p–d Orbitals Coupling Heterosites of Ni₂P/NiFe‐LDH Interface Enable O─H Cleavage for Water Splitting

Abstract Electrocatalytic water splitting for hydrogen production still faces a bottleneck due to sluggish reactive kinetics and high reactive energy barriers. Herein, p–d orbital coupling P–Fe heterosites are constructed at Ni₂P–FeNi‐LDH interfaces to enhance the O─H bond cleavage of reaction intermediates H₂O* and OH* for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), respectively. The Ni₂P/NiFe‐LDH heterostructure shows superior HER and OER activities for alkaline water splitting with overpotentials of 230 and 270 mV at 100 mA cm⁻², respectively, and even exhibits high activity for electrocatalytic alkaline seawater splitting. The interaction of P 2p and Fe 3d orbitals at Ni₂P–FeNi‐LDH interfaces upshifts the d‐band center of Fe and downshifts the p‐band center of P. This finding not only facilitates the dissociation of O─H bonds in H₂O and promotes the Volmer–Heyrovsky step for HER, but also reduces the energy barrier for the rate‐determining step of OER from OH* to O* transition. This work proposes a new approach to constructing p–d heterosites at heterojunctions to facilitate reactive kinetics and reduce the energy barrier for electrocatalysis.