Search

Seawater electrolysis is an innovative technique that can potentially transform hydrogen production and contribute to environmental redemption. However, the lack of good bifunctional electrocatalysts may hinder further development of this technology. Herein, nickel hydroxide nanosheets can be employed as a precursor to producing a 3D Prussian blue analogue (PBA) with a distinct dimensional structure. Nickel hydroxide nanosheets are formed within a nickel foam and undergo a reaction with potassium ferricyanide (K3[Fe(CN)6]). The nickel hydroxide structure is sheets‐like and well‐preserved, containing a multitude of PBA nanocubes. Following phosphidation at 350 °C, the iron‐doped nickel phosphide (Fe‐doped Ni2P (1.0 mM) nanosheets) demonstrates remarkable potential as a bifunctional electrocatalyst for total water/seawater splitting. This electrocatalyst demonstrates exceptional performance in overall water splitting, achieving current densities of 100 and 500 mA cm−2 in 1.0 M KOH at remarkably low voltages of 1.65 and 2.06 V, respectively. Additionally, its improved ability to resist corrosion and its hydrophilic surface makes it suitable for the seawater splitting process. The material can generate current densities of 100 to 500 mA cm−2 in seawater with 1.0 M KOH, resulting in voltages of 1.74 and 2.32 V. These outstanding results, together with its durability, indicate the material's strong potential for practical seawater electrolysis. [ABSTRACT FROM AUTHOR]

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]

Developing cost-effective, efficient, and durable bifunctional non-noble metal electrocatalysts is crucial for addressing the energy crisis. Electronic modulation of intrinsic materials by vanadium doping enhances catalytic activity; thus, unique nanodendrites over 2D nanosheets of vanadium-doped CoTe2/MoTe2 on carbon cloth (V-CoTe2/MoTe2@CC) are engineered by hydrothermal treatment and subsequent tellurization. V dopants modulate the electronic environment of CoTe2/MoTe2, increasing binding energies, decreasing the energy barrier, and creating multiple active sites at elevated lattices to accelerate the reaction kinetics for water splitting. As a result, V-CoTe2/MoTe2@CC shows outstanding catalytic performance for the HER (η10 = 79 mV), OER (η10 = 249 mV), and overall water splitting requiring 1.51 V to deliver 10 mA cm−2. V-CoTe2/MoTe2@CC demonstrates impressive durability for up to 100 h of continuous operation, signifying its potential practical application. This work establishes V-CoTe2/MoTe2@CC as an effective bifunctional electrocatalyst and also introduces a salient approach to tuning electronic structures for high-performance electrocatalysts. [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]

The investigation of using medicinal plants for the production and application of silver nanoparticles (AgNPs) has attracted growing research interest. In this study, AgNPs are synthesized from the stem barks of the Pyrus pashia medicinal plant using a biosynthetic strategy. The reaction conditions were optimized under ambient conditions, including concentration, temperature, time, and pH, and various techniques were employed, such as UV-visible, FTIR, XRD, FESEM, and TEM, to characterize the synthesized AgNPs. The AgNPs produced through this biosynthesis method were found to be spherical and polydispersed, with an average size of 23.92 ± 7.04 nm. The synthesized AgNPs demonstrated an enhanced DPPH free radical scavenging capacity compared to the aqueous extract, with IC50 values of 10.67 ± 0.05 µg/mL and 13.66 ± 0.35 µg/mL, respectively. In the agar well diffusion method, the synthesized AgNPs showed higher antibacterial activity than that of the extract against Escherichia coli (ATCC 25922), Staphylococcus aureus (ATCC 25923), Enterococcus faecalis (ATCC 29212), Salmonella typhi (ATCC 14028), and Shigella sonnei (ATCC 25931). Based on these findings, the study suggests that green synthesized AgNPs from P. pashia could be used for biomedical applications. [ABSTRACT FROM AUTHOR]

Rational modification of Ti3C2Tx MXenes for the preparation of freestanding and flexible carbon-based electrodes with great prospects for an energy storage facility is a crucial task for new-generation supercapacitors. Herein, a novel Ti3C2Tx MXene-decorated porous carbon nanofiber (PCNF) freestanding/flexible electrode is engineered through a sequential approach of electrospinning, in situ growth of ZIF67, and a carbonization process. By varying the concentration of MXenes in the fiber, the electrochemical performance of a set of MXene-integrated PCNFs is investigated, and flexible symmetric and asymmetric supercapacitor devices are assembled. The optimized MX-5@PCNF achieves a specific capacitance of 572.7 F g-1 at 1 A g-1 with high cycling stability (96.4% capacitance retention after 10 000 cycles) and superior rate capability (71.24% at 30 A g-1). Furthermore, MX-5@PCNF-based flexible symmetric and asymmetric (Co3O4@NF//MX-5@PCNF) devices furnish high energy densities of 22.53 W h kg-1 and 74.2 W h kg-1, respectively, along with a long life cycle, ideal coulombic efficiency, and rate capability, demonstrating their practical applicability. This study provides an alternative strategy to prepare MXene-decorated PCNF freestanding electrodes with high performance, and the technique can be extended to other 2D MXenes for designing efficient electrodes for flexible supercapacitors. [ABSTRACT FROM AUTHOR]

Alkaloids are aromatic hydrocarbons with nitrogen as heteroelements in the ring structure that are responsible for bonding with the metal surface and help to reduce corrosion of metals such as mild steel (MS) in an acidic medium. In this study, the alkaloid of Rhynchostylis retusa (RR) was extracted by solvent extraction method and confirmed by chemical test as well as FTIR spectroscopic test. Extracted alkaloids were tested as green inhibitors for the MS corrosion in a 1.0 M H2SO4 solution. The inhibition efficiency (IE) of alkaloid extracts of RR was studied by the weight loss measurement method and electrochemical polarization method. Results showed that the maximum IE in the gravimetric method was 87.51% in 1000 ppm solution at 6 h immersion time. Open circuit potential (OCP) and potentiodynamic polarization results indicated that the extracted alkaloids acted as a mixed type of inhibitor. IE by polarization method was found to be 93.24% for the sample immersed for 6 h. The temperature effect study reveals that inhibitors can work only below 35 °C. Alkaloids of RR can be successfully extracted and used as corrosion inhibitors for MS in an acidic medium below 35 °C. [ABSTRACT FROM AUTHOR]