Low‐Cost Chitosan‐Derived N‐Doped Carbons Boost Electrocatalytic Activity of Multiwall Carbon Nanotubes

Abstract

An effective strategy is proposed to enhance the oxygen reduction reaction (ORR) performance of multiwall carbon nanotubes (MWCNTs) in both acid and alkaline electrolytes by coating them with a layer of biomass derivative N‐doped hydrothermal carbons. The N‐doped amorphous carbon coating plays triple roles: it (i) promotes the assembly of MWCNTs into a 3D network therefore improving the mass transfer and thus increasing the catalytic activity; (ii) protects the Fe‐containing active sites, present on the surface of the MWCNTs, from H2O2 poisoning; (iii) creates nitrogenated active sites and hence further enhances ORR activity and robustness.

Restructured Fe−Mn Alloys Encapsulated by N‐doped Carbon Nanotube Catalysts Derived from Bimetallic MOF for Enhanced Oxygen Reduction Reaction

“…The possible reason for this phenomenon is that the pyridinic N species working as active sites in the alkaline solution are limited in the acid medium. To confirm this statement, the sample of Fe 3 Mn 1 /N‐CNTs‐100 has soaked in the 0.1 M HClO 4 containing 0.01 M KSCN with moderate stirring for 12 h. The strong coordination between Fe 3+ ions and SCN − may be helpful to remove the Fe 3+ ions and have less negative impact on the pyridinic N species ,. However, as shown in the Figure S7, the catalyst after KSCN treatment (named as Fe 3 Mn 1 /N‐CNTs‐100‐SCN) still displays the two obvious peaks of Fe 2 N species in the Raman spectra, suggesting that some residual Fe 2 N species exist in the Fe 3 Mn 1 /N‐CNTs‐100‐SCN.…”

“…In addition, as shown in the Figure b, the Raman spectra of Fe 3 Mn 1 /N‐CNTs‐100 and Fe 3 Mn 1 /N‐CNTs‐100‐act show two difference: (i) at around 270 cm −1 , the peaks assigned to Fe 2 N get vanished after acid treatment indicating that the Fe 2 N species get removed after this process; (ii) at around 1584 cm −1 , the peak of G band gets stronger and I D /I G gets lower, which could be attributed to two reasons. The first one is the oxidation process, in which the carbon matrix lose defects and edges . The other one is leaking of the pyridinic N species in acid treatment .…”

Nanowire‐Templated Synthesis of FeNx‐Decorated Carbon Nanotubes as Highly Efficient, Universal‐pH, Oxygen Reduction Reaction Catalysts

“…The linear K–L plots also demonstrate first‐order reaction kinetics and an electron‐transfer number close to four; thus indicating that the catalyst can effectively directly catalyze the transformation of oxygen into water (Figure C and D). Although the catalytic activity of FeN x ‐NCNT‐2‐NH 3 is poorer than that of Pt/C with respect to the onset and half‐wave potentials, it exhibits a similar limiting current density to that of Pt/C at 0.2 V. The catalytic activity still surpasses that of most previously reported noble‐metal‐free ORR catalysts under similar conditions . Moreover, FeN x ‐NCNT‐2‐NH 3 also show a higher durability and better methanol tolerance than that of Pt/C in HClO 4 (Figure E and F).…”

Engineering the Interface of Carbon Electrocatalysts at the Triple Point for Enhanced Oxygen Reduction Reaction

“…[52] Chem. [50] We have used the hydrothermal carbonization of chitosan, ar enewable biomass-derived low-cost precursor,t oi ntroduce at hin layer of N-doped amorphous carbon onto the surface of as-prepared MWCNTs ( Figure 5d). 2018, 24,18374 -18384 www.chemeurj.org 2018 Wiley-VCH Verlag GmbH &Co. KGaA, Weinheim lated Fe nanoparticles within CNT compartments are active towards ORR, even without direct contact with electrolyte.…”