VICTORIA AMATHEUS MAIA

VICTORIA AMATHEUS MAIA

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Synthesis and performance of PdAu/ITO electrocatalysts in urea oxidation reaction
2024 - ABREU, ISABELY M.G.; MAIA, VICTORIA A.; SOUZA, RODRIGO F.B. de; NETO, ALMIR O.
PdAu electrocatalysts were prepared in different atomic compositions supported on ITO by sodium Borohydride process. XRD results show intense crystalline peaks related to ITO, which may mask the appearance of less crystalline Pd or Au phases. Transmission results indicate agglomeration of palladium and gold nanoparticles on the support, a phenomenon compatible with metal oxide supports. Cyclic voltammograms in the absence of urea display characteristics commonly observed for PdAu electrodes, with an increase in oxygenated species compared to pure Pd or Au. Voltammograms in the presence of urea showed oxidation processes and lower current values, indicating catalyst deactivation processes. PdAu 75:25 demonstrated higher power density values compared to other prepared electrocatalysts, suggesting a synergy between Pd and Au for urea oxidation reaction.
Optimizing PtSn composition in direct sugarcane extract fuel cells
2024 - VILLARDI, BRUNO D.Q.; MAIA, VICTORIA A.; NANDENHA, JULIO; ZAMBIAZI, PRISCILLA J.; SOUZA, RODRIGO F.B. de; NETO, ALMIR O.
Pt90Sn10/C composition exhibited a strong maximum power density value and a good sugar oxidation response in sugar extract solution in comparison with others electrocatalysts prepared. Pt90Sn10/C demonstrated a maximum power density approximately 93% higher than that of Pt80Sn20/C, which is the second most active material and more than 8 times bigger than Pt/C. The primary difference between the two lies in glucose consumption, which is approximately 90% higher in Pt90Sn10/C. It is important to highlight that in the more active materials; fructose consumption remains relatively constant, ranging between 7 and 8%. The enhanced performance could be attributed to both the altered electronic properties resulting from tin integration into the platinum crystal lattice and the activation of water at less positive potentials by a bifunctional mechanism. XRD results showed that the lattice parameters were expanded indicating the insertion of Sn to Pt, while that cyclic voltammetry showed that all materials present the hydrogen adsorption–desorption region over Pt (− 0.2 to 0.15 V); however, when increasing the tin content in the catalyst, the region decreases the definition and is associated with the presence of transition metals such as Sn. TEM images and histograms for PtSn showed the increase in the average particle size accompanying the tin enrichment in the composition; this effect could be tin oxide in material surface and is in agreement with other works.
Innovative lead-carbon battery utilizing electrode-electrolyte assembly inspired by PEM-FC architecture
2024 - SOUZA, RODRIGO F.B. de; SILVESTRIN, GABRIEL A.; CONCEICAO, FELIPE G. da; MAIA, VICTORIA A.; OTUBO, LARISSA; NETO, ALMIR O.; SOARES, EDSON P.
This study explores the innovative integration of a lead‑carbon battery with an electrode-electrolyte assembly inspired by Proton Exchange Membrane Fuel Cell (PEM-FC) architecture. The lead‑carbon material, synthesized with a 40 % mass ratio using the Flash Joule Heating Method, exhibits predominant Pb0 and PbO phases, as observed in lattice parameter fringes, with additional detection of the PbO2 phase. The resulting Carbon-Lead Acid Battery (CLAB) demonstrates a specific capacity of 11.2 mAh g−1. The incorporation of carbon enhances nanoparticle stability, yielding a highly stable battery performance over 100 cycles, with discharge potential variations of <2 %. This innovative CLAB assembly not only showcases stable performance and also introduces the potential for constructing flexible lead batteries, expanding technological applications. The study provides comprehensive insights into the synthesis, performance, and prospects of this novel lead‑carbon battery architecture, emphasizing its significance in the realm of energy storage solutions.
Methane to methanol conversion using proton-exchange membrane fuel cells and PdAu/antimony-doped tin oxide nanomaterials
2023 - MAIA, VICTORIA A.; NANDENHA, JULIO; GONCALVES, MARLON H.; SOUZA, RODRIGO F.B. de; O.NETO, ALMIR
This study investigates the use of Au-doped Pd anodic electrocatalysts on ATO support for the conversion of methane to methanol. The study uses cyclic voltammetry, in situ Raman spectra, polarization curves, and FTIR analysis to determine the optimal composition of gold and palladium for enhancing the conversion process. The results demonstrate the potential for utilizing methane as a feedstock for producing sustainable energy sources. The Pd75Au25/ATO electrode exhibited the highest OCP value, and Pd50Au50/ATO had the highest methanol production value at a potential of 0.05 V. Therefore, it can be concluded that an optimal composition of gold and palladium exists to enhance the conversion of methane to methanol. The findings contribute to the development of efficient and sustainable energy sources, highlighting the importance of exploring alternative ways to produce methanol.
Effective phosphate removal from water by electrochemically mediated precipitation with coffee grounds biocarbon obtained by non-thermal plasma method
2023 - SILVESTRIN, G.A.; GONCALVES, M.H.; GODOI, C.M.; MAIA, V.A.; FERREIRA, J.C.; GUILHEN, S.N.; NETO, A.O.; SOUZA, R.F.B. de
This study investigates the use of biocarbon electrodes, produced from coffee grounds through plasma pyrolysis, in the electrochemically mediated precipitation process for phosphorus removal in a flow reactor. The structural and electrochemical properties of biocarbon were analyzed using X-ray powder diffraction (XRD), Raman spectroscopy, and cyclic voltammetry. The results show that biocarbon consists of both graphene oxide and lignocellulose with surface OH groups that facilitate the breakdown of water, a key step in the electrochemically mediated precipitation process for phosphorus removal. The addition of graphite to the biocarbon paste was found to be necessary to obtain a response from the biocarbon in cyclic voltammetry. The Gr75BC25 electrode achieved higher phosphorus removal rates than other tested electrodes, particularly at low flows, due to the functional groups present in biocarbon enhancing the breakdown of water. However, electrodes with a greater amount of biocarbon exhibit lower rates of phosphorus removal and higher consumption of electrical power, which can be attributed to their higher electrical resistivity. Thus, to optimize its use, it is important to balance the benefits of increased phosphorus removal rates with the trade-off of increased energy consumption and decreased phosphorus removal at higher levels of biocarbon. The results suggest that biocarbon produced from coffee grounds by plasma pyrolysis has the potential to be used as an effective electrode material for electrochemically mediated precipitation processes.
Conversion of nitrogen to ammonia using a Cu/C electrocatalyst in a polymeric electrolyte reactor
2023 - MAIA, VICTORIA A.; SANTOS, CAMILA M.G.; AZEREDO, NATHALIA F.B.; ZAMBIAZI, PRISCILLA J.; ANTOLINI, ERMETE; NETO, ALMIR O.; SOUZA, RODRIGO F.B. de
The electrochemical conversion of N2 to NH3 using a polymeric electrolyte reactor is a promising method to accelerate the green production of hydrogen carriers. On this basis, we report the efficiency of ammonia production by the nitrogen reduction reaction using a Cu/C catalyst in a polymeric electrolyte membrane reactor. The Cu/C catalyst was prepared by the NaBH4 reduction method and characterized by X-ray diffraction, transmission electron microscopy, cyclic voltammetry, and conversion experiments performed in a polymer electrolyte membrane fuel cell type reactor. The X-ray diffraction results showed the presence of CuO2 and carbon phases, while the TEM images showed a high agglomeration of copper nanoparticles on carbon. The onset potential of nitrogen reduction was near to the Cu (I) to Cu0 reduction peak. Mass spectroscopy was used to observe the production of N2H2 and NH3 and the consumption of N2. Maximum ammonia production was detected at 0.0 V with a NH3 yield rate of 38.4 µg h−1 cm−2 and a faradaic efficiency of 42.57 %.
PtSb/C electrocatalysts for glycerol oxidation in alkaline electrolyte
2022 - PEREIRA, C.V.; MAIA, V.A.; ZAMBIAZI, P.J.; SOUZA, R.F.B. de; ANTOLINI, E.; NETO, A.O.
Pt/C and PtSb/C catalysts in various atomic ratios were synthesized by the sodium borohydride reducing method and their activity for the glycerol oxidation reaction (GOR) was evaluated in alkaline media. Transmission Electron Microscopy (TEM) images showed that Pt particle size increases with increasing Sb content in the catalyst. X-ray photoelectron spectroscopy (XPS) showed that the ratio of Pt and Sb is close to that expected. By XPS measurements, the presence of Sb2O5 in Pt70Sb30/C and Pt50Sb50/C was observed. X-ray diffraction (XRD) analysis revealed the presence of the face-centered cubic (FCC) structure of Pt and PtSb and of some others phases that could be identified as Sb oxides. By linear sweep voltammetry (LSV) measurements, Pt80Sb20/C showed the highest activity for the GOR in alkaline media for potentials >−0.35 V vs. Ag/AgCl, while Pt50Sb50/C showed the highest GOR activity in the potential range between −0.60 and −0.35 V vs. Ag/AgCl. The direct glycerol fuel cells with Pt80Sb20/C as the anode catalyst showed the best performance. These results attest the beneficial effect of Sb addition to platinum: the activity enhancement in the presence of Sb atoms has to be ascribed to both a bifunctional mechanism related to the presence of Sb oxides, and an electronic effect between platinum and antimony in the PtSb alloy.
Facile, clean and rapid exfoliation of boron-nitride using a non-thermal plasma process
2021 - SOUZA, RODRIGO F.B. de; MAIA, VICTORIA A.; ZAMBIAZZI, PRISCILLA J.; OTUBO, LARISSA; LAZAR, DOLORES R.R.; NETO, ALMIR O.
Non-Thermal Plasma source was used in this work to exfoliated boron-nitride (BN) powders. The generation of hexagonal BN nanosheets (h-BNNSs) few-layered was observed by TEM. The hBN exfoliation occurred along their transverse axis, preserving the hexagonal structure. The micrographs showed ordered lattice fringes with d-spacing of approximately 0.33 nm indicating the increase of (0 0 2) h-BNNSs crystal lattice planes, also confirmed by the relative peak intensity decrease in relation to the other peaks in XRD measures. The few amounts of layers were confirmed by intensity decrease, enlargement, and blue shift of E2 g vibrational mode in Raman spectra. Moreover, the appearance of the FTIR band corresponding to the hydroxyl group occurs due to large amounts of defects such as vacancy defects.