Fe‐Co LDH/MoP heterostructure with Fe and Co as intercalants for oxygen evolution electrocatalysis

Due to the sluggish kinetics and unfavorable thermodynamics, oxygen evolution reaction (OER) remains as the bottleneck for efficient water splitting. Transition metal-based layered double hydroxides (LDHs) such as Fe-doped Co-based hydroxides (Fe-Co(OH)₂) are exceptionally appealing OER catalyst due to their decent affordability and activity. To simultaneously enhance the active site exposure and electrical conductivity, Fe-Co(OH)₂ is deposited on the surface of MoP nanoribbon (Fe-Co(OH)₂/MoP) through a novel "MoO₃ intercalation-phosphorization" protocol, where the atomically dispersed Fe and Co intercalants in the van der Waals (vdW) gap of 2D MoO₃ are utilized as precursors to facilitate the exposure of Fe/Co sites at Fe-Co(OH)₂/MoP surface. As results, Fe-Co(OH)₂/MoP heterostructure exhibits remarkable electrocatalytic activity toward OER (overpotential: 240 mV at 10 mA cm^-2; Tafel slope: 39.6 mV dec^-1). Experimental and theoretical results suggest the Fe dopant in Fe-Co(OH)₂/MoP facilitates the formation of Co(III) active species by inducing superexchange interaction between high-spin Fe(III) and low-spin Co(II), which substantially enhanced the electrocatalytic activity toward OER.