Enhanced trace gadolinium(III) extraction via tailored chemisorption on defect-engineered molybdenum disulfide electrodes

Separation and recovery of trace gadolinium(III) from rare earth elements (REEs) with similar properties is increasingly crucial for renewable energy resources and sustainable development. This study proposed a method to regulate the chemisorption activity of gadolinium(III) using defects-rich molybdenum disulfide (DR-MoS 2 ) electrodes, enabling the separation and recovery of gadolinium(III) from aqueous solutions. Lanthanum(III), gadolinium(III), and yttrium(III), representing light, medium, and heavy REEs respectively, were selected to investigate their adsorption behaviors of on MoS 2 and DR-MoS 2 electrodes at low concentrations. Experiments and simulation results verified distinct adsorption behaviors of REEs on MoS 2 , influenced by their out-shell electron binding capabilities. Interestingly, gadolinium(III) exhibited a unique interaction where its f orbitals strongly interacted with p orbitals of unsaturated sulfur atoms, unlike the other REEs, facilitating effective separation and recovery of gadolinium(III). Furthermore, increased binding affinity enhanced the electric double layer capacity (EDLC) and reduced electrons immigration resistance. Consequently, DR-MoS 2 electrodes achieved 100% recovery of trace gadolinium(III) recovery with high separation efficiency. Hopefully, strongest lanthanum(III) interaction with unsaturated Mo atoms was expected to realize lanthanum(III) separation and recovery. This study presented a promising approach to selectively recover target REEs from similar elements through modulating the chemisorption.