Over the past few decades, exciton-polaritons have attracted substantial research interest due to their half-light-half-matter bosonic nature. Coupling exciton-polaritons with magnetic orders grants access to rich many-body phenomena, but has been limited by the availability of material systems that exhibit simultaneous exciton resonances and magnetic ordering. Here we report magnetically-dressed microcavity exciton-polaritons in the van der Waals antiferromagnetic (AFM) semiconductor CrSBr coupled to a Tamm plasmon microcavity. Using angle-resolved spectroscopy, we reveal an exceptionally high exciton-photon coupling strength, up to 169 meV, demonstrating ultrastrong coupling that persists up to room temperature. By performing temperature-dependent spectroscopy, we show the magnetic nature of the exciton-polaritons in CrSBr microcavity as the magnetic order changes from AFM to paramagnetic. By applying an out-of-plane magnetic field, we achieve effective tuning of the polariton energy while maintaining the ultrastrong exciton-photon coupling strength. We attribute this to the spin canting process that modulates the interlayer exciton interaction.
The world is facing an ever-growing global energy crisis with unprecedented depth and complexity. The sustainable development of high energy density lithium-ion batteries for electric vehicles and portable electric devices has become a feasible way to deal with this problem. Silicon suboxides (SiOx) have been deemed as one of the most promising anode materials because of their ultrahigh theoretical lithium storage capacity, proper working potential, natural abundance, and environmental friendliness. However, the mass utilization of SiOx-based anodes is severely obstructed by their low electrical conductivity and inevitable volume expansion. While lithium silicate and lithium oxide formed in the first lithiation process act as buffer layers to some extent, it is urgent to address the accompanying low initial Coulombic efficiency and unsatisfactory cycling stability. In this review, we summarized recent advances in the synthesis methods of SiOx-based materials. Besides, the benefits and shortcomings of the various methods are briefly concluded. Then, we discussed the effective combination of SiOx with carbon materials and designs of porous structure, which could considerably enhance the electrochemical performance in detail. Furthermore, progresses on the modified strategies, advanced characteristics and industrial applications for SiOx-based anodes are also mentioned. Finally, the remaining challenges encountered and future perspectives on SiOx-based anodes are highlighted.
The fabrication of electrocatalysts with high activity and acid stability for acidic oxygen evolution reaction (OER) is an urgent need, yet extremely challenging. Here, we report the design and successful fabrication of a high performance self-supported cogwheel arrays-like nanoporous IrxRu1−xO2 catalyst with abundant atomic steps for acidic OER using a facile alloy-spinning-electrochemical activation method that allows large-scale fabrication. The obtained IrxRu1−xO2 catalysts merely need overpotentials of 211 and 295 mV to deliver catalytic current densities of 10 and 300 mA·cm−2 in 0.5 M H2SO4, respectively, and can sustain constant OER electrolysis for at least 140 h at a high current density of 300 mA·cm−2. Further density functional theory (DFT) calculations uncover that such high intrinsic activities mainly originate from the largely exposed high-index atomic step planes, which markedly lower the limiting potential of the rate-determining step (RDS) of OER. These findings provide an insight into the exploration of high performance electrocatalysts, and open up an avenue for further developing the state-of-the-art Ir and/or Ru-based catalysts for large-scale practical applications.
Combining logical function and memory characteristics of transistors is an ideal strategy for enhancing computational efficiency of transistor devices. Here, we rationally design a tri-gate two-dimensional (2D) ferroelectric van der Waals heterostructures device based on copper indium thiophosphate (CuInP2S6) and few layers tungsten disulfide (WS2), and demonstrate its multi-functional applications in multi-valued state of data, non-volatile storage, and logic operation. By co-regulating the input signals across the tri-gate, we show that the device can switch functions flexibly at a low supply voltage of 6 V, giving rise to an ultra-high current switching ratio of 107 and a low subthreshold swing of 53.9 mV/dec. These findings offer perspectives in designing smart 2D devices with excellent functions based on ferroelectric van der Waals heterostructures.
Hyperbolic polaritons have drawn great attention in nanoscale light manipulation due to their unique properties. Currently, most studies focus on natural hyperbolic phonon materials in the mid-infrared, limiting their application in the visible to near-infrared range. Here, we present a work on broadband near-infrared hyperbolic plasmon polaritons in a van der Waals material MoOCl2 by a perturbation-free direct imaging technique of photoemission electron microscopy. In particular, the hyperbolic polariton behavior has been dynamically tailored and manipulated by wavelength, polarization, interlayer twist, and artificial structure, providing a reconfigurable platform for nanophotonic applications. Notably, the full iso-frequency contours can be reconstructed via polarization-selective excitations. Our work has contributed to hyperbolic materials in the broadband near-infrared with MoOCl2, and has revealed PEEM to be an ideal method for studying hyperbolic plasmon polaritons at the space-time limit.