Single‐entity electrochemistry (SEE) was employed to quantitatively investigate the adsorption–desorption behavior of Cd 2+ on individual graphene oxide (GO) and Fe 3 O 4 particles, providing nanoscale insight into interfacial processes that are inaccessible to bulk methods. Distinct collision signals were observed for the two adsorbents, where GO generated larger and broader current spikes, reflecting higher Cd 2+ loading and slower electron transfer. Adsorption isotherms constructed from SEE data closely followed the Langmuir model and yielded comparable affinity constants and separation factors (0 < R L < 1) to traditional batch experiments, confirming the quantitative accuracy of SEE. Desorption kinetics for both materials were well described by the pseudo‐second‐order model, revealing chemisorption‐controlled behavior. Fe 3 O 4 exhibited faster, more uniform desorption (constant CV%), whereas GO showed slower and more heterogeneous release due to stronger surface complexation. In mixed‐particle systems, desorption kinetics remained independent, though GO increased Fe 3 O 4 's event‐to‐event variability, indicating subtle interparticle interactions. Overall, SEE provides a reliable, real‐time, and particle‐resolved approach for linking electrochemical dynamics with adsorption thermodynamics in complex adsorbent systems.
Li et al. (Wed,) studied this question.