Banca de QUALIFICAÇÃO: JAILSON DA SILVA LUIS

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
DISCENTE: JAILSON DA SILVA LUIS
DATA: 25/11/2022
HORA: 14:00
LOCAL: Sala virtual - Google Meet
TÍTULO: S doped ZnO photoelectrode modified with Ag0 and Pt0 nanoparticles and their photocatalytic activity for progesterone degradation
PALAVRAS-CHAVES: S doping ZnO, Visible light irradiation, Metallic Nanoparticles, Photoelectrochemistry, Progesterone degradation
PÁGINAS: 22
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Química
SUBÁREA: Físico-Química
ESPECIALIDADE: Eletroquímica
RESUMO:

Zinc oxide doped with sulfur (ZnO-S) can display enhanced photocatalytic activity under visible irradiation. In this research ZnO-S was efficiently prepared by thermal decomposition of zinc sulfide (ZnS) in oxidizing atmosphere. X-ray diffraction analysis showed occurred a phase transformation from cubic sphalerite for ZnS (ICSD No. 110) to hexagonal wurtzite of ZnO (ICSD No. 65119) at temperature between 500° and 600 °C. Thus, ZnO-S electrodes were prepared onto transparent conductive substrate and modified by silver (Ag⁰) and platinum (Pt⁰) nanoparticles (NPs). Optical studies show that sulfur acts as doping for ZnO and changed its UV-Vis absorption spectrum from ultraviolet region toward visible region. X-ray photoelectron spectroscopy (XPS) confirms that sulfur was incorporated in ZnO structure. Field Emission Gun – Scanning Electron Microscope (FEG-SEM) images revealed that there is a drastic change in the particles morphology of the films treated at different temperatures. Sample treated at 600 ºC displayed morphology like nanoplates clustered into larger structures, with size ranging from 1,0 to 5,0 µm. Photoelectrochemical characterizations revealed a negative photopotential (ΔE<0) confirming the n-type behavior for all photoelectrode. Superior photocurrents were registered for samples modified with metallic Agº and Ptº NPs, probably due to surface plasmonic resonance and entrapment state in semiconductors surface. This superior photoresponse can increases its efficiency, avoiding the recombination of the electron-hole pair and photoelectrochemical limitations of the semiconductor ZnO. To investigate the photoelectroactivity, electrodes of ZnO-S, Agº/ZnO-S, Ptº/ZnO-S and commercial ZnO were used to degrade 1.57 mg L⁻¹ of aqueous solution of the hormone progesterone under polychromatic irradiation for 3 h. The degradation studies were investigated under electrochemically assisted heterogeneous photocatalysis (EHP) conditions, with higher performance when ZnO-S was functionalized with Ag⁰ and Pt⁰ nanoparticles and adopted the EHP configuration at +0.7 V vs Ag/AgCl potential. Therefore, the results showed advances in the degradation of organic contaminants in the water treatment process and possible contributions to a better use of solar radiation.

MEMBROS DA BANCA:
Interno - 1553988 - EDSON CAVALCANTI DA SILVA FILHO
Interno - 1998602 - EVERSON THIAGO SANTOS GERONCIO DA SILVA
Interno - 1714193 - JOSE MILTON ELIAS DE MATOS
Interno - 1722880 - JOSY ANTEVELI OSAJIMA FURTINI
Interno - 794.918.553-87 - REGINALDO DA SILVA SANTOS - UESPI