The purpose of this work was to synthetize TiO2 photoanodes through potentiostatic plasma electrolytic oxidation (PEO) of titanium in direct and pulsed unipolar regime. The effect of the operation parameters (i.e. pulse frequency, pulse on-time and potential ramp slope) on the photoactivity on the obtained TiO2 photoanode was investigated. Linear Scan Voltammetry measurements in dark and under VIS and UV-C were carried out to assess photoelectrochemical response, Scanning Electron Microscopy and X-ray Diffraction were used to characterize surface morphology and microstructure, Glow-Discharge Optical Emission Spectroscopy was exploited to determine the thickness of the TiO2 coating, flat band potential values was evaluated by means of the photocurrent onset method, the photoelectrocatalytic activity of the coating was assessed by decolorization tests of 5 M Methylene Blue (MB) aqueous solutions and Langmuir-Hinshelwood fitting. The synthesis conditions corresponding to the best photoelectrochemical and photoelectrocatalytic activities were identified.
Lo scopo di questo lavoro è stato sintetizzare fotoanodi di TiO2 mediante l’ossidazione elettrolitica al plasma (PEO) del titanio in regime continuo e pulsato unipolare. In particolare, è stato studiato l’effetto dei parametri operativi (frequenza dell’impulso, tempo di on dell’impulso e pendenza della rampa di potenziale) sulla fotoattività dei fotoanodi di TiO2 ottenuti. La risposta fotoelettrochimica è stata valutata mediante misure di voltammetria a scansione lineare in assenza di illuminazione e sotto illuminazione VIS e UV-C, morfologia di superficie e microstruttura sono state studiate mediante Microscopia Elettronica a Scansione e Diffrazione a Raggi X, lo spessore dei rivestimenti di TiO2 è stato determinato mediante Spettroscopia Ottica a Scarica a Bagliore, i valori di potenziale di banda piatta sono stati valutati mediante il metodo di inizio di fotocorrente, l’attività fotoelettrocatalitica dei rivestimenti è stata analizzata tramite prove di decolorazione di soluzioni acquose contenenti 5 M di Blu di Metilene (MB) ed interpolazione della curva di decolorazione utilizzando il modello Langmuir-Hinshelwood. Lo studio ha permesso di identificate le condizioni di sintesi atte ad ottimizzare l'attività fotoelettrochimica e fotoelettrocatalitica dei fotoanodi.
TiO2 photoelectrodes by pulsed unipolar plasma electrolytic oxidation of titanium
Liviero, Giordano
2021/2022
Abstract
The purpose of this work was to synthetize TiO2 photoanodes through potentiostatic plasma electrolytic oxidation (PEO) of titanium in direct and pulsed unipolar regime. The effect of the operation parameters (i.e. pulse frequency, pulse on-time and potential ramp slope) on the photoactivity on the obtained TiO2 photoanode was investigated. Linear Scan Voltammetry measurements in dark and under VIS and UV-C were carried out to assess photoelectrochemical response, Scanning Electron Microscopy and X-ray Diffraction were used to characterize surface morphology and microstructure, Glow-Discharge Optical Emission Spectroscopy was exploited to determine the thickness of the TiO2 coating, flat band potential values was evaluated by means of the photocurrent onset method, the photoelectrocatalytic activity of the coating was assessed by decolorization tests of 5 M Methylene Blue (MB) aqueous solutions and Langmuir-Hinshelwood fitting. The synthesis conditions corresponding to the best photoelectrochemical and photoelectrocatalytic activities were identified.File | Dimensione | Formato | |
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TiO2 photoelectrodes by pulsed unipolar plasma electrolytic oxidation of titanium.pdf
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Executive_Summary_TiO2 photoelectrodes by pulsed unipolar plasma electrolytic oxidation of titanium.pdf
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https://hdl.handle.net/10589/211944