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In this work, we demonstrate that pure three-dimensional honeycomb-like porous carbons (3D-HPC) can be prepared by one-step simultaneous carbonization and activation of Ganoderma lucidum spores (GLS) with KOH active agent. Benefiting from the specific natural morphology of GLS and uniform activation process, the obtained 3D-HPC exhibits pure honeycomb-like hierarchical structures. The obtained 3D-HPC-900 shows the honeycomb-like structures and a high density of narrow mesopores, leading to a high accessible surface area. Combined with high specific surface area of 1995 m2 g−1 and oxygen/nitrogen doping, 3D-HPC-900 exhibits a high specific capacitance of 224 F g−1 at a current density of 0.25 A g−1, an ultrahigh capacitance retention of 75.9% even the current density increased by 80 times, and an excellent cycling stability with 100% capacitance retention after 50,000 cycles. More importantly, the maximum energy density can reach up to 75.7 W h kg−1 at the power density of 1750 W kg−1 in ionic liquid. Meanwhile, the experimental results clearly reveal the exclusive effects of mesopores on improving the rate performance in electrochemical capacitors. Therefore, the work provides a clear method on preparation of high-valued honeycomb-like structured carbon materials to enhance the rate capability of carbon-based electrochemical capacitors.

In recent years, multi-heteroatom-doped hierarchical porous carbons (HPCs) derived from natural potential precursors and synthesized in a simple, efficient and environmentally friendly manner have received extensive attention in many critical technology applications. Herein, bean worms (BWs), a pest in bean fields, were innovatively employed as a precursor via a one-step method to prepare N–O–P–S co-doped porous carbon materials. The pore structure and surface elemental composition of carbon can be modified by adjusting KOH dosage, exhibiting a high surface area (SBET) of 1967.1 m2 g−1 together with many surface functional groups. The BW-based electrodes for supercapacitors were shown to have a good capacitance of up to 371.8 F g−1 in 6 M KOH electrolyte at 0.1 A g−1, and good rate properties with 190 F g−1 at a high current density of 10 A g−1. Furthermore, a symmetric supercapacitor based on the optimal carbon material (BWPC1/3) was also assembled with a wide voltage window of 2.0 V, demonstrating satisfactory energy density (27.5 W h kg−1 at 200 W kg−1) and electrochemical cycling stability (97.1% retention at 10 A g−1 over 10 000 charge/discharge cycles). The facile strategy proposed in this work provides an attractive way to achieve high-efficiency and scalable production of biomass-derived HPCs for energy storage.

Herein, nitrogen-enriched hierarchical porous carbons (HPCs) were synthesized by soaking, carbonization and pickling process using natural discarded pears (DP) as the precursor, ZnCl2 as a chemical etching agent and Mg(NO3)2·6H2O as a template. The ZnCl2 activation could produce abundant micropores, while Mg(NO3)2·6H2O can serve as mesopores template. Consequently, the as-prepared carbon material exhibits a three-dimensional interconnected porous structure with a high specific surface area (SBET) of 1642 m2 g−1 and a pore volume of 1.06 cm3 g−1 as well as high nitrogen content (1.7 at.%). On the basis of electrochemical tests, the SCs involve the final products as electrode material presented remarkable gravimetric capacitance (443.5 F g−1) and volumetric capacitance (285.2 F cm−3) at the current density of 1 A g−1 and excellent rate capability (45.1% capacitance retention from 0.5 A g−1 to 40 A g−1). Most attractively, the constructed DP-Zn-Mg-PC/DP-Zn-Mg-PC symmetric SC cell in 1 M Na2SO4 with a wide potential window of 2.2 V displays an ultra-high energy density of 95.8 Wh kg−1 at 550 W kg−1 together with superior cycling stability (98.6% retention after 10,000 cycles), which is outperform those of some similar peer reported biochars. Thus, this work provides an important guideline for preparing HPCs with high-energy density from eco-friendly and sustainable biomass precursors.

Novel composite polymeric material was prepared from coal, carboxymethyl starch (CMS) and polyvinyl alcohol (PVA). Coal was first treated with NaOH to partially dissolve the coal into sodium humate (SH) and the SH along with undissolved residue was blended with CMS and PVA solution to prepare a polymeric composite though hydrogen bonding. The composite materials showed tensile strength in the range of 8–10 MPa for potential applications including plastic bags and films. The residue after coal dissolution in NaOH served as filler while the SH led to bonding with CMS/PVA in water though hydrogen bonds as detected by Fourier Transform Infrared (FTIR) spectroscopy and X-ray Photoelectron Spectroscopy (XPS).