Nanoporous carbons derived from breakfast waste as sustainable hydrogen storage materials

The transition towards a low-carbon energy landscape requires the development of efficient and sustainable hydrogen (H2) storage technologies. Nanoporous carbons represent promising adsorbents due to their high specific surface area, chemical stability and relatively low production cost. At the same time, the utilization of organic waste as precursor materials offers significant environmental and circular-economy benefits. In this work, the conversion of common breakfast bio-waste such as spent coffee grounds, orange peels and used tea leaves into nanoporous activated carbons is presented. The materials are synthesized through thermochemical carbonization followed by chemical activation using potassium hydroxide (KOH). This process results in highly microporous carbons with very large specific surface areas (up to 3300 m²/g) and significant pore volumes (up to 1.6 cm3 /g), which are favorable for H2 adsorption [1,2]. The materials were characterized using a combination of advanced techniques including gas sorption analysis, scanning electron microscopy, Raman spectroscopy, X-ray diffraction and small-angle X-ray scattering. H2 adsorption measurements performed under cryogenic conditions (77 K) reveal excess hydrogen uptakes of up to ~6 wt.% at pressures of 30-40 bar, while total storage capacities may exceed 9 wt.% at 100 bar, depending on the pore structure characteristics of the materials [1,2]. These results demonstrate that widely available organic waste streams can be transformed into high-value nanoporous carbons for H2 storage applications, contributing simultaneously to waste valorization, circular economy strategies and the advancement of clean energy technologies.