Bulletin of the Korean Chemical Society最新文献

Gold nanoparticles (AuNPs) exhibit excellent plasmonic properties, including bright color and generation of localized electric field, hot carriers, and heat. These properties are widely applied in biology, sensing, spectroscopy, catalysis, and medicine. More attractive is that these properties are tremendously enhanced when AuNPs are assembled and form nanogaps between the particles. Therefore, assembling AuNPs in a controlled fashion is a key step for the study and applications of plasmonic properties. In this Account, I will introduce my group's collective efforts that have been made for a decade to develop the best assembly method. I will describe the assembly procedure in detail and demonstrate the various nanoassemblies produced by the method. The controlled assembly allows us to systematically examine the relationship between the plasmonic properties and structural parameters of the nanogaps. Among many properties, I focus on plasmon coupling. To conclude, I will discuss the prospects of nanoassembly plasmonics.

We report on the preparation of a polyethyleneimine-incorporated hydroxyapatite (PEI-HAP) and its enhanced colloidal stability. Three PEI-HAPs having different amine contents are synthesized by hydrothermal treatment (200 °C) of the HAP prepared at room temperature (rt-HAP). The crystallinity of PEI-HAP is improved compared to rt-HAP due to the heat treatment. In addition, the size of PEI-HAP (50.4 nm) increased compared to rt-HAP (32.1 nm) after heat treatment. However, the presence (or concentration) of PEI has little effect on the crystallinity and size of the samples. Ninhydrin test indicates the presence of amine group in PEI-HAPs. XPS experiments verified that maximum amine content amounts to 2.81%. As the amount of amine increases, the zeta potential is changed from −22.6 to +31.7 mV due to the adsorption of PEI on HAP surface. Consequently, the sample having high positive valuable zeta potential of +31.7 mV exhibits colloidal stability of more than 6 h.

While lithium metal anodes (LMAs) offer the highest energy density, positioning them as a promising material for graphite, they suffer from uneven electroplating morphology and the formation of Li dendrites. Given the pivotal role of the solid-electrolyte interphase (SEI), which is formed by electrolyte decomposition, in mitigating dendritic growth, extensive research has been conducted on liquid electrolytes in Li metal batteries (LMBs). This mini-review presents the historical advancements in LMB electrolytes, focusing on modulating the Li⁺ microenvironment and LMA interface chemistry to inhibit Li dendrite formation. We traced the evolution of LMB electrolytes from traditional formulations to advanced designs. In particular, the reinforcement of the SEI and the compact morphology of the deposited Li are deeply discussed at each advancement in liquid electrolytes. We subsequently identify common characteristics among these advanced electrolytes and conclude by discussing future directions and strategies for rational design.

This review focuses on the redox reactivities of MLCT and LMCT excited states of earth-abundant metal complexes, such as iron, manganese, cobalt, and chromium, together with the lifetime and redox potentials of the MLCT and LMCT excited states. More details are available in the article by Wonwoo Nam, Yong-Min Lee, Shunichi Fukuzumi.

Anthropogenic carbon dioxide (CO₂) emissions pose a significant threat to the delicate balance between human society and the natural environment. Carbon capture and sequestration is a technology designed to selectively capture CO₂ emissions generated from power plants and industrial facilities, preventing them from entering the atmosphere. Diamine-modified metal–organic frameworks (MOFs) show promising capabilities in achieving remarkable CO₂ capacities, highlighting their potential for effective CO₂ capture applications. Herein, using MOF-74 type frameworks, we discussed our various methodologies designed to enhance the CO₂ adsorption capacity, while also tackling the issue of maintaining structural integrity over prolonged periods, especially in humid environments. The challenges and prospects for CO₂ capture by diamine-functionalized hydrophobic MOFs are highlighted.

Fabrication of thin films is the most crucial step in introducing promising new materials into practical devices. Among the various materials, metal–organic framework (MOF) thin films have gained widespread attention with the advantage of diverse applications. In this review, two representative vapor-phase synthetic methods, (1) molecular layer deposition (MLD), (2) chemical vapor deposition (CVD) are addressed as emerging techniques.

MoS₂ and WS₂ are spotlighted as fungible materials of graphene that can be used in electronic devices owing to being semiconductors with indirect and direct band gaps. Precursors (Mo(N^tBu)₂(S^tBu)₂ (1), W(N^tBu)₂(S^tBu)₂ (2)) suitable for the deposition of these materials were synthesized and characterized. The molecular structures of 1 and 2 exhibit a tetrahedral geometry according to single-crystal x-ray crystallography. Thermogravimetric analyses of 1 and 2 showed two-step weight loss. The residues from each step of 1 were MoS₃ and MoS₂, and these results were consistent with the subsequent deposition results of 1. We successfully established a PEALD-MoS₂ process using 1 and H₂S plasma as the precursor and reactant, respectively, at relatively low temperatures of 150–300 °C without any post-sulfurization process. A temperature-dependent selective deposition of MoS_x phases was observed with the growth of amorphous MoS₃ films (150–200 °C), and crystalline MoS₂ films (250–350 °C).

Research into enhancing the performance and durability of anion exchange membrane (AEM)-based water electrolysis (AEMWE) cells has primarily aimed to facilitate commercialization efforts and improve the chemical stability of AEMs, with anion exchange ionomers (AEIs) playing an increasingly important role. This study aimed to reduce ionomer swelling and enhance AEM–catalyst adhesion via AEM–ionomer crosslinking within a membrane electrode assembly (MEA), using allyl- and quaternary ammonium-functionalized poly(phenylene oxide) (PPO), allyl-m-PPO, as both the AEM and AEI. Bis(aryl azide) was added as a crosslinker to an ionomer solution to generate the MEA, which was heated to induce allyl–azide crosslinks at the membrane–ionomer interface. Peel test indicated an increased adhesion at both electrodes for the crosslinked x-allyl-0.05-PPO (5 mol% allyl content relative to the total ion-conducting head group content). Further, x-allyl-0.05-PPO exhibited a smaller voltage increase due to crosslinking compared to TA-PPO, signifying a notable improvement in durability.

A novel all-sequential-dip-coated (SDC) deposited FA₁MA_1−yPbI_3−xBr_x perovskite films have been synthesized from an aqueous non-halide lead precursor towards an environmentally benign, cost-effective, and efficient approach for high-performance perovskite solar cells (PrSCs). The mixed-cationic FA₁MA_1−yPbI_3−xBr_x perovskite layers ensure the fractional incorporation of Br into the perovskite crystal lattice. The insertion of Br contents was regulated by modulating the FABr concentration into the FABr/MAI mixed-cationic precursor solution. The incorporation of minor FABr into MAI helps to improve the surface coverage and crystallinity of the synthesized per-ovskite layer in contrast to the other perovskite films prepared with higher FABr content under the same environment. The PrSCs with these FA₁MA_1−yPbI_3−xBr_x perovskite layers displayed good de-vice performances and stability with a PCE of 11.1%. These outcomes reveal that the synthesis of FA₁MA_1−yPbI_3−xBr_x perovskite films with the SDC approach is more efficient because of the use of environmentally benign solvents for synthesizing lead and perovskite layers.

Precious metal complexes, which act as excellent photoredox catalysts, have now being replaced by earth-abundant metal complexes. This review focused on redox reactivity of ligand-to-metal charge transfer (LMCT) and metal-to-ligand charge transfer (MLCT) excited states of earth-abundant metal complexes. Iron complexes with strongly σ-donating NHC-ligands (NHC = N-heterocyclic carbene) has emerged, featuring long lived LMCT excited states due to a significantly increased barrier for deactivation via metal centered states. A Fe(III)-NHC complex acts as an effective photoredox catalyst for various photocatalytic redox reactions. Although manganese(IV)-oxo complexes have no long-lived excited states (τ < < 1 ns). Once acids such as Sc(OTf)₃ and HOTf are bound to the oxo moiety of Mn(IV)-oxo complexes, the photoexcitation of acid-bound Mn(IV)-oxo complexes resulted in formation of the excited states with microseconds lifetimes, which are capable of oxidation of substrates including benzene to phenol. Photoexcited states of Mn(III), Mn(II) and Mn(I) complexes act as photoreductants to reduce substrates including O₂. On the other hand, photoexcited states of Co(IV) and Co(III) complexes act as photooxidants, whereas those of Co(II) and Co(I) complexes act as photoreductants. With regard to the excited state lifetime, [Cr(tpe)₂]³⁺ (tpe = 1,1,1-tris(pyrid-2-yl)ethane) exhibited the longest luminescence lifetime (τ = 4500 μs), acting as an effective photoredox catalyst for photocatalytic redox reactions. The LMCT state of a Cr(0) complex acts as a super photoreductant. Thus, LMCT and MLCT excited states of earth-abundant metal complexes are utilized as strong photooxidants and photoreductants, respectively.