The direct conversion of mechanical energy into electricity by nanomaterial-based devices offers potential for green energy harvesting . A conventional triboelectric nanogenerator converts frictional energy into electricity by producing alternating current (a.c.) triboelectricity. However, this approach is limited by low current density and the need for rectification . Here, we show that continuous direct-current (d.c.) with a maximum density of 10 A m can be directly generated by a sliding Schottky nanocontact without the application of an external voltage. We demonstrate this by sliding a conductive-atomic force microscope tip on a thin film of molybdenum disulfide (MoS). Finite element simulation reveals that the anomalously high current density can be attributed to the non-equilibrium carrier transport phenomenon enhanced by the strong local electrical field (10-10 V m) at the conductive nanoscale tip . We hypothesize that the charge transport may be induced by electronic excitation under friction, and the nanoscale current-voltage spectra analysis indicates that the rectifying Schottky barrier at the tip-sample interface plays a critical role in efficient d.c. energy harvesting. This concept is scalable when combined with microfabricated or contact surface modified electrodes, which makes it promising for efficient d.c. triboelectricity generation.

No abstract

No abstract

Articles you may be interested inInvestigation of the mechanical bending and frequency shift induced by adsorption and temperature using microand nanocantilever sensors

No abstract

The role of localized surface plasmon resonance (LSPR) in UV-Vis light irradiated Au/TiO2 photocatalysis systems has been investigated, and it is demonstrated experimentally for the first time that both pros and cons of LSPR exist simultaneously for this photocatalytic reaction. We have proved that when operating under mixed UV and green light irradiation, the LSPR injected hot electrons (from the Au nanoparticles to TiO2 under green light irradiation) may surmount the Schottky barrier (SB) formed between the Au nanoparticles and TiO2, and flow back into the TiO2. As a result, these electrons may compensate for and even surpass those transferred from TiO2 to the Au nanoparticles, thus accelerating the recombination of UV excited electron-hole pairs in TiO2. This is the negative effect of LSPR. On the other hand, more hot electrons existing on the surface of the Au nanoparticles due to LSPR would favor the photocatalytic reaction, which accompanied by the negative effect dominates the overall photocatalytic performance. The presented results reveal the multi-faceted essence of LSPR in Au/TiO2 structures, and is instructive for the application of metal-semiconductor composites in photocatalysis. Moreover, it is confirmed that the extent to which the above pros and cons of LSPR dominate the overall photocatalytic reaction depends on the intensity ratio of visible to UV light.

A micromechanical technique for measuring solution pH using modi®ed silicon (SiO 2 ) and silicon nitride (Si 3 N 4 ) microcantilevers is described. As the modi®ed surface of the cantilever accumulates charge proportional to the pH of the surrounding liquid, the cantilever undergoes bending due to the differential surface stress. Results are presented for chemically modi®ed (4-aminobutyltriethoxysilane, 11-mercaptoundecanoic acid) and metal-modi®ed (Au/Al) surfaces over a pH range 2±12. Aminosilane-modi®ed SiO 2 /Au cantilevers performed robustly over pH range 2±8 (49 nm de¯ection/pH unit), while Si 3 N 4 /Au cantilevers performed well at pH 2±6 and 8±12 (30 nm de¯ection/pH unit). The in¯uences of other ions on cantilever bending were found to be negligible below 10 À2 M concentration. #

No abstract