In-situ confinement growth of FeNi alloy within B/N co-doped carbon nanotubes as efficient electrocatalyst for water splitting

Abstract

Developing low-cost and efficient catalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) still remains a challenge in water electrolysis. Herein, FeNi alloy encapsulated within boron and nitrogen co-doped carbon (FeNi@BNC) nanotubes are synthesized through a simple one-step pyrolysis method using FeCl₃·6H₂O, NiCl₂·6H₂O, H₃BO₃, urea and PEG-2000 as precursors. The BNC nanotubes are quite requisite for dispersing and stabilizing FeNi alloy nanoparticles (NPs) during pyrolysis. Benefiting from the synergistic catalytic effect of Fe and Ni, as well as the confinement effect of BNC nanotubes, such FeNi@BNC catalyst demonstrates impressive activities for both HER and OER, much superior to pristine Fe@BNC and Ni@BNC. Notably, the overpotentials needed to achieve a current density of 10 mA·cm⁻² are just 230 mV for HER and 280 mV for OER. Moreover, the FeNi@BNC catalyst demonstrates significant stability, showing no noticeable degradation during potentiostatic electrolysis or repeated CV tests. Furthermore, FeNi@BNC exhibits remarkable activity for overall water splitting, requiring cell voltages of just 1.24 V and 1.60 V vs. RHE to achieve current densities of 10 mA·cm⁻² and 20 mA·cm⁻², respectively. This study introduces a novel strategy for developing bifunctional electrocatalysts with high-efficiency water splitting performance.