Search

Novel two-dimensional carbon nitride hexagonal-like sheets were fabricated from thermal condensation, which uses hexaazatriphenylene-based precursor prepared microporous and oxidation resistant carbons materials (HAT-CN). The results show that the as-prepared HAT-CN is the first electrode utilized in capacitive deionization, due to the rich heteroatom and border-group content, as well as the potential collaborative effect of C and N atoms, displaying the quick ion diffusion and strong charge transfer performance. Additionally, the capacitive deionization performance of HAT-CN is improved by the synergistic contribution of a large accessible surface area, large pore volume, and high graphitization. The electrode of HAT-CN was carbonized at 550 °C which display an excellent specific capacitance of 179.2 F g−1 in 1-M NaCl solution at a scan rate of 5 mV s−1. Subsequently, a high salt adsorption capacity of 24.66 mg g−1 was attained for an applied voltage of 1.2 V in 500 mg L−1 NaCl solution, showing good cyclic stability at 30 cycles. Considering those excellent properties of the prepared HAT-CN, the capacitive deionization electrode should be an ideal candidate for high-performance deionization application. [ABSTRACT FROM AUTHOR]

Capacitive deionization (CDI) is a promising technology for the desalination of brackish water due to its potentially high energy efficiency and its relatively low costs. One of the most challenging issues limiting current CDI cell performance is poor cycling stability. CDI can show highly reproducible salt adsorption capacities (SACs) for hundreds of cycles in oxygen-free electrolyte, but by contrast poor stability when oxygen is present due to a gradual oxidation of the carbon anode. This oxidation leads to increased concentration of oxygen-containing surface functional groups within the micropores of the carbon anode, increasing parasitic co-ion current and decreasing SAC. In this work, activated carbon (AC) was chemically modified with titania to achieve additional catalytic activity for oxygen-reduction reactions on the electrodes, preventing oxygen from participating in carbon oxidation. Using this approach, we show that the SAC can be increased and the cycling stability prolonged in electrochemically highly demanding oxygen-saturated saline media (5 mM NaCl). The electrochemical oxygen reduction reaction (ORR) occurring in our CDI cell was evaluated by the number of electron transfers during charging and discharging. It was found that, depending on the amount of titania, different ORR pathways take place. A loading of 15 mass% titania presents the best CDI performance and also demonstrates a favorable three-electron transfer ORR. [ABSTRACT FROM AUTHOR]

Flow electrode capacitive deionization (FCDI) has great advantages in high salinity wastewater desalination. However, due to the limited adsorption capacity of electrode material, membrane concentration polarization would form and increase energy consumption, and affect the continuity of desalination. In this work, milling technology was used to modify original activated carbon (AC), the obtained ball milled activated carbon (BAC) was used as FCDI electrode material. The milling process modified multiple physical and electrochemical characteristics of original AC. The highest average salt removal rate (ASRR) of BAC was 2.2 times of that of AC, which was attributed to the modified surface properties including more oxygenated functional group, larger electrostatic gravitation characteristics and better hydrophilicity. The reduced concentration polarization during the desalination was responsible for the increased adsorption capacity, which was due to larger electrolyte contact area, enhanced ions capacity by more suitable pore structures, and 5 times higher energy normalized removal salt (ENRS) of BAC flow electrode than that of AC. Because of its simple operation and remarkable modification effect, ball milling technology shows great potential in large scale modification of electrode materials. [ABSTRACT FROM AUTHOR]

• The first high entropy oxides based multifunctional electrode material is synthesized by simple grinding technique. • Nano-sized (< 10 nm) high entropy oxides are incorporated in surface functionalized biowaste derived activated carbon. • High salt adsorption capacity of 241 mg g−1 and cycle repeatability upto 20 cycles is demonstrated. • The excellent desalination capacity is attributed to the combined electric-double layer and pseudocapacitive mechanism. Nano-sized high entropy oxides (particle size < 10 nm) are expected to possess enhanced stability, electrochemical properties and increased potential in versatile applications than bulk metal oxides. In this study, nano-sized high entropy oxides incorporated surface functionalized coconut shell derived activated carbon (HEO/f-CSAC) is synthesized, characterised and used as an advanced multifunctional material for electrochemical energy storage and desalination. Attributed to its unique microstructure and extraordinary properties, HEO/f-CSAC shows an excellent salt adsorption capacity of 241 mg g−1 at 1.2 V in 500 mg L−1 concentration of NaCl solution, which is very high as compared to previous reports. The reason behind high salt adsorption capacity is its outstanding specific capacitance of 147.5 F g−1 at current density 1 A g−1. Moreover, the assembled lab-scale CDI unit demonstrates extremely good performance upto 20 adsorption-desorption cycles due to the long cycle life with good capacitance retention of fabricated HEO/f-CSAC based two-electrode supercapacitor. Additionally, a red light-emitting diode illumination by connecting three supercapacitors in series, indicates the high efficiency and potential of HEO/f-CSAC for real life energy-related application. These results prove that HEO/f-CSAC can be implemented for water desalination with enhanced supercapacitive performance manifesting its multifunctionality for energy and environmental applications. [Display omitted] [ABSTRACT FROM AUTHOR]

• Faradic deionization (FDI) with the outstanding desalination capacity and high feed salt concentration is emerging as a promising desalination technology. • A carbon-embedded hierarchical and dual-anion C@MoSP heterostructure was synthesized by a facile hydrothermal method accompanied by the phosphorization treatment. • The C@MoSP electrode realized an outstanding adsorption capacity of 25.43 mg/g, excellent adsorption rate, and good durability. • The strong synergy of highly conductive carbon and dual anions boosted the CDI performance of pristine MoS 2. Recently, two-dimensional transition-metal disulfides (TMDs) with amazing chemical and physical superiorities are emerging as promising faradic ion intercalation materials for effective capacitive deionization (CDI) application. Herein, a carbon-embedded hierarchical and dual-anion C@MoSP nanoflowers was synthesized by a facile hydrothermal reaction accompanied by the phosphorization treatment, and explored as an advanced CDI electrode material. Benefiting from the specific microstructure (e.g., hierarchically porous arrangement, enriched porosity and highly open pore network) and the strong synergistic effect of highly conductive carbon and low-electronegativity P dopant, the C@MoSP electrode demonstrated high surface area, enrich accessible interlayer, superior ion diffusion pathway and good electric conductivity for effective salty ion intercalation/deintercalation; Accordingly, the C@MoSP electrode realized an outstanding gravimetric adsorption capacity of 25.43 mg/g, excellent intercalation rate, and good durability in a NaCl aqueous solution with an initial concentration of 500 mg/L at an operation voltage of 1.2 V, which were evidently enhanced in comparison to MoSP and pristine MoS 2 ones. [Display omitted] [ABSTRACT FROM AUTHOR]