Heterointerface engineering of layered oxyhydroxides reconfigures local hydrogen-bond coordination for efficient aqueous ammonium storage

Layered oxyhydroxides are promising hosts for aqueous NH₄⁺ storage. However, their uniform interlayer environments typically induce random hydrogen-bond coordination with unfavorable adsorption energies, severely impeding intercalation kinetics and reversibility. Herein, a heterointerface engineering strategy is proposed, utilizing a fluorine-free/fluorinated nickel‑cobalt oxyhydroxide heterostructure (H-MOOH) to reconfigure the local hydrogen-bond coordination. Combined experimental and theoretical analyses reveal that the structural disparity at the heterointerface triggers Fermi level alignment and anisotropic charge redistribution, reshaping the interlayer electrostatic microenvironment. Crucially, this polarized interfacial field governs the host-guest interactions, directing NH₄⁺ states to converge predominantly into a thermodynamically favorable, F-mediated six-coordinated configuration. Coupled with bond-length contraction and bond-angle modulation, this tailored coordination optimally balances dynamic confinement and rapid dissociation within interlayer channels. As a result, the H-MOOH electrode delivers an exceptional high-rate capacity of 169 mAh g^-1 at 5 A g^-1, achieving a 3.5-fold enhancement over the pristine counterpart, and demonstrates outstanding reversibility, retaining 89.2% of its capacity after 5000 cycles. This work highlights the pivotal role of rational heterointerface design in regulating local coordination environments, offering a new paradigm for exploring efficient aqueous ammonium storage materials.