Urban sound management is required in a variety of fields such as transportation, security, water conservancy and construction, among others. Given the diverse array of available noise sensors and the widespread opportunity to connect these sensors via mobile broadband Internet access, many researchers are eager to apply sound-sensor networks for urban sound management. Existing sensing networks typically consist of expensive information-sensing devices, the cost and maintenance of which limit their large-scale, ubiquitous deployment, thus narrowing their functional measurement range. Herein, an innovative, low-cost, sound-driven triboelectric nanogenerator (SDTENG)-based self-powered sensor is proposed, from which the SDTENG is primarily comprised of fluorinated ethylene propylene membranes, conductive fabrics, acrylic shells, and Kapton spacers. The SDTENG-based sensor has been integrated with a deep learning technique in the present study to construct an intelligent sound monitoring and identification system, which is capable of recognizing a suite of common road and traffic sounds with high classification accuracies of 99% in most cases. The novel SDTENG-based self-powered sensor combined with deep learning technique demonstrates a tremendous application potential in urban sound management, which will show the excellent application prospects in the field of ubiquitous sensor networks.

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2D piezoelectric materials have strong intrinsic piezoelectricity and superior flexibility, which are endowed with huge potential to develop piezoelectric nanogenerators (PENGs). However, there are few attempts to investigate the energy harvesting of 2D ferroelectric materials. Herein, an enhanced output performance is reported by ferroelectric polarization in a PENG with exfoliated 2D ferroelectric CuInP2S6 (CIPS). Specifically, the polarized CIPS‐based PENG produces a short‐circuit current of 760 pA at 0.85% tensile strain, which is 3.8 times higher than that of unpolarized CIPS‐based PENG. Systematical PFM and Raman analysis reveal that the ferroelectric polarization remarkably reinforces the effective piezoelectric constant of CIPS nanoflakes and boosts the in‐plane migration and out‐of‐plane hopping of copper ions, which is the main reason for the enhancement of output performance. Furthermore, the CIPS‐based PENG can not only be utilized to harvest biomechanical energy such as wrist joints movement, but also exhibits a potential for a voice recognition system integrated with deep learning technology. The classification accuracy of a series of letter sounds is as high as 96%. This study commendably broadens the application scope of 2D materials in micro‐nano energy and intelligent sensors, which will have profound implications for exploring wearable nanoelectronic devices.

Despite the fact that photoactive piezoelectric nanogenerators (PENGs) have been getting more attention due to their significant potential as a self-powered photodetector and pressure sensor, investigations on the interaction mechanism between photogenerated carriers and piezoelectric charges are still insufficient. In this study, photoactive PENGs based on methylammonium lead halides-poly(vinylidene) (MAPI-PVDF) composite were fabricated, in which the presence of MAPI in the PVDF matrix plays a dual role in enhancing the nucleation of the electroactive β-phase as well as inducing photoactivity in the composite. It has an optimal open-circuit voltage of 4.7 V and short-circuit current of 0.2 μA at 10 wt. % concentration of MAPI under illumination, which is nearly halved in the dark. Furthermore, we have thoroughly explored the interaction mechanism between photogenerated carriers and piezoelectric charges by piezoresponse scanning force microscopy techniques, photoluminescence spectroscopy, and a bandgap analysis. The results demonstrate that the photogenerated carriers screen part of the piezoelectric potential induced by the piezoelectric charges, while the piezoelectric charges promote more photogenerated carriers recombination. This work opens up horizons for the piezoelectric community in designing photoactive PENGs with multiple application modes and provides an effective approach to the development of piezoelectric materials.