Jungkyu Choi

Copper (Cu)-based catalysts have been extensively investigated for CO2 hydrogenation. Their practical application is often hindered by poor thermal stability and a strong tendency for Cu nanoparticles to agglomerate at elevated temperatures. Although various strategies have been explored to improve the performance of Cu catalysts, many rely heavily on introducing metal promoters or oxide supports. In this work, histidine-modulated Cu catalysts supported on SiO2 were synthesized by dispersing Cu nanoparticles and incorporating nitrogen-containing species via coordination with an organic ligand. The histidine-modulated Cu catalysts exhibit significantly higher metal dispersion (∼17%) than the unmodulated catalyst (∼5%). The histidine-modulated Cu catalysts showed enhanced catalytic performance, with CO2 conversion more than an order of magnitude higher than that with the conventional Cu/SiO2 catalysts (9.2% vs 0.8%), accompanied by a moderate rise in methanol selectivity (11.4% vs 19.4%) at 260 °C, 2.0 MPa, and 3000 mL·gcat−1·h−1 for the 10 wt % Cu catalysts. XPS and in situ DRIFT analyses further reveal that histidine modulation effectively enhances CO2 adsorption and facilitates Cu+ stabilization. Overall, the histidine-modulated Cu catalysts are much less susceptible to sintering, thereby enhancing stability and offering a practical and sustainable route to more efficient CO2-to-methanol catalysis.

Although a Cu‐impregnated ZSM‐5 (zeolite socony m obil‐ fi ve; MFI type) zeolite having a finite Si/Al ratio serves as a promising hydrocarbon (HC) trap in the fresh state, its hydrothermal stability should be significantly improved to ensure its long‐term use in real vehicles. In this study, the Cu‐impregnated ZSM‐5 zeolite (i.e., core) and, accordingly, the active Cu species therein were protected by forming a highly siliceous MFI‐type zeolite shell. Despite the inevitable modest decrease in the HC removal efficiency owing to the inactive shell part, the original key ability of the core part was well maintained after harsh hydrothermal treatments (HTs) at 800°C. Indeed, an optimal shell structure (obtained after 9‐h epitaxial growth), which could cover the core part effectively, resulted in improved long‐term HC removal efficiency during the cold‐start tests (11.9% vs. nil with the core part alone). The adsorption capacities of two representative HCs (propene and toluene) were effectively correlated with the physicochemical properties (mainly related to the active Cu species and microporous zeolite structure, respectively). In addition, the shell structure effectively preserved HC oxidation ability after HT. Finally, we demonstrated the synergistic roles of the HC adsorption and oxidation abilities in determining the overall HC removal efficiency.

Ion-solvating membranes (ISMs) have emerged as promising dense separators for alkaline water electrolysis (AWE) because they enable ion transport through absorbed KOH/water phases without relying on fixed ionic groups. However, enhancing electrolyte retention while preserving membrane integrity and long-term alkaline stability remains a key challenge. In this study, mixed-ligand BDC-ZIF-8 was synthesized using benzene-1,4-dicarboxylic acid recovered from waste PET depolymerization and incorporated into a poly [2,2’-(1,4-naphthalene)-5,5′-bibenzimidazole] (NPBI) matrix to fabricate NPBI/BDC-ZIF-8 mixed-matrix membranes (MMMs). The effects of BDC-ZIF-8 loading on electrolyte uptake, dimensional stability, gas-blocking integrity, ion transport, and AWE performance were systematically investigated. The BDC-ZIF-8 filler retained a ZIF-8-like crystalline framework while exhibiting a high BET surface area of 1488 m ² g ^-1 and a porous structure. Its incorporation increased the water fraction from 34% to 37% and the KOH fraction from 17% to 23%, while mitigating excessive dimensional changes after KOH uptake. The resulting MMMs maintained bubble point pressures of 6.2–6.5 bar, comparable to pristine NPBI, indicating that dense membrane integrity was preserved. In addition, the area resistance decreased from 0.067 Ω cm ² for pristine NPBI to 0.037 Ω cm ² for the 40 wt% MMM, leading to improved initial AWE cell performance. The NPBI/BDC-ZIF-8 20 wt% MMM also sustained 100 h single-cell operation at 0.3 A cm ^-2 in 6 M KOH at 80 °C, with an average cell voltage of 1.798 V. However, high BDC-ZIF-8 loadings induced greater morphological heterogeneity and less stable area resistance during prolonged ex situ alkaline exposure. These results demonstrate that waste PET-derived BDC-ZIF-8 can function as an electrolyte-retaining MOF filler for NPBI-based ISMs, while also emphasizing that filler loading must be optimized to balance electrolyte retention, ion transport, membrane morphology, and alkaline stability.

Catalytic conversion of oxygenated PET‐derived intermediates into deoxygenated chemicals provides a viable strategy for plastic waste valorization. In this study, selective hydrodeoxygenation (HDO) and hydrodecarboxylation of bis(2‐hydroxyethyl) terephthalate (BHET) were conducted using Ru‐containing perovskite‐based catalysts. Among the investigated perovskites, SrTiO ₃ exhibited the highest yield of deoxygenated products. The Ru/(Ru+Ti) ratio at the B‐site and the reduction temperature for Ru exsolution were systematically adjusted to optimize surface structure and catalytic performance. The catalyst with Ru/(Ru+Ti) = 0.1 (SrTi _0.9 Ru _0.1 O _y ) reduced at 550 °C achieved the highest cyclohexane selectivity (69%) and deoxygenated product yield (40 carbon%). Compared with catalysts prepared by Ru impregnation on SrTiO ₃ and TiO ₂ supports, the exsolved catalyst exhibited superior activity. Analysis using control catalysts indicates that the improved performance originates from the interaction between exsolved Ru species and surface oxygen vacancies. These findings demonstrate the potential of perovskite‐based catalysts for deoxygenation reactions in plastic upcycling and clarify the influence of surface structure on catalytic performance.

The KOH treatment of thermally degraded PVC residues produces a microporous carbon support with a BET surface area of 3273 m ² g ⁻¹ . Ru catalysts supported on this carbon exhibit high guaiacol hydrodeoxygenation activity.

The functionalization of DNA origami with peptides is a powerful strategy for creating nanodevices for therapeutic and diagnostic applications. A critical but often overlooked challenge is the non‐specific electrostatic binding of cationic peptides to the anionic DNA nanostructure, which leads to uncontrolled stoichiometry and undermines functional predictability. Here, the study systematically characterizes this issue and demonstrates a practical purification strategy to mitigate it. It is quantitatively shown that cationic peptides associate with DNA origami in vast excess of their intended binding sites, a phenomenon not observed with anionic control peptides. This non‐specific binding is confirmed to be electrostatic and is effectively screened by high salt. To address this, a charge‐dependent purification approach is evaluated using polyethylene glycol (PEG) precipitation, showing that cationic peptides require extensive purification (≥7 cycles), whereas anionic peptides need only minimal treatment (2 cycles) to achieve precise loading. Crucially, the study provides definitive functional evidence that a therapeutic peptide (brain‐derived neurotrophic factor‐mimicking peptide) must be attached via stable, site‐specific hybridization to elicit a potent biological response; non‐specifically adsorbed peptides are largely inactive. This work provides a set of critical design guidelines and purification considerations necessary for the rational design of reliable and functionally predictable DNA nanodevices.