The incorporation of oxygen functional groups (OFGs) into cobalt-nitrogen-carbon (CoNC) catalysts is widely regarded as a promising strategy for enhancing hydrogen peroxide (H₂O₂) electrosynthesis via the two-electron oxygen reduction reaction (2e⁻ ORR). However, the roles and effects of OFGs in CoNC catalysts on H₂O₂ electrosynthesis, especially on the actual production, remain unclear. Herein, we conducted a comprehensive investigation into a series of typical CoNC catalysts with or without OFGs for H₂O₂ electrosynthesis. Contrary to the traditional insight, our finding demonstrates that the incorporation of OFGs into CoNC leads to a notable decline in actual H₂O₂ productivity. Remarkably, this phenomenon occurs across diverse oxidizing agents and CoNC catalysts, indicating its generality. Mechanistic investigations reveal that the OFGs regulate the surface chemical states and interfacial hydrophobicities of CoNC, resulting in hindered O₂ diffusion, thus harming H₂O₂ productivity. This study not only clarifies the complex role of OFGs in CoNC catalysts for H₂O₂ electro-synthesis but also promotes their more extensive application in the field of electrocatalyst development.

Electrochemical production of hydrogen peroxide (H₂O₂) via the two-electron (2e⁻) pathway of oxygen reduction reaction (ORR) supplies an auspicious alternative to the current industrial anthraquinone process. Nonetheless, it still lacks efficient electrocatalysts to achieve high ORR activity together with 2e⁻ selectivity simultaneously. Herein, a boron-doped defective nanocarbon (B-DC) electrocatalyst is synthesized by using fullerene frameworks as the precursor and boric oxide as the boron source. The obtained B-DC materials have a hierarchical porous structure, befitting boron dopants, and abundant topological pentagon defects, exhibiting a high ORR onset potential of 0.78 V and a dominated 2e⁻ selectivity (over 95%). Remarkably, when B-DC electrocatalyst is employed in a real device, it achieves a high H₂O₂ yield rate (247 mg·L⁻¹·h⁻¹), quantitative Faraday efficiency (~ 100%), and ultrafast organic pollutant degradation rate. The theoretical calculation reveals that the synergistic effect of topological pentagon defects and the incorporation of boron dopants promote the activation of the O₂ molecule and facilitates the desorption of oxygen intermediate. This finding will be very helpful for the comprehension of the synergistic effect of topological defects and heteroatom dopants for boosting the electrocatalytic performance of nanocarbon toward H₂O₂ production.

Sodium metal is a promising anode for sodium batteries due to its high theoretical capacity and low cost. However, the serious Na dendrite growth and low Coulombic efficiency, especially at high current densities/cycling capacities, severely limit the application of sodium metal anodes. Herein, trifluoromethylfullerene, C₆₀(CF₃)₆, is designed as an electrolyte additive to enable the high-rate cycling of sodium metal anodes with high Coulombic efficiency. The CF₃ groups contribute to the formation of stable NaF-rich solid electrolyte interface layer, while C₆₀ cages induce the uniform distribution of sodium ions and promote the formation of smooth and compact morphology. Thus, Na||Cu cell with C₆₀(CF₃)₆ can be cycled at 2 mA·cm⁻² and 10 mAh·cm⁻² over 180 cycles with an average Coulombic efficiency of 99.9%, and Na||Na cell can be cycled at 10 mA·cm⁻² over 600 cycles. Furthermore, Na||NaV₂(PO₄)₃@C full cell exhibits high capacity retention of 84% over 2,000 cycles at 20 C (~ 3 mA·cm⁻²).

Two-dimensional (2D) graphitic carbon nitride (g-CN) is a promising anode material for sodium-ion batteries (SIBs), but its insufficient interlayer spacing and poor electronic conductivity impede its sodium storage capacity and cycling stability. Herein, we report the fabrication of a fullerene (C₆₀)-modified graphitic carbon nitride (C₆₀@CN) material which as an anode material for SIBs shows a high-reversible capacity (430.5 mA h g⁻¹ at 0.05 A g⁻¹, about 3 times higher than that of pristine g-CN), excellent rate capability (226.6 mA h g⁻¹ at 1 A g⁻¹) and ultra-long cycle life (101.2 mA h g⁻¹ after 5000 cycles at 5 A g⁻¹). Even at a high-active mass loading of 3.7 mg cm⁻², a reversible capacity of 316.3 mA h g⁻¹ can be obtained after 100 cycles. Such outstanding performance of C₆₀@CN is attributed to the C₆₀ molecules distributed in the g-CN nanosheets, which enhance the electronic conductivity and prevent g-CN sheets from restacking, thus resulting in enlarged interlayer spacing and exposed edge N defects (pyridinic N and pyrrolic N) for sodium-ion storage. Furthermore, a sodium-ion full cell combining C₆₀@CN anode and NVPF@rGO cathode provides high-coulombic efficiency (>96.5%), exceptionally high-energy density (359.8 W h kg_anode⁻¹ at power density of 105.1 W kg_anode⁻¹) and excellent cycling stability (89.2% capacity retention over 500 cycles at 1 A g_anode⁻¹). This work brings new insights into the field of carbon-based anode materials for SIBs.