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Carbon nanofibers (CNF) with a 1D porous structure offer promising support to encapsulate transition-metal oxides in energy storage/conversion relying on their high specific surface area and pore volume. Here, the preparation of NiO nanoparticle-dispersed electrospun N-doped porous CNF (NiO/PCNF) and as free-standing film electrode for high-performance electrochemical supercapacitors is reported. Polyacrylonitrile and nickel acetylacetone are selected as precursors of CNF and Ni sources, respectively. Dicyandiamide not only improves the specific surface area and pore volume, but also increases the N-doping level of PCNF. Benefiting from the synergistic effect between NiO nanoparticles (NPs) and PCNF, the prepared free-standing NiO/PCNF electrodes show a high specific capacitance of 850 F g at a current density of 1 A g in 6 m KOH aqueous solution, good rate capability, as well as excellent long-term cycling stability. Moreover, NiO NPs dispersed in PCNF and large specific surface area provide many electroactive sites, leading to high CO uptake, and high-efficiency CO electroreduction. The synthesis strategy in this study provides a new insight into the design and fabrication of promising multifunctional materials for high-performance supercapacitors and CO electroreduction.

Heteroatom-doped carbon materials have been considered as potential substitutes for Pt-based electrocatalysts for the oxygen reduction reaction (ORR) in alkaline fuel cells. Here we report the synthesis of oxygen-containing nitrogen-doped carbon (ONC) nanosheets through the carbonization of a mixture that contained glucose and dicyandiamide (DCDA). In situ formed graphitic carbon nitride (g-C N ) derived from DCDA provided a nitrogen-rich template, thereby facilitating the formation of ONC nanosheets. The resultant ONC materials with high nitrogen content, high specific surface areas, and highly mesoporous total volume displayed excellent electrochemical performance, including a similar ORR onset potential, half-potential, a higher diffusion-limited current, and excellent tolerance to methanol than that of the commercial Pt/C catalyst, respectively. Moreover, the ONC-850 nanosheet displayed high long-term durability even after 1000 cycles as well as a high electron transfer number of 3.92 (4.0 for Pt/C). Additionally, this work provides deeper insight into these materials and a versatile strategy for the synthesis of cost-effective 2D N-doped carbon electrocatalysts.

CO2 poisoning of alkaline electrolytes is a critical issue that affects the energy efficiency and lifespan of Zn‐air batteries. However, few strategies have been explored to address this issue because it is challenging to block CO2 from the outer atmosphere. Herein, a CO2‐tolerant flexible quasi‐solid‐state electrolyte for Zn‐air batteries, which is achieved by the pre‐fixation of CO2 on poly(vinyl alcohol) (PVA) via its ionization in the form of side ‐OCO2‐ groups (PVA‐TMG), is reported. The pre‐fixation of CO2 enables excellent CO2 tolerance and alleviates the Zn dendrite and ZnO deposition, because the ‐OCO2‐ groups can strongly interact with the Zn2+. In addition, PVA‐TMG exhibits higher ionic conductivity and better water retention capability than the pristine PVA. Consequently, the fabricated Zn‐air batteries deliver excellent performance in both air and a CO2‐rich atmosphere. The optimized PVA‐TMG presents a cycling lifetime 12 times longer than that of the pristine PVA in the atmosphere with 22.7 vol% CO2. The feasible study presented here presents a new milestone in CO2 utilization with energy storage technology.

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