Multifunctional Template Prepares N-, O-, and S-Codoped Mesoporous 3D Hollow Nanocage Biochar with a Multilayer Wall Structure for Aqueous High-Performance Supercapacitors

Abstract

To recycle wastes and develop renewable energy, much effort has been focused on converting biowastes into porous carbon for supercapacitors. Porous nanocage-like carbons have excellent capacitive properties, but generally their preparation methods are costly or complex. Herein, a “one-step” strategy of synchronous activation and support through the thermal decomposition of a multifunctional template (magnesium acetate, Mg(Ac)2) is designed to prepare N-, O-, and S-codoped mesoporous hollow biochar nanocages (BNC-700). The BNC-700 prepared displays an interconnected porous structure and a two-dimensional (2D) multilayer wall/three-dimensional (3D) hollow nanocage structure with abundant active heteroatoms and edge defects. Due to their specific structures, high surface areas (1369 m2 g–1), and large pore volumes (1.81 cm3 g–1), the assembled supercapacitor delivers a considerable energy density of 37.4 Wh kg–1 at 212 W kg–1 and cycling stability of 99.5% after 15,000 cycles. The unique structure and N, O, and S codoping characteristics ensure a potential application for BNC-700 in supercapacitors. In summary, a strategy is designed for the green, simple, and cost-effective preparation of high-performance biochar for advanced energy storage devices.

Valorization of Biomass-Derived Polymers to Functional Biochar Materials for Supercapacitor Applications via Pyrolysis: Advances and Perspectives

“…The doped elements can also come from the raw biomass feedstock. For example, Lin et al [ 82 ] used magnesium acetate (C 6 H 6 MgO 4 ) as a multifunctional template for one-step conversion of onionskin to hollow mesoporous biochar nanocages for application as PC electrodes. The N, O, and S contained in onionskin was self-doped on the resultant nanocages to improve the wettability, conductivity, and pseudo-capacitance effect of the SC electrode.…”

One-pot synthesis of biomass-derived porous carbons for multipurpose energy applications

“…Additionally, hollow carbon nanocages with sp 2 hybrid carbon shells and hollow interior cavities are an important kind of carbon nanomaterial, which shows unique advantages in energy applications 140 owing to their special characteristics. 147 Lin et al 148 recently used magnesium acetate (Mg(Ac) 2 ) as a multifunctional template for the one-pot synthesis of N,O, and S-doped hollow mesoporous nanocages with a multilayer wall structure from waste onion skins (the precursor of C, N, and S) for supercapacitor application (Fig. 9).…”

NiS Nanosheets Decorated on Hollow Carbon Spheres from Liquefied Wood for Supercapacitors

“…Lin et al prepared N-, O-, and S-codoped mesoporous hollow biochar nanocages (BNC-700) by a “one-step” strategy of synchronous activation and support through the thermal decomposition of a multifunctional template (magnesium acetate, Mg­(Ac) 2 ). Due to their specific structures, high surface areas, and large pore volumes, the assembled supercapacitor delivers a considerable energy density of 37.4 Wh kg –1 at 212 W kg –1 . It is worth noting that hollow porous carbon spheres (HCS) have large specific surface area and superior electrochemical performance attributed to their nanoscaled shell thickness, rich mesoporous structure, and large cavity structure, making them potential materials for the next-generation supercapacitors. − Ariga et al reported the electrochemical supercapacitance properties of hollow carbon spheres prepared by high-temperature carbonization of self-assembled fullerene-ethylenediamine hollow spheres (FE-HS), which have enormous potential for electrochemical energy storage supercapacitor applications .…”