Highly stable GO/formamide based GOLLCs for free standing film fabrication and their photodegradation applications against organic dyes

In this context, formamide is explored as an efficient solvent for the dispersion of GO sheets and preparation of graphene oxide lyotropic liquid crystals (GOLLCs). Polarizing optical microscopy (POM) studies confirm that GO/formamide dispersion shows smectic phase at lower concentration (< 2 mg/mL) and nematic phase up to 300 mg/mL. GOLLCs are found stable for up to 24 months. Probably it is the first report on the formation of GOLLCs in formamide and their long-term stability up to 24 months. GOLLCs are studied for steady and dynamic rheological behavior at room temperature. All the GOLLCs exhibit shear-thinning fluid behavior under the shear rate 1–100 s−1. Dynamic rheology reveals that GOLLCs follow solid viscoelastic behavior till 20 mg/mL concentration and then depict long range viscoelastic behavior at higher concentrations. Complex moduli behavior of GOLLCs has been studied to predict their elasticity. The scaling analysis of tunable viscoelastic GOLLCs is computed from Er=Ax−xc4.43. The free-standing film is prepared via thermal treatment method from 2 mg/mL GOLLCs and studied for structural and photocatalytic degradation behavior. rGO film shows 99.18% and 97.87% degradation efficiency for malachite green and methyl orange organic dyes respectively under UV light and is found stable up to 3 cycles. [Display omitted] •Highly stable formamide/GO based GOLLCs are prepared considering intermolecular interactions.•Smectic and nematic LLCs phases are observed as a function of increasing GO concentration.•Shear and dynamic rheological behavior are correlated with the structural parameters considering the domain size concept.•Shear thinning, viscoelastic and long-range viscoelastic behavior of GOLLCs.•rGO film from GOLLCs has been developed and tested for photodegradation of organic dyes.