Photoelectrochemical water treatment using solar cells and Earth abundant materials

92 Pages·2017·8.7 MB·English

Photoelectrochemical
water treatment using
solar cells and Earth
abundant materials
Carlos Maquieira González
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TECHNISCHE UNIVERSITEIT DELFT
MASTER THESIS
Photoelectrochemical water treatment using
solar cells and Earth-abundant materials
Supervisors:
Author:
ir. PaulaPérezRodriguez
CarlosMaquieiraGonzález
Prof. Dr. ir. A.H.M.Smets
Athesissubmittedinfulfillmentoftherequirements
forthedegreeofMScSustainableEnergyTechnology
inthe
PhotovoltaicMaterialandDevicesGroup
TUDelft
ThesisCommittee:
Prof. Dr. ir. A.H.M.Smets
Prof. Dr. ir. LuukRietveld
Dr. ir. OlindoIsabella
ir. PaulaPérezRodríguez
September7,2017

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“Welookattheworldonce,inchildhood. Therestismemory.”
LouiseGlück

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TECHNISCHEUNIVERSITEITDELFT
Abstract
PhotoelectrochemicalwatertreatmentusingsolarcellsandEarth-abundant
materials
byCarlosMaquieiraGonzález
Theworldwideavailabilityofsafeandcleandrinkingwaterconstitutesoneofthemain
challenges of our era. Unfortunately, due to progress-related issues such as global
warming, population growth and industrial development, the availability and qual-
ityofdrinkingwaterisexpectedtodeteriorateinthecomingyears,posingnewthreats
forhumansandtheenvironment. Inviewofthesepredictions,itbecomesincreasingly
necessary to develop novel, economical and easily scalable methods for water treat-
ment.
Within the context of this thesis, two novel devices for water treatment based on solar
energyandEarth-abundantmaterialsareproposed: aphotoelectrochemical(PEC)cell
using amorphous silicon carbide (a-SiC:H) photoelectrodes and a PV/electrochemical
systembasedongraphiteelectrodes. Inordertoevaluatetheirperformance,bothsys-
temsaretestedinthedegradationofrecalcitrantorganicpollutants.
In the photoelectrochemical cell, a-SiC:H was used first as a photoanode (n-i-p struc-
ture), and afterwards as a photocathode material (p-i and p-i-n structures). In both
photoelectrodeconfigurations,thedegradationofphenolwasmonitoredunderdiffer-
entappliedbiasvoltages. Additionally,photoresponsemeasurementswererecordedin
ordertodeterminethebehaviourofthephotoelectrodesinthesolution. Unfortunately,
none of the photoelectrode configurations were able to develop noticeable photocur-
rents,resultinginapoorwatertreatmentperformance.
WithregardtothePV/electrochemicalsystem,thegraphiteelectrodeswerefirsttested
under an external power supply. Here, the electrochemical oxidation of phenol was
studied in detail under different applied voltages. Additionally, the chemical oxygen
demand (COD) was measured in order to identify intermediate compounds in the re-
action. Overall, it was found that the optimum voltage for the degradation reaction
was 1.6 V (80% phenol removal, 59% COD reduction). In addition to this study, the
effectofanalternativecoppercounter-electrodewasinvestigated,andthedegradation
of an organic dye (methylene blue) was examined. Finally, several PV structures were
proposedfortheintegrationwiththegraphiteelectrodes. Thebestoverallperformance
wasachievedbytwomicromorphsolarcellsconnectedinseries. However,intermsof
utilizedarea,anindividuala-Si:H/a-Si:Htandemcellwasthemostappropriatechoice.

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Acknowledgements
WhenIfirstcametoDelfttwoyearsago,Iwasfilledwithinsecuritiesaboutthefuture.
Now that this adventure comes to an end, I find myself in pretty much the same posi-
tion, but with a lot less hours of sleep. Still, this has been an amazing experience, and
IwouldnotbeabletomakeitwithoutthehelpofallthepeopleI’vemetinthislovely,
rainycountry.
First, I would like to thank my daily supervisor, Paula Pérez, for her endless patience
and support throughout the year. I know I have been a mess sometimes, especially in
theselastweeksofthethesis,butyouhadthepatiencetocalmmedownandmakeme
seethingsinperspective. ThanksalsotoArnoSmetsandLuukRietveld,forgivingme
thechancetoworkinaprojectbetweentwogreatresearchdepartments.
Special thanks to Leonie Boortman and Olindo Isabella, for helping Patri & I get back
intotheSETprogramafterallwe’vebeenthroughlastyear.
Onamorepersonallevel,IwouldliketothankallthefriendsIhavemethereinDelft.
I don’t think I would be able to make it through this year without our 2-hour coffee
breaks,thebarbecuesinthelake,thememes,thesillyyoutubevideosorthejokesabout
NicolasCage.
Iwouldalsoliketothankmyall-timefriendsfromNoia,fornotmakingmefeelguilty
atallforspendingthesummerintheNetherlandstryingtofinishmythesis.
Thanks to my parents and my dear sister Laura, for cheering me up whenever I felt
down, for making me feel a little bit better about myself, and for always checking up
onmetomakesurethatIamhappy. SometimesIwouldliketosinkthroughtheSkype
screenandbetherewithyou, evenif itisjusttolaythereonthe couch, havingdinner
whilewewatchTV.Nonsabedescantovosbotodemenos.
ThankstoPatri’sfamily,forraisingthemostcaringpersonintheworld.
And, above all, thanks Patri, for standing by my side after all these years. I know I
tendtobecomethedarkcenteroftheuniverse,butyoualwaysfindawaytomakeme
happy. ThankyoufortakingmetoKrakow,forlisteningtoTownesVanZandtat3AM
andforalltheautumnsweaters. Icherisheverysinglemomentthatwespenttogether,
andIamsureabrightfutureawaitsus. Todovaiirben,ruliña.
CarlosMaquieira
Delft,September2017