We report the template-free pyrolysis of easily available natural seaweed, Undaria pinnatifida, as a single precursor, which results in "seaweed carbon" (SCup). Interestingly, thus-obtained SCup not only contains heteroatoms such as nitrogen and sulfur in its framework, but it also possesses a well-developed porous structure with high surface area. The heteroatoms in SCup originate from the nitrogen- and sulfur-containing ingredients in seaweed, whereas the porosity is created by removal of salts inherently present in the seaweed. These essential and fundamental properties make seaweed a prime choice as a precursor for heteroatom-containing highly porous carbon as a metal-free efficient electrocatalyst. As-synthesized SCup showed excellent electrocatalytic activity in the oxygen reduction reaction (ORR) in alkaline medium, which can be addressed in terms of the presence of the nitrogen and sulfur heteroatoms, the well-developed porosity, and the electrical conductivity in the carbon framework. The pyrolysis temperature was a key controlling parameter that determined the trade-off between heteroatom doping, surface properties, and electrical conductivity. In particular, SCup prepared at 1000 °C showed the best ORR performance. Additionally, SCup exhibited enhanced durability and methanol tolerance relative to the state of the art commercial Pt catalyst, which demonstrates that SCup is a promising alternative to costly Pt-based catalysts for the ORR.
A binder-free
and solvent-free pencil-trace electrode with intercalated
clay particles (mainly SiO2) is prepared via a simple pencil-drawing
process on grinded Cu substrate with rough surface and evaluated as
an anode material for lithium-ion battery. The pencil-trace electrode
exhibits a high reversible capacity of 672 mA h g–1 at 100 mA g–1 after 100 cycles, which can be attributed
to the unique multilayered graphene particles with lateral size of
few micrometers and the formation of Li
x
Si alloys generated by interaction between Li+ and an
active Si produced in the electrochemical reduction of nano-SiO2 in the clay particles between the multilayered graphene particles.
The multilayered graphene obtained by this process consists of 1 up
to 20 and occasionally up to 50 sheets and thus can not only help
accommodating the volume change and alleviating the structural strain
during Li ion insertion and extraction but also allow rapid access
of Li ions during charge–discharge cycling. Drawing with a
pencil on grinded Cu substrate is not only very simple but also cost-effective
and highly scalable, easily establishing graphitic circuitry through
a solvent-free and binder-free approach.
The Back Cover picture shows how porous carbon with a high surface area and which is naturally doped with nitrogen and sulfur heteroatoms, can be prepared from the easily available seaweed Undaria pinnatifida (U. pinnatifida) as a single precursor for obtaining carbon with heteroatoms. U. pinnatifida is highly abundant, available at a low price, and proves to be a prime choice precursor for heteroatom‐rich highly porous carbon materials as efficient metal‐free electrocatalyst for the oxygen reduction reaction. More details can be found in the Full Paper by Yu et al. on page 1755 (DOI: ).
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