# The Sol–Gel Metal-Oxide Skeleton Affects the Catalytic Properties of In Situ Formed Metal Nanoparticles

## TL;DR

This study shows how different metal-oxide materials influence the performance of metal nanoparticles in breaking down harmful disinfection byproducts.

## Contribution

The paper reveals how sol–gel matrices affect the catalytic activity of in situ formed metal nanoparticles in dehalogenation reactions.

## Key findings

- SiO2 supports higher Cu0 activity in dechlorination compared to Al2O3 and TiO2.
- Al2O3 enhances Ni0 reactivity more than SiO2 and TiO2 in similar reactions.
- The sol–gel matrix significantly alters the reduction behavior of encapsulated metals.

## Abstract

The interaction between
the mesoporous metal-oxide matrix and the
adsorbed/entrapped active metal species attracts attention and curiosity
due to its critical role in defining catalytic performance. Herein,
the effects of TiO2, Al2O3, and SiO2 sol–gel matrices on the catalytic properties of encapsulated
Cu0 and Ni0 species catalyzing the dehalogenation
of the hazardous disinfection byproducts, chloro and bromoacetic acids,
are reported. A precatalyst approach is employed in which a matrix
is prepared by incorporating M­(II) species into the pores of the sol–gel,
which are later reduced to the active catalyst, M(0), during the reduction
reaction by BH4
–. The synthesized precatalysts
are thoroughly studied using BET isotherms, X-ray diffraction, X-ray
fluorescence, X-ray photoelectron spectroscopy, and scanning electron
microscopy. The results point out that the relative effect of the
metal-oxide environment on the adsorbed active metal species affects
the process studied: for example, in the dechlorination of chloroacetic
acid by Cu0-NPs, the order of activities is SiO2 > Al2O3 > TiO2; whereas for
the
analogous processes catalyzed by Ni0-NPs, the order of
reactivities is Al2O3 > SiO2 >
TiO2. For the other processes studied, other orders of
activity
are observed. Thus, the results indicate that the different sol–gel
materials encapsulating the catalytic metals affect the reduction
reactions differently.