(FeSe₂ + CoSe₂) Nanoparticles Anchored on 3D Porous Ultrathin Carbon Nanosheets for High-Activity Oxygen Evolution Reaction

Since the sluggish kinetics of the oxygen evolution process (OER) at the anode of water splitting remains to be a crucial bottleneck for hydrogen production, it is imperative to develop low-cost OER electrocatalysts with high efficiency. Here, (FeSe₂ + CoSe₂) nanoparticles loaded on nitrogen-doped three-dimensional porous carbon nanosheets (referred to as (FeSe₂ + CoSe₂)/N-3DCN) were prepared by freeze-drying, heat treatment and selenization. The favorable affinity and large surface area of N-3DCN enabled the synthesis of the ultrafine (FeSe₂ + CoSe₂) nanoparticles with a diameter of 10 nm, which were highly dispersed on carbon nanosheets and provided a significant number of active sites. The density functional theory (DFT) calculation demonstrated that the free energy of oxygen-containing intermediates during OER was optimized by coupling FeSe₂ with CoSe₂. The overpotential of (FeSe₂ + CoSe₂)/N-3DCN is 312 mV at 10 mA cm^–2, which is superior to those of (FeSe₂ + CoSe₂) (390 mV), CoSe₂/N-3DCN (377 mV), RuO₂ (320 mV), and FeSe₂/N-3DCN (479 mV). Additionally, after the 80 h stability test, the overpotential of (FeSe₂ + CoSe₂)/N-3DCN can still be maintained at 316 mV. © 2023 American Chemical Society.