# Issues of Using Benzyl Ether in Nanomaterials’ Synthesis: Insights for a Standardized Synthesis of FeWO x Nanocrystals and Their Use as Photocatalysts

## TL;DR

This paper improves the synthesis of FeWOx nanocrystals using benzyl ether and shows their effectiveness in degrading pollutants under sunlight.

## Contribution

The discovery that benzoic acid is essential for stabilizing tungsten intermediates in FeWOx synthesis.

## Key findings

- Fe0.1WOx showed the highest photocatalytic activity with 67% degradation of rifampicin in 150 minutes.
- Reduced band gap and favorable band-edge positions in Fe0.1WOx enhance its photocatalytic performance.
- Holes and hydroxyl radicals are the main reactive species in the degradation process.

## Abstract

The synthesis of nonstoichiometric FeWO
x
nanocrystals via thermal decomposition in benzyl ether has
been
systematically optimized, addressing reproducibility issues typically
associated with this solvent. A key finding of this work is the identification
of benzoic acid, a benzyl ether oxidation byproduct, as a necessary
ligand for stabilizing tungsten intermediates and enabling consistent
FeWO
x
formation. The optimized protocol
allows fine-tuning of the Fe/W atomic ratio, leading to a series of
materials with tailored stoichiometry, surface properties, and electronic
structure. Fe1.5WO
x
, Fe1.0WO
x, and Fe0.1WO
x
have been
selected as representative examples of materials with Fe excess, slight
Fe excess, and an Fe/W ratio close to 1. Among them, Fe0.1WO
x
exhibited the best photocatalytic performance in
the degradation of rifampicin under simulated solar irradiation, achieving
a 67% degradation within 150 min and displaying a kinetic rate constant
(0.0076 min–1) three times higher than the other
compositions. This superior activity is attributed to its reduced
band gap (1.45 eV) and favorable band-edge positions. Scavenger experiments
confirmed that holes and hydroxyl radicals (•OH)
are the main reactive species involved in the degradation process.
These findings provide key insights for designing reproducible benzyl
ether-based syntheses and demonstrate the potential of FeWO
x
nanomaterials for photocatalytic water treatment
applications.