ABSTRACT
Correction for 'Multifunctional mixed valence N-doped CNT@MFe2O4 hybrid nanomaterials: from engineered one-pot coprecipitation to application in energy storage paper supercapacitors' by Clara Pereira et al., Nanoscale, 2018, 10, 12820-12840.
ABSTRACT
This work reports on the design of novel mixed valence hybrid N-doped carbon nanotubes/metal ferrite nanomaterials (MFe2O4, M(ii) = Mn, Fe, Co) with tailored composition, and magnetic and electrical properties through a straightforward eco-sustainable and less time consuming one-pot in situ coprecipitation process. The potentialities of this strategy rely on the lack of oxidative treatments to the support and thermal annealing, besides the use of aqueous conditions, a chelating base (isopropanolamine) and low temperatures. The process afforded the controlled nucleation/growth of the MFe2O4 nanoparticles (NPs), with sizes of 3.2-5.4 nm and superparamagnetic properties, on the surface of the N-doped carbon nanotubes (CNT-N) and their immobilization by covalent bonding. The nitrogen-based functionalities of CNT-N allied with the use of a coprecipitation agent with coordinating properties towards M(ii)/Fe(iii) cations were responsible for these achievements. To unravel the potentialities of the novel nanohybrids (CNT-N@M), they were tested as electrode active nanomaterials in the fabrication of all-solid-state asymmetric paper supercapacitors (SCs). All asymmetric SCs presented significantly higher performance than the symmetric CNT-N based one, with an enhancement of the energy density to up to 6.0× and of the power density to up to 4.3× due to the occurrence of both non-faradaic and faradaic charge storage mechanisms. Moreover, they led to enhanced volumetric energy density (up to 11.1×) and power density (up to 5.2×) compared with other solid-state hybrid paper SCs based on carbon materials recently reported in the literature. These results highlight the importance of conjugating a conductive support bearing N-based functionalities with MFe2O4 NPs featuring redox properties towards synergistically enhanced energy storage.
ABSTRACT
The role of Maillard reaction products isolated from barley malt by gel permeation chromatography and ultrafiltration on the antioxidant potential of pale, melano80 and black malts was evaluated. The roasting process is responsible for the polymerisation of early formed lower molecular weight compounds (<10 kDa) into high molecular weight melanoidins (>300 kDa). Melanoidins showed 3-fold higher capacity to scavenge radicals than the lower molecular weight colorants by the metmyoglobin assay. However, a significant decrease of the capacity of black malt and high molecular weight melanoidins to inhibit Fenton induced hydroxyl degradation of deoxyribose was observed. As the high molecular weight fraction, isolated from the black malt extract, exhibited 4-fold higher reducing power than the lower molecular weight fraction, our results support a pro-oxidant effect due to the catalytic formation of hydroxyl radicals in the presence of ferric ions.
