Ultrasensitive Iron-Triggered Nanosized Fe–CoOOH Integrated with Graphene for Highly Efficient Oxygen Evolution

Effectively active oxygen evolution reaction (OER) electrocatalysts are highly desired for water splitting. Herein, the design and fabrication of nanometer-sized Fe-modulated CoOOH nanoparticles by a novel conversion tailoring strategy is reported for the first time and these nanoparticles are assembled on graphene matrix to construct 2D nanohybrids (FeCoOOH/G) with ultrasmall particles and finely modulated local electronic structure of Co cations. The Fe components are capable of tailoring and converting the micrometer-sized sheets into nanometer-sized particles, indicative of ultrasensitive Fe-triggered behavior. The as-made FeCoOOH/G features highly exposed edge active sites, well-defined porous structure, and finely modulated electron structure, together with effectively interconnected conducting networks endowed by graphene. Density functional theory calculations have revealed that the Fe dopants in the FeCoOOH nanoparticles have an enhanced adsorption capability toward the oxygenated intermediates involved in OER process, thus facilitating the whole catalytic reactions. Benefiting from these integrated characteristics, the as-made FeCoOOH/G nanohybrids as an oxygen evolution electrocatalyst can deliver a low overpotential of 330 mV at 10 mA cm−2 and excellent electrochemical durability in alkaline medium. This strategy provides an effective, durable, and nonprecious-metal electrocatalyst for water splitting.