Seung Woo Lee

This comprehensive Review focuses on the key challenges and recent progress regarding sodium-metal anodes employed in sodium-metal batteries (SMBs). The metal anode is the essential component of emerging energy storage systems such as sodium sulfur and sodium selenium, which are discussed as example full-cell applications. We begin with a description of the differences in the chemical and physical properties of Na metal versus the oft-studied Li metal, and a corresponding discussion regarding th

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Multiwall carbon nanotube (MWNT)/manganese oxide (MnO2) nanocomposite ultrathin film electrodes have been created via redox deposition of MnO2 on layer-by-layer (LbL)-assembled MWNT films. We demonstrate that these LbL-assembled MWNT (LbL-MWNT)/MnO2 thin films consist of a uniform coating of nanosized MnO2 on the MWNT network structure using SEM and TEM, which is a promising structure for electrochemical capacitor applications. LbL-MWNT/MnO2 electrodes yield a significantly higher volumetric cap

All multiwall carbon nanotube (MWNT) thin films are created by layer-by-layer (LBL) assembly of surface functionalized MWNTs. Negatively and positively charged MWNTs were prepared by surface functionalization, allowing the incorporation of MWNTs into highly tunable thin films via the LBL technique. The pH dependent surface charge on the MWNTs gives this system the unique characteristics of LBL assembly of weak polyelectrolytes, controlling thickness and morphology with assembly pH conditions. We

Access to nitrogen-based fertilizers is critical to maximize agricultural yield, as nitrogen is the most common rate-limiting nutrient. Nearly all nitrogen-based fertilizers rely on ammonia and nitric acid as feedstocks, and thus the demand for these chemicals is heavily dependent on the global population and food demand. Over the next three decades, the global population will continue to dictate the market size and value for ammonia and nitric acid, which consequently will have a significant im

The design of electrocatalysts capable of selectively reducing nitrate to ammonia is gaining interest as a means of transforming waste into fertilizers. However, most prior investigations of prototypical electrocatalysts, such as polycrystalline Pd and Pt, have focused on unraveling the mechanisms responsible for the selective reduction of nitrate to nitrogen gas. Such polycrystalline noble metals demonstrate notoriously low activity for nitrate reduction (nitrate to nitrite) and high activity f

The fast evolution of portable electronic devices and micro-electro-mechanical systems (MEMS) requires multi-functional microscale energy sources that have high power, high energy, long cycle life, and the adaptability to various substrates. Nanostructured thin-film lithium-ion batteries and electrochemical capacitors (ECs) are among the most promising energy storage devices that can meet these demands. This perspective presents an overview of recent progresses and challenges associated with the

Transition-metal oxide and phosphate materials, commonly used for lithium battery devices, are active as oxygen evolution reaction (OER) catalysts under alkaline and neutral solution conditions. Electrodes composed of LiCoO(2) and LiCoPO(4) exhibit progressive deactivation and activation for OER catalysis, respectively, upon potential cycling at neutral pH. The deactivation of LiCoO(2) and activation of LiCoPO(4) are coincident with changes in surface morphology and composition giving rise to sp

Redox-active, self-polymerized dopamine shows promise as organic cathode materials for Li- and Na-ion batteries.

Design of highly active nanoscale catalysts for electro-oxidation of small organic molecules is of great importance to the development of efficient fuel cells. Increasing steps on single-crystal Pt surfaces is shown to enhance the activity of CO and methanol electro-oxidation up to several orders of magnitude. However, little is known about the surface atomic structure of nanoparticles with sizes of practical relevance, which limits the application of fundamental understanding in the reaction me

To achieve excellent photoelectrochemical water-splitting activity, photoanode materials with high light absorption and good charge-separation efficiency are essential. One effective strategy for the production of materials satisfying these requirements is to adjust their band structure and corresponding bandgap energy by introducing oxygen vacancies. A simple chemical reduction method that can systematically generate oxygen vacancies in barium stannate (BaSnO₃ (BSO)) crystal is intro

Organic-inorganic hybrid nanoflowers, a newly developed class of flower-like hybrid nanoparticles, have received much attention due to their simple synthesis, high efficiency, and enzyme stabilizing ability. This article covers, in detail, the types, structural features, mechanism of formation, and bio-related applications of hybrid nanoflowers. The five major types of hybrid nanoflowers are discussed, i.e., copper-protein, calcium-protein, and manganese-protein hybrid nanoflowers, copper-DNA hy

A structure-mechanism-performance relationship of metal-free carbon catalysts for outstanding H 2 O 2 production activity and selectivity in alkaline media.

Binder-free and self-standing carbon nanotube (CNT) electrodes of tens of microns in thickness have been assembled via a vacuum-filtration process of oxidized few-walled CNTs (FWNTs), with different amounts of oxygen functional groups on FWNTs. Sub-millimetre long FWNTs can provide high electrical conductivity and mechanical strength in self-standing porous networks by reducing the number of junctions among FWNTs. We show that the gravimetric capacity of FWNT electrodes in lithium cells can be e

The design of highly active nanoscale catalysts for the oxygen reduction reaction (ORR) and oxidation of small molecules such as the methanol oxidation reaction (MOR) constitutes the grand scientific and technological challenge in fuel cells. Although increasing surface steps on Pt nanoparticles was shown recently to enhance the activity of electrochemical oxidation of carbon monoxide and methanol electro-oxidation, little is known about the role of surface steps of nanoparticles on ORR activity