Polydimethylsiloxane-modified super hydrophobic porous graphene filled with palmitic acid as a phase change energy storage material

A porous graphene (PG) was synthesized using calcium carbonate micro-spheres as a hard template, graphene oxide prepared by the Hummers' method as graphene precursor, hydrazine hydrate as a reduction agent and N,N-dimethylformamide as a dispersion agent. The as-prepared PG was modified by chemical vapor deposition of polydimethylsiloxane (PDMS) to obtain a super hydrophobic porous material (PG-PDMS) with a water contact angle of 152.3°, which was used as a porous host for palmitic acid. It was found that the pores of the PG-PDMS were completely filled with palmitic acid. The hydrophobic modification significantly increased the palmitic acid content from 62.3 to 80.2%. The incorporation of palmitic acid did not change the crystal structure of the PG and PG-PDMS. The latent heats of melting and crystallization for the palmitic acid-filled PG-PDMS are 167.8 and 170.1 kJ·kg¹, respectively. This phase change material has great potential for energy saving applications and solar energy storage.