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Achieving both high redox activity and rapid ion transport is a critical and pervasive challenge in electrochemical energy storage applications. This challenge is significantly magnified when using large‐sized charge carriers, such as the sustainable ammonium ion (NH4+). A self‐assembled MXene/n‐type conjugated polyelectrolyte (CPE) superlattice‐like heterostructure that enables redox‐active, fast, and reversible ammonium storage is reported. The superlattice‐like structure persists as the CPE:MXene ratio increases, accompanied by a linear increase in the interlayer spacing of MXene flakes and a greater overlap of CPEs. Concurrently, the redox activity per unit of CPE unexpectedly intensifies, a phenomenon that can be explained by the enhanced de‐solvation of ammonium due to the increased volume of 3 Å‐sized pores, as indicated by molecular dynamic simulations. At the maximum CPE mass loading (MXene:CPE ratio = 2:1), the heterostructure demonstrates the strongest polymeric redox activity with a high ammonium storage capacity of 126.1 C g−1 and a superior rate capability at 10 A g−1. This work unveils an effective strategy for designing tunable superlattice‐like heterostructures to enhance redox activity and achieve rapid charge transfer for ions beyond lithium. [ABSTRACT FROM AUTHOR]

We have designed and realized a temperature and pressure controlled cell for Neutron Reflectometry (NR) and Small Angle Neutron Scattering (SANS) that is compatible with simultaneous optical transmission and resistivity measurements. The cell can accommodate samples up to 102 mm (4 inch) in diameter, can be pressurized from vacuum up to 10 bar gas pressure and the sample temperature can be controlled up to 350°C. The four single crystal quartz windows ensure both a good neutron and optical transmission and hence can be used in combination with in-situ optical transmission measurements. We present the cell and illustrate its performance with a series of neutron reflectometry experiments performed on Ta based thin films under a hydrogen containing atmosphere. [ABSTRACT FROM AUTHOR]

At ambient conditions, rare‐earth oxyhydride thin films show reversible photochromism and photoconductivity, while their mechanism and relation are still unclear. In this work, this question is explored with in situ time‐resolved measurements of both optical and transport properties of Gd‐based oxyhydride thin films. It is found that p‐type large polaron conduction is the initial mechanism of charge transport; however, upon photo‐darkening, a 104‐fold increase of conductivity occurs, and n‐type carriers become dominant. Further, photochromism and photoconductivity are shown to originate from a single process, as indicated by the fact that the photoconductivity is exponentially proportional to the increase of optical absorption. This exponential relation, notably, cannot stem from any of the optically absorbing species thought responsible for photochromism and, therefore, suggests that their formation is accompanied by a concerted increase of negative charge carriers in the Gd oxyhydride films. [ABSTRACT FROM AUTHOR]

Anode-free aqueous zinc metal batteries (AZMBs) offer significant potential for energy storage due to their low cost and environmental benefits. Ti 3 C 2 T x MXene provides several advantages over traditional metallic current collectors like Cu and Ti, including better Zn plating affinity, lightweight, and flexibility. However, self-freestanding MXene current collectors in AZMBs remain underexplored, likely due to challenges with Zn deposition reversibility. This study investigates the combination of a Ti 3 C 2 T x self-freestanding film with advanced electrolyte engineering, specifically examining the effects of Li-salt and propylene carbonate (PC) as additives on Zn plating reversibility. While using Li + ions as an additive alone facilitates uniform Zn deposition on bulk metals through the electrostatic shielding effect, the addition of Li-salt negatively impacts Zn plating uniformity on Ti 3 C 2 T x . Meanwhile, using PC additive alone forms an organic SEI layer on Ti 3 C 2 T x and causes Zn agglomeration. The use of both additives together results in a ZnF 2 -containing hybrid SEI layer with improved interfacial kinetics, promoting more uniform Zn deposition. This approach achieves an average Coulombic efficiency (CE) of 96.8% over 150 cycles (a maximum CE of 97.8%). The study highlights the strategic difference in electrolyte design, emphasizing the need for tailored approaches to optimize Zn deposition on MXenes, contrasting with traditional metallic current collectors., (© 2025 The Author(s). Small published by Wiley‐VCH GmbH.)