Oxygen-vacancy enhanced peroxidase-like activity of Cu-SnO2 for dual-mode sensing of hydrogen peroxide

Hydrogen peroxide (H2O2) is an important oxidant and one common active oxygen species in organisms. It is critically important to realize fast and accurate detection of H2O2. In this work, Cu-SnO2 is successfully evaluated as a dual mode-sensing material for H2O2 detection. The study proves that the peroxidase-like activity increases steadily with the oxygen vacancy concentration on the material surface. The material Cu-SnO2-1.5, which shows the highest amount of oxygen vacancy, successfully oxidizes colorless substrate (TMB) to blue (ox TMB) in the presence of H2O2. The peroxidase-like behaviors of this material are consistent with the Michaelis-Menten equation. An electrochemical sensor based on this material exhibits a wide working range (0.2 mu M-0.745 mM and 0.745-5.345 mM), a low detection limit of 67 nM, and promising sensitivity of 158.16 mu A.mM(-1)cm(-2) for H2O2 in 0.1 M phosphate buffered (PB) solution. In addition, the H2O2 released from human liver cancer (HepG2) cells is successfully detected by the sensor, proving its potential application in situ H2O2 detection.