Alternative Local Melting-Solidification of Suspended Nanoparticles for Heterostructure Formation Enabled by Pulsed Laser Irradiation

Phase formation by pulsed laser irradiation of suspended nanoparticles has recently been introduced as a promising synthesis technique for heterostructures. The main challenge still lingers regarding the exact mechanism of particle formation due to the non-equilibrium kinetic by-products resulting from the localized alternative, fast, high-temperature nature of the process. Here, the authors analyze the bond breaking/formation of copper or copper (II) interfaces with ethanol during the absorption of pulses for Cu-CuO-Cu₂O formation applicable as an electrocatalyst in ethanol oxidation fuel cells. This study includes but is not limited to, a comprehensive discussion of the interaction between nano-laser pulses and suspension for practical control of the synthesis process. The observed exponential and logarithmic changes in the content of heterostructures for the CuO-ethanol and Cu-ethanol samples irradiated with different fluences are interpreted as the dominant role of physical and chemical reactions, respectively, during the pulsed laser irradiation of suspensions synthesis. It is also shown that the local interface between dissociated ethanol and the molten sphere is responsible for the oxidative/reductive interactions resulting in the formation of catalytic-augmented Cu³⁺ by-product, thanks to the reactive bond force field molecular dynamics studies confirmed by ab-initio calculations and experimental observations.