Three-dimensional hybrid of iron-titanium mixed oxide/nitrogen-doped graphene on Ni foam as a superior electrocatalyst for oxygen evolution reaction

Growing demands for clean and renewable energy technologies have sparked broad research on the development of highly efficient and stable non-noble metal electrocatalysts for oxygen evolution reaction (OER). In this regard, in the present work a three-dimensional Fe₂TiO₅/nitrogen-doped graphene (denoted as 3D FTO/NG) hybrid electrocatalyst was synthesized via a facile in-situ process using a hydrothermal method. Structural characterization of the prepared nanocomposite is performed by various techniques e.g. field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM) analysis, Fourier transform infrared spectra (FT-IR), X-ray photoelectron spectroscopy spectra (XPS), X-ray diffraction (XRD) and Raman spectroscopic methods. A novel binder-free electrode for OER activity has been prepared by coating a 3D FTO/NG onto nickel foam (NF). In particular, the 3D FTO/NG nanocomposite, which is synthesized with in-situ hydrothermal process, exhibited a remarkable OER performance in alkaline media. The prepared electrocatalyst showed a small overpotential of 0.36 V with a Tafel slope of 0.07 V dec^-1 at 100 A m^-2 with a long-term stability for OER reaction in 1 M KOH. The outstanding OER performance and durability of 3D FTO/NG can be attributed to the synergistic effects originating from NG and FTO in the prepared electrocatalyst, which helps to enhance the conductivity of the nanocomposite. The presence of conductive NG in the prepared 3D nanocomposite can not only improve the mechanical stability, but also facilitate its electron transport. Also, N atoms and FTO provide abundant electrocatalytic active sites, which accelerate evolution of gas bubbles. This work provides a promising approach for synthesis of inexpensive and efficient OER electrocatalysts.