Photoelectrochemical water treatment using solar cells and Earth abundant materials PDF
Preview Photoelectrochemical water treatment using solar cells and Earth abundant materials
Photoelectrochemical water treatment using solar cells and Earth abundant materials Carlos Maquieira González t f el D t ei t si r e v ni U e h c s ni h c e T 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 iii “Welookattheworldonce,inchildhood. Therestismemory.” LouiseGlück v 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. vii 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
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