Multifunctional NiO-decorated graphene nanocomposites as a potential electrocatalytic, photo-electrocatalytic degradation of methylene blue dye: Structure, optical and electrical properties

The sol-gel/auto-combustion method was utilized to prepare NiO-decorated graphene nanocomposites (NiO-G NCs). These samples are characterized using FTIR, XRD, SEM, UV–Vis diffuse reflectance spectroscopy, and XPS. FTIR spectra confirmed the fabrication of disordered graphene and a mixed phase between NiO and graphene. Meanwhile, XRD data demonstrated that NOG NCs possessed highly crystalline cubic NiO shape-structures. SEM image indicates a non-uniform spherical shape of NiO NPs decorated on a graphene sheet. Additionally, the UV–Vis-DRS characteristics indicated that the energy band gap of NOG-0 and NOG-3 NCs decreased from 3.363 to 3.216 eV. During the application test, NOG-3 NCs were utilized as a multifunctional material for the degradation of methylene blue dye. Electrolysis, EC, and PEC of MB dye are 57.01 %, 92.24 %, and 96.02 % after 25 min, in the presence of Cl − ion. Trapping investigations revealed that the main species causing PEC degradation of MB dye is • OH. After five cycles, degradation of approximately 91 % was confirmed, indicating the material's viability for the treatment of PEC wastewater. Furthermore, the observed dielectric constant of examined composites revealed a highly attractive dielectric constant for dielectric media. The investigated AC electrical conductivity increases with increasing graphene concentration, while their dielectric constant and dielectric loss decrease exponentially with the growth of incident frequency. • Sol-gel/auto-combustion method was utilized to prepare NiO-decorated graphene nanocomposites (NiO-G NCs). • The investigated AC electrical conductivity increases with increasing graphene concentration. • Their dielectric constant and dielectric loss decrease exponentially with the growth of incident frequency.