In consideration of energy conversion and/or environmental
protection,
it is important to develop electrocatalytic and/or photocatalytic
active materials for the oxygen evolution reaction (OER) and photodegradation
of methylene blue (MB), respectively. To meet these requirements,
mixed spinel ferrites such as Ni
x
Cu1–x
Fe2O4 anchored
at sulfur-doped graphitic carbon nitride (SCN) nanosheets was developed
for the first time via a simple one-pot hydrothermal method for the
construction of a novel bifunctional Ni
x
Cu1–x
Fe2O4@SCN nanocomposite. Initially, the crystal structure, optical properties,
surface morphology, elemental composition, and surface area of different
nanocomposites, such as NiFe2O4, Ni0.8Cu0.2Fe2O4, Ni0.5Cu0.5Fe2O4, Ni0.2Cu0.8Fe2O4, SCN, and Ni0.5Cu0.5Fe2O4@SCN, were studied through XRD, UV-DRS
analysis, FT-IR, FE-SEM with EDX, HR-TEM, and BET analysis. Furthermore,
when compared to other prepared electrode nanocomposites such as spinel
ferrites or different proportion mixed spinel ferrites, the Ni0.5Cu0.5Fe2O4@SCN nanocomposite
loaded 316 SSL mesh electrode demonstrated exceptional electrocatalytic
oxygen evolution performance with a very low overpotential of 250
mV at 10 mA cm–2 current density and outstanding
stability. Subsequently, the photocatalytic activities of the prepared
mixed spinel ferrites, Ni
x
Cu1–x
Fe2O4@SCN nanocomposites, were
tested through the degradation of MB under visible-light irradiation.
Among the prepared photocatalysts, Ni0.5Cu0.5Fe2O4@SCN nanocomposite showed superior photocatalytic
MB degradation under visible light, which is firmly due to the equi-proportion
blending of Cu+2 substitutions in mixed spinel ferrites
at SCN. Accordingly, the Ni0.5Cu0.5Fe2O4@SCN nanocomposite shows excellent photocatalytic degradation
(POD) efficiency of 99.1% for MB in 40 min, while other nanocomposites
such as NiFe2O4, SCN, and Ni0.5Cu0.5Fe2O4 show 40.2, 42.5, and 91.2% degradation
efficiencies, respectively. Thus, the Ni0.5Cu0.5Fe2O4@SCN nanocomposite could be a promising
material for electrocatalytic OER and/or photocatalytic degradation
of MB under visible-light irradiation.