Hydrogen storage in polymer-functionalized Pd-decorated single wall carbon nanotubes

Area of Science:

• Materials Science
• Nanotechnology
• Chemical Engineering

Background:

• Palladium nanoparticles on porous supports enhance hydrogen storage capacity beyond individual components.
• Hydrogen spillover, where atomic hydrogen moves from palladium to the support, is a key phenomenon.
• Single-walled carbon nanotubes (SWNTs) are promising supports due to their high surface area.

Purpose of the Study:

• To synthesize palladium nanoparticles supported on SWNTs using a facile method.
• To investigate the hydrogen storage properties of the synthesized Pd/SWNTs composite.
• To understand the contribution of different mechanisms to the overall hydrogen storage.

Main Methods:

• Palladium nanoparticles were synthesized on commercial SWNTs using palladium chloride (PdCl2) precursor in polyethylene glycol (PEG 200) solution.
• The synthesis involved heating at 200°C, followed by washing and drying.
• Hydrogen storage capacity was measured using the gravimetric method up to 2 MPa, complemented by thermal desorption experiments.

Main Results:

• A 3 wt% palladium loading was achieved with 50% of Pd nanoparticles having a diameter less than 8 nm.
• A satisfactory hydrogen storage capacity of 1.2 wt% was observed at 0.2 MPa.
• A portion (0.2 wt%) of the storage capacity was attributed to water formation from hydrogen and adsorbed oxygen.

Conclusions:

• The synthesized Pd/SWNTs composite exhibits significant hydrogen storage capabilities.
• Understanding the role of surface chemistry, like oxygen presence, is crucial for optimizing hydrogen storage.
• The study provides insights into the hydrogen adsorption/desorption cycles and material regeneration.