Multifaceted β-cyclodextrin encapsulated cerium oxide nanoparticles incorporated poly(vinylidene fluoride) nanocomposites towards mechanical energy harvesting and strain modulated optoelectronic sensor

Abstract

There has been a considerable thrust to develop flexible piezoelectric polymer nanocomposites towards fabricating piezoelectric nanogenerators (PENGs) utilizing various types of nanoparticles (NPs). In this context, we have fabricated solution-casted poly(vinylidene fluoride) (PVDF) nanocomposites of cerium oxide (CeO₂)/β-cyclodextrin encapsulated CeO₂ (β-CD-CeO₂) nanoparticles (NPs), wherein we have demonstrated PVDF nanocomposites could be utilized as piezoelectric sensors and self-powered photodetectors (PDs). In the case of PVDF/CeO₂ (PVNC) and PVDF/β-CD-CeO₂ (PMNC) nanocomposites, CeO₂ and β-CD-CeO₂ NPs acted as heterogeneous nucleating agents that enhance the electroactive phase fraction of PVDF. Further, CeO₂ and β-CD-CeO₂ NPs could enhance up to ∼93 % and ∼95 % of the electroactive phases in the corresponding PVDF nanocomposite, respectively. Furthermore, we have thoroughly explored the interaction mechanism between the surface charges and functional groups of CeO₂/β-CD-CeO₂ NPs and PVDF dipoles via Fourier transform infrared, and Raman spectroscopic analyses. The maximum piezoelectric coefficient (d₃₃ value) achieved in PVDF/2 wt% CeO₂ nanocomposite was ∼114 pm/V and for PVDF/1 wt% β-CD-CeO₂ nanocomposite the corresponding value registered the d₃₃ value of ∼138 pm/V, whereas the pristine PVDF showed the d₃₃ value of ∼19.2 pm/V, which is significantly lower as compared to both PVNC and PMNC nanocomposites. Moreover, piezoelectric nanogenerators (PENGs) were fabricated using optimized concentration of CeO₂ (2 wt% CeO₂) and β-CD-CeO₂ (1 wt% β-CD-CeO₂) NPs in PVDF matrix, which show significantly higher open-circuit voltage and short-circuit current (∼88 V, ∼ 2.8 μA for the device made with PVDF/CeO₂ nanocomposite and ∼93 V, ∼ 4.4 μA for the device made with PVDF/β-CD-CeO₂ nanocomposite), with higher sensitivity of ∼11.5 V/N and ∼15.8 V/N, respectively. The fabricated devices could also generate electricity from various biomechanical actions. Further, PVDF/CeO₂ and PVDF/β-CD-CeO₂ nanocomposites were strategically designed to maximize device performance, offering a beneficial alternative for the development of novel piezo-phototronics materials.