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Transition metal dichalcogenides, whose valley degrees of freedom are characterized by the degree of circular polarization (DCP) of the photoluminescence, draw broad interests due to their potential applications in information storage and processing. However, this DCP is usually low at room temperature due to the phonon-assisted intervalley scattering, severely degrading the fidelity of the valley-stored signals. Therefore, achieving high DCP at room temperature is vital for valley-encoded nanophotonic devices. In this work, we demonstrate a high DCP of 48.7% at room temperature by embedding monolayer MoS2into a compact plasmonic nanocavity. Such a high DCP is proven to originate from the prominent chiral Purcell effect owing to the degeneracy-lifted circularly polarized local density of states in the nanocavity. In addition, the DCP can be further manipulated by an in situ plasmon-scanned technique. This highly compact system provides possibilities for developing versatile valley-encoded light-emitting devices at room temperature.

Living organisms utilize spatially organized enzyme complexes to carry out signal transduction and metabolic pathways in an efficient and specific way. Herein, inspired by natural enzyme complexes, we report the polymerization-induced coassembly (PICA) of enzyme–polymer conjugates into comicelles with tunable and enhanced cascade activity by using the cascade reaction implemented by glucose oxidase (GOX) and horseradish peroxidase (HRP) as a model system. Notably, the cascade activity of GOX/HRP–polymer comicelles monotonically increases with the GOX/HRP ratio. The cascade activity of GOX/HRP–polymer comicelles is up to 4.9 times higher than that of free GOX and HRP mixtures at the same GOX/HRP ratio. We further demonstrate that our system can quickly detect glucose in contrast with a commercially available glucose assay kit. These findings provide a new and general method of PICA for the controlled construction of artificial enzyme complexes with tunable and enhanced activity in enzyme cascades for advanced biomedical applications.

The fact that metallic nanostructures are an excellent light receiver and transmitter connects the underlying principles of two widely applied optical processes: surface-enhanced Raman scattering (SERS) and surface-enhanced fluorescence (SEF). A comparative study of SERS and SEF can eliminate the typical unknown quantities of the system and reveal important parameters that cannot be accessed by conventional techniques. Here, we use this simultaneous SERS and SEF technique in a monolayer MoSe2coupled plasmonic nanocavity. After optimizing the spatial and the spectral overlaps between excitonic and plasmonic resonances, the SERS and SEF enhancement factors can exceed 107and 6000, respectively, at the same time on the same nanocube. The comparison of the SERS and SEF enhancements allows the estimation of the ultrafast total decay rate of the bright exciton in monolayer MoSe2in the nanocavity down to tens of femtoseconds, which is otherwise hard to realize using time-resolved techniques.

Reducing building energy consumption, improving aesthetics, and improving occupant privacy as well as comfort by dynamically adjusting solar radiation are important application areas for electrochromic (EC) smart windows. However, the current transition metal oxides still cannot meet the requirements of neutral coloration and large optical modulation. We report NiMoO4nanosheet films directly grown on fluorine-doped tin oxide glasses. The as-grown NiMoO4film not only achieves neutral coloration from transparent to dark brown but also shows an ultralarge optical modulation (86.8% at 480 nm) and excellent cycling stability (99.4% retention of maximum optical modulation after 1500 cycles). Meanwhile, an EC device demonstrating good EC performance was constructed. These results will greatly promote the research and development of binary transition metal oxides for both EC and energy-storage applications, and NiMoO4films may be an excellent candidate to replace NiO films as ion-storage layers in complementary EC devices with WO3films as EC layers.