Flash Nitrogen‐Doped Carbon Nanotubes for Energy Storage and Conversion

Abstract

In recent years, nitrogen‐doped carbons show great application potentials in the fields of electrochemical energy storage and conversion. Here, the ultrafast and green preparation of nitrogen‐doped carbon nanotubes (N‐CNTs) via an efficient flash Joule heating method is reported. The precursor of 1D core–shell structure of CNT@polyaniline is first synthesized using an in situ polymerization method and then rapidly conversed into N‐CNTs at ≈1300 K within 1 s. Electrochemical tests reveal the desirable capacitive property and oxygen catalytic activity of the optimized N‐CNT material. It delivers an improved area capacitance of 101.7 mF cm−2 at 5 mV s−1 in 1 m KOH electrolyte, and the assembled symmetrical supercapacitor shows an energy density of 1.03 µWh cm−2 and excellent cycle stability over 10 000 cycles. In addition, the flash N‐CNTs exhibit impressive catalytic performance toward oxygen reduction reaction with a half‐wave potential of 0.8 V in alkaline medium, comparable to the sample prepared by the conventional long‐time pyrolysis method. The Zn–air battery presents superior charge–discharge ability and long‐term durability relative to commercial Pt/C catalyst. These remarkable electrochemical performances validate the superiorities of the Joule heating method in preparing the heteroatom‐doped carbon materials for wide applications.

Surface N Sites Mediate the Formation of Li Metal Cluster@N-Enriched Hierarchically Porous Carbon for Ultrahigh-Capacity Lithium Storage

“…They validate the existence of carbon, nitrogen, and oxygen species within NHPC, with no detection of magnesium residues. It is well-known that moderate nitrogen doping in a carbon matrix plays an important role in capacity storage, owing to the increase in the number of produced active sites as well as the enhanced conductivity and wettability. ,,− Elemental analyses indicate that by increasing the carbonization temperature, the nitrogen species of the precursor can be partly retained as their contents decrease (11.3% for NHPC-600, 10.0% for NHPC-700, 4.3% for NHPC-800, and 3.5% for NHPC-900). N content obtained in NHPC-700 with the highest surface area of 904 m 2 g –1 is as high as 10.0 wt %, which is considerably greater than that reported in most N-doped carbon materials for supercapacitors and LIBs (Tables S4 and S5).…”

“…10 Another approach to enhance the storage capacity of carbon electrodes is to modify their chemical and electronic properties by doping them with electron-rich nitrogen (N) atoms. 11,12 The introduction of N atoms into a carbon matrix produces extra active sites and defects in carbon materials. In addition, the electrical conductivity and wettability can be enhanced with moderate N doping.…”

“…Recent works have shown that a structural design for carbon materials with nanosheet morphology can effectively enhance the storage capacity and rate performance of carbon material by offering more exposed surface active sites and shorting paths for fast electron transport and electrolyte ion diffusion. , Development of carbons with hierarchical pores that consist of macropores, mesopores, and micropores is also highly recommended in terms of structural design because it offers rapid ion transport with improved rate capability . Another approach to enhance the storage capacity of carbon electrodes is to modify their chemical and electronic properties by doping them with electron-rich nitrogen (N) atoms. , The introduction of N atoms into a carbon matrix produces extra active sites and defects in carbon materials. In addition, the electrical conductivity and wettability can be enhanced with moderate N doping.…”

One-Pot Ultrafast Molten-Salt Synthesis of Anthracite-Based Porous Carbon for High-Performance Capacitive Energy Storage

“…21 The small peaks are triggered by the escape of CH 4 (1508 cm −1 ) and polycyclic aromatic (1650 cm −1 ) compounds resulting from the reaction between molten salts and anthracite during the annealing process. 22,23 Since the Joule thermal shock possesses much higher heating rate, 24 therefore, the differences in structure and electrochemical behavior of anthracite-based porous carbon through two molten-salt processes, require in-depth understanding.…”