▎ 摘　　要

Here we presented a new facile strategy to fabricate ultrathin two-dimensional (2D) metal oxide nanosheets, by using polydopamine-coated graphene (rGO@PDA) as a template under simplywet-chemicalconditions. Based on the strategy, graphene-like CeO2-TiO(2)mesoporousnanosheet (MNS-CeO2-TiO2) was prepared and was loaded with dispersive Ag nanoparticles (AgNPs) to obtain effective electrocatalysts (denoted asAg/MNS-CeO2-TiO2) forelectrochemical detectionof superoxide anion (O-2(center dot & minus;)). Characterizations demonstrated that MNS-CeO2-TiO(2)exhibited ultrathin thickness, larger specific surface area, andpore volumein comparison with its bulk counterpart. The above properties of MNS-CeO2-TiO(2)shorten electron transmission distance, promotes mass transfer, and is conducive to the dispersion of post-modified AgNPs. Therefore, the recommended Ag/MNS-CeO2-TiO(2)sensors (denoted asAg/MNS-CeO2-TiO2/SPCE) exhibited satisfactory properties, including the sensitivity of 737.1 mu Acm(& minus;2)mM(& minus;1), the detection limit of 0.0879 mu M (S/N=3), and good selectivity. Meanwhile, the sensors also successfully realized in the online monitoring of O(2)(center dot & minus;)released from HepG2 cells, meaning the prepared sensors had practical application potential towards the analysis of O(2)(center dot & minus;)in biological samples.