Pulsed laser engineering of composite submicron particles in colloidal systems: A high-performance catalyst for ethanol fuel cells

Abstract

Nanoparticles are widely regarded as optimal for catalytic reactions; however, larger particles with highly active surfaces may offer an intriguing alternative for advancing catalytic technologies. This study employs pulsed laser melting to transform colloidal copper/magnetite nanoparticles into surface-active submicron Cu_xFe_3-xO₄-Cu_yO-Cu_zFe_1-z composite particles, tailored for ethanol oxidation fuel cells. The findings reveal that colloidal particles tend to cluster into either homogeneous or heterogeneous aggregates, mediated by the surrounding liquid. This clustering aids the formation of desired phases during pulsed laser processing. Temperature-dependent thermodynamic phase transitions, combined with pulse-driven heating-cooling dynamics, promote copper oxidation and magnetite reduction, achieving both compositional control and microstructural surface activation. The synthesized heterostructures demonstrated excellent performance in ethanol oxidation, both as primary catalytic materials and as activity-enhancing supports for platinum. Oxidation state analysis post electrocatalysis indicated a reduction in graphite bonds and an increase in oxygen bonds, attributed to the high oxygen content of the catalysts’ surface. The electrocatalysis ethanol oxidation process generated potent oxidizing agents, including ozone, oxygen and hydroxyl radicals, with the ability of degrading the sp² hybrid structure of graphite. Despite their submicron size, the kinetically activated composite particles exhibited exceptional surface activity, positioning them as cost-effective alternatives to the conventional catalysts for fuel cell technologies.