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1. Electrochemical lithiation of the layered superionic conductors AgCrSe₂ and CuCrSe₂

   https://doi.org/10.26434/chemrxiv-2025-wg75n  

   Moon, Seongbak; Rahman, Md Towhidur; Holzapfel, Noah P; Zevalkink, Alexandra; Augustyn, Veronica (October 2025, ChemRxiv)

   The layered transition metal chalcogenides MCrX₂ (M = Ag, Cu; X = S, Se, Te) are of interest for energy storage because chemically Li-substituted analogs were reported as superionic Li⁺ conductors. The coexistence of fast ion transport and reducible transition metal and chalcogen elements suggests that this family may offer multifunctional capability for electrochemical storage. Here, we investigate the electrochemical reduction of AgCrSe₂ and CuCrSe₂ in non-aqueous Li- and Na-ion electrolytes using electrochemical measurements coupled with ex situ characterization (scanning electron microscopy, energy-dispersive spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy). Both compounds delivered high initial specific capacities (~ 560 mAh/g), corresponding to 6.64 and 5.73 Li⁺/e^- per formula unit for AgCrSe₂ and CuCrSe₂, respectively. We attribute this difference to distinct reduction pathways: 1) Li⁺ intercalation to form LiCrSe₂ and extruded Ag or Cu, 2) conversion of LiCrSe₂ to Li₂Se, and 3) formation of an Ag-Li alloy at the lowest potential, operative only in AgCrSe₂. Consistent with this proposed mechanism, step 3 was absent during reduction of AgCrSe₂ in a Na-ion electrolyte since Ag does not alloy with Na. These results demonstrate the complex reduction chemistry of MCrX₂ in the presence of alkali ions, providing insights into the use of MCrX₂ materials as alkali ion superionic conductors or high capacity electrodes for lithium or sodium-ion type batteries. 

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2. Chemo-mechanical degradation in V ₂ O ₅ thin film cathodes of Li-ion batteries during electrochemical cycling

   https://doi.org/10.1039/c9ta05243g  

   Zhang, Yuwei; Luo, Yuting; Fincher, Cole; Banerjee, Sarbajit; Pharr, Matt (October 2019, Journal of Materials Chemistry A)

   We have devised an approach to fabricate dense textured V 2 O 5 thin films, which allows us to scrutinize the root cause of capacity fade in V 2 O 5 cathodes of Li-ion batteries. Specifically, we performed in situ measurements of stress of V 2 O 5 thin films during 50 electrochemical cycles. Surprisingly, electrochemical cycling appears to induce elastic and rate-independent deformation over a voltage range relevant to battery operation (4–2.8 V). However, the compressive stresses gradually increase with cycle number during the first few cycles, likely due to side reactions and/or residual Li left in the V 2 O 5 , even after delithiation (to 4 V). Further cycling leads to accumulated mechanical damage ( e.g. , fracture, delamination) and structural damage ( e.g. , amorphization), which ultimately result in severe capacity fade. 

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3. Point defect creation by proton and carbon irradiation of α-Ga ₂ O ₃

   https://doi.org/10.1063/5.0100359  

   Polyakov, Alexander Y.; Nikolaev, Vladimir I.; Meshkov, Igor N.; Siemek, Krzysztof; Lagov, Petr B.; Yakimov, Eugene B.; Pechnikov, Alexei I.; Orlov, Oleg S.; Sidorin, Alexey A.; Stepanov, Sergey I.; et al (July 2022, Journal of Applied Physics)

   Films of α-Ga 2 O 3 grown by Halide Vapor Phase Epitaxy (HVPE) were irradiated with protons at energies of 330, 400, and 460 keV with fluences 6 × 10 15  cm −2 and with 7 MeV C 4+ ions with a fluence of 1.3 × 10 13  cm −2 and characterized by a suite of measurements, including Photoinduced Transient Current Spectroscopy (PICTS), Thermally Stimulated Current (TSC), Microcathodoluminescence (MCL), Capacitance–frequency (C–f), photocapacitance and Admittance Spectroscopy (AS), as well as by Positron Annihilation Spectroscopy (PAS). Proton irradiation creates a conducting layer near the peak of the ion distribution and vacancy defects distribution and introduces deep traps at E c -0.25, 0.8, and 1.4 eV associated with Ga interstitials, gallium–oxygen divacancies V Ga –V O , and oxygen vacancies V O . Similar defects were observed in C implanted samples. The PAS results can also be interpreted by assuming that the observed changes are due to the introduction of V Ga and V Ga –V O . 

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4. Selective Electrochemical Conversion of CO ₂ into Methane on Ag‐Decorated Copper Microsphere

   https://doi.org/10.1002/open.202400173  

   Dahal, Rabin; Srivastava, Rohit; Prasad_Bastakoti, Bishnu (October 2024, ChemistryOpen)

   Abstract We synthesized the silver‐decorated copper microsphere via the hydrothermal method followed by photoreduction of silver ions. Sub 100 nm Ag nanoparticles anchored on the surface of Cu microspheres enhance the electrochemical performance and the selectivity of the CO₂reduction into CH₄. Incorporating Ag nanoparticles onto Cu lowers the charge transfer resistance, enhancing the catalyst's conductivity and active site and increasing the rate of CO₂reduction. The faradaic efficiency of silver nanoparticles decorated copper microsphere for methane was 70.94 %, almost twice that of a copper microsphere (44 %). The electrochemical performance showed higher catalytic properties, stability, and faradaic efficiency of silver‐decorated copper microspheres. 

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5. Epitaxial NiCo ₂ O ₄ film as an emergent spintronic material: Magnetism and transport properties

   https://doi.org/10.1063/5.0095326  

   Xu, Xiaoshan; Mellinger, Corbyn; Cheng, Zhi Gang; Chen, Xuegang; Hong, Xia (July 2022, Journal of Applied Physics)

   The ferrimagnetic inverse spinel NiCo 2 O 4 has attracted extensive research interest for its versatile electrochemical properties, robust magnetic order, high conductivity, and fast spin dynamics, as well as its highly tunable nature due to the closely coupled charge, spin, orbital, lattice, and defect effects. Single-crystalline epitaxial thin films of NiCo 2 O 4 present a model system for elucidating the intrinsic physical properties and strong tunability, which are not viable in bulk single crystals. In this Perspective, we discuss the recent advances in epitaxial NiCo 2 O 4 thin films, focusing on understanding its unusual magnetic and transport properties in light of crystal structure and electronic structure. The perpendicular magnetic anisotropy in compressively strained NiCo 2 O 4 films is explained by considering the strong spin–lattice coupling, particularly on Co ions. The prominent effect of growth conditions reveals the complex interplay between the crystal structure, cation stoichiometry, valence state, and site occupancy. NiCo 2 O 4 thin films also exhibit various magnetotransport anomalies, including linear magnetoresistance and sign change in anomalous Hall effect, which illustrate the competing effects of band-intrinsic Berry phase and impurity scattering. The fundamental understanding of these phenomena will facilitate the functional design of NiCo 2 O 4 thin films for nanoscale spintronic applications. 

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