Banca de QUALIFICAÇÃO: ARTHUR ANSELMO PEREIRA
Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.STUDENT : ARTHUR ANSELMO PEREIRA
DATE: 20/12/2023
TIME: 10:00
LOCAL: https://meet.google.com/cme-muxv-vmd
TITLE:
PAGES: 26
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Físico-Química
SPECIALTY: Eletroquímica
SUMMARY:
Urea is a promising source of energy generation, since this compound is non-toxic, has a high energy density (16.9 MJ L-1), and is considered an excellent hydrogen carrier. Several researches have suggested the development of alkaline fuel cells fed with urea to generate electricity, through the oxidation of this compound. In this line this work aims to synthesize, characterize and evaluate electrocatalysts consisting of Ni, Co and Ce, supported in carbon, for urea oxidation reactions (ROU), which are later applied in fuel cells. The materials were synthesized by the chemical reduction method with NaBH4, using different mass ratios: Ni; NiCe (1:1 and 3:1); NiCo (1:1); NiCoCe (1:1:1) and CoCe (1:1) (20% by mass) and were supported on Vulcan XC-72 carbon (80% by mass). The electrocatalysts were characterized by X-ray diffraction, Raman spectroscopy, contact angle and X-ray photoelectron spectroscopy. The electrocatalytic activity of the materials for ROU was evaluated by cyclic voltammetry (CV) and chronoamperometry (CA). Efficiency as fuel cell anodes has been tested. The Ni50Ce50/C electrocatalyst showed higher peak current for ROU (4.7 mA) and less positive oxidation initiation potential values (0.325 V) in CV than Ni/C (4.2 mA and 0.335V) for the same process. In CA experiments, Ni50Ce50/C showed higher current for ROU than Ni/C, respectively 1.5 and 1.2 mA, and in cell it presented a higher power density than Ni/C, being 0.22 and 0.14 mW cm-2, respectively. The results suggest that Ce decreased CO poisoning at the Ni surface due to the bifunctional mechanism in which Ce provides oxygenated species for CO oxidation at the Ni poisoned active sites. It is noteworthy that the incorporation of cerium in the process promotes a significant change in the mechanism, clearly distinguishing itself from the approach that employs only nickel. This result represents an innovative contribution to the literature in the context of the fuel cell investigated.
COMMITTEE MEMBERS:
Presidente - Interno ao Programa - 1544381 - MAURO COELHO DOS SANTOS
Membro Titular - Examinador(a) Interno ao Programa - 1864481 - HUEDER PAULO MOISES DE OLIVEIRA
Membro Titular - Examinador(a) Externo à Instituição - ALMIR OLIVEIRA NETO - IPEN
Membro Suplente - Examinador(a) Interno ao Programa - 1933328 - HELOISA FRANCA MALTEZ
Membro Suplente - Examinador(a) Interno ao Programa - 233.691.308-90 - YVAN JESUS OLORTIGA ASENCIOS - UNIFESP
Membro Suplente - Examinador(a) Externo à Instituição - RAFAEL DE QUEIROZ FERREIRA - UFES