While global energy consumption has steadily increased in the past decades due to industrialization and population growth, [ 1 ] society is facing a problem with the depletion of fossil energy resources as well as environmental problems (such as global warming, carbon dioxide emissions, and damage to the ozone layer). [ 2 ] These challenges can be addressed by renewable energy resources, which are always available everywhere. [ 1 , 2 ] Outdoor renewable energy sources such as solar energy (15 000 μ W/cm 3 ), [ 3 , 4 ] wind energy (380 μ W/cm 3 ), [ 5 ] and wave energy (1 000 W/cm of wave crest length) [ 6 , 7 ] can provide largescale needs of power. However, for driving small electronics in indoor or concealed environments [ 3 , 8 ] (such as in tunnels, clothes, and artifi cial skin) and implantable biomedical devices, innovative approaches have to be developed.One way of energy harvesting without such restraints is to utilize piezoelectric materials that can convert vibrational and mechanical energy sources from human activities such as pressure, bending, and stretching motions into electrical energy. [9][10][11] Wang and co-workers [ 9 , 10 , 12-15 ] have used piezoelectric ZnO nanowire arrays to develop a nanogenerator technologies, who have demonstrated the feasibility using this type of generator to power commercial light-emitting diodes (LEDs), [ 13 ] liquid crystal displays, [ 14 ] and wireless data transmission. [ 15 ] These nanogenerators can also convert tiny bits of biomechanical energy (from sources such as the movement of the diaphragm, the relaxation and contraction of muscle, heartbeat, and the circulation of blood) into power sources. [ 16 , 17 ] Recently, there have been attempts to fabricate thin fi lmtype nanogenerators [ 11 , 18 ] with perovskite ceramic materials (PbZr x Ti 1-x O 3 and BaTiO 3 ), which have a high level of inherent piezoelectric properties. The BaTiO 3 thin fi lm nanogenerator has demonstrated by the authors [ 11 ] using the transfer process [19][20][21][22] of high temperature annealed perovskite thin fi lm from bulk substrates onto fl exible substrates; it generates a much higher level of power density than other devices with a similar structure. [ 10 ] Herein, we report the nanocomposite generator (NCG) achieving a simple, low-cost, and large area fabrication based on BaTiO 3 nanoparticles (NPs) synthesized via a hydrothermal reaction (see Method S1) [ 23 ] and graphitic carbons, such as single-walled and multi-walled carbon nanotubes (SW/MW-CNTs), and reduced graphene oxide (RGO). The BaTiO 3 NPs and carbon nanomaterials are dispersed in polydimethylsiloxane (PDMS) by mechanical agitation to produce a piezoelectric nanocomposite (p-NC). The p-NC is spin-casted onto metalcoated plastic substrates and cured in an oven. Under periodic external mechanical deformation by bending stage or biomechanical movements from fi nger/feet of human body, electric signals are repeatedly generated from the NCG device and used to operate a commercial red LED.The schematic diagrams ...

Monoclinic S8 , an uncommon allotrope of sulfur at room temperature, can be formed when common orthorhombic S8 is heat-treated under enclosed environments in nanometer dimensions. Monoclinic S8 prevents the formation of soluble polysulfides during battery operation, resulting in unprecedented cycling performance over 1000 cycles under the highest sulfur content to date.

A facile synthetic strategy was implemented to obtain nanosized barium titanate (BaTiO3) powders with tetragonal structure. The nanoparticles were synthesized using solvothermal process employing diethanolamine and triethanolamine to suppress the particle growth and the as‐prepared nanopowders were characterized using X‐ray diffraction, scanning electron microscopy, and high‐resolution dispersive Raman spectroscopy. It was found that the particle size can be easily tuned by adjusting the experimental parameters while retaining the tetragonality. The average diameters of the particles prepared with and without the organic amines were found to be 80 and 100 nm, respectively. All the synthesized BaTiO3 nanopowders exhibit a narrow size distribution with a uniform morphology. Rietveld refinement of the XRD patterns and Raman spectra revealed that the synthesized BaTiO3 nanopowders have tetragonal asymmetry dominant structures. A slight decrease in the tetragonality of the prepared powders with decrease in particle size is attributed to the presence of cubic shell layer and inner defects. The tetragonal‐dominant structure was also confirmed by normalizing the peak area of the Raman spectra.

Flexible piezoelectric generators constructed using one-dimensional nanostructures are well known for their efficient energy harvesting. Herein, we have fabricated a flexible piezoelectric energy harvester (PEH) consisting of a single 0.65Pb(Mg 1/3 Nb 2/3 )O 3 -0.35PbTiO 3 nanowire (PMN-PT NW) using a facile transferring approach onto a Au electrode-patterned plastic substrate. The well-developed device effectively harvested the maximum output signals (9 mV and 1.5 nA) originating from a single PMN-PT nanowire under mechanical bending/unbending motions. The designed PEH is also expected to be utilized as a versatile tool to evaluate the performance of a one-dimensional nanostructure.