The structural, electronic and optical properties of the two-dimensional (2D) heterostructure of ZnO/GeC are calculated using hybrid density functional theory. The results suggest that the ZnO monolayer has a stable contact with the GeC monolayer. Biaxial strains can significantly tune the bandgaps and band alignments of the ZnO/GeC heterostructures and all the strained heterostructures are beneficial for absorbing visible light. The induced built-in electric field across the ZnO/GeC heterostructure interface can reduce photoinduced carrier recombination rates, which is favorable for enhancing the photocatalytic performance. In particular, the band edge positions of the ZnO/GeC heterostructures of biaxial strains of , 0, 2%, 4%, and 6% are thermodynamically favorable for overall water redox processes in the pH range of 6.9–12.4, 9.4–13.1, 12.1–14.0, 12.9–14.0, 12.5–14.0, 10.9–14.0 and 5.5–8.6. Our investigation exhibits an effective method to design 2D material based water-splitting photocatalysts.

In this letter, an all-optical modulator with high modulaiton efficiency based on graphene-plasmonic slot waveguide structure is proposed. The modulation efficiency is enhanced by the strong interaction between the light and the graphene-plasmonic structures. The results indicate that a modulation efficiency of 0.21 dB/m is obtained at the signal light with wavelength of 1550 nm. And graphene-plasmonic slot waveguide device length of 10 m is fabricated in the experiment. Benefits by the strong modulation, it provides a promising candidate for on-chip optical modulator with high modulation efficiency and micrometer-scale footprint.

All-optical modulators based on graphene show great promise for on-chip optical interconnects. However, the modulation performance of all-optical modulators is usually based on the interaction between graphene and the fiber, limiting their potential in high integration. Based on this point, an all-optical modulator in a dielectric-loaded waveguide (DLW) with a graphene-silicon heterojunction structure (GSH) is proposed. The DLW raises the waveguide mode, which provides a strong light–graphene interaction. Sufficient tuning of the graphene Fermi energy beyond the Pauli blocking effect is obtained with the presented GSH structure. Under the modulation light with a wavelength of 532 nm and a power of 60 mW, a modulation efficiency of 0.0275 dB µ m ⁻¹ is achieved for light with a communication wavelength of 1.55 µ m in the experiment. This modulator has the advantage of having a compact footprint, which may make it a candidate for achieving a highly integrated all-optical modulator.

Many human genetic diseases are caused by single-base mutation in the gene sequence. Since DNA molecules with single-base mutation are extremely difficult to differentiate, existing detection methods are invariably complex and time-consuming. We propose a new label-free and fast terahertz (THz) spectroscopic technique based on a home-made terahertz attenuated total reflection (ATR) microfluidic cell and a terahertz time-domain spectroscopy (THz-TDS) system to detect single-base-mutated DNA molecules. The detected object DNA molecules are normal hemoglobin gene, sickle cell anemia gene (15 nt), JAK2 gene wild type and JAK2 V617F gene mutation (39 nt) from sickle cell anemia and thrombocytopenia, respectively. Results show that the oligonucleotide fragments with single-base mutation can be identified by THz spectroscopy combined with the ATR microfluidic cell, and the recognition effect of short oligonucleotide fragments with single-base mutation is better than that of long oligonucleotide fragments. The terahertz biosensor is shown to have high sensitivity and can be used to detect DNA molecules directly in the solution environment.

In this study, we report a flexible single-electrode-based triboelectric nanogenerator based on double-sided polymer surface nanostructures. The triboelectric nanogenerators have been applied to harvest all kinds of mechanical energy in our daily life and convert them into electricity, and also used as a self-powered sensor system for touching pad and smart skin technologies. To enhance the performance of triboelectric nanogenerator, we fabricate a single-electrode-based triboelectric nanogenerator based on double-sided polydimethylsiloxane nanostructures and indium tin oxide electrode film using nanoimprint lithography. The nanostructures are nanopillar arrays with the diameter of about 200 nm to enhance the triboelectric effect. Open-circuit voltage and short-circuit current of the as-prepared samples are recorded using an oscilloscope with applying different external force at room temperature. The single-electrode-based triboelectric nanogenerator delivers an open-circuit voltage up to about 160 V, a short-circuit current of about 3 μA, and power density of 423.8 mW/m², which provides an attractive solution to work as self-powered devices. This study greatly expands the applications of triboelectric nanogenerator as energy harvesting, environmental monitoring, and self-powered sensor systems.

In this paper, a high-efficiency terahertz amplitude modulation device based on a field-effect transistor has been proposed. The polarization insensitive modulator is designed to achieve a maximum experimental modulation depth of about 53% within 5 V of gate voltages using monolayer graphene. Moreover, the manufacturing processes are inexpensive. Two methods are adopted to improve modulation performance. For one thing, the metal metamaterial designed can effectively enhance the electromagnetic field near single-layer graphene and therefore greatly promote the graphene’s modulation ability in terahertz. For another, polyethylene oxide-based electrolytes (PEO:LiClO₄) acts as a high-capacity donor, which makes it possible to dope single-layer graphene at a relatively low voltage.