# Femtosecond Laser Generation of LaCoO3 Perovskite Nanocatalysts for Preferential CO Oxidation

## TL;DR

Femtosecond laser synthesis creates efficient LaCoO3 nanocatalysts with defects that improve CO oxidation performance over traditional chemical methods.

## Contribution

A novel laser-based method for generating defect-rich LaCoO3 nanocatalysts with superior CO oxidation activity and selectivity.

## Key findings

- Laser-synthesized LaCoO3 nanoparticles at 5.8 J cm–2 achieved the highest CO conversion during PROX at 400 °C.
- Laser-produced nanoparticles showed CO2 selectivity of 89% and 83% at 5.8 J cm–2 and 5.1 J cm–2, respectively, compared to 28% for chemical methods.
- Laser synthesis creates internal defects absent in chemically derived nanoparticles, enhancing catalytic performance and stability.

## Abstract

Green synthesis and defect engineering of LaCoO3 model
nanocatalysts by femtosecond pulsed laser ablation in liquid (fs-PLAL)
led to the formation of two types of nanoperovskites: stoichiometric
LaCoO3 and nonstoichiometric cobalt-rich nanoparticles.
Micro-Raman analysis revealed pronounced second-order phonon scattering,
suggesting a high defect density. The defect spatial distribution
was evaluated by high-resolution electron microscopy, employing Fourier
filtering and image reconstruction. Increasing the laser fluence increases
the surface defect density due to the fast cooling of primary nanoparticles,
a process intensified by the inherently ultrashort pulses. Laser-produced
nanoparticles exhibited internal defects, a characteristic absent
in those produced by a chemical method. Chemically derived nanoparticles,
originally perfectly crystalline, formed grain/twin boundaries during
calcination when their irregular shapes coalesced. Compared to a chemically
synthesized reference catalyst, nanoparticles laser-synthesized at
5.8 J cm–2 showed the highest CO conversion during
PROX in excess H2 at 400 °C. Perovskite produced at
5.8 J cm–2 and 5.1 J cm–2 also
showed higher CO2 selectivity (89% and 83%, respectively,
versus 28% of the reference), as well as excellent stability at 350–400
°C.