Core/Shell Au/MnO Nanoparticles Prepared Through Controlled Oxidation of AuMn as an Electrocatalyst for Sensitive H2O2 Detection

Abstract Monodisperse 5 nm AuMn nanoparticles were synthesized by hydride reduction of manganese acetylacetonate in the presence of Au nanoparticles. The alloy was formed through fast Mn diffusion into the Au structure. The AuMn nanoparticles were converted to Au‐MnO composite particles through air annealing at 170 °C. These Au‐MnO particles, especially the core/shell Au/MnO nanoparticles, were active for the electrochemical reduction of H 2 O 2 , with a detection limit reaching 8 n M . This highly sensitive electrochemical sensor based on the Au/MnO nanoparticles was used to monitor H 2 O 2 concentrations released from living cells, from which tumorigenic cells were discovered to release higher levels of H 2 O 2 than the non‐tumorigenic cells.