High-Electrification Performance and Mechanism of a Water-Solid Mode Triboelectric Nanogenerator.

With the advantages of superior wear resistance, mechanical durability, and stability, the liquid-solid mode triboelectric nanogenerator (TENG) has been attracting much attention in the field of energy harvesting and self-powered sensors. However, most reports are primarily observational, and there still lacks a universal model of this kind of TENG. Here, an equivalent circuit model and corresponding governing equations of a water-solid mode TENG are developed, which could easily be extended to other types of liquid-solid mode TENGs.

Crystal face dependent intrinsic wettability of metal oxide surfaces.

Knowledge of intrinsic wettability at solid/liquid interfaces at the molecular level perspective is significant in understanding crucial progress in some fields, such as electrochemistry, molecular biology and earth science. It is generally believed that surface wettability is determined by the surface chemical component and surface topography. However, when taking molecular structures and interactions into consideration, many intriguing phenomena would enrich or even redress our understanding of surface wettability.

Interactions in stanene centred van der Waals trilayers structures of boron-nitride and graphene: effect of mirror symmetry on electronic interactions.

Dispersion-corrected density functional theory was used to investigate structures consisting of a stanene layer sandwiched between atomically-thin boron nitride and graphene. The parameters controlling the mirror symmetry, lattice rotation and stacking sequences were varied systematically to generate fifteen candidate trilayers. Two types of structural buckling occur in the heterostructures depending on whether the lattice vectors are co-aligned or non-collinear.

Voltage-induced penetration effect in liquid metals at room temperature.

Room-temperature liquid metal is discovered to be capable of penetrating through macro- and microporous materials by applying a voltage. The liquid metal penetration effects are demonstrated in various porous materials such as tissue paper, thick and fine sponges, fabrics, and meshes. The underlying mechanism is that the high surface tension of liquid metal can be significantly reduced to near-zero due to the voltage-induced oxidation of the liquid metal surface in a solution.

Discovery of a Voltage-Stimulated Heartbeat Effect in Droplets of Liquid Gallium.

Chemomechanical effects are known to initiate fluid oscillations in certain liquid metals; however, they typically produce an irregular motion that is difficult to deactivate or control. Here we show that stimulating liquid gallium with electrochemistry can cause a metal drop to exhibit a heart beating effect by shape shifting at a telltale frequency. Unlike the effects reported in the past for mercury, the symmetry-breaking forces generated by using gallium propel the drop several millimeters with velocities of the order of 1 cm per second.

Defect introduced paramagnetism and weak localization in two-dimensional metal VSe.

We have carried out a detailed investigation of the magnetism, valence state, and magnetotransport in VSe bulk single crystals, as well as in laminates obtained by mechanical exfoliation. In sharp contrast to the ferromagnetic behavior reported previously, here, no ferromagnetism could be detected for VSe single crystal and laminate from room temperature down to 2 K. Neither did we find the Curie paramagnetism expected due to the 3d odd-electronic configuration of covalent V ions.

Tuning the electronic structure in stanene/graphene bilayers using strain and gas adsorption.

Epitaxial growth of stanene monolayers on graphene substrates is an attractive synthesis route for atomically-thin electronic components, however, it remains unclear how such composites will tolerate lattice strain and exposure to ambient atmosphere. Using density functional theory, we identified several epitaxial configurations for the stanene-graphene bilayer system and determined the effect of strain and water adsorption. In addition to previously reported co-aligned bilayers, we identify a second family of low energy structures involving rotation of one layer by thirty degrees.

Desert Beetle-Inspired Superwettable Patterned Surfaces for Water Harvesting.

With the impacts of climate change and impending crisis of clean drinking water, designing functional materials for water harvesting from fog with large water capacity has received much attention in recent years. Nature has evolved different strategies for surviving dry, arid, and xeric conditions. Nature is a school for human beings.