Search for: All records

Hydrogen gas (H₂) is the primary storable fuel for pollution‐free energy production, with over 90 million tonnes used globally per year. More than 95% of H₂is synthesized through metal‐catalyzed steam methane reforming that produces 11 tonnes of carbon dioxide (CO₂) per tonne H₂. “Green H₂” from water electrolysis using renewable energy evolves no CO₂, but costs 2–3× more, making it presently economically unviable. Here catalyst‐free conversion of waste plastic into clean H₂along with high purity graphene is reported. The scalable procedure evolves no CO₂when deconstructing polyolefins and produces H₂in purities up to 94% at high mass yields. The sale of graphene byproduct at just 5% of its current value yields H₂production at a negative cost. Life‐cycle assessment demonstrates a 39–84% reduction in emissions compared to other H₂production methods, suggesting the flash H₂process to be an economically viable, clean H₂production route.

A challenge in the synthesis of single‐wall carbon nanotubes (SWCNTs) is the lack of control over the formation and evolution of catalyst nanoparticles and the lack of control over their size or chirality. Here, zeolite MFI nanosheets (MFI‐Ns) are used to keep cobalt (Co) nanoparticles stable during prolonged annealing conditions. Environmental transmission electron microscopy (ETEM) shows that the MFI‐Ns can influence the size and shape of nanoparticles via particle/support registry, which leads to the preferential docking of nanoparticles to four or fewer pores and to the regulation of the SWCNT synthesis products. The resulting SWCNT population exhibits a narrow diameter distribution and SWCNTs of nearly all chiral angles, including sub‐nm zigzag (ZZ) and near‐ZZ tubes. Theoretical simulations reveal that the growth of these unfavorable tubes from unsupported catalysts leads to the rapid encapsulation of catalyst nanoparticles bearing them; their presence in the growth products suggests that the MFI‐Ns prevent nanoparticle encapsulation and prologue ZZ and near‐ZZ SWCNT growth. These results thus present a path forward for controlling nanoparticle formation and evolution, for achieving size‐ and shape‐selectivity at high temperature, and for controlling SWCNT synthesis.