ABSTRACT Natural pentamer dodecahedra (Ddhs) span six orders of magnitude in diameter. Among proteins, only two catalytic Ddhs have been structurally characterized: lumazine synthase (LS) and the core of pyruvate dehydrogenase (PDH). Zuzalysin (ZUZ) is a ≈95‐kDa metallopeptidase secreted for virulence by Porphyromonas gingivalis . Calcium converts latent flexible monomers into active ≈0.5‐MDa pentamers that further assemble hierarchically into bipentamers, tripentamers, and a ≈5.6‐MDa, ≈355‐Å virus‐like dodecahedron (Ddh ZUZ ). Experimental structures (1.8–3.6 Å) across these states reveal the molecular basis of activation, association, and catalysis, culminating in Ddh ZUZ , which is physiologic, exceeds small viral capsids, and has 20 main entry pores and 60 lumen‐facing active sites. ZUZ represents the largest catalytic protein assembly resolved at high resolution, exceeding LS, PDH, and major peptidase complexes in size and/or resolution.
ABSTRACT Sustainable ammonia production can be achieved via an electrochemical process coupling the lithium redox‐mediated nitrogen reduction (Li‐NRR) with hydrogen oxidation, but a more practical approach uses water oxidation (the oxygen evolution reaction; OER) as the anode reaction. However, coupling the Li‐NRR and the OER is restricted by incompatibility of the anhydrous conditions required for nitrogen reduction with water. Aiming to resolve this, we investigated an electrolyser with an electrochemical palladium‐based membrane, which transforms protons generated by the OER to palladium hydride in aqueous media and releases protons into non‐aqueous Li‐NRR media to sustain ammonia production. The hydride formation/oxidation mechanism, validated through experiments with deuterated water, ensures exclusive membrane selectivity to protons, and is facilitated by the palladium‐gold electrocatalysts. We demonstrate ammonia electrosynthesis from nitrogen (15 bar) and water at a faradaic efficiency of 59 ± 4%, yield rate of 20 ± 1 nmol s −1 cm −2 and energy efficiency of 9.0 ± 0.7% over more than two days. However, deeper investigation of the system revealed ammonia‐promoted corrosion of the palladium‐based membrane—a challenge that needs to be addressed in the future developments of this technology.
ABSTRACT Anisotropic swelling of ion‐exchange membranes (IEMs)—a phenomenon that is both physically inevitable and operationally detrimental—poses disproportionately severe interfacial instability challenges in ultralow‐Pt membrane electrode assemblies (MEAs). Here, we report a counterintuitive yet effective strategy, termed resolving swelling by swelling, in which the catalyst layer/IEM (CL/IEM) interface is constructed directly on a fully preswollen membrane. By exploiting the dynamic interplay between interchain hydrogen bonding and intrachain elastic contraction inherent to the membrane network, this approach harnesses controlled swelling to drive the in situ optimization of a three‐dimensional interpenetrating CL/IEM interface. The resulting interface exhibits reinforced interfacial stability under operating conditions, a water‐mediated active area resistant to ionomer poisoning, and enhanced gas and ion transport pathways. MEAs fabricated via this strategy deliver a peak power density of 1.22 W cm −2 under H 2 /Air conditions at an ultralow cathode Pt loading of 0.05 mg Pt cm −2 , representing a 1.68‐fold improvement over conventionally fabricated proton exchange membrane fuel cells, alongside a record‐breaking cathode Pt utization of 24.4 kW g Pt −1 . These MEAs sustain excellent electrochemical performance under low‐humidity operating conditions, long‐term durability and 10 000 wet‐dry cycles. The broad applicability of this strategy is further validated by its successful extension to anion exchange membrane fuel cells.
ABSTRACT While highly ordered self‐assembled monolayers (SAMs) are critically important for inverted perovskite solar cells (i‐PSCs), precise control over molecular orientation remains a persistent challenge, hindering the concurrent achievement of high efficiency and long‐term stability. To address this issue, we unveil that the molecular orientation of SAMs based on bis‐carbazole phosphonates is governed by their conformational structures, which can be finely modulated through tailored carbazole–carbazole binding geometries. These structurally ordered layers provide a robust platform for deliberate energy level alignment and enhanced charge transport selectivity, enabling a certified power conversion efficiency of 27.2%, an impressive value that ranks among the highest reported for i‐PSCs. Moreover, owing to the robust anchoring capability afforded by the bis‐phosphonate design, the devices exhibit extended operational stability—retaining 96% of their initial efficiency after 1400 h under one‐sun illumination and maximum power point tracking, and show excellent compatibility with scalable fabrication in ambient air. This work thus establishes a powerful chemical strategy for tailoring molecular orientation, providing a promising molecular design paradigm for advancing perovskite photovoltaics.
ABSTRACT Red multi‐resonance (MR) emitters are highly desirable for high‐definition OLED displays, yet achieving narrowband emission, high efficiency, and suppressed efficiency roll‐off simultaneously remains a formidable challenge. Herein, we introduce a C‐C bond‐linked fluorene‐framework engineering that modulates the 3D environment around the BNO core through σ‐decoupled sp 3 node at C9 position of a fluorenol unit. Two emitters, SF‐BNO, and PF‐BNO, sharing a π‐system, but differing in the ring‐closure state of the two aryl arms at C9, provide a controlled test of decoupling strategy. Both emitters exhibited narrowband red emission at 618 nm with a full‐width half‐maximum (FWHM) of 34 nm, while PF‐BNO achieved a high photoluminescence quantum yield (PLQY) of 98%. When implemented in exciplex‐assisted phosphorescence‐sensitized fluorescence OLEDs using SF‐BNO and PF‐BNO as final emitters, the devices delivered maximum external quantum efficiencies (EQE max ) of 29.51% and 31.87%, respectively, and retained to ultra‐low roll‐off ratios of 0.3% and 1.1%, respectively. Furthermore, optimized top‐emission (TE) PF‐BNO OLED achieved a current efficiency of 61.03 cd A −1 . Microcavity‐mediated spectral narrowing produced saturated red emission at 620 nm with an ultra‐narrow 23 nm FWHM and CIE coordinates of (0.68, 0.31), approaching BT.2020 while maintaining high efficiency and reduced roll‐off, confirming the effectiveness of this strategy.
