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The specific capacity of Li- and Mn-rich layered oxide (LMROs) cathodes can be enhanced by the oxidation of lattice oxygen at high voltages. Nevertheless, an irreversible oxygen loss emerges with cycling, which triggers interlocking surface/interface issues and results in the fast deterioration of cycling performance. Herein, we prepare a surface modified LMRO electrode by one step doctor-blade casting and introducing a benzoquinone species DBBQ redox couple. The electrochemical test shows that the DBBQ-modified electrode has a high reversible capacity (>320 mAh g -1 ) and excellent rate performance, while the cyclic stability has been significantly improved as well. The capacity retention reaches as high as 93.3% after 500 cycles at 1 C. Mechanism analysis shows that DBBQ can not only play a redox couple in LMROs which achieves the adsorption and reduction of surface oxygen gas but also significantly enhance anionic redox in the bulk, thus realizing extraordinary capacity.

Ultrathin topological insulator membranes are building blocks of exotic quantum matter. However, traditional epitaxy of these materials does not facilitate stacking in arbitrary orders, while mechanical exfoliation from bulk crystals is also challenging due to the non-negligible interlayer coupling therein. Here we liberate millimeter-scale films of the topological insulator Bi 2 Se 3 , grown by molecular beam epitaxy, down to 3 quintuple layers. We characterize the preservation of the topological surface states and quantum well states in transferred Bi 2 Se 3 films using angle-resolved photoemission spectroscopy. Leveraging the photon-energy-dependent surface sensitivity, the photoemission spectra taken with 6 and 21.2 eV photons reveal a transfer-induced migration of the topological surface states from the top to the inner layers. By establishing clear electronic structures of the transferred films and unveiling the wave function relocation of the topological surface states, our work lays the physics foundation crucial for the future fabrication of artificially stacked topological materials with single-layer precision.

The efficient capture and immobilization of radioiodine (I - , IO 3 - ) is of great importance in radioactive waste management. Here, a Cu 2 O-loaded three-dimensional bulk cationic hydrogel composite (Cu 2 O@CH) was successfully prepared by simple redox reactions and UV photopolymerization, which realized the rapid enrichment and efficient immobilization of I - and IO 3 - . The adsorption experiments showed that the maximum adsorption capacity of Cu 2 O@CH for I - in the solution at pH = 3 reached 416.5 mg/g, and the adsorption capacity of IO 3 - in the solution at pH = 6 could reach 313.4 mg/g. It exhibited extremely fast adsorption kinetics for I - and IO 3 - . In addition, Cu 2 O@CH also exhibited efficient I - and IO 3 - removal from simulated high-level liquid waste. The rapid capture and effective immobilization of radioiodine (I - , IO 3 - ) were realized by the electrostatic interaction of -N + (CH 3 ) 3 groups in Cu 2 O@CH with I - and IO 3 - , as well as the chemical reactions between Cu 2 O and I - . The bulk cationic hydrogel composite explored the multifunctional role toward fast, high adsorption capability and easy handling, highlighting its superiority compared to the powder adsorbent, which renders it a potential adsorbent for the removal of radioactive iodine (I - , IO 3 - ) in nuclear wastewater treatment.

Tailoring magnetic orders in topological insulators is critical to the realization of topological quantum phenomena. An outstanding challenge is to find a material where atomic defects lead to tunable magnetic orders while maintaining a nontrivial topology. Here, by combining magnetization measurements, angle-resolved photoemission spectroscopy, and transmission electron microscopy, we reveal disorder-enabled, tunable magnetic ground states in MnBi 6 Te 10 . In the ferromagnetic phase, an energy gap of 15 meV is resolved at the Dirac point on the MnBi 2 Te 4 termination. In contrast, antiferromagnetic MnBi 6 Te 10 exhibits gapless topological surface states on all terminations. Transmission electron microscopy and magnetization measurements reveal substantial Mn vacancies and Mn migration in ferromagnetic MnBi 6 Te 10 . We provide a conceptual framework where a cooperative interplay of these defects drives a delicate change of overall magnetic ground state energies and leads to tunable magnetic topological orders. Our work provides a clear pathway for nanoscale defect-engineering toward the realization of topological quantum phases.

When a metal makes contact with a band insulator, charge transfer occurs across the interface leading to band bending and a Schottky barrier with rectifying behavior. The nature of metal-Mott insulator junctions, however, is still debated due to challenges in experimental probes of such vertical heterojunctions with buried interfaces. Here, we grow lateral polymorphic heterostructures of single-layer metallic 1H and Mott insulating 1T NbSe 2 by molecular beam epitaxy. We find a one-dimensional metallic channel along the interface due to the appearance of quasiparticle states with an intensity decay following 1/ x 2 , indicating an impenetrable barrier. Near the interface, the Mott gap exhibits a strong spatial dependence arising from the difference in lattice constants between the two phases, consistent with our density functional theory calculations. These results provide clear experimental evidence for an impenetrable barrier at the metal-Mott insulator junction and the high tunability of a Mott insulator by strain.

Halide solid electrolytes have been considered as the most promising candidates for practical high-voltage all-solid-state lithium-ion batteries (ASSLIBs) due to their moderate ionic conductivity and good interfacial compatibility with oxide cathode materials. Aliovalent ion doping is an effective strategy to increase the ionic conductivity of halide electrolytes. However, the effects of ion doping on the electrochemical stability window of halide electrolytes and carbon additive on electrochemical performance are still unclear by far. Herein, a series of Zr-doped Li 3- x Er 1- x Zr x Cl 6 halide solid electrolytes (SEs) are synthesized through a mechanochemical method and the effects of Zr substitution on the ionic conductivity and electrochemical stability window are systematically investigated. Zr doping can increase the ionic conductivity, whereas it narrows the electrochemical stability window of the Li 3 ErCl 6 electrolyte simultaneously. The optimized Li 2.6 Er 0.6 Zr 0.4 Cl 6 electrolyte exhibits both a high ionic conductivity of 1.13 mS cm -1 and a high oxidation voltage of 4.21 V. Furthermore, carbon additives are demonstrated to be beneficial for achieving high discharge capacity and better cycling stability and rate performance for halide-based ASSLIBs, which are completely different from the case of sulfide electrolytes. ASSLIBs with uncoated LiCoO 2 cathode and carbon additives exhibit a high discharge capacity of 147.5 mAh g -1 and superior cycling stability with a capacity retention of 77% after 500 cycles. This work provides an in-depth understanding of the influence of ion doping and carbon additives on halide solid electrolytes and feasible strategies to realize high-energy-density ASSLIBs.

The downscaling of nonlinear optical devices is significantly hindered by the inherently weak nonlinearity in regular materials. Here, we report a giant third-harmonic generation discovered in epitaxial thin films of V-VI chalcogenide topological insulators. Using a tailored substrate and capping layer, a single reflection from a 13 nm film can produce a nonlinear conversion efficiency of nearly 0.01%, a performance that rivals micron-scale waveguides made from conventional materials or metasurfaces with far more complex structures. Such strong nonlinear optical emission, absent from the topologically trivial member in the same compound family, is found to be generated by the same bulk band characteristics that are responsible for producing the band inversion and the nontrivial topological ordering. This finding reveals the possibility of obtaining superior optical nonlinearity by examining the large pool of newly discovered topological materials with similar band characteristics.

How superconductivity emerges from antiferromagnetic ordering is an essential question for Fe-based superconductors. Here, we explore the effect of dimensionality on the interplay between antiferromagnetic ordering and superconductivity by investigating nanoribbons of single-layer FeTe 1- x Se x films grown on SrTiO 3 (001) substrates by molecular beam epitaxy. Using scanning tunneling microscopy/spectroscopy, we find a one-dimensional (1D) superconducting channel 2 nm wide with a T C of 42 ± 4 K on the edge of FeTe 1- x Se x ( x < 0.1) ribbons, coexisting with a non-superconducting ribbon interior that remains bicollinear antiferromagnetically ordered. Density functional theory calculations indicate that both Se and the presence of the edge destabilize the bicollinear antiferromagnetic magnetic order, resulting in a paramagnetic region near the edge with strong local checkerboard fluctuations that is conducive to superconductivity. Our results represent the highest T C achieved in 1D superconductors and demonstrate an effective route toward stabilizing superconductivity in Fe-based superconductors at reduced dimensions.

The de Gennes extrapolation length is a direction dependent measure of the spatial evolution of the pairing gap near the boundary of a superconductor and thus provides a viable means to probe its symmetry. It is expected to be infinite and isotropic for plain s-wave pairing, and finite and anisotropic for d-wave. Here, we synthesize single-layer FeSe films on SrTiO 3 (001) (STO) substrates by molecular beam epitaxy and measure the de Gennes extrapolation length by scanning tunneling microscopy/spectroscopy. We find a 40% reduction of the superconducting gap near specular [110] Fe edges, yielding an extrapolation length of 8.0 nm. However, near specular [010] Fe edges, the extrapolation length is nearly infinite. These findings are consistent with a phase changing pairing with 2-fold symmetry, indicating d-wave superconductivity. This is further supported by the presence of in-gap states near the specular [110] Fe edges, but not the [010] Fe edges. This work provides direct experimental evidence for d-wave superconductivity in single-layer FeSe/STO and demonstrates quasiparticle scattering at boundaries to be a viable phase sensitive probe of pairing symmetry in Fe-based superconductors.