Utjecaj žrtvujućeg agensa na stabilnost SnS2 fotoanode

undergraduate thesis

• Title (english): Influence of sacrificial agent on stability of SnS2 photoanode
• Author: Mihaela Ćorić
• Mentor: Marijana Kraljić Roković (mentor)
• Mentor: Dijana Jadreško (komentor)
• Committee member: Marijana Kraljić Roković (predsjednik povjerenstva)
• Committee member: Marin Kovačić (član povjerenstva)
• Committee member: Dijana Jadreško (član povjerenstva)
• Granter: University of Zagreb; Faculty of Chemical Engineering and Technology; Zagreb
• Defense date and country: 2023-09-21, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Chemical Engineering

Abstract

Cilj ovog rada bio je provesti fotoelektrokemijski proces dobivanja vodika te ispitati ponašanje SnS2 elektrode u vodenoj otopini 0.1 mol/dm3 NaCl uz dodatak čiste 1 i
3 mmol/dm^3 kofeinske kiseline (CA) ili kofeinske kiseline u kombinaciji s 1 mmol/dm^3 askorbinskom kiselinom (AA). Mjerenja su provedena za osvijetljene i neosvijetljene elektrode, a izvor svjetla bila je LED lampa. Provedena su i elektrokemijska ispitivanja na elektrodi od staklastog ugljika (GC elektroda) kako bi se utvrdila stabilnost CA i AA tijekom osvjetljenja te kako bi se ispitala njihova antioksidativna svojstva prema O2.- radikalu. Metode korištene u ovom radu za ispitivanje elektroda su ciklička voltametrija, linearna polarizacija, elektrokemijska impedancijska spektroskopija i kronoamperometrija. Rezultati dobiveni metodom linearne polarizacije i kronoamperometrije ukazuju da su struje za SnS2 elektrodu uz dodatak žrtvujućeg sredstva puno veće nego bez prisustva žrtvujućeg sredstva što potvrđuje dobru aktivnost CA i AA. Također, uz dodatak žrtvujućeg sredstva uočava se i porast stabilnosti elektrode. Ispitivanja provedena na GC elektrodi ukazuju da nije došlo do fotolize CA i AA prilikom izlaganja elektrode svjetlu te da AA ima veću djelotvornost kao žrtvujuće sredstvo, zbog niže vrijednosti potencijala strujnog vrha. Porastom koncentracije CA i dodatkom AA antioksidativna aktivnost prema O2.- radikalu raste. Impedancijska mjerenja pokazuju da su za osvijetljenu SnS2 elektrodu dobiveni puno manji otpori prijelazu naboja nego za neosvijetljenu što također potvrđuje dobru fotoaktivnost ove elektrode. Najveća stabilnost elektrode kao i najbolja fotoaktivnost dobivena je u otopini 1 mM CA i
1 mM AA što je potvrđeno metodom linearne polarizacije i elektrokemijske impedancijske spektroskopije.

Abstract (english)

The aim of this work was to carry out a photoelectrochemical process of hydrogen production and to examine the behavior of the SnS2 electrode in an aqueous solution of 1 and
3 mmol/dm^3 caffeic acid (CA) in 0.1 mol/dm3 NaCl in the presence or absence of
1 mmol/dm^3 ascorbic acid (AA). Measurements were performed for illuminated and
non-illuminated electrodes, and the light source was an LED lamp. Electrochemical experiments were also carried out on a glassy carbon electrode (GC electrode) in order to determine the stability of CA and AA during illumination and to test the antioxidant properties of CA and AA against the O2.- radical. The methods used in this work for testing electrodes are cyclic voltammetry, linear polarization, electrochemical impedance spectroscopy and chronoamperometry. The results obtained using linear polarization and chronoamperometry methods indicate that the currents for the SnS2 electrode with the addition of sacrificial agent are much higher than without the presence of sacrificial agent, confirming the good activity of CA and AA. Also, the addition of sacrificial agents results in an increase in electrode stability. Investigations conducted on the GC electrode suggest that there was no photolysis of CA and AA when exposed to light, and AA is more effective as a sacrificial agent due to its lower potential value of the current peak. The increase in CA concentration and the addition of AA lead to an increase in antioxidant activity towards O2.- radicals. Impedance measurements show that illuminated SnS2 electrodes have much lower charge transfer resistances than non-illuminated ones, further confirming the good photoactivity of this electrode. The highest electrode stability and best photoactivity were achieved in a solution containing 1 mM CA and 1 mM AA, as confirmed by linear polarization and electrochemical impedance spectroscopy.

• Keywords: antioksidativna aktivnost; askorbinska kiselina; elektrokemijske metode; fotoelektrokemijski proces; fotokorozija; kofeinska kiselina
• Keywords (english): antioxidant activity; ascorbic acid; electrochemical methods; photoelectrochemical process; photocorrosion; caffeic acid
• Language: croatian
• URN:NBN: urn:nbn:hr:149:846291
• Project: Number: IP-2018-01-1982; Title: Nano-katalizatori aktivirani Sunčevim zračenjem u tehnologijama zaštite okoliša; Title: Nano-sized solar-active catalysts for environmental technologies; Acronym: NaSCEnT; Leader: Hrvoje Kušić; Jurisdiction: Croatia; Funder: HRZZ; Funding stream: IP
• Project: Number: KK.01.1.1.04.0001; Title: Pročišćavanje vode i dobivanje energije korištenjem novih kompozitnih materijala uz Sunčevo zračenje; Leader: Hrvoje Kušić; Jurisdiction: eu; Funder: EC; Funding stream: KF
• Study programme: Title: Materials Science and Engineering - Undergraduate study; Study programme type: university; Study level: undergraduate; Academic / professional title: sveučilišni/a prvostupnik/prvostupnica (baccalaureus/baccalaurea) inženjer/inženjerka kemijskog inženjerstva (sveučilišni/a prvostupnik/prvostupnica (baccalaureus/baccalaurea) inženjer/inženjerka kemijskog inženjerstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Embargoed access; Embargo expiration date: 2024-09-01
• Created on: 2023-11-29 13:22:27