Highly
enhanced CO2 and H2 adsorption properties
were achieved with a series of phenolic resin-based carbon spheres
(resorcinol–formaldehyde carbon (RFC) and phenol–formaldehyde
carbon (PFC)) by carbonization of RF and PF polymer (RFP and PFP)
spheres synthesized via a sol–gel reaction and subsequent activation
with hot CO2 or NH3 treatment. Monodisperse
and size-tunable (100–600 nm) RFC and PFC spheres had intrinsic
nitrogen contents (ca. 1.5 wt %), which are attributed to the synthesis
conditions that utilized NH3 as a basic catalyst as well
as nitrogen precursor. A series of CO2-activated and N-doped
RFC and PFC spheres showed almost perfect correlation (R
2 = 0.99) between CO2 adsorption capacities
and accumulated pore volumes of fine micropores (ultramicropore <1
nm) obtained using the nonlocal density functional theory (NLDFT)
model. Interestingly, NH3 activation served not only as
an effective method for heteroatom doping (i.e., nitrogen) into the
carbon framework but also as an excellent activation process to fine-tune
the surface area and pore size distribution (PSD). Increased nitrogen
doping levels up to ca. 2.8 wt % for NH3-activated RFC
spheres showed superior CO2 adsorption capacities of 4.54
(1 bar) and 7.14 mmol g–1 (1 bar) at 298 and 273
K, respectively. Compared to CO2-activated RFC spheres
with similar ultramicropore volume presenting CO2 uptakes
of 4.41 (1 bar) and 6.86 mmol g–1 (1 bar) at 298
and 273 K, respectively, NH3-activated nitrogen-enriched
RFC was found to have elevated chemisorption ability. Moreover, prolonged
activation of RFC and PFC spheres provided ultrahigh surface areas,
one of which reached 4079 m2g–1 with
an unprecedented superb H2 uptake capacity of 3.26 wt %
at 77 K (1 bar), representing one of the best H2 storage
media among carbonaceous materials and metal–organic frameworks
(MOFs).
The electrochemical performance of MOFs for supercapacitor and oxygen reduction reaction applications is significantly improved when conjugated with conductive and 3D connected nanoporous carbon matrices.
Polyimide
is one of the most important high-performance polymers,
which is widely used due to its excellent mechanical performance and
thermal stability. Unlike the conventional synthetic approach, hydrothermal
polymerization enables the synthesis of polyimides without any toxic
solvent and catalyst. Herein, we report the synthesis of polyimide-based
microparticles (PIMs) through one-pot hydrothermal polymerization
using precursors of mellitic acid (MA) and three isomers of phenylenediamine
(PDA) (o-, m-, and p-PDA). Interestingly, the chemical composition of PIMs was highly
tunable with the choice of the PDA isomers, leading to considerable
morphological differences between PIMs. The molecular dynamics simulation
and density functional theory calculation of the polymeric segment
of the respective PIMs suggested that the relative ratio of amide
to imide influenced the rotational freedom of the polymeric chains
and number of hydrogen bonds, resulting in the well-defined structures
of respective PIMs. Considering the highly tunable nature of PIMs
coupled with the facile synthetic protocol, we anticipate prospective
potentials of PIMs in materials, energy, and composite applications.
ORR activity of Fe, Si, and N co-doped carbons (FeSiNCs) is first reported that DFT calculations reveal the origin of the ORR activity of FeSiNC, presenting excellent ORR activity and single-cell performances in Zn–air battery and AEMFC.
Ionic liquids (ILs) or solidified ionic liquids, known as ionogels, have been actively employed in supercapacitors (SCs) owing to their superior electrochemical stabilities to aqueous and organic electrolytes. However, initial efforts of using ILs and ionogels in SCs were not successful because bulky and sluggish ions cannot effectively access tiny pores of conventional microporous carbons. To address this, a strategy is developed to optimize the electrochemically active surfaces of carbonaceous electrodes and thus to improve the energy storage performance by incorporating 3D ordered/interconnected large mesoporous carbons with ionogel electrolytes. Precisely designed large mesopores interconnected via windows promote mass transport of the electrolyte ions within the solid ionogel electrolytes and effectively utilize the surface of the carbon electrodes for capacitive energy storage, giving rise to record‐high energy storage performance that surpasses the upper bound of the Ragone plots of the current state‐of‐the‐art SCs. In addition, all‐solid‐state SCs with outstanding bending/folding durability are successfully demonstrated. Overall, these results provide critical insight into surface utilization of carbon electrodes as well as capacitive energy storage, when viscous and bulky ILs or ionogels are used as electrolytes.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.