Graphene oxide dispersed in N-TiO2 nanoplatelets and their implication in wastewater remediation under visible light illumination: Photoelectrocatalytic and photocatalytic properties

Abstract Graphene oxide (1–3 wt %) interspersed on nitrogen doped mesoporous TiO 2 (N-TiO 2 ) and synthesized via deposition-precipitation technique was characterized using XRD, TEM-SAED, N 2 sorptimetry, FTIR, Raman and UV–vis diffuse reflectance spectroscopy. Inspiringly, the nanoplatelets 2 wt%GO/N-TiO 2 exhibited the highest photocatalytic performance than rest of nanophotocatalysts over the degradation of methylene blue dye (MB; 20 ppm, k = 0.0146 min −1 ), phenol (15 ppm, k = 0.0045 min −1 ) as well as a mixture of both (k = 0.02 min −1 ) under visible light irradiation. The characterization results validated that the high activity is basically depends on the intimate contact formed between N-TiO 2 and GO that facilitates not only photo-generated charges transfer but also helps delaying their recombination, as confirmed from electrical conductivity, IPCE%, cyclic voltammetry and impedance results. Other parameters such as structure, morphology, surface texturing and optical properties verified the importance of decreasing the band gap (1.6 eV), crystallite size decrement (7 nm) and pore volume (0.42 cm 3  g -1 ) enlargement than small differences in surface areas and shape similarity. Photoelectrochemical (PEC) experiments also demonstrate that the photocurrent density of 2 wt%GO/N-TiO 2 is greatly boosted (3.9 mA cm −2 ) compared to rest of photocatalysts (1.6–2.4 mA cm -2 ) and pristine N-TiO 2 (0.4 mA cm −2 ). The specific mechanistic information imposed the major role of OH and electrons together with the synergistic effects manifested from N and Ti 3+ moieties. The application of the photocatalyst 2 wt%GO/N-TiO 2 in treating El Manzala Lake-Egypt from humic acids (146.0 ppm); attained from different sources, has shown fascinating activity as established from COD and TOC analyses.