Undoped and praseodymium-doped zinc oxide (Pr-doped ZnO) (with 2.0-mol%-6.0-mol% Pr) nanoparticles as sunlight-driven photocatalysts are synthesized by means of co-precipitation with nitrates followed by thermal annealing. The structure, morphology, and chemical bonding of the photocatalysts are studied by x-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive x-ray emission spectroscopy (EDS), x-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR), respectively. The optical properties are studied by photoluminescence (PL) and UV-vis diffuse reflectance spectroscopy (UV-vis DRS). We find that Pr doping does not change the crystallinity of ZnO; but it reduces the bandgap slightly, and restrains the recombination of the photogenerated electron-hole pairs. The photocatalytic performance of the photocatalysts is investigated by the photodegradation reaction of 10-mg/L rhodamine B (RhB) solution under simulated sunlight irradiation, showing a degradation rate of 93.75% in ZnO doped with 6.0-mol% Pr.

We fabricated a silver ion emitter based on the solid state electrolyte film of RbAg4I5 prepared by pulsed laser deposition. The RbAg4I5 target for PLD process was mechano-chemically synthesized by high-energy ball milling in Ar atmosphere using β-AgI and RbI as raw materials. The ion-conducting properties of RbAg4I5 were studied by alternating current (AC) impedance spectroscopy and the ionic conductivity at room temperature was estimated 0.21 S/m. The structure, morphology, and elemental composition of the RbAg4I5 film were investigated. The Ag+ ion-conducting property of the prepared superioni-conductor film was exploited for ion–beam generation. The temperature and accelerating voltage dependences of the ion current were studied. Few nA current was obtained at the temperature of 196 °C and the accelerating voltage of 10 kV.

In recent decades, nanogenerators based on several techniques such as triboelectric effects, piezoelectric effects, or other mechanisms have experienced great developments. The nanoenergy generated by nanogenerators is supposed to be used to overcome the problem of energy supply problems for portable electronics and to be applied to self-powered microsystems including sensors, actuators, integrated circuits, power sources, and so on. Researchers made many attempts to achieve a good solution and have performed many explorations. Massive efforts have been devoted to developing self-powered electronics, such as self-powered communication devices, self-powered human–machine interfaces, and self-powered sensors. To take full advantage of nanoenergy, we need to review the existing applications, look for similarities and differences, and then explore the ways of achieving various self-powered systems with better performance. In this review, the methods of applying nanogenerators in specific circumstances are studied. The applications of nanogenerators are classified into two categories, direct utilization and indirect utilization, according to whether a treatment process is needed. We expect to offer a line of thought for future research on self-powered electronics.

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