Ultrathin Boundary-Less SnO Films with Surface-Activated Two-Dimensional Nanograins Enable Fast and Sensitive Hydrogen Gas Sensing.

Fast and reliable semiconductor hydrogen sensors are crucially important for the large-scale utilization of hydrogen energy. One major challenge that hinders their practical application is the elevated temperature required, arising from undesirable surface passivation and grain-boundary-dominated electron transportation in the conventional nanocrystalline sensing layers. To address this long-standing issue, in the present work, we report a class of highly reactive and boundary-less ultrathin SnO films, which are fabricated by the topochemical transformation of 2D SnO transferred from liquid Sn-Bi droplets.

Noncontact rotation, levitation, and acceleration of flowing liquid metal wires.

This paper reports the noncontact manipulation of free-falling cylindrical streams of liquid metals into unique shapes, such as levitated loops and squares. Such cylindrical streams form in aqueous media by electrochemically lowering the interfacial tension. The electrochemical reactions require an electrical current that flows through the streams, making them susceptible to the Lorentz force.

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.

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.

High-performance piezoelectric energy harvesting of vertically aligned Pb(Zr,Ti)O nanorod arrays.

Recent developments of self-powered devices and systems have attracted much attention. Lead zirconate titanate (PZT) has been regarded as one of the most promising materials for building high-performance nanogenerators. Herein, vertically aligned PZT nanorod arrays were synthesized on a pre-oxidized Ti substrate in the presence of a surfactant by a one-step hydrothermal method.

Self-Powered Viscosity and Pressure Sensing in Microfluidic Systems Based on the Piezoelectric Energy Harvesting of Flowing Droplets.

The rapid development of microscaled piezoelectric energy harvesters has provided a simple and highly efficient way for building self-powered sensor systems through harvesting the mechanical energy from the ambient environment. In this work, a self-powered microfluidic sensor that can harvest the mechanical energy of the fluid and simultaneously monitor their characteristics was fabricated by integrating the flexible piezoelectric poly(vinylidene fluoride) (PVDF) nanofibers with the well-designed microfluidic chips. Those devices could generate open-circuit high output voltage up to 1.