PVP assisted sol-electrospraying, unlike sol electrospinning, yields highly pure rhombohedral zinc titanate particles that reduce 4-nitrophenol under visible light

Abstract

This work demonstrates for the first time that switching from sol-electrospinning to sol-electrospraying using PVP as a carrier polymer leads to enhanced purity of rhombohedral zinc titanate (Rh-ZTO) after calcination. Unlike in sol-electrospinning, the purity systematically increases and crystallite size decreases as PVP concentration is increased in sol-electrospraying. 100% pure Rh-ZTO powders were prepared with PVP fraction of 31.25 wt%. After careful characterization by XRD, rheology, zeta potential measurements, and SEM, we conclude that the interaction of multipole moments of the incipient sol-clusters with the electrostatic field influences the purity. We propose that in electrospinning the sol clusters spatially separate to yield multiple crystalline phases whereas in electrospraying they intermix due to polymeric cages in droplets and yield a single crystalline phase. The highest purity samples were found to enhance photo-reduction of 4-nitrophenol in presence of visible light, with rate constant increasing from 0.000415 to 0.00104 min−1. This could result from complex formed between oxygen vacancy and the shallow donor states of Ti3+ as confirmed by DRS, XPS, and PL.