Exploring anode materials with an excellent electrochemical performance is of great significance for supercapacitor applications. In this work, a N-doped-carbon-nanofiber (NCNF)-supported Fe₃C/Fe₂O₃ nanoparticle (NCFCO) composite was synthesized via the facile carbonizing and subsequent annealing of electrospinning nanofibers containing an Fe source. In the hybrid structure, the porous carbon nanofibers used as a substrate could provide fast electron and ion transport for the Faradic reactions of Fe₃C/Fe₂O₃ during charge–discharge cycling. The as-obtained NCFCO yields a high specific capacitance of 590.1 F g⁻¹ at 2 A g⁻¹, superior to that of NCNF-supported Fe₃C nanoparticles (NCFC, 261.7 F g⁻¹), and NCNFs/Fe₂O₃ (NCFO, 398.3 F g⁻¹). The asymmetric supercapacitor, which was assembled using the NCFCO anode and activated carbon cathode, delivered a large energy density of 14.2 Wh kg⁻¹ at 800 W kg⁻¹. Additionally, it demonstrated an impressive capacitance retention of 96.7%, even after 10,000 cycles. The superior electrochemical performance can be ascribed to the synergistic contributions of NCNF and Fe₃C/Fe₂O₃.

Efficient and selective electrocatalytic reduction of nitrate (NO₃⁻) to ammonia (NH₃) is a crucial step in addressing environmental and energy challenges. Here, we present the synthesis and characterization of Cu/CF, Co-OH/CF, and a series of Cu/Co-OH/CF electrocatalysts on copper foam (CF) substrates using a hydrothermal method. These catalysts were utilized as working electrodes for nitrate reduction, resulting in the production of NH₃. Through X-ray photoelectron spectroscopy (XPS) analysis, we confirm the presence of metallic Cu species and oxidized Co²⁺ states in the electrocatalysts, indicating the successful formation of Cu/Co-OH/CF composites. By precisely controlling the quantities of cobalt in the composite, we demonstrate the ability to finely tune the nitrate reduction efficiency and selectivity of the final product. Notably, our findings reveal that the Co-(OH) species in the Cu/Co-OH/CF electrocatalysts play a pivotal role in determining the selectivity of the final product by effectively suppressing the undesired hydrogen evolution reaction. Simultaneously, Cu acts as an active component in the reduction of NO₃⁻ into ammonia. Our work offers valuable guidance for designing advanced electrocatalytic systems with enhanced Faraday efficiency and selectivity, thereby contributing to the development of sustainable and efficient nitrate reduction technologies.