Mechanochemical Synthesis of Defective Molybdenum Trioxide, Titanium Dioxide, and Zinc Oxide at Room Temperature

Defect engineering on metal oxide semiconductors is considered as a versatile approach to regulate their properties. The traditional method for preparation of defective metal oxide semiconductors always requires harsh reaction conditions such as high temperature, high pressure, and explosive chemicals. Here we report an environmentally friendly mechanochemical synthesis way for preparation of several defective metal oxide semiconductors (MoO3, TiO2, and ZnO) in 10 g quantities by grinding semiconductor powders with ascorbic acid. The resulting vacancy-rich TiO2 and ZnO show a strong visible-light absorption. Meanwhile, the obtained hydrogen-doped MoO3 (H0.5MoO3) exhibits an exceptional localized surface plasmon resonance (LSPR), which follows Prout-Tompkins B1 solid-state reaction model. In addition, the plasmonic H0.5MoO3 is further utilized for colorimetric detection of H2O2. This colorimetric assay is able to determine concentrations of H2O2 from 0.05 to 3 mM with a detection limit of 30 μM. It can distinguish the presence of 3 mM H2O2 by the naked eye.