Eduardo Villalobos-Portillo

Label-free X-ray fluorescence imaging tracks nanomedicine diffusion in biological matrices within 3D-printed microfluidic devices.

The rational design of single‐cluster catalysts (SCCs) for the oxygen reduction reaction (ORR) is hindered by difficulties in achieving atomic precision, high site‐density and resistance to aggregation during synthesis and operation. To address these challenges, we report a NiN ₄ C‐coordinated cobalt‐based SCC which is synthesized via a gradient pyrolysis‐driven stepwise anchoring strategy that enables the sequential thermal anchoring of Ni and Co species. Well‐defined NiN ₄ C moieties are anchored on the carbon support at the lower pyrolysis temperature; these sites subsequently capture cobalt oxide fragments at a higher pyrolysis temperature, leading to the formation of a NiN ₄ C‐site coordinated stable Co ₃ O ₅ NiN ₄ C ensemble. Advanced in situ spectroscopy, cyclic voltammetry and density functional theory calculations infer its electrochemical transformation into an active Co ₃ O ₁ NiN ₄ C phase prior to the onset of ORR. The triangular Co ₃ motif facilitates side‐on adsorption, elongating the O‐O bond and lowering the dissociation energy barrier for the rate‐determining step. Consequently, the catalyst delivers exceptional ORR performance, achieving a half‐wave potential of 0.923 V vs. RHE, an active‐site density of 4.16 × 10 ²⁰ sites g ⁻¹ , and a peak power density of 247.3 mW cm ⁻² in Zinc‐air batteries. This work provides an effective strategy for designing stable, efficient oxygen electrocatalysts by precisely engineered cluster architecture.

Oxygen-vacancy engineering regulates the electronic structure and Zn ²⁺ /H ⁺ storage kinetics of Mn ₂ O ₃ , promoting ion transport, reversible dual-ion storage, and improved rate capability and cycling stability in aqueous zinc-ion batteries.

Understanding the dynamic evolution of heterogeneous catalysts under harsh conditions is critical for controlling active site activation and deactivation. In this work, we investigate the hydrothermal evolution and reaction-driven dynamics of Pd confined within CHA zeolite. The confinement effect of the CHA framework successfully stabilizes Pd as subnanometer clusters, even after severe hydrothermal aging at 850 °C. Utilizing this robust system, we elucidate the structural transformations of Pd species during methane combustion to establish the structure–reactivity relationship. We find that ∼10 nm Pd nanoparticles exhibit higher activity relative to subnanometer clusters and larger aggregates (>20 nm), a trend consistent across CHA, MCM-22, MOR, and ZSM-5. Notably, Pd sintering under reaction conditions is driven by CO, a key intermediate in methane activation. Furthermore, steam exacerbates this CO-mediated sintering by enhancing methane activation and accelerating catalyst deactivation. These findings provide fundamental insights into the evolution of zeolite-confined metal catalysts, guiding the design of durable catalytic systems.

Substituting homogeneous metal catalysts with recyclable heterogeneous metal catalysts has long been a goal in catalysis. However, most approaches yield heterogeneous metal catalysts that often exhibit relatively low stability and diminished catalytic activity under practical reaction conditions. Herein, we present an inorganic Rh catalyst obtained by confining subnanometer Rh clusters within a self-pillared zeolite structure. This catalyst design not only stabilizes the subnanometer Rh active sites but also facilitates efficient mass transport properties during solvent-free olefin hydroformylation reaction. Owing to the unique electronic properties of the Rh clusters and the optimal morphology of the zeolite support, the optimal catalyst achieves over 1,100,000 total turnovers across a broad substrate range under solvent-free conditions. This strategy can be extended to other metals confined within self-pillared zeolite, offering a general approach to circumvent the wettability issue of heterogeneous metal catalysts for solvent-free organic transformations.

Rare-earth barium copper oxide (REBCO) coated conductors (CCs) are regarded as promising candidates for next-generation superconducting technologies operating in photon-rich environments, such as particle accelerators, fusion reactors, and high-field radio-frequency (RF) systems. Although the effects of ion and neutron irradiation on the superconducting properties of REBCO have been partially investigated, particularly in the context of enhancing vortex pinning, the radiation environments relevant to emerging applications require more thorough studies. This also includes photon-induced degradation, which remains less explored, particularly in the low-energy hard x-ray regime. In this study, the influence of synchrotron-generated photons in the 2–30 keV range on the superconducting performance of commercially available REBCO-CCs is investigated. The evolution of critical current density, critical temperature, and surface impedance is examined through in-situ measurements of DC and RF properties conducted during irradiation at the NOTOS beamline (ALBA Synchrotron). The findings reveal that photon exposure within this energy range showed no evidence of irreversible radiation-induced changes under the conditions tested. At higher power levels, reversible perturbations in superconducting properties were observed, primarily due to thermal effects, underscoring the importance of thermal management. These effects are influenced by the experimental setup and may be mitigated in practical applications by ensuring sufficient thermal contact with a cold sink or through direct cooling using refrigerated gases or liquids. Nevertheless, these results emphasise the importance of considering thermal management and photon-induced effects when implementing REBCO-based systems in radiation-rich environments.

Structural repair is a vital step in the direct recycling of spent LiNi _x Co _y Mn _z O ₂ lithium‐ion batteries, yet its underlying mechanisms remain insufficiently clear. Herein, the thermal solid‐state structural repair of spent LiNi _0.6 Co _0.2 Mn _0.2 O ₂ (NCM622) layered cathode material is systematically investigated. Through multiscale techniques combining XRD, XAS, and ⁶ Li solid‐state NMR, we identify the structural degradation in spent NCM622 and monitor both long‐ and short‐range structural evolution during repair. Our findings reveal that degradation predominantly occurs through Ni migration into Li octahedral sites, while Co and Mn demonstrate relatively lower occupancies in the Li layer. Such occupancies are primarily responsible for structural disorder and cubic‐symmetry domain formation within the spent material. The repair process is demonstrated to involve re‐lithiation, oxygen capture, increased transition metal (TM) oxidation states, and the migration of TM ions from the Li layer back to the TM layer, followed by cation diffusion. Both temperature and lithium compensation ratio are identified as critical factors promoting these processes. Capacity recovery studies show a strong correlation between reduced TM occupancy in the Li layer and improved electrochemical performances. These insights allow us to move beyond conventional phase‐transition perspectives, offering an atomic‐level understanding of structural degradation and repair mechanisms in spent layered cathode materials.