Dimensional reduction of hydrogen-bonding networks induced by hierarchical confinement to promote ultra-fast adsorption of hydrated ions to targeted sites

Salt ions typically exist as hydrated states in aqueous environments, wherein the hydration shell impedes their contact with active sites, limiting adsorption efficiency. To address this, we innovatively design hierarchical confined structure to achieve complete removal of hydrated shell. This structure is constructed by intercalating one-dimensional (1D) nanochannel metal–organic framework (MOF) into two-dimensional (2D) graphene oxide (GO) interlayers. The resulting M-MOF@GO adsorbent exhibits exceptional performance, achieving capacities of 250.2 mg·g^‒1 for hydrated phosphate and 281.6 mg·g^‒1 for hydrated fluoride, respectively, plus ultra-high mass transfer rates of 13.09 and 11.97 mg·(g·min^0.5)⁻¹. Such exceptional performance stems from confinement-induced dimensionality reduction mechanism of the hydrogen-bond network. Under GO-based 2D interlayers, abundant hydrophilic groups synergize with the confined environment forms a superhydrophilic microenvironment, inducing siphon effect that attracts hydrated ions into the confined spaces while simultaneous promoting dehydration. Released water form an ordered 2D network at the inner interface, reducing diffusion resistance to accelerate ion mobility. Partially dehydrated ions then transport into the 1D M-MOF channels, where enhance confinement enable near-complete desolvation. This facilitates unhindered ions coordination with increased coordination number and binding strength on active sites. Such mechanism guarantees high performance across multiple application scenarios, offering a groundbreaking solution to hydration-limited adsorption.