Decoding Short-Range Order in Amorphous Two-Dimensional Nanosheets for Efficient and Durable Ampere-Level Seawater Electrolysis: A Case Study of Amorphous Ni(OH)2

Amorphous nanomaterials, once considered structurally disordered, are now recognized for exceptional catalytic performance, yet their atomic-scale origins remain elusive. Here, we combine atom probe tomography (APT), theoretical simulation, and operando spectroscopy to reveal the hidden architecture of amorphous Ni(OH)₂ nanosheets (a-Ni(OH)₂ NSs)—a highly active and durable catalyst for alkaline seawater electrolysis. As cathodes in anion exchange membrane water electrolyzers, a-Ni(OH)₂ NSs deliver a remarkably low cell voltage of 1.89 V at 1.0 A cm⁻², outperforming crystalline Ni(OH)₂ (2.53 V) and commercial Pt/C (2.39 V), while sustaining over 1000 h of stable operation with negligible decay (<0.02 mV h⁻¹). APT enables 3D, atom-by-atom mapping—including hydrogen—revealing four distinct short-range order (SRO) motifs with thickness-dependent distributions. These motifs act synergistically: surface O–Ni–OH SROs promote water dissociation, interior Ni–OH SROs optimize proton reduction, and bridging O–Ni–O and Ni–OH₂ SROs accelerate proton transport via hydrogen-bond networks. This coordinated motif network fully accounts for the exceptional performance, transforming the view of amorphous materials from “black boxes” to atomically designable systems. Our findings establish APT as a transformative platform for uncovering functional motifs in amorphous catalysts, paving the way for rational design of next-generation materials for sustainable energy conversion.