In Situ Encapsulation of Iron Complex Nanoparticles into Biomass‐Derived Heteroatom‐Enriched Carbon Nanotubes for High‐Performance Supercapacitors

Abstract

continuous increase in energy production from sustainable and renewable resources, there is an ever increasing research effort toward highly efficient storing and delivering energy in the form of either electricity or chemical fuel. [1][2][3][4][5][6][7] Among various electricity storage technologies, supercapacitors are the highly desirable one to store electricity in an electrochemical way attributing to their high power capability, fast charge/discharge processes, and extraordinary cycle stability, making them probably the most promising candidates for the next generation of energy storage devices. [8][9][10][11][12] However, when comparing with the rechargeable batteries, one of the key issues of supercapacitors is their lower energy density that severely limits their extended applications. [13] Therefore, considerable research efforts have been devoted to improving the energy density of supercapacitors through either materials engineering or electrode nanostructuring strategies. [14][15][16][17] Carbon materials have been widely studied as electroactive materials for supercapacitors. Unfortunately, they generally suffer from the low energy density due to their limited capacitance arising from the energy storage via the ionic adsorption at the interfaces between carbon materials and electrolyte to form electric double layer. [18][19][20][21][22][23][24] Considering the surface-dependent energy storage mechanism, increasing surface area is believed as an efficient strategy to improve the capacitance of carbon materials. [25][26][27][28] Nanostructured carbon materials such as carbon nanotubes and graphene provide high specific surface area offering opportunities to store more charges, but it is still not enough to realize significant improvement in energy density of supercapacitors based on carbon materials. [29][30][31] An alternative strategy for further enhancing the specific capacitance of nanostructured carbon materials has been developed through incorporating heteroatoms into the carbon framework. [32][33][34][35] The incorporated heteroatoms could provide extra pseudocapacitive contributions from the fast faradic reactions between the heteroatom containing functional groups and the electrolyte ions, and sometimes the heteroatoms doping could optimize the surface wettability and the electronic conductivity of carbonThe capacitive performance of carbon materials could be enhanced by means of increasing the number of active sites, the surface area, and the porosity as well as through incorporating heteroatoms into the carbon framework. However, the charge storage through electric double-layer mechanism results in limited increase in capacitance of modified carbon materials. Herein, a simple and straightforward strategy is introduced for in situ synthesizing iron complex (FeX, which X includes O, C, and P) nanoparticles encapsulated into biomass-derived N, P-codoped carbon nanotubes (NPCNTs), using a natural resource, egg yolk, as heteroatom-enriched carbon sources and potassium ferricyanide as the precurso...

N-Doped Modified Graphene/Fe2O3 Nanocomposites as High-Performance Anode Material for Sodium Ion Storage

“…The assembled devices were tested for EIS, CV, galvanostatic charge and discharge (GCD), etc., and the test parameters are the same as before. The specific energy density and power density of the sodium ion capacitor were calculated by the following formula [28]:…”

Biomass carbon dual‐doped with iron and nitrogen for high‐performance electrocatalyst in water splitting

“…CA-400 exhibits typical amorphous carbon peaks with 2θ at 26 and 43 , whereas CA@Fe (1:3)-600, CA@Fe(1:3)-700 and CA@Fe(1:3)-800 show three characteristic peaks at 2θ = 30.2 , 35.5 , 42.9 , which are corresponding to (220), (311), and (400) crystal planes of Fe 3 O 4 , demonstrating the nanoparticles are Fe 3 O 4 . 25 It is noteworthy that the sharp peaks of Fe 3 O 4 crystal may cover up the carbon lattices in CA@Fe (1:3)-y. Figure S2A Raman spectra in Figure 2B show two obvious characteristic peaks at 1359 and 1590 cm −1 or so, which are ascribed to disordered sp 3 (D band) and graphitic sp 2 (G band) of carbon, respectively.…”

Solid‐State Hybrid Supercapacitor Assembled from a Heterostructured Co−Ni Battery‐like Cathode and Supercapacitor‐Type Highly Disordered Carbon Nanosheets

“…On the anode side of HSC, carbonaceous materials are the most suitable electrode materials due to their rather high power densities, unique charge storage mechanism (results from the electric double layer capacitance, abbr. EDLC, a fast physical reversible ions adsorption/desorption process at the electrode/interface), desirable physical properties, controllable porosities and relatively inert electrochemical characters . Besides, the combination of EDLC‐typed carbon materials with the redox reaction‐typed heterostructured materials in a full cell device could potentially lead to the charge storage process simultaneous integrates the electrophysical (accumulation of charge) and electrochemical process (redox of central metal ions via electron gain/loss) .…”

“…EDLC, a fast physical reversible ions adsorption/desorption process at the electrode/interface), desirable physical properties, controllable porosities and relatively inert electrochemical characters. [13,[28][29][30] Besides, the combination of EDLC-typed carbon materials with the redox reaction-typed heterostructured materials in a full cell device could potentially lead to the charge storage process simultaneous integrates the electrophysical (accumulation of charge) and electrochemical process (redox of central metal ions via electron gain/loss). [13] Consequently, a hybrid energy storage system can be achieved by hybridization at either the mechanism or the device level, which can also generate a hybridization effect to the kinetics and electrochemical characteristics of a SC.…”