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Developing an energy storage electrocatalyst that excels in efficiency, cost-effectiveness, and long-term stability over numerous charge–discharge cycles is paramount for advancing energy storage technologies. In this work, we present a simple and environmentally friendly method to fabricate an asymmetric supercapacitor device (ASCD) as a viable energy storage system. The ASCD features binder-free, oxygen–nitrogen dual functionalized, and sulfurized iron–nickel hydroxysulfide (FNMOS) electrocatalysts, self-grown on nickel foam as a positive electrode, and waste biomass-derived activated carbon (CFAC) as a negative electrode. The FNMOS electrode in a 3-electrode configuration has the highest area-specific capacity of 1.6 mA h cm−2 at 1 mA cm−2, and even at a high current density of 10 mA cm−2, it maintained 0.94 mA h cm−2. The enhanced electrocatalytic activity is due to the synergistic contribution of the sulfurized NiFe composite along with the meticulous oxygen–nitrogen co-functionalization. Additionally, the ASCD with the FNMOS positive electrode and the CFAC negative electrode achieves maximum energy density (ED) and power density (PD) values of 350 μW h cm−2 (825 μW per cm2 PD) and 7960 μW cm−2 (200 μW h per cm2 ED). Furthermore, the device demonstrated exceptional rate capability by maintaining over 96% of its initial capacity even after 25 000 cycles of charge and discharge. The exceptional stability was further characterized by the ex situ post-mortem analysis of the FNMOS electrode after the stability test. These encouraging electrochemical results, paired with some practical use cases, demonstrate the applicability of FNMOS as a next-generation energy storage material. [ABSTRACT FROM AUTHOR]

Titanium dioxide nanoparticles (TiO2 NPs) have garnered considerable attention due to their diverse applications. Introducing niobium (Nb) and nitrogen (N) doping, followed by functionalization with Mucuna pruriens beans methanolic extracts, offers a novel avenue to harness their antioxidant potential. This functionalization enables Nb-N doped TiO2 NPs to engage with the bioactive compounds inherent to M. pruriens beans methanolic extracts, thereby fostering a synergistic enhancement of antioxidant activity. This study focuses on the functionalization of doped Nb-N-TiO2 NPs and evaluates the antioxidative capabilities of those functionalized NPs to pure doped Nb-N-TiO2 NPs. These functionalized NPs (FNb-N-TiO2) underwent characterization through ultraviolet–visible spectroscopy (UV–Vis), Fourier Transform Infrared Spectroscopy (FTIR), and Scanning electron microscopy (SEM) analysis. Subsequently, their antioxidant capabilities were evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and Ferric Reducing Antioxidant Power Assay (FRAP) assays. Functionalized Nb-N-TiO2 NPs FTIR peaks exhibited at 2430 and 2010 cm−1; unrelated peak vibrations are associated with the (Nb-N) doping, and the increased transmittance signifies successful functionalization and potential bonding between M. pruriens extract phytochemicals. A distinctive triangular aggregation pattern in SEM ranging in size from 5 µm to 500 nm was seen in FNb-N-TiO2. At a concentration of 500 μL−1, FNb-N-TiO2 exhibited exceptionally high antioxidant activity, reaching an impressive 70% compared with pure Nb-N-TiO2 NPs at 51%. The results demonstrated that FNb-N-TiO2 NPs exhibit significant antioxidant properties compared to their non-functionalized, pure Nb-N-TiO2 NPs. In conclusion, this study substantiates the considerable antioxidant potential of doped Nb-N-TiO2 NPs mediated by M. pruriens methanolic extract, thereby emphasizing their potential for diverse applications in both biomedical and environmental sciences. [ABSTRACT FROM AUTHOR]

The metal‐organic framework (MOF) derived Ni–Co–C–N composite alloys (NiCCZ) were "embedded" inside the carbon cloth (CC) strands as opposed to the popular idea of growing them upward to realize ultrastable energy storage and conversion application. The NiCCZ was then oxygen functionalized, facilitating the next step of stoichiometric sulfur anion diffusion during hydrothermal sulfurization, generating a flower‐like metal hydroxysulfide structure (NiCCZOS) with strong partial implantation inside CC. Thus obtained NiCCZOS shows an excellent capacity when tested as a supercapacitor electrode in a three‐electrode configuration. Moreover, when paired with the biomass‐derived nitrogen‐rich activated carbon, the asymmetric supercapacitor device shows almost 100% capacity retention even after 45,000 charge–discharge cycles with remarkable energy density (59.4 Wh kg–1/263.8 µWh cm–2) owing to a uniquely designed cathode. Furthermore, the same electrode performed as an excellent bifunctional water‐splitting electrocatalyst with an overpotential of 271 mV for oxygen evolution reaction (OER) and 168.4 mV for hydrogen evolution reaction (HER) at 10 mA cm−2 current density along with 30 h of unhinged chronopotentiometric stability performance for both HER and OER. Hence, a unique metal chalcogenide composite electrode/substrate configuration has been proposed as a highly stable electrode material for flexible energy storage and conversion applications. [ABSTRACT FROM AUTHOR]

Recently, Zeolitic Imidazolate Frameworks (ZIFs) and their hybrid composites have incited a lot of interest in the research community and have shown promising potential in supercapacitors owing to their excellent conductivity, high surface area, tunable structure, rich redox chemistry, composition diversity, etc. Even though many ZIFs are being studied for the advancement of electrode materials used for energy storage applications, in this review, we are focused on ZIF-8 and ZIF-67 only. The electrochemical performance of pure ZIFs is poor due to low electronic conductivity and poor cycling life. To counter this, ZIFs are mixed with other materials like conducting polymers, other transitional metals composites, and activated carbons to prepare hybrid composites. Furthermore, the highly porous structure and large surface area of the ZIFs cage act as an ideal template for designing composites with excellent supercapacitor applications. This reviewis focus on the synthesis and electrochemical performance of such materials. This review is divided into two main parts: the design and synthesis of ZIF-8 and ZIF-67 derivatives for supercapacitor applications and the electrochemical performance of ZIF-8 and ZIF-67-based derivatives in three-electrode and two-electrode setups. Lastly, the challenges and obstacles encountered while employing ZIF-8 and ZIF-67-based composites in supercapacitors will be reviewed and commented on. [ABSTRACT FROM AUTHOR]

To solve the problem of water pollution, using environment friendly and cost effective method in short time is the need of hour. In this work, chromium (Cr) and nitrogen (N) co-doped TiO2 nanoparticles were synthesized and were used for the photocatalytic degradation of dyes under visible light. The synergistic effect of metal and non-metal co-dopants added would result in appropriate reduction of band gap {from 3.2 eV of TiO2 to 2.67 eV}, decrease in recombination rate of charge carriers by trapping electrons and holes, and in better light harvesting capacity. Nanoparticles were synthesized by sol–gel method and characterized using ultraviolet–visible (UV–VIS) spectroscopy, fourier transform infrared (FTIR) spectroscopy, atomic force microscopy (AFM), zeta potential, X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) analysis, field emission scanning electron microscopy (FE-SEM), and RAMAN spectroscopy. Eosin yellow (EY) and rose bengal (RB) were subjected to photocatalytic degradation under solar light to check the photocatalytic activity of the synthesized nanoparticles. Effects of dye concentration, the concentration of nanoparticles, time, and pH were investigated to optimize the parameters. The results obtained were remarkable for 20 ppm EY solution took 10 min using 1 gL−1 NPs at pH 3 and 10 ppm RB solution took 5 min using 0.75 gL−1 NPs at pH 5.78 (original pH) for complete degradation. Kinetics studies were also performed and both dyes followed pseudo-second-order kinetics with R2 values 0.99312 and 0.99712 for EY and RB, respectively. The study of degraded products was conducted using high-performance liquid chromatography (HPLC) hyphenated with electron spray ionization mass spectroscopy (ESI–MS) (LC–MS) and possible degradation pathways were made for both dyes. A reusability test was also performed showing the efficiency of the particles was up to 88% after 3 cycles of use. These notable results can be attributed to the efficient removal of organic pollutants using the proposed dopants in this study. [ABSTRACT FROM AUTHOR]