourier transforminfrared (FTIR) spectroscopy and X-ray photoelectronspectroscopy (XPS) which adds detailed informationto help understand the catalysis.Quantum Mechanical ModellingChapter 3, ‘Theoretical Studies of Formic AcidOxidation’, by Wang Gao and Timo Jacob (UniversitätUlm, Germany), is the only chapter dedicated tothe use of quantum mechanical modelling for theunderstanding of chemical reactions at the molecularlevel. Although formic acid is not an alcohol, it is ofinterest in terms of fuel cell effi ciency for low powerelectronics. The authors cover the oxidation of formicacid in ultra-high vacuum conditions and also withincreasing water coverage. Importantly, they payattention to the effect of the electrochemical potentialon the formic acid dehydrogenation and include adetailed discussion of the adsorbed products thatare formed. A detailed and informative discussion ofthe different reaction pathways, direct and indirect, ispresented. Readers with some experience in the fi eldwill fi nd the content extremely interesting. It is slightlydisappointing that the editors did not include morecontent towards the use of theoretical modelling forthe oxidation of alcohols.Catalysis by GoldChapter 4, ‘Gold Leaf Based Electrocatalysts’, byRongyue Wang and Yi Ding (Shandong University,China) is dedicated to the use of nanoporous gold leaf(NPG-leaf) as an alternative catalyst for the oxidationof formic acid and alcohols in alkaline media. Thechapter describes the formation of NPG by chemicaldissolution also known as dealloying. This is a wellknownprocess and has been applied for many yearsin the manufacturing of high surface area catalysts.The authors present as an example the formation ofNPG from a gold-silver alloy. Selective dissolution of Agleads to the formation of a porous structure (Figure 2)(3). The authors describe the excellent research doneby John Newman (University of California, Berkeley,USA) et al. (4) and Jonah Erlebacher (Johns HopkinsUniversity, USA) et al. (5) and the reader is advisedto follow up these references for further, detailedinformation. Overall NPG-Pt catalysts give very lowbenefi t compared to Pt/C.In fact, the area of dealloying is currently an ongoingresearch topic aimed at the design of highlyactive catalysts for the oxygen reduction reaction inH2/O2 fuel cells. Experts in the area such as ProfessorDoctor Peter Strasser, now at Technische UniversitätBerlin, Germany, have documented very interestingresults with the study of dealloyed particles and theiruse as catalysts for the oxygen reduction reaction(6, 7). However, the use of dealloyed catalysts has notbeen well documented for alcohol oxidation.(a)120 nm(b)500 nmFig. 2. Scanningelectron microscopyimages of ananoporous goldleaf (Reproduced bypermission of The RoyalSociety of Chemistryand Alkali Metal BorohydridesChapter 5, ‘Nanocatalysts for Direct BorohydrideOxidation in Alkaline Media’ by ChristopheCoutanceau et al. considers the use of alkali metalborohydrides as fuels. Sodium borohydride ispreferred because it offers a compromise betweenspecifi c energy density and relative abundance. Theauthors clearly explain the anodic and cathodicreactions that occur in a direct borohydride fuelcell (DBFC) and the theoretical effi ciency of asystem capable of achieving the 8 electron reaction.Due to the alkaline environment used the catalystsconsidered are the usual binaries and ternaries,such as PdAu, PdNi and PdPtBi. The authorsdescribe a very interesting study of the kineticsof the electrode reaction but most importantlythey present a discussion of what makes a catalystselective towards complete oxidation and also tothe inhibition of hydrogen oxidation. The use ofPt0.9Bi0.1/C is presented as the most selective catalystthat leads to the 8e-- pathway without signifi canthydrogen evolution. Although this anode catalyst ledto lower performance compared to Pt/C, in terms ofcurrent density, it is of interest for a DBFC becauseof increased fuel effi ciency, a prime parameter forthe use of the fuel. It is important to highlight that asystem with high cell effi ciency is more attractive formany practical applications than a system with loweffi ciency and high current density. The authors havewritten a very interesting chapter and this readergained useful knowledge about the technology.The Use of EnzymesChapter 6, ‘Bioelectrocatalysis in Direct Alcohol FuelCells’, by Holly Reeve and Kylie Vincent (Universityof Oxford, UK), is dedicated to the use of enzymesfor the oxidation of sugars such as fructose, lactoseand glucose. The use of sugars for fuel cells is avery interesting area for research since it is basedon the generation of electricity by the oxidation ofnatural products. Actually, the full oxidation of aprimary alcohol to carbon dioxide is also possiblewhen using a chain of enzymes via a sequence ofchemical reactions. This is a key characteristic thatdifferentiates enzymes from metal nanoparticles.For instance, there are very few metal catalystscapable of achieving the full oxidation of diluteethanol to CO2 without the formation of incompleteproducts such as acetaldehyde and acetic acid(8). The authors give a fair and realistic view ofthe practical problems of enzymes as catalystsdue to their relatively large size, which leads tolow volumetric density and their limited stabilitywhen varying conditions such as pH, temperature,pressure and solvent type. The authors highlightthat biofuel cells could have their main applicationas bioimplantable fuel cells for pacemakers and forthe purifi cation of waste water. Although researchin this area is in its infancy, the authors give anexcellent overview of the use of biofuel cells and thereader with an interest in biocatalysis will fi nd thischapter extremely interesting.Problems in Alcohol OxidationThe book closes with Chapter 7, ‘Challenges andPerspectives of Nanocatalysts in Alcohol-FuelledDirect Oxidation Fuel Cells’, by Eileen Hao Yu(Newcastle University, UK) et al. This chapter coverssome of the main problems in alcohol oxidationfocusing on the factors affecting activity and stability,including the need for more active catalysts capable ofoxidising adsorbed CO. The authors report on the useof binary and ternary catalysts in alkaline and acidmedia, such as PtRu, PtSn and PtRuM (M = tungsten,molybdenum, nickel) and PtSnM (M = Ni or Ru), PtAu,PdNi and PdIrNi. The use of metal oxides such ascerium(IV) oxide, nickel(II) oxide, cobalt(II,III) oxideand manganese(II,III) oxide as promoters capable ofintroducing oxygenated species to remove adsorbedCO is also described. A brief mention of the benefi tsand disadvantages of the use of core–shell catalystsis presented with a special emphasis on PtAu core–shell catalysts. In terms of stability, some interestingapproaches are mentioned such as the use ofalternative carbon supports (graphene and N-dopedcarbon nanotubes) and supports such as titaniumdioxide and tungsten carbide. The authors, however, donot mention the main problems of anode stability, suchas base metal dissolution, membrane contaminationand the impact on cathode performance or relatethese issues to real fuel cell data.ConclusionThe authors describe in a detailed manner theelectrocatalytic oxidation of primary alcohols andother relevant fuels of interest for low power fuelcells in both acid and alkaline media. The readergains a useful introduction to the catalysis involvedin the oxidation of different fuels, such as methanol,ethanol, ethylene glycol, glycerol, borohydride andsugars. While enzymes and gold catalysts have beenintroduced, platinum group metal catalysts, especiallythose based on Pt and Pd, are the state of the art forthese technologies. The book only disappoints insome areas such as the lack of real fuel cell data and,for this reviewer’s taste, an overemphasis on alcoholoxidation in alkaline media. Overall, this book canbe a good starting point for students and researcherswith an interest in low power fuel cells.References1 N. Cabello-Moreno, E. Crabb, J. Fisher, A. E. Russell andD. Thompsett, ECS Trans., 2008, 16, (2), 4832 J. M. Fisher, N. Cabello-Moreno, E. Christian and D.Thompsett, Electrochem. Solid-State Lett., 2009, 12, (5),B773 J. Erlebacher, M. J. Aziz, A. Karma, N. Dimitrov and K.Sieradzki, Nature, 2001, 410, (6827), 4504 R. C. Newman and K. Sieradzki, Science, 1994, 263,(5 154), 17085 R. Zeis, A. Mathur, G. Fritz, J. Lee and J. Erlebacher, J.Power Sources, 2007, 165, (1), 656 P. Mani, R. Srivastava and P. Strasser, J. Phys. Chem. C,2008, 112, (7), 27707 L. Gan, M. Heggen, R. O’Malley, B. Theobald and P.Strasser, Nano Lett., 2013, 13, (3), 11318 A. Kowal, M. Li, M. Shao, K. Sasaki, M. B. Vukmirovic,J. Zhang, N. S. Marinkovic, P. Lui, A. I. Fre
