2D Heterostructure of Amorphous CoFeB Coating Black Phosphorus Nanosheets with Optimal Oxygen Intermediate Absorption for Improved Electrocatalytic Water Oxidation

The
oxygen evolution reaction (OER) plays a paramount role in a
variety of electrochemical energy conversion devices, and the exploration
of highly active, stable, and low-cost electrocatalysts is one of
the most important topics in this field. The exfoliated black phosphorus
(EBP) nanosheet with a two-dimensional (2D) layered structure has
high carrier mobility but is limited by excessive oxygen-containing
intermediate absorption and fast deterioration in air. We here report
the fabrication of nanohybrids of amorphous CoFeB nanosheets on EBP
nanosheets (EBP/CoFeB). The 2D/2D heterostructure, thanks to the electronic
interactions and oxygen affinity difference between EBP and CoFeB
nanosheets, is capable of balancing the oxygen-containing intermediate
absorption to an optimal status for facilitating the OER process.
While the crystalline EBP contributes to the improved conductivity,
the amorphous coating protects EBP and thus ensures the catalytic
stability. The EBP/CoFeB electrocatalyst shows excellent OER performance
with an ultralow overpotential of 227 mV at 10 mA cm–2 with an ultrasmall Tafel slope of 36.7 mV dec–1 with excellent stability. This study may inspire more researches
to develop heterostructured nanohybrid electrocatalysts for a diversity
of electrochemical reactions.