Porous N,P-doped carbon from coconut shells with high electrocatalytic activity for oxygen reduction: Alternative to Pt-C for alkaline fuel cells

In this study, poplar‐catkin‐derived N, P co‐doped carbon microtube catalysts with highly active sites and a large accessible surface area exhibit desirable oxygen reduction reaction (ORR) activity in an alkaline solution and excellent applications in Zn‐air batteries (ZABs). In particular, the catalytic activity of the N, P co‐doped carbon microtubes toward the ORR is as good as that of benchmark Pt/C, albeit better in terms of tolerance and stability. Furthermore, a ZAB fabricated using the as‐developed catalyst exhibits a specific capacity of 649 mAh gZn−1 and a peak power density of 125 mW cm−2; these values are comparable to those of Pt/C catalysts (644 mAh gZn−1 and 130 mW cm−2, respectively), indicative of the promising applications for sustainable energy storage. In addition, an alkaline water‐splitting cell powered by this assembled ZAB can generate H2 gas in a stable manner under ambient conditions. The successful conversion of considerable catkin sources to high‐value carbon materials will provide insights into the future development of other high‐performance electrocatalysts from abundant “green” bio‐waste.

Section: Resultssupporting

confidence: 92%

“…Generally, a high I D / I G ratio is indicative of carbon structures with high disorder . In this case, similar I D / I G values are observed for both catalysts (Figure f), i.e., similar to 1 : 1, indicating that NH 3 treatment does not create a high number of defects.…”

Section: Resultssupporting

confidence: 67%

Poplar‐Catkin‐Derived N, P Co‐doped Carbon Microtubes as Efficient Oxygen Electrocatalysts for Zn‐Air Batteries

Wan

Liu

et al. 2018

“…This change is clearly illustrated in Figure d. As increasing of the temperature from 700 °C to 900 °C, the contents of all the nitrogen functional groups except graphitic N gradually decreased during KOH activation in an NH 3 atmosphere, which could be ascribed to the different thermal stabilities of these groups . Figure e shows that S mainly existed in the forms C‐SOx−C (163.8 eV), C−S−C2p3/2 (164.9 eV), and C−S−C2p1/2 (169.1 eV) .…”

Section: Resultsmentioning

confidence: 88%

“…Figure e shows that S mainly existed in the forms C‐SOx−C (163.8 eV), C−S−C2p3/2 (164.9 eV), and C−S−C2p1/2 (169.1 eV) . The high‐resolution P2p peak could be fitted by two peaks at 132.9 eV (C−P) and 134.1 eV (P−O) in Figure f . Figure g illustrates the possible locations of N, S and P incorporation in the carbon network.…”

Section: Resultsmentioning

confidence: 92%

Nitrogen, Sulfur, Phosphorous Co‐doped Interconnected Porous Carbon Nanosheets with High Defect Density for Enhancing Supercapacitor and Lithium‐Ion Battery Properties

Wang

Dang

et al. 2018

Porous carbon nanosheets with open 2D nanostructure have been considered a desirable and high‐efficient energy‐storage material. Herein, N, S, P co‐doped interconnected porous carbon nanosheets (CPCNs) with high defect density and open 2D ultrathin nanostructure are prepared by using a cork‐shaped soybean aerogel as carbon source. A reasonable design of the preparation technology controls the formation of the distinctive and ordered structure of intermediates during the synthetic process. The as‐prepared CPCN material is made of interconnected nanosheets with a thickness of 4.9 nm and have a maximum N‐dopant content of 5.83 at. % and a high specific surface area of 3586 m2 g−1. Due to the synergistic effects of the features, the CPCN electrode for supercapacitors has a high capacitance of 427 F g−1 with a long cycling stability of 97.42 % after 10 000 cycles. For lithium‐ion batteries, the CPCN material also exhibits an excellent capacity of 1220 mAh g−1 at 100 mA g−1 with a high rate capability and cycling stability. Moreover, a scenario through using CPCN to enhance the electrochemical performance of nano‐inorganic material proves a high scalability in the application for the products.

“…[4] Chemical doping [5] especially N doping is found to be the most efficient way to achieve remarkable catalytic activities toward ORR. For example, the common morphology regulation tactics often involve the use of templates and/or active agents (such as ZnCl 2 , [4b,7] H 3 PO 4 , [8] KOH, [4a,9] and NH 3 ), [9][10] which successfully prepared various nanostructured carbon catalysts with large specific surface area (SSA), such as carbon nanofibers, [4c, [10][11] nanosheets, [9] and sub-micrometer spheres. For example, the common morphology regulation tactics often involve the use of templates and/or active agents (such as ZnCl 2 , [4b,7] H 3 PO 4 , [8] KOH, [4a,9] and NH 3 ), [9][10] which successfully prepared various nanostructured carbon catalysts with large specific surface area (SSA), such as carbon nanofibers, [4c, [10][11] nanosheets, [9] and sub-micrometer spheres.…”

Section: Introductionmentioning

confidence: 99%

Metal‐Free Hybrid of Nitrogen‐Doped Nanocarbon@Carbon Networks for Highly Efficient Oxygen Reduction Electrocatalyst

Shi

Qin

et al. 2019

Further improving the oxygen reduction reaction (ORR) catalytic activity of carbon catalysts is highly challenging and remains a key issue to push forward their commercial progress as Pt alternatives in fuel cells and metal-air batteries. Herein, a facile and economic strategy was proposed to maximize the active sites exposed in porous carbon catalysts by growing dense Ndoped carbon nanonodules firmly located within carbon fiber networks (NCN@CF) via the in situ polymerization of dopamine on bacterial cellulose fibers and a subsequent carbonization process. This metal-free hybrid catalyst exhibits enhanced ORR activity and better stabilities against long duration and the methanol crossover effect than the commercial Pt/C catalyst in 0.1 M KOH. Notably, when the NCN@CF hybrid was used as an air electrode catalyst in a Zn-air battery, the as-fabricated battery presented a larger peak power density of 168 mW cm À 2 , higher specific capacity of 720.5 mA h g À 1 and energy density of 900.0 Wh kg À 1 compared to those based on commercial Pt/C and most N-doped carbon catalysts ever reported, evidencing its highly promising use as a Pt-alternative catalyst for the ORR.