Tuning ceria catalysts in aqueous media at the nanoscale: how do surface charge and surface defects determine peroxidase- and haloperoxidase-like reactivity

Abstract

Designing the shape and size of catalyst particles, and their interfacial charge, at the nanometer scale can radically change their performance. We demonstrate this with ceria nanoparticles. In aqueous media,...

In situ generation of H2O2 using CaO2 as peroxide storage depot for haloperoxidase mimicry with surface-tailored Bi-doped mesoporous CeO2 nanozymes

“…The surface area increases with synthesis time, whilst the Ce 3+ /Ce 4+ ratio scales inversely with decreasing ζ -potential (because Ce 4+ is reduced to Ce 3+ with time during the reaction). 41…”

“…The surface area increases with synthesis time, whilst the Ce 3+ /Ce 4+ ratio scales inversely with decreasing ζ-potential (because Ce 4+ is reduced to Ce 3+ with time during the reaction). 41 ζ-Potential measurements were carried out to evaluate the effect of reaction time on the surface potential and to obtain information about the stability of the colloidal system and its catalytic activity. Interactions of substrates with the catalyst surface may differ due to electrostatic attraction or repulsion.…”

“…Since haloperoxidase-like reactions are controlled by electrostatic interactions between negatively charged halide ions and the Bi 0.2 Ce 0.8 O 1.9 particle surface, the ζ-potential of the Bi 0.2 Ce 0.8 O 1.9 colloids is a key factor for halide adsorption and thus for the catalytic (haloperoxidase) activity. 36,41 If the surface potential of densely packed and hollow spheres were identical, the morphologies and the resulting different surfaces would affect activity. Consequently, the reaction rate decreases with increasing reaction time.…”

“…The activity of Bi 0.2 Ce 0.8 O 1.9 can even be enhanced by surface engineering with mesoporous Bi 0.2 Ce 0.8 O 1.9 particles, which have an increased BET surface area ( S BET ) and a variable ζ -potential owing to different Ce 3+ /Ce 4+ ratios. 41 Since polyether sulfones and poly(vinylidene fluoride) (PVDF) are used in filter membranes and for medical purposes ( e.g. , in fluid contact for food, beverage, or pharmaceutical applications) where prevention of biofilm formation is important, 42,43 CaO 2 /Bi 0.2 Ce 0.8 O 1.9 /polyether sulfone and CaO 2 /Bi 0.2 Ce 0.8 O 1.9 /PVDF nanocomposites were prepared to test the efficacy of the haloperoxidase reaction.…”

Regulating the H2O2 Activation Pathway on a Well-Defined CeO2 Nanozyme Allows the Entire Steering of Its Specificity between Associated Enzymatic Reactions

“…It was recently shown that the HPO-like activity is proportional to the ζ-potential of CeO 2 surfaces as it promotes the adsorption of negatively charged Br − . 38 Although a good correlation can be seen for CeO 2 shapes here (Figure S25), this does not explain the selective oxidation of the added Br − by the monodentate peroxo species on Ce 7c(111) (or Ce 6c(110) ). DFT computations were thus employed to study the interplay between surface peroxo species and neutral Br atoms.…”