The stacking and aggregation of graphene nanosheets have been obstacles to their application as electrode materials for microelectronic devices. This study deploys a one-step, scalable, facile electrochemical exfoliation technique to fabricate nitrogen (N) and chlorine (Cl) co-doped graphene nanosheets (i.e., N–Cl–G) via the application of constant voltage on graphite in a mixture of 0.1 mol/L H2SO4 and 0.1 mol/L NH4Cl without using dangerous and exhaustive operation. The introduction of Cl (with its large radius) and N, both with high electrical negativity, facilitates the modulation of the electronic structure of graphene and creation of rich structural defects in it. Consequently, in the as-constructed supercapacitors, N–Cl–G exhibits a high specific capacitance of 77 F/g at 0.2 A/g and remarkable cycling stability with 91.7% retention of initial capacitance after 20,000 cycles at 10 A/g. Furthermore, a symmetrical supercapacitor assembled with N–Cl–G as the positive and negative electrodes (denoted as N–Cl–G//N–Cl–G) exhibits an energy density of 3.38 Wh/kg at a power density of 600 W/kg and superior cycling stability with almost no capacitance loss after 5000 cycles at 5 A/g. This study provides a scalable protocol for the facile fabrication of high-performance co-doped graphene as an electrode material candidate for supercapacitors.
N, Cl co-doped graphene (i.e., N–Cl–G) is fabricated in situ via a one-step, scalable, facile electrochemical exfoliation process. Benefiting from the ultrathin nanosheet structure of N–Cl–G with large margin size and rich functional groups, the as-prepared N–Cl–G-based supercapacitor exhibits high specific capacitance and remarkable cycling stability. Precisely, the symmetrical N–Cl–G//N–Cl–G supercapacitor (N–Cl–G as both the positive and negative electrodes) exhibits high-energy density and superior cycling stability, highlighting its considerable potential for industrial application.
The presence of iron (Fe) has been found to favor power generation in microbial fuel cells (MFCs). To achieve long-term power production in MFCs, it is crucial to effectively tailor the release of Fe ions over extended operating periods. In this study, we developed a composite anode (A/IF) by coating iron foam with cellulose-based aerogel. The concentration of Fe ions in the anode solution of A/IF anode reaches 0.280 μg/mL (Fe2+ vs. Fe3+ = 61%:39%) after 720 h of aseptic primary cell operation. This value was significantly higher than that (0.198 μg/mL, Fe2+ vs. Fe3+ = 92%:8%) on uncoated iron foam (IF), indicating a continuous release of Fe ions over long-term operation. Notably, the resulting MFCs hybrid cell exhibited a 23% reduction in Fe ion concentration (compared to a 47% reduction for the IF anode) during the sixth testing cycle (600–720 h). It achieved a high-power density of 301 ± 55 mW/m2 at 720 h, which was 2.62 times higher than that of the IF anode during the same period. Furthermore, a sedimentary microbial fuel cell (SMFCs) was constructed in a marine environment, and the A/IF anode demonstrated a power density of 103 ± 3 mW/m2 at 3240 h, representing a 75% improvement over the IF anode. These findings elucidate the significant enhancement in long-term power production performance of MFCs achieved through effective tailoring of Fe ions release during operation.