Elucidation of inter/intra molecular H-bonding mediated charge transportation mechanism in water swelled, hydrophilic organic PVA-Co3O4 nanocomposite films

Abstract

In this article, we have explored the water molecules mediated charge transportation kinetics in Polyvinyl alcohol (PVA)-Cobalt Oxide (Co3O4) flexible nanocomposite films that rely heavily on the comprehension of surface and interface chemistry. Understanding the chemical interactions at the aqueous hydrophilic PVA-Co3O4 interface is essential in recognising the H-bonding revolution for complex nanocomposite films. The amount of water intake with time evolution has been monitored by the contact angle and wettability measurements. The chemical interactions and the revolution of the weak dangling bonds have been studied by Fourier transform infrared spectroscopy (FTIR), Raman and photoluminance (PL) spectra of the water-swollen hydrophilic PVA-Co3O4 nanocomposite films. The dissociation of water molecules following the fragmentation of inter/intra-molecular dangling bonds is correlated with the water diffusion kinetics and saturation in the sorption capacity of water-swollen PVA-Co3O4 nanocomposite films. The trap-states development due to the interfacial charge accumulation, after absorption of water molecules, are favourable for the trap-assisted space charge limited current conduction (TA-SCLC) mechanism and increase current density ∼ 102 times as compared to the dehydrated nanocomposite films. Meticulous tuning of the strong interfacial interactions and the manifestations of fragmented H+ ions have been identified as the primary craftsman for enhancing the dielectric constant up to eight times in the presence of 30 μL deionized water. Due to the disintegration of the free water molecules at the measurement voltage, the ac conductivity (charge transport) changes from the Jonscher's power law type variation to the jump relaxation model (JRM). The origin and accumulation of H+ ions at the grain boundary interfaces have been analyzed with impedance spectroscopic (IS) studies. An electrical equivalent circuit model is proposed for the water-mediated charge transport mechanism in swelled, hydrophilic, organic nanocomposite films.