Breaking efficiency Limits in solar water Splitting: Ferroelectric CuInP₂Se₆ with Ni Single-Atom cocatalysts for...

Photocatalytic water splitting represents a promising approach for sustainable energy production, yet its practical implementation remains hindered by insufficient light absorption, rapid charge recombination, and inadequate catalytic efficiency. This study proposes a two-dimensional ferroelectric Ni₂/CuInP₂Se₆ that addresses these fundamental limitations through rational material design. Through systematic screening of ABP₂X₆ materials (A=Cu; B = In/Cr; X=S/Se), the ferroelectric CuInP₂Se₆ monolayer emerges as an optimal substrate due to its exceptional stability, appropriate band alignment, and superior light absorption coefficient. Subsequent selection of Ni single-atom cocatalysts from nine transition metals reveals optimal hydrogen evolution (η_HER = 0.09 V) and oxygen evolution (η_OER = 0.37 V) overpotentials, achieving remarkable solar-to-hydrogen efficiency (24.63 %). Crucially, the ferroelectric polarization-induced built-in electric field enables spatial separation of photogenerated carriers while modulating the Ni d-band center, which effectively regulates the adsorption strength of reaction intermediates, facilitating the adaptive optimization of distinct reaction. The proposed strategy not only demonstrates the viability of 2D ferroelectric materials for photocatalytic applications but also establishes a general framework for designing high-performance photocatalysts through coupled polarization engineering and single-atom catalysis.