Banca de DEFESA: LAÍS PETRA MACHADO

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : LAÍS PETRA MACHADO
DATE: 19/12/2025
TIME: 08:00
LOCAL: Defesa remota. Link a ser criado
TITLE:

THEORETICAL DESCRIPTION OF THE OXYGEN RELEASE REACTION IN THE SHEET OF G-C3N4 AND OF G-C3N4 DOPED WITH PHOSPHORUS, PLATINUM AND NIOBIUM

KEY WORDS:

hydrogen production; g-C3N4; doping; electrocatalysis.

PAGES: 176
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Físico-Química
SPECIALTY: Química Teórica
SUMMARY:

The growing demand for sustainable energy sources drives the development of technologies based on alternative fuels, among which hydrogen stands out as a clean and versatile energy vector. Its production through water electrolysis, however, depends on the efficiency of electrocatalytic reactions, such as the oxygen evolution reaction (OER), which faces high energy barriers. In this context, graphitic carbon nitride (g-C₃N₄) emerges as a promising material due to its two-dimensional structure, thermal stability, and abundance of active sites, although its intrinsic catalytic activity remains limited.

This work investigates, through computational modeling based on Density Functional Theory (DFT), the behavior of the OER on surfaces of pristine g-C₃N₄ and functionalized with different dopant elements: platinum (Pt), phosphourus (P) and niobium (Nb). Optimized geometries, adsorption energies of the main reaction intermediates (OH*, O*, OOH*, and OO*), and Gibbs free energy (ΔG) profiles for the key steps of the OER under various electrochemical potential conditions were analyzed. The objective was to assess how these structural and electronic modifications influence the stability of the intermediates and the thermodynamic feasibility of the reaction.

The results showed that Pt doping significantly reduced the OER overpotential to 0.67 V, rendering all steps exergonic from 1.90 V onward, thus standing out as the most efficient system among those studied. Nb doping, on the other hand, enhanced the interaction with oxygenated intermediates (especially O*), promoting strong anchoring and localized structural stability, but requiring a higher potential (2.60 V) to complete the catalytic cycle. Pure g-C₃N₄, although structurally stable, exhibited inferior performance with an overpotential of 1.14 V. These findings reinforce the importance of doping in g-C₃N₄ for the development of more active catalysts for oxygen evolution

COMMITTEE MEMBERS:
Presidente - 1354432 - CLARISSA OLIVEIRA DA SILVA
Interno - 3131055 - GLADSON DE SOUZA MACHADO
Interno - 1097247 - LUCAS MODESTO DA COSTA
Externo ao Programa - 1808284 - MARCIO SOARES PEREIRA - UFRRJExterno à Instituição - FELIPE FANTUZZI SOARES
Externo à Instituição - LEONARDO BAPTISTA - UERJ