Necklace‐like Nitrogen‐Doped Tubular Carbon 3D Frameworks for Electrochemical Energy Storage

Abstract

The design and synthesis of a necklace‐like nitrogen‐doped tubular carbon (NTC) are presented by growing microporous polyhedral ZIF‐8 particles and a uniform layer of ZIF‐8 on sacrificial ZnO tetrapods (ZTPs). Oxygen vacancies together with defect regions on the surface of the ZTPs result in the formation of ZIF‐8 polyhedra in conjunction with a very thin shell. This necklace‐like NTC structure has a high N content, very large surface area, ultrahigh microporosity, and quite high electrical conductivity. NTC‐based symmetrical supercapacitor and zinc‐ion capacitor (ZIC) devices are fabricated and their electrochemical performance is measured. The NTC supercapacitor shows an ultrahigh rate capability (up to 2000 mV s−1) and promising cycle life, retaining 91.5% of its initial performance after 50 000 galvanostatic charge–discharge cycles. An aqueous ZIC, constructed using the NTC, has a specific capacitance of 341.2 F g−1 at a current density of 0.1 A g−1 and an energy density of 189.6 Wh kg−1 with a 2.0‐V voltage window, respectively. The outstanding performance is attributed to the NTC high N‐doping content, a continuous “polyhedral 3D hollow” architecture and the highly porous microtubular arms exhibiting very high surface area.

Metal‐Organic Framework Integrated Anodes for Aqueous Zinc‐Ion Batteries

“…The CH stretching bands are located at 2928 and 3134 cm −1 and belong to methyl and imidazole units, respectively. [ 12 ] The ZnO and ZIF‐8 related bands in Raman spectra have disappeared at 650, 750, and 840 °C, where intense D (at 1328 cm −1 ) and G (at 1582 cm −1 ) bands are detected indicating disordered/porous graphitic carbon formation.…”

“…[ 3,4 ] As opposed to lithium and sodium, it is safe to operate Zn as an anode material in air and aqueous media, which significantly decreases the cost because it eliminates the necessity of having an inert atmosphere or using organic solvents. Thus, Zn‐based energy storage systems such as Zn‐ion, [ 5,6 ] Zn‐alkali, [ 2,7 ] Zn‐flow, [ 8 ] Zn‐I 2 , [ 9 ] Zn‐air, [ 10 ] and Zn‐ion capacitors [ 11,12 ] have received attention because of their practicality and good performance. The easy and scalable production of Zn electrodes is crucial for securing the continued development of improved Zn‐based battery systems, but recent research has highlighted the problem of dendrite formation caused by non‐uniform charge distribution and side reactions (hydrogen evolution, Zn corrosion) during plating and stripping which causes severe deterioration of Zn batteries, and significantly limits their efficiency and life.…”

“…ZIF‐8, one of the zeolitic imidazole frameworks (a subgroup of the metal‐organic frameworks [MOFs]), has a Zn‐coordinated crystal structure and high microporosity. [ 12,18 ] The use of ZIF‐8‐derived carbon nanoparticles as a host for electrodeposited Zn has been reported in the literature. [ 9 ] We reasoned that a monolithic (conformal) ZIF‐8 layer that is directly grown on Zn metal might be a unique strategy to ensure a uniform charge and ion distribution at the anode–electrolyte interface.…”

Heteroatom‐Doped and Oxygen‐Functionalized Nanocarbons for High‐Performance Supercapacitors

“…It is important to note that the specific capacitance of N-doped nanocarbons is limited to 128.2 F g −1 with 45% N/C, [127] 390 F g −1 at 5 A g −1 with 29.82 at% N 2 , [37] and 203.8 F g −1 at 0.1 A g −1 with 9.7 at% N 2 . [128] In fact, the gravimetric capacitance and surface area has been found to decrease drastically and creates undesirable pore distributions with increasing N-content beyond a limit. [127,129] Importantly, N-doped mesoporous carbon with 8.2 at% N-content shows the highest gravimetric capacitance of 840 F g −1 at 1 A g −1 (2E).…”

Laser Induced Anchoring of Nickel Oxide Nanoparticles on Polymeric Graphitic Carbon Nitride Sheets Using Pulsed Laser Ablation for Efficient Water Splitting under Visible Light

“…Photocatalytic and photoelectrochemical activities of the semiconductor widely depend on the shape size and morphology of the synthesized material, and these factors are decided by the physical and chemical environment that prevails during the synthesis [ 31 , 32 , 33 , 34 , 35 ]. The well-established methods of synthesis by solvothermal, hydrothermal, and photochemical reduction have some major disadvantages, like the need for heavy instrumentation and post-purification, due to the use of various chemical intermediates.…”