Boosting the electrocatalytic performance of FeSe2 in oxygen evolution reaction via composite formation with halloysite clay mineral

Developing high-performance and cheap electrocatalysts to boost the indolent kinetics of the oxygen evolution reaction (OER) is pivotal for the green and efficient production of molecular hydrogen and the advancement of metal-air batteries. Here, we report the synthesis, characterization, and OER catalytic activity of a series of novel nanocomposites comprising FeSe ₂ nanoparticles and the naturally abundant halloysite clay mineral. The FeSe ₂/halloysite nanocomposites (FeSe ₂/H) were prepared via a simple one-step hydrothermal route. The halloysite content of the nanocomposites was systematically varied to achieve the maximum electrocatalytic performance toward OER in 1.0 M KOH solution. It was found that a particular nanocomposite (designated as FeSe ₂/H-15) possessed a considerably improved OER performance compared to the rest of the as-prepared materials, with a low overpotential of 195 mV (at 20 mA cm ⁻² current density), a Tafel slope of 67.5 mV dec ⁻¹ , and remarkable electrochemical stability for 22 h. In addition, this nanocomposite required only 274 mV of overpotential to deliver the high current density of 250 mA cm ⁻² . These findings suggest that halloysite can be employed as a promising cocatalyst for boosting the activity of common OER electrocatalysts.