Sung Jong Yoo

The hydrogen economy expansion triggered studies on the durability of hydrogen-powered proton-exchange membrane fuel cells (PEMFCs), which revealed that their performance is largely hindered by the degradation of cathode support. Herein, Ti3+-enriched N,C-codoped mixed-phase TiO2 nanoparticles featuring a reduced (compared to that of pristine TiO2) band gap and containing Ti3+ ions, oxygen vacancies, and Ti–X bonds (X = O, OH, N, C) were synthesized as a durable PEMFC cathode support by annealin

Electrochemical nitrogen reduction reaction (NRR) is a promising method for energy-efficient and low-emission NH3 production. Herein, we report electrochemical NH3 production using a copper sulfide-based electrocatalyst. A solid-state synthesis is employed to prepare the Cu9S5 catalyst for artificial N2 fixation in a neutral aqueous electrolyte. Despite an excellent NRR activity of 10.8 ± 0.4 μg/hcm2 at −0.5 VRHE, however, the catalyst itself is reductively degraded during the NRR. To achieve co

Development of a novel flow-field design for improving the water management of proton exchange membrane fuel cells (PEMFCs) is critical for realizing a practical high-performance energy conversion system. The conventional serpentine flow-field designs with the two-dimensional channel and rib configuration often cause water accumulation, thus blocking the transport of reactants and interfering with the removal of water, which in turn result in reduced fuel cell performance at high current densiti

Performance degradation generated by reverse current flow during fuel cell shut-down/start-up is a big challenge for commercialization of polymer electrolyte membrane fuel cells in automobile applications. Under transient operating conditions, the formation of H₂/O₂ boundaries on Pt surfaces and the occurrence of undesired oxygen reduction reaction (ORR) in an anode cause severe degradation of carbon supports and Pt catalysts in a cathode because of an increase of the catho

Biomass is the ideal precursor for fabricating oxygen reduction reaction (ORR) electrocatalysts due to its large-scale and low-cost production, as well as its renewability. Among various forms of biomass, especially waste pig blood is a sustainable precursor for the synthesis of functional electrocatalysts. However, various proteins or metal substances present in the waste pig blood act as impurities and impede the electrocatalytic performance, preventing its direct use as an electrocatalyst. He

Galvanic displacement reaction has been considered a simple method for fabricating hollow nanoparticles. However, the formation of hollow interiors in nanoparticles is not easily achieved owing to the easy oxidization of transition metals, which results in mixed morphologies, and the presence of surfactants on the nanoparticle surface, which severely deteriorates the catalytic activity. In this study, we developed a facile gram-scale methodology for the one-pot preparation of carbon-supported Pt

Electrochemical nitrogen reduction reaction (eNRR) is a promising alternative to the Haber–Bosch process for environmentally sustainable ammonia synthesis. However, the reduction of the dinitrogen molecule to ammonia is known for its extremely sluggish kinetics, and the catalytic activity and selectivity of eNRR catalysts remain significantly low for practical deployment of the technology. Herein, a sacrificial dopant for eNRR catalysts is introduced in order to improve the activity and durabili

Low-Ir electrocatalysts are crucial for developing large-scale polymer-electrolyte-membrane water electrolysis (PEMWE) facilities, which are necessary to advance the hydrogen economy. However, the performance and durability of low-Ir electrocatalysts are unsatisfactory. To address this issue, we prepared selenium-modified Ir nanoparticles on high-crystalline-carbon (HCC) supports. The introduction of HCC supports effectively reduced Ir usage, and Se incorporation mitigated Ir degradation. Se nuc

Understanding catalytic-conversion determinants will blueprint an efficient electrocatalyst design for electrochemical nitrogen reduction. In metal chalcogenide-based catalysts, metal-site nitrogen adsorption initiates nitrogen fixation, and successive hydrogen supply from nearby chalcogen sites hydrogenates the nitrogen to ammonia. However, surface geometry-dependent reaction kinetics are rarely studied because the reaction is very fast. Here, we investigate the relationship between catalyst ge

Proton exchange membrane fuel cells (PEMFCs) are emerging as a key technology in the transition to hydrogen-based energy systems, particularly for heavy-duty vehicles (HDVs) that face operational challenges, such as frequent startup-shutdown cycles and fuel starvation. However, the widespread adoption of PEMFCs has been limited by their durability and long-term performance issues, which are crucial for heavy-duty applications. This Perspective focuses on recent advancements in PEMFC catalysts an

In fuel cells, carbon corrosion occurs due to electrochemical oxidation under driving conditions. The carbon used as a catalyst layer in polymer electrolyte membrane fuel cells (PEMFCs) negatively affects the durability of the membrane electrode assembly (MEA). Although various support materials have been investigated to prevent carbon corrosion, the problem remains unresolved. In this article, we present a strategy for preventing carbon corrosion by depositing a nanoscale TiO2 film on a carbon

A simple wet-chemical route for the preparation of core-shell-structured catalysts was developed to achieve high oxygen reduction reaction (ORR) activity with a low Pt loading amount. Nickel nitride (Ni₃N) nanoparticles were used as earth-abundant metal-based cores to support thin Pt layers. To realize the site-selective formation of Pt layers on the Ni₃N core, hydrogen molecules (H₂) were used as a mild reducing agent. As H₂ oxidation is catalyzed by

Metal- and nitrogen-doped carbon (M–N-C) catalysts are effective alternatives to oxygen reduction reaction (ORR) catalysts, such as platinum-based systems, in fuel cell technology. Among various transition metals, Mn is an abundant metal; in biological systems, enzymes including Mn effectively catalyze oxygen-evolving reactions at low potentials. Herein, a hollow and single-atom Mn–N–C catalyst was synthesized by using a pseudomorphic replication strategy. This approach is an efficient way to sy

Nanostructured high-/medium-entropy compounds have emerged as important catalytic materials for energy conversion technologies, but complex thermodynamic relationships involved with the element mixing enthalpy have been a considerable roadblock to the formation of stable single-phase structures. Cation exchange reactions (CERs), in particular with copper sulfide templates, have been extensively investigated for the synthesis of multicomponent heteronanoparticles with unconventional structural fe