Nano-cluster Assembled Films, Produced by Pulsed Laser Deposition, for Catalysis and the Photocatalysis
Catalyst architected in form of coating with nano-particles (NPs) are under intense investigation in the catalysis community due to their exceptional activity and selective nature in catalytic processes as compared to the corresponding bulk counterpart, especially because of their large surface-to-volume atomic ratio, size- and shape-dependent properties, and high concentration of low-coordinated active surface sites. Here we report on selected examples to demonstrate how Pulsed Laser Deposition (PLD) technique is able to synthesize NPs in a single step with the required relevant features for catalysis application. Co NPs embedded in B matrix films have been synthesized by PLD technique by taking advantage of the phase explosion process of superheated liquid where a mixture of vapor and liquid droplets leave the irradiated target surface and get deposited on the substrate. Just these NPs of low cost materials (Co–B) exhibit catalytic properties comparable to that of precious metals in hydrogen production by hydrolysis of NaBH4 and NH3BH3. The catalytic activity increases further when the Co–B NPs are supported over a porous C films with high surface area synthesized by PLD. PLD was also utilized to produce Co3O4 NPs assembled coating by reactive ablation of Co metal in oxygen atmosphere at various substrate temperatures from room temperature to 250 °C. The important characteristics for catalysis such as shape and the size of NPs with narrow size distribution and mixed disordered-nanocrystalline phase were obtained in a single step in Co3O4 NPs synthesized by PLD technique. The Co3O4 NPs assembled coatings on glass have been tested in degradation of methylene blue dye solution, considered as a water pollutant, via photo-Fenton reaction in presence of H2O2. It was observed that the present Co3O4 NPs heterogeneous catalyst exhibits significantly better degradation activity for methylene blue solution than that obtained with homogeneous Co2+ ions.
KeywordsMethylene Blue Pulse Laser Deposition Laser Fluence Pulse Laser Deposition Technique Ammonia Borane
The research activity is partially supported by the PAT (Provincia Autonoma di Trento) project ENAM in cooperation with Istituto MCB of CNR (Italy).