Thermal and light irradiation effects on the electrocatalytic performance of hemoglobin modified CoO-g-CN nanomaterials for the oxygen evolution reaction.

The oxygen evolution reaction (OER) plays a key role in the water splitting process and a high energy conversion efficiency is essential for the definitive advance of hydrogen-based technologies. Unfortunately, the green and sustainable development of electrocatalysts for water oxidation is nowadays a real challenge. Herein, a successful mechanochemical method is proposed for the synthesis of a novel hemoglobin (Hb) modified CoO/g-CN composite nanomaterial. The controlled incorporation of cobalt entities as well as Hb functionalization, without affecting the g-CN nanoarchitecture, was evaluated using different physicochemical techniques, such as X-ray diffraction, N-physisorption, scanning electron microscopy, UV-visible spectroscopy and X-ray photoelectron spectroscopy. The beneficial effect of the resulting ternary bioconjugate together with the influence of the temperature and light irradiation was investigated by electrochemical analysis. At 60 °C and under light exposition, this electrocatalyst requires an overpotential of 370 mV to deliver a current density of 10 mA·cm, showing a Tafel slope of 66 mV·dec and outstanding long-term stability for 600 OER cycles. This work paves a way for the controlled fabrication of multidimensional and multifunctional bio-electrocatalysts.