Mn-CeO2 Nanomaterial for the Colorimetric Sensing of H2O2 and Ascorbic Acid

Owing to the high stability and low cost of nanozymes, they have been extensively investigated and reported. In this work, highly active CeO2 nanoflowers were first prepared and then different metal elements were doped into the CeO2 nanoflower matrix via a novel synthesis method to fabricate M-CeO2 (M = Cu, Fe, Co, Mn, La) nanomaterials. Mn-CeO2 with the highest peroxidase-like activity was selected via systematic screening, the as-prepared Mn-CeO2 nanocomposites exhibited enhanced enzyme-like activity due to the strong metal-support interaction. This article explored the effects of doping ratio, pH, temperature, reaction time, and material concentration on its activity. A simple sensitive and selective colorimetric method was established and successfully used to detect hydrogen peroxide and ascorbic acid sensitively. When the hydrogen peroxide (H2O2) concentration is within the 2.0–120.0 μM range, the UV-visible absorbance at 652 nm was associated linearly with the H2O2 concentration, R2 = 0.9959, LOD = 1.7 μM (S/N = 3). The absorbance of the reaction system showed a good linear relationship with the ascorbic acid (AA) concentration (1.0–40.0 μM, R2 = 0.992), LOD = 0.98 μM (S/N = 3). This study provides an effective way to construct efficient nanozymes and their potential applications in sensing and detection.