In Situ Chemical Oxidation of Ultrasmall MoOx Nanoparticles in Suspensions

Figure 2

Effect of chemical oxidation with H₂O₂ on MoO_𝑥 nanoparticle properties. (a) Dependence of nanoparticle size on chemical oxidation time (up to 24 hrs), showing that compared to as-synthesized nanoparticles (dashed line), both 0.1 M H₂O₂ (blue) and 0.3 M caused npMoO_𝑥 size to decrease to 1 nm (up to 3 hrs) and then increase back to 2 nm (24 hr). (b) Dependence of nanoparticle film Φ versus chemical oxidation conditions, showing Φ of as-synthesized npMoO_𝑥 (black) was increased from 4.48 eV to 4.85 eV with 0.05 M H₂O₂ (purple) and that the increase was independent of the reaction time between 20 min and 24 hr. In contrast, 0.1 M (blue), 0.2 M (green), and 0.3 M (red) H₂O₂, all caused work function to increase to 5.0 eV with a reaction time of up to 3 hr. However, a further increase in reaction time to 24 hrs decreased Φ to 4.9 eV.

(a)

(b)