Greatly Enhanced Raman Scattering of Graphene on Metals by a Boron Nitride Film Covering.

Raman spectroscopy, a nondestructive fingerprinting technique, is mainly utilized to identify molecular species and phonon modes of materials. However, direct Raman characterization of two-dimensional materials typically synthesized on catalytic metal substrates is extremely challenging because of the significant electric screening and interfacial electronic couplings. Here, we demonstrate that by covering as-grown graphene with boron nitride (BN) films, the Raman intensity of graphene can be enhanced by two orders of magnitude and is also several times stronger than that of suspended graphene.

Designed growth of large bilayer graphene with arbitrary twist angles.

The production of large-area twisted bilayer graphene (TBG) with controllable angles is a prerequisite for proceeding with its massive applications. However, most of the prevailing strategies to fabricate twisted bilayers face great challenges, where the transfer methods are easily stuck by interfacial contamination, and direct growth methods lack the flexibility in twist-angle design. Here we develop an effective strategy to grow centimetre-scale TBG with arbitrary twist angles (accuracy, <1.

Computational Screening of High Activity and Selectivity TM/g-CN Single-Atom Catalysts for Electrocatalytic Reduction of Nitrates to Ammonia.

Electrocatalytic reduction of nitrates (NORR) selectively generating ammonia (NH) opens up a new idea for treating nitrates in wastewater, which not only reduces nitrates but also obtains the valuable product ammonia. By first-principles calculations, we explore the activity and selectivity for NORR to NH of TM/g-CN single-atom catalysts. Six TM/g-CN catalysts (TM = Ti, Os, Ru, Cr, Mn, and Pt) are selected by a four-step screening method.

Static volumetric three-dimensional display based on an electric-field-controlled two-dimensional optical beam scanner.

Using the quadratic electro-optic effect and the gradient of the composition ratio m [Nb/(Ta+Nb) in mol. %] in a potassium tantalate niobate crystal, we have designed an electric-field-controlled two-dimensional optical beam scanner with a wide wavelength range and fast response. This scanner is used to realize a volumetric display based on a two-frequency, two-step upconversion technique that is used to address the imaging volume.

Electric field control of a Bragg diffraction optical beam splitter based on a cubic K(0.99)Li(0.01)Ta(0.63)Nb(0.37)O3 single crystal.

We have realized an electric field controlled Bragg diffraction optical beam splitter based on a photorefractive Bragg diffraction grating. In our experiments, the splitter was produced by wave coupling (532.0 nm) with a potassium lithium tantalate niobate single crystal.

Properties of strong anisotropic a-axis single-crystal fiber with an applied electric field.

The effect of an applied electric field on the properties of strongly anisotropic a-axis single-crystal fiber is studied theoretically. We solve the electromagnetic field equations for strongly anisotropic a-axis single-crystal fiber and numerically analyze the mode characteristics of the fiber that conducts only the zeroth-order elementary mode. We discuss the effects that an applied electric field has on the refractive index anisotropy and the mode characteristics of the fiber that conducts only the zeroth-order elementary mode.

Photorefractive real-time phase-coded optical correlation storage using a crossed cylindrical-collimating lens system.

Phase-coded optical correlation storage in photorefractive crystals, using a crossed cylindrical-collimating lens system, has been realized. It possesses the advantages of both storage and correlator. It can perform real time and fast selection of the information correlated to the input information from a great amount of stored information.