Study of molar properties of GO after doping with transition metals for photodegradation of fluorescent dyes

Abstract

We synthesized graphene oxide (GO) doped with transition metal ions and characterized it using XPS, FT-IR, TGA/DTG, XRD, SEM, AFM, ICP-OES, UV/vis, and Raman spectroscopy. An intrinsic viscosity [η] of 0.002–0.012 g% @ 0.002 aq-GO was determined for viscosity average molecular weight (M_v) of GO at 288.15, 298.15, and 308.15 K. Mark–Houwink (M–H) constants k (cm³ g⁻¹) and a (cm³ mol g⁻²) were calculated for 5–15 mg/100 mL polyvinylpyrrolidone (PVP), using 29, 40, 55 kg mol⁻¹ as markers for calculating M_v by fitting the [η] to the Mark–Houwink–Sakurada equation (MHSE). We obtained 48 134.19 g mol⁻¹ M_v at 298.15 K, and the apparent molar (V_ϕm, cm³ mol⁻¹), limiting molar volumes (V⁰_GO)_G0, enthalpy (ΔH_m, J mol⁻¹), entropy (ΔS_m, J mol⁻¹ K⁻¹), viscosity (η_m, mPa s mol⁻¹), surface tension (γ_m, mN m⁻¹ mol⁻¹), friccohesity (σ_m, scm⁻¹ mol⁻¹), fractional volume (ϕ_m, cm³ mol⁻¹), isentropic compressibility (K_sϕ,m, 10⁻⁴ cm s² g⁻¹ mol), infer GO molar consistency throughout the chemical processes. Molar properties (MPs) infer a GO monodispersion producing negative electrons (e⁻) and positive holes (h⁺) under sunlight. The transition metal ions (Fe²⁺, Mn²⁺, Ni²⁺, Cr³⁺, TMI) doped onto GO (TMI-GO), can photodegrade methylene blue (MB) in 60 min compared with 120 min using GO alone. The 4011 C atoms, 688 hexagonal sheets, 222 π-conjugations, and 4011 FE were calculated from the 48 134.19 g mol⁻¹. The functional edges are the negative and positive holes generating centres of the GO 2D sheets.