The search for low-cost, highly active, and stable catalysts to replace the Pt-based catalysts for oxygen reduction reaction (ORR) has recently become a topic of interest. Herein, we report a new strategy to design a nitrogen-doped carbon nanomaterial for use as a metal-free ORR catalyst based on facile pyrolysis of protein-rich enoki mushroom (Flammulina velutipes) biomass at 900 °C with carbon nanotubes as a conductive agent and inserting matrix. We found that various forms of nitrogen (nitrile, pyrrolic and graphitic) were incorporated into the carbon molecular skeleton of the product, which exhibited more excellent ORR electrocatalytic activity and better durability in alkaline medium than those in acidic medium. Remarkably, the ORR half-wave potential measured on our material was around 0.81 V in alkaline medium, slightly lower than that on the commercial 20 wt% Pt/C catalyst (0.86 V). Meanwhile, the ORR followed the desired 4-electron transfer mechanism involving the direct reduction pathway. The ORR performance was also markedly better than or at least comparable to the leading results in the literature based on biomass-derived carbon-based catalysts. Besides, we significantly proposed that the graphitic-nitrogen species that is most responsible for the ORR activity can function as the electrocatalytically active center for ORR, and the pyrrolic-nitrogen species can act as an effective promoter for ORR only. The results suggested a promising route based on economical and sustainable fungi biomass towards the large-scale production of valuable carbon nanomaterials as highly active and stable metal-free catalysts for ORR under alkaline conditions.

With the growing energy demand for a low carbon economy, it is important to develop new materials that can enhance the effectiveness of energy storage and energy conversion systems. We report a kinetics-controlled reaction for the synthesis of bimetallic organic frameworks. Furthermore, uniform ZnCoS@CoS yolk–shell structures were fabricated via sulfidation and then converted to ZnCoS@Co₉S₈/N-doped carbon single-holed hollow core–shell structures by calcination under nitrogen. Such a core–shell structure effectively withstands the dramatic volume change and inhibits the aggregation of metal nanoparticles. Meanwhile, the N-doped porous carbon offers fast electron transport to achieve exceptionally high rate capability. As a result, single-holed hollow core–shell ZnCoS@Co₉S₈/N-doped carbon shows admirable electrochemical activity as an anode material in lithium ion batteries. Furthermore, this paper also discloses the synergistic effect of the chalcogenide phase and metal on the Li storage capability.

Lithium–sulfur batteries are strongly expected to be the next-generation energy storage technology due to their superior theoretical specific capacity and energy density. However, the low conductivity of sulfur and the discharge species (Li₂S₂, Li₂S), the “shuttle” issue of soluble intermediates, and the large volume change hinder their further practical application. In this study, vanadium dioxide (VO₂) was successfully grown on reduced graphene oxide (rGO) surface via a one-step rapid and facile solvothermal method, and named as the VO₂@rGO binary host. In this structure, the VO₂ nanoflakes displayed intensive chemical adsorption for polar lithium polysulfide species (LiPSs), accelerating the conversion of long-chain LiPSs to Li₂S₂/Li₂S discharge products and thus suppressing the shuttling of soluble LiPSs. Additionally, rGO could ensure good electronic conductivity of the sulfur cathode and significantly enhanced the electrochemical reaction kinetics. Particularly, the VO₂@rGO/S cathode demonstrated a high initial discharge capacity of 1358 mA h g⁻¹ at 0.2C and retained a stable cycling performance with a reversible capacity of 1049 mA h g⁻¹ over 370 cycles (low capacity decay of 0.06% per cycle). Such excellent performance revealed its good potential for use in advanced lithium–sulfur batteries.

Electrodes for supercapacitors made from metal–organic frameworks (MOFs) are still hindered by electron transfer properties. Therefore, an electrode composite material Ni-MOF@PPy was synthesized from a Ni-based metal–organic framework (Ni-MOF) doped with poly-pyrrole (PPy) using a simple chemical oxidation method to improve its electron transfer property. After introducing the electrochemically active substance K₄Fe(CN)₆ into the electrolyte, the composite material had a specific capacitance of 1815.4 F g⁻¹ at a current density of 1 A g⁻¹. Ni-MOF@PPy and active carbon (AC) as the positive and negative electrodes have been used, respectively, to assemble asymmetric supercapacitors (ASCs) in the KOH and K₄Fe(CN)₆ mixed electrolyte. This novel Ni-MOF@PPy//AC ASC energy storage device can provide 38.5 W h kg⁻¹ energy density, 7001 W kg⁻¹ power density, and 90.2% capacitance retention after 3000 cycles. Therefore, Ni-MOF@PPy//AC ASC is an excellent energy storage device with practical and economic value. The synergistic effect strategy proposed in this work can be easily applied to develop other MOFs with unique crystal structures as well as other redox active additives, providing new avenues and research ideas for exploring novel energy storage devices.