High-Entropy (FeCoNiMnAl)3O4/CNT and (FeCoNiMnAl)3O4/rGO Hybrid Bi-functional Catalyst for Hydrogen and Oxygen Evolution Reactions

Author

• Bhumikaben V. Makawana, Pittsburg State UniversityFollow

Date of Award

Spring 5-16-2025

Document Type

Thesis

Degree Name

Master of Science in Material Science Engineering (MSMatSE)

Department

Physics

First Advisor

Dr. Ram K. Gupta, [email protected]

Second Advisor

Dr. Serif Uran, [email protected]

Third Advisor

Dr. Timothy Dawsey, [email protected]

Keywords

High entropy oxide, hydrogen evolution reaction, oxygen evolution reaction, water splitting

Abstract

Developing efficient and durable electrocatalysts for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is crucial for advancing sustainable energy conversion technologies. In this study, high-entropy (FeCoNiMnAl)₃O₄ and its hybrid forms supported on carbon nanotubes (CNTs) and reduced graphene oxide (rGO) were synthesized with varying carbon concentrations (5 mM, 10 mM, and 15 mM) and evaluated for their bifunctional electrocatalytic performance in alkaline media. The rGO-supported catalyst with 10 mM concentration exhibited the best HER performance, achieving a low overpotential of 162 mV at 10 mA/cm², followed by rGO (15 mM) and rGO (5 mM) with 189 mV and 212 mV, respectively. Among CNT-based catalysts, the 5 mM CNT sample showed an overpotential of 172 mV, while 10 mM and 15 mM CNTs both had 226 mV. The pristine high-entropy oxide, without any conductive support, exhibited a significantly higher overpotential of 222 mV, indicating limited HER activity. The CNT-supported catalyst with 15 mM concentration demonstrated the highest double-layer capacitance, electrochemical surface area, and roughness factor, contributing to its excellent OER activity with an overpotential of 248 mV at 10 mA/cm². Furthermore, it exhibited outstanding operational durability, maintaining stable performance for over 24 hours in alkaline conditions without significant degradation, confirming its robust catalytic nature. While the pure oxide possessed relatively high ECSA and surface roughness, its poor conductivity limited overall performance. CNT support provided superior OER efficiency through enhanced structural stability, electrical conductivity, and gas bubble release, whereas rGO support promoted HER through faster charge transfer and effective exposure of active sites. Overall, the synergy between high-entropy oxide nanostructures and conductive carbon materials led to enhanced electrocatalytic activity, improved long-term durability, and bifunctional behavior, offering a promising strategy for efficient overall water splitting and sustainable hydrogen production.

Recommended Citation

Makawana, Bhumikaben V., "High-Entropy (FeCoNiMnAl)3O4/CNT and (FeCoNiMnAl)3O4/rGO Hybrid Bi-functional Catalyst for Hydrogen and Oxygen Evolution Reactions" (2025). Electronic Theses & Dissertations. 830.
https://digitalcommons.pittstate.edu/etd/830