Banca de QUALIFICAÇÃO: NATANE MARTINIANO DOS SANTOS

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
STUDENT : NATANE MARTINIANO DOS SANTOS
DATE: 16/03/2026
TIME: 15:00
LOCAL: online
TITLE:

OBTAINING IRON-DOPED MOLYBDENUM CARBIDE ELECTROCATALYZER BY GAS-SOLID REACTION FOR OXYGEN EVOLUTION REACTION

KEY WORDS:

Electrocatalysts, Mo2C, iron, gas-solid reaction, OER.

PAGES: 87
BIG AREA: Engenharias
AREA: Engenharia de Materiais e Metalúrgica
SUBÁREA: Materiais Não-Metálicos
SPECIALTY: Cerâmicos
SUMMARY:

The increase in the use of fossil fuels in recent decades, responsible for significant environmental impacts, has driven global interest in the development and application of clean, sustainable, and renewable energy sources. One alternative that has been gaining prominence is the use of hydrogen (H₂), widely recognized as one of the most promising renewable energy sources to meet growing global demand. One method of obtaining hydrogen that has received considerable attention is water electrolysis, which occurs through two half-reactions: the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). However, the water electrolysis process still has limitations, since the oxygen evolution reaction (OER) occurs slowly due to the multiple steps involved, which compromises the energy efficiency of the system. Thus, the development of efficient, stable, and low-cost electrocatalysts is a central challenge to make this technology viable on a large scale. Molybdenum carbide (Mo₂C) has emerged as an attractive catalytic material due to its electronic properties similar to those of noble metals and its high chemical stability. However, its activity for OER can still be improved through structural engineering and electronic modulation strategies. In this context, the present study aims to synthesize and investigate iron-doped Mo₂C electrocatalysts (1%, 3%, and 5% by mass), obtained by gas-solid reaction from ammonium heptamolybdate and iron nitrate, under a reducing/carburizing atmosphere (H₂/CH₄) at 700 °C for 2 hours, in order to understand how the incorporation of Fe influences the structural and electronic properties and the electrocatalytic performance in the oxygen evolution reaction (OER). °C for 2 hours, aiming to understand how the incorporation of Fe influences the structural and electronic properties and the electrocatalytic performance in the oxygen evolution reaction (OER). Transmission electron microscopy (TEM) micrographs showed predominantly spherical nanometric particles with heterogeneous size distribution. From an electrochemical point of view, the incorporation of Fe (1%–5%) into Mo₂C promoted a significant improvement in catalytic activity for OER in an alkaline medium (KOH 1.0 mol L⁻¹). The overpotential required to reach 20 mA cm⁻² was reduced from 346 mV (pure Mo₂C) to 268 mV (Mo₂C–Fe5%). Mo2C–Fe5% exhibited higher intrinsic activity due to Fe-induced electronic effects, corroborated by a sharp decrease in charge transfer resistance (21 → 1.93 Ω cm-2). Both materials exhibited excellent stability for 24 hours of continuous operation. The results show that iron-promoted electronic modification is an effective strategy for optimizing the electrocatalytic performance of Mo₂C in OER, contributing to the advancement of alternative materials based on abundant metals for applications in sustainable hydrogen production.

COMMITTEE MEMBERS:
Presidente - ***.121.804-** - UILAME UMBELINO GOMES - UFRN
Interno - 1674707 - MARCO ANTONIO MORALES TORRES
Externa à Instituição - MARIA JOSE SANTOS LIMA
Externo à Instituição - RAFAEL ALEXANDRE RAIMUNDO