Research Area

Electrochemical N2 reduction reaction for green ammonia synthesis

전기화학적 질소 환원 반응을 통한 친환경 암모니아 합성 

The transition toward carbon neutrality has accelerated the development of sustainable and low-carbon energy technologies, highlighting the importance of green ammonia as both a chemical feedstock and an energy carrier. Electrochemical ammonia synthesis via the electrochemical nitrogen reduction reaction (eNRR) has emerged as a promising alternative to the conventional Haber–Bosch process because it can potentially operate at relatively low temperatures and pressures and can be directly integrated with renewable electricity sources. However, the high stability of the nitrogen triple bond (N≡N) and the low solubility of N₂ in many electrolytes, particularly aqueous systems, present significant challenges for electrochemical ammonia synthesis. In addition, eNRR is strongly affected by the competing hydrogen evolution reaction (HER), which limits ammonia production rates and Faradaic efficiency.

Various electrocatalysts, electrolyte systems, and reactor configurations are currently being investigated to improve ammonia production rate, selectivity (Faradaic efficiency), and long-term stability. Nevertheless, significant challenges remain, particularly in achieving efficient N₂ transport, controlling interfacial reactions at the electrode–electrolyte interface, and suppressing competing reactions under practical operating conditions.

Our laboratory focuses on developing sustainable approaches for green ammonia synthesis using electrochemical reactions involving N₂ and water. We investigate electrocatalysts, reaction conditions, electrode structures, mass-transfer characteristics, and integrated electrochemical system design to overcome the fundamental and practical limitations of eNRR. Through these efforts, we aim to contribute to the development of scalable and environmentally sustainable ammonia production technologies and to provide insights into future directions for electrochemical ammonia synthesis.

Electrochemical Ammonia Electrolysis to Hydrogen Production (eAEH)

전기화학적 암모니아 전해를 통한 수소 생산

Electrochemical ammonia electrolysis for hydrogen production (eAEH) offers a promising pathway for low-carbon hydrogen production using ammonia as a hydrogen carrier. The process can potentially be integrated with renewable electricity and operated at relatively low temperatures (<100 °C) and atmospheric pressure. Unlike conventional thermal ammonia decomposition, eAEH can produce high-purity hydrogen (~99.9%) through an electrochemical pathway, potentially reducing the need for complex downstream separation and purification processes. These characteristics provide important advantages for the development of compact, energy-efficient, and carbon-free hydrogen production systems.

Thermodynamic Potential of Ammonia Electrolysis

Ammonia electrolysis has a significant thermodynamic advantage due to its low theoretical reversible cell voltage (E°rev = 0.06 V) and thermoneutral voltage (E°th = 0.08 V). Compared with conventional water electrolysis, which theoretically requires substantially higher electrical energy, ammonia electrolysis requires only a small fraction of the energy input for hydrogen production. The theoretical electrical energy requirement of eAEH can be less than 0.175 kWh m⁻³-H₂, compared with more than 3.24 kWh m⁻³-H₂ for water electrolysis. This substantial difference highlights the thermodynamic potential of ammonia electrolysis as an energy-efficient pathway for hydrogen production.

Key Challenges in eAEH Research

Despite these thermodynamic advantages, the practical performance of eAEH is largely limited by the sluggish kinetics of the ammonia oxidation reaction (AOR) at the anode. Consequently, considerably higher operating voltages than the theoretical cell voltage are typically required. Competing reactions, including the oxygen evolution reaction (OER), must also be effectively controlled depending on the electrolyte and operating conditions. In addition, catalyst poisoning and surface deactivation caused by adsorbed intermediates such as NHx, NxHy, and NOx species can significantly reduce catalytic activity and long-term stability. Complex N–N coupling and multi-electron reaction pathways further complicate the selective oxidation of ammonia to N₂.

Our laboratory focuses on understanding ammonia oxidation mechanisms, developing highly active and durable electrocatalysts, and optimizing electrode and reactor configurations for efficient ammonia electrolysis. In particular, we investigate catalyst–electrolyte interfaces, reaction intermediates, mass-transfer behavior, and integrated cell and system designs to overcome kinetic and durability limitations. Through these efforts, we aim to develop scalable and energy-efficient eAEH technologies for high-purity hydrogen production from ammonia.

 High-pressure PEM water electrolysis cell to stack

가압 PEM 수전해: 셀에서 스택 개발

Our laboratory focuses on the development of advanced proton exchange membrane water electrolysis (PEMWE) technologies for efficient and sustainable hydrogen production. In particular, we investigate high-pressure PEM water electrolysis from fundamental cell components to stack-level integration, with the goal of improving electrochemical performance, durability, and system efficiency.

Development of Advanced PEM Water Electrolysis Technologies

We are developing and optimizing PEM water electrolysis cells capable of efficient operation under elevated hydrogen pressures. High-pressure operation can enable direct production of pressurized hydrogen, potentially reducing the energy and equipment requirements associated with downstream mechanical compression. Our research investigates advanced materials, cell components, and operating strategies to improve performance while reducing cost and enhancing long-term durability.

Scale-Up from Cell to Stack

A major objective of our research is to translate laboratory-scale electrolysis cells into larger-area cells and multi-cell stacks. Scale-up requires careful consideration of current and flow distribution, thermal management, sealing, mechanical compression, pressure control, and electrochemical uniformity across individual cells. We therefore investigate both cell-level performance and stack-level integration to maintain high efficiency and stable operation as system size and hydrogen production capacity increase.

Integration with Renewable Energy Sources

PEM water electrolysis is particularly suitable for integration with variable renewable energy sources such as solar and wind power because of its rapid dynamic response and broad operating range. Our research investigates electrolysis operation under fluctuating power inputs and develops operating and control strategies to improve hydrogen production efficiency, durability, and system stability under realistic renewable-energy conditions.

Advanced Catalysts, Electrodes, and MEAs

Our research also focuses on the development and optimization of electrocatalysts, porous transport layers, electrodes, membranes, and membrane electrode assemblies (MEAs). Particular attention is given to reducing the loading of critical noble-metal catalysts while maintaining high activity and durability under high current density and pressurized operating conditions. Through the integrated development of materials, electrodes, cells, and stacks, we aim to advance PEM water electrolysis toward scalable, efficient, and cost-effective hydrogen production.