A highly active and durable Co–N–C electrocatalyst synthesized using exfoliated graphitic carbon nitride nanosheets

Abstract

Exfoliated graphitic carbon nitride nanosheets (g-C3N4-NS) were applied for the first time for the preparation of an electrocatalyst for the oxygen reduction reaction (ORR). A less dense structure with increased surface area was observed for g-C3N4-NS compared to bulk g-C3N4 from detailed analyses including TEM, STEM, AFM with depth profiling, XRD, and UV-Vis spectroscopy. The pyrolysis of the prepared g-C3N4-NS with Co and carbon under an inert environment provided an enhanced accessibility to the N functionalities required for efficient interaction of Co and C with N for the formation of Co-N-C networks and produced a hollow and interconnected Co-N-C-NS structure responsible for high durability. The Co-N-C-NS electrocatalyst exhibited superior catalytic activity and durability and further displayed fast and selective four electron transfer kinetics for the ORR, as evidenced by various electrochemical experiments. The hollow, interconnected structure of Co-N-C-NS with increased pyridinic and graphitic N species has been proposed to play a key role in facilitating the desired ORR reaction.

Exfoliation-induced O-doped g-C3N4 nanosheets with improved photoreactivity towards RhB degradation and H2 evolution

“…[11][12][13] Traditionally, liquid-phase exfoliation (LPE) is regarded as a simple and convenient method to prepare g-C 3 N 4 nanosheets. 14,15 In this approach, strong acids (H 2 SO 4 , HCl, HNO 3 ), [16][17][18][19] organic solvents (isopropanol, N-methyl-pyrroli-done), 20 mixed solvents (IPA/H 2 O, DMF/H 2 O), 21 and alkaline or acid medium solutions 22 are used as intercalation agents to break the interlayer van der Waals forces, and thus g-C 3 N 4 nanosheets are exfoliated by delamination. However, it is difficult to remove these dispersion solvents, and the use of high concentrations of strong acids and organic solvents is harmful to the environment.…”

Cobalt Oxide Nanoparticles/Nitrogen-Doped Graphene as the Highly Efficient Oxygen Reduction Electrocatalyst for Rechargeable Zinc-Air Batteries

“…Among the transition metals, the cobalt (Co) element is low-cost, earth-abundant, and environment-friendly and has been applied for ORR electrocatalysts . For instance, cobalt oxide catalysts exhibit comparable ORR activity and long-term stability with platinum-based materials . However, the CoO nanoparticles suffer from small specific surface area, insufficient conductivity, and poor durability, which will significantly decrease the ORR catalytic performance and long-term stability. − Hence, in order to avoid these drawbacks, carbon composites with considerable conductivity and excellent durability are generally utilized to support the CoO nanoparticles .…”

Fe– and Co–P4-embedded graphenes as electrocatalysts for the oxygen reduction reaction: theoretical insights

“…Therefore, the development of inexpensive and highly-effective non-precious-metal or metal-free electrocatalysts has recently become a major focus in fuel cells. [5][6][7][8][9][10][11][12][13][14] Ternary Fe/N/C is generally considered as one of the most promising candidates for replacing Pt for catalyzing the ORR in fuel cells, [15][16][17][18][19][20][21] which can be traced back to the pioneering work on transition-metal macrocyclic compounds by Jasinski. 22 For example, Zelenay et al demonstrated that FeN x -embedded polymer materials exhibit high oxygen reduction activity, along with good performance durability.…”