Re-usable self-poled piezoelectric/piezocatalytic films with exceptional energy harvesting and water remediation capability

Abstract

The need for sustainable technologies to address environmental pollution and energy crisis is paramount. Here we present a novel multifunctional nanocomposite, free standing film by combining piezoelectric molybdenum sulphide (MoS 2 ) nanoflower with poly vinylidene fluoride (PVDF) polymer, which can harness otherwise wasted mechanical energy for useful energy generation and/or water purification. The unique MoS 2 nanoflower morphology is exploited to render the whole nanocomposite piezo active. A number of features are demonstrated to establish potential practical usage. Firstly, the nanocomposite is piezoelectric and piezocatalytic simultaneously without requiring any poling step (i.e. self-poled). Secondly, the self-poled piezoelectricity is exploited to make a nanogenerator. The nanogenerator produced >80 V under human finger tapping with a remarkable power density, reaching 47.14 mW cm −3 . The nanocomposite film is made by simple solution casting, and the corresponding nanogenerator powers up 25 commercial LEDs by finger tapping. Last but not the least, the developed films show efficient, fast and stable piezocatalytic dye degradation efficiency (>90% within 20 min) against four different toxic and carcinogenic dyes under dark condition. Reusability of at least 10 times is also demonstrated without any loss of catalytic activity. Overall, our nanocomposite has clear potential for use as self-powered sensor and energy harvester, and in water remediation systems. It should potentially also be deployable as a surface mounted film/coating in process engineering, industrial effluent management and healthcare devices systems.

Recent Progress of Wearable Piezoelectric Nanogenerators

“…90,91 The group added molybdenum sulfide (MoS 2 ) to PVDF to obtain a multifunc-tional film that can be used for water remediation and energy harvesting. 92 Films of PVDF/barium titanate/cellulose nanocrystal composites (PVDF/BTO/CNC) were produced by Ram et al, who studied the effect of the mechanical properties of the films using BTO and CNC nanofillers. 93 In addition, a simple method makes it possible to obtain a pure β-phase by preparing films of PVDF and ionic liquid using a solution casting method and subsequent annealing.…”

Progress in Piezoelectric Nanogenerators Based on PVDF Composite Films

“…When the mass fraction of GeSe NSs is only 4 wt % at a pressure of 50 N cm −2 , the maximum open-circuit voltage density is 17.58 V cm −2 , the short-circuit current density is 1.14 µA cm −2 , and the power density is 9.76 µW cm −2 . Furthermore, a new multifunctional nanocomposite film was developed by integrating piezoelectric molybdenum disulfide (MoS 2 ) and PVDF polymers [71]. Wasted mechanical energy can be used to effectively generate power and purify water.…”

“…In addition, this PENG could perform robustly even after 45 days and 1500 bending periods. As mentioned above, Bagchi et al reported a reusable self-poled PENG based on a MoS2/PVDF film, and the piezoelectric film exhibits a stable piezocatalytic dye degradation efficiency and could be used repeatedly at least 10 times [71]. Reproduced with the permission from reference [76].…”

PVDF/Ag2CO3nanocomposites for efficient dye degradation and flexible piezoelectric mechanical energy harvester

“…Water is commonly polluted by pesticides, organic dyes and biological contaminants such as bacteria, lipids, viruses, DNA, and proteins. 16 Air pollution and wastewater are both considered to pose a serious threat to human health. Therefore, it is important to deal with environmental pollution urgently.…”

“…However, although photocatalysis has shown very promising applications, there are few issues such as the low efficiency and difficult separation of catalysts, which limit its commercial application. 16,26 Recently, piezoelectric-based catalysts have attracted signicant attention due to their high charge separation efficiency. 26 Furthermore, in the presence of mechanical stress (i.e., either low frequency vibration or high frequency ultrasound vibration), piezoelectric materials (i.e., noncentrosymmetric in nature) generate a piezo-potential due to spontaneous polarization.…”