Boron–carbon–nitrogen foam surfaces for thermal physisorption applications

A surface chemical treatment of highly porous carbon foams was adopted to synthesize boron–carbon–nitrogen (B–C–N) foams for thermal energy storage and release using an adsorption/desorption cycle with lightweight hydrocarbons. Microwave treatment in boric acid and urea was used to modify carbon foams with a B–C–N surface. Depending on the initial carbon foam state, B–C–N surface layers were produced with both amorphous and crystalline structures. The resultant B–C–N foams were characterized by TEM, XPS, XRD, FESEM and Raman measurements to quantify their stoichiometry, structure, and morphology. Adsorption enthalpy with methanol and thermal stability of foams was analyzed with DSC and TGA respectively. Thermal conductivity was measured by a transient laser flash technique. Results indicate that the crystalline graphitic carbon foam produces superior B–C–N surfaces compared to amorphous carbon foam. The crystalline B–C–N foams are found to provide the highest adsorption capacity, better thermal and oxidation stability.

► Boron and nitrogen doping in amorphous and graphitic carbon foam surfaces.
► Graphitic carbon foam surface is superior for boron and nitrogen diffusion.
► Improved desorption enthalpy with methanol for graphitic B–C–N foam.
► Improved thermal stability in air and thermal conductivity for graphitic B–C–N foam.