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1. High‐Valence Metal Modulating Lattice Oxygen in High‐Entropy Layered Double Hydroxides for Enhanced Oxygen Evolution Reaction

   https://doi.org/10.1002/adfm.202518240  

   Zhong, Xiahua; Wang, Hong‐Yi; Zhang, Chen; Wang, Wenhu; Nelson, Christopher T; He, Xiaoqing; Sun, Qingqing; Gibson, Benjamine G; Neupane, Manish; Deng, Baolin; et al (November 2025, Advanced Functional Materials)

   Abstract The oxygen evolution reaction (OER) is hindered by sluggish kinetics due to its complex four‐electron, proton‐coupled mechanism. While noble metal oxides like IrO₂and RuO₂are effective OER catalysts, their high cost and unsatisfactory stability limit large‐scale applications. High‐entropy layered double hydroxides (HE‐LDHs) offer a promising alternative by enabling multi‐metallic site tuning and entropy‐driven phase stabilization. Herein, VCoNiCuZn and MoCoNiCuZn HE‐LDHs respectively modulated by high‐valence V⁴⁺/V⁵⁺and Mo⁶⁺are hydrothermally synthesized on Ni foam. The MoCoNiCuZn HE‐LDH achieved an overpotential of 186 mV at 10 mA cm⁻², which is significantly lower than that of 306 mV obtained from CoNiCuZn LDH. The strong M‐O covalency induced by high‐valence metals facilitates charge redistribution andd‐porbital overlap, activating lattice oxygen and promoting the lattice oxygen mechanism (LOM). The resulting OER performance surpasses most reported multi‐principal element materials and rivals noble‐metal‐doped LDHs. Moreover, high‐entropy stabilization presents excellent structural durability and long‐term electrochemical stability, highlighting the promise of noble‐metal‐free HE‐LDHs for water splitting. 

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2. Spin-orbital Jahn-Teller bipolarons

   https://doi.org/10.1038/s41467-024-46621-0  

   Celiberti, Lorenzo; Fiore_Mosca, Dario; Allodi, Giuseppe; Pourovskii, Leonid V; Tassetti, Anna; Forino, Paola Caterina; Cong, Rong; Garcia, Erick; Tran, Phuong M; De_Renzi, Roberto; et al (December 2024, Nature Communications)

   Abstract Polarons and spin-orbit (SO) coupling are distinct quantum effects that play a critical role in charge transport and spin-orbitronics. Polarons originate from strong electron-phonon interaction and are ubiquitous in polarizable materials featuring electron localization, in particular 3d transition metal oxides (TMOs). On the other hand, the relativistic coupling between the spin and orbital angular momentum is notable in lattices with heavy atoms and develops in 5d TMOs, where electrons are spatially delocalized. Here we combine ab initio calculations and magnetic measurements to show that these two seemingly mutually exclusive interactions are entangled in the electron-doped SO-coupled Mott insulator Ba₂Na_1−xCa_xOsO₆(0 < x < 1), unveiling the formation ofspin-orbital bipolarons. Polaron charge trapping, favoured by the Jahn-Teller lattice activity, converts the Os 5d¹spin-orbital J_eff = 3/2 levels, characteristic of the parent compound Ba₂NaOsO₆(BNOO), into a bipolaron 5d²J_eff = 2 manifold, leading to the coexistence of different J-effective states in a single-phase material. The gradual increase of bipolarons with increasing doping creates robust in-gap states that prevents the transition to a metal phase even at ultrahigh doping, thus preserving the Mott gap across the entire doping range from d¹BNOO to d²Ba₂CaOsO₆(BCOO). 

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3. Nanoscale visualization and spectral fingerprints of the charge order in ScV6Sn6 distinct from other kagome metals

   https://doi.org/10.1038/s41535-024-00623-9  

   Cheng, Siyu; Ren, Zheng; Li, Hong; Oh, Ji Seop; Tan, Hengxin; Pokharel, Ganesh; DeStefano, Jonathan M; Rosenberg, Elliott; Guo, Yucheng; Zhang, Yichen; et al (December 2024, npj Quantum Materials)

   Abstract Charge density waves (CDWs) in kagome metals have been tied to many exotic phenomena. Here, using spectroscopic-imaging scanning tunneling microscopy and angle-resolved photoemission spectroscopy, we study the charge order in kagome metal ScV₆Sn₆. The similarity of electronic band structures of ScV₆Sn₆and TbV₆Sn₆(where charge ordering is absent) suggests that charge ordering in ScV₆Sn₆is unlikely to be primarily driven by Fermi surface nesting of the Van Hove singularities. In contrast to the CDW state of cousin kagome metals, we find no evidence supporting rotation symmetry breaking. Differential conductance dI/dVspectra show a partial gapΔ¹_CO ≈ 20 meV at the Fermi level. Interestingly, dI/dVmaps reveal that charge modulations exhibit an abrupt phase shift as a function of energy at energy much higher thanΔ¹_CO, which we attribute to another spectral gap. Our experiments reveal a distinctive nature of the charge order in ScV₆Sn₆with fundamental differences compared to other kagome metals. 

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4. Mapping Acid–Base Sites on Anatase Titania (100) and (101) Surfaces by Density Functional Theory: The Link Between Lewis Acidity and the Surface Ability to Flex

   https://doi.org/10.3390/surfaces7040070  

   Ignatchenko, Alexey V; Denman, Paige E (December 2024, Surfaces)

   The acidity of anatase titania before and after KOH doping was probed by pyridine adsorption in a pulse microreactor and modeled by DFT optimization of the geometry of CO and pyridine adsorption on a periodic slab of (101) and (100) surfaces using a GGA/PBE functional and verified by an example of a single-point calculation of the optimized geometry using an HSE-06 hybrid functional. The anatase (101) surface was slightly more acidic compared to the (100) surface. Both experimental and computational methods show that the acidity of anatase surfaces decreased after KOH doping and increased after the dissociative adsorption of water. Higher acidity of Ti metal centers was indicated by the shortening of the Ti-N, Ti-C, and C-O bond lengths, increasing the IR frequency of CO and pyridine ring vibrations and energy of adsorption. The DFT calculated energy of pyridine adsorption was analyzed in terms of binding energy and the energy of lattice distortion. The latter was used to construct Hammett plots for the adsorption of 4-substituted pyridines with electron-donating and -withdrawing substituents. The Hammett rho constant was obtained and used to characterize the acidity of various metal centers of −1.51 vs. −1.46 on pristine (101) and (100) surfaces, which were lowered to −1.07 and −1.19 values on KOH-doped (101) and (100) surfaces, respectively. The mechanism of lowering surface acidity via KOH doping proceeds through the stabilization of the atomic structure of Lewis acid centers. When an alkaline metal cation binds to several lattice oxygen atoms, the surface structure becomes more rigid. The ability of Ti atoms to move toward the adsorbate is restricted. Consequently, the lattice distortion energy and binding energy are decreased. In contrast, higher flexibility of the outermost layer of Ti atoms as a result of electron density redistribution, for example, in the presence of water on the surface, allows them to move farther outward, make shorter contacts with the adsorbate, and attain higher energies of binding and lattice distortion. 

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5. Concentrated ternary ether electrolyte allows for stable cycling of a lithium metal battery with commercial mass loading high‐nickel NMC and thin anodes

   https://doi.org/10.1002/cey2.275  

   Yang, Jun; Li, Xing; Qu, Ke; Wang, Yixian; Shen, Kangqi; Jiang, Changhuan; Yu, Bo; Luo, Pan; Li, Zhuangzhi; Chen, Mingyang; et al (March 2023, Carbon Energy)

   Abstract A new concentrated ternary salt ether‐based electrolyte enables stable cycling of lithium metal battery (LMB) cells with high‐mass‐loading (13.8 mg cm⁻², 2.5 mAh cm⁻²) NMC622 (LiNi_0.6Co_0.2Mn_0.2O₂) cathodes and 50 μm Li anodes. Termed “CETHER‐3,” this electrolyte is based on LiTFSI, LiDFOB, and LiBF₄with 5 vol% fluorinated ethylene carbonate in 1,2‐dimethoxyethane. Commercial carbonate and state‐of‐the‐art binary salt ether electrolytes were also tested as baselines. With CETHER‐3, the electrochemical performance of the full‐cell battery is among the most favorably reported in terms of high‐voltage cycling stability. For example, LiNi_xMn_yCo_1–x–yO₂(NMC)‐Li metal cells retain 80% capacity at 430 cycles with a 4.4 V cut‐off and 83% capacity at 100 cycles with a 4.5 V cut‐off (charge at C/5, discharge at C/2). According to simulation by density functional theory and molecular dynamics, this favorable performance is an outcome of enhanced coordination between Li⁺and the solvent/salt molecules. Combining advanced microscopy (high‐resolution transmission electron microscopy, scanning electron microscopy) and surface science (X‐ray photoelectron spectroscopy, time‐of‐fight secondary ion mass spectroscopy, Fourier‐transform infrared spectroscopy, Raman spectroscopy), it is demonstrated that a thinner and more stable cathode electrolyte interphase (CEI) and solid electrolyte interphase (SEI) are formed. The CEI is rich in lithium sulfide (Li₂SO₃), while the SEI is rich in Li₃N and LiF. During cycling, the CEI/SEI suppresses both the deleterious transformation of the cathode R‐3m layered near‐surface structure into disordered rock salt and the growth of lithium metal dendrites. 

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