Facile Electron Transfer Research Articles

The Anti-Inflammatory Activities of Benzylideneacetophenone Derivatives in LPS Stimulated BV2 Microglia Cells and Mice.

A previously reported study highlighted the neuroprotective potential of the novel benzylideneacetophenone derivative, JC3, in mice. In pursuit of compounds with even more robust neuroprotective and anti-inflammatory properties compared to JC3, we synthesized substituted 1,3-diphenyl-2-propen-1-ones based on chalcones. Molecular modeling studies aimed at discerning the chemical structural features conducive to heightened biological activity revealed that JCII-8,10,11 exhibited the widest HOMOLUMO gap within this category, indicating facile electron and radical transfer between HOMO and LUMO in model assessments. From the pool of synthesized compounds, JCII-8,10,11 were selected for the present investigation. The biological assays involving JCII-8,10,11 demonstrated their concentration-dependent suppression of iNOS and COX-2 protein levels, alongside various cytokine mRNA expressions in LPS-induced murine microglial BV2 cells. Furthermore, western blot analyses were conducted to investigate the MAPK pathways and NF-κB/p65 nuclear translocation. These evaluations conclusively confirmed the inflammatory inhibition effects in both in vitro and in vivo inflammation models. These findings establish JCII-8,10,11 as potent anti-inflammatory agents, hindering inflammatory mediators and impeding NF-κB/p65 nuclear translocation via JNK and ERK MAPK phosphorylation in BV2 cells. The study positions them as potential therapeutics for inflammation-related conditions. Additionally, JCII-11 exhibited greater activity compared to other tested JCII compounds.

CuS nanoparticle/TiO2 nanosheets heterojuncture boosting paired electrosynthesis of formate

There is still a gap in research on the use of TiO2 as a multiphase catalyst for electrocatalysis. This paper explores the boosting effect of TiO2 nanosheets (NSs) in CuS/TiO2 NSs bifunctional catalysts which enhances their electrocatalytic formate production in both anodic methanol oxidation reaction (MOR) and cathodic carbon dioxide reduction reaction (CO2R). The boosting effect of TiO2 nanosheet is ascribed to the in-built CuS/TiO2 heterojunctions which have abundant heterointerface boundaries, adjusted electrolyte/catalyst environment, improved electrochemical active area as well as facile electron transfer. The cathodic CO2RR with CuS/TiO2 NSs showed a formate Faraday efficiency (FE formate) of 75 % at −0.9 V (vs. RHE), while the anodic MOR exhibited 97 % FE formate at 1.7 V (vs. RHE). Particularly, paired electrolysis of formate was realized in an H-type cell through simultaneous cathodic CO2RR and anodic MOR, achieving a total FE formate of 168.7 % at 10 mA cm−2.

Comparing fluoro- and trifluoromethyl-functionalized Ni(II) 1,1-dithiolates with 1,1′-bis-(diphenylphosphino)ferrocene co-ligand in DSSC applications

Four new heteroleptic Ni(II)-dithiolates with general formula [Ni(dppf)(dithiolate)] (dithiolate = 2-cyano-2-(4-fluorophenyl)ethene-1,1-bis(dithiolate) (Ni-1); 2-cyano-2(2-(trifluoromethyl)phenyl)ethene-1,1-bis(thiolate) (Ni-2); 2-cyano-2(3-(trifluoromethyl)phenyl)ethene-1,1-bis(thiolate) (Ni-3) and 2-cyano-2(4-(trifluoromethyl)phenyl)ethene-1,1-bis(thiolate) (Ni-4); dppf = 1,1′-bis(diphenylphosphino) ferrocene) have been synthesized and characterized spectroscopically as well as by single crystal X-ray diffraction technique. Single crystal X-ray analyses for Ni-1 and Ni-2 reveal distorted square planar geometry around Ni(II) that are satisfied by two sulfur and two phosphorus centers of the dithiolate and dppf ligands, respectively. These complexes have been used as photosensitizers in TiO2-based dye-sensitized solar cells (DSSCs) which suggest that the performance of fluoro-substituted sensitizer Ni-1 is superior to that of the other three trifluoromethyl-substituted sensitizers. Ni-1 showcases an efficiency (η) of 5.47 %, open circuit potential (Voc) of 0.699 V, short circuit current (Jsc) of 12.17 mA∙cm−2 and display 64 % incident photon-to-current conversion efficiency. The plausible reason for the variation in photovoltaic performances have been explained by integrated experimental methods and theoretical calculations. Results indicate that the small sized fluoro-group exhibits significant p-orbital overlap with the aromatic fragment of the dithiolate ligand, allowing facile photo-induced electron transfer from sensitizer to titania, thereby enhancing the electron donation from dppf→Ni(II)→dithiolate. Further, the cell fabricated with Ni-1 retains approximately 93 % of its initial conversion efficiency in 800 h time span.

2D/1D VSe2/MWCNT hybrid-based electrochemical sensor for carbendazim quantification of environmental, food, and biological samples.

Forthe first time the sensitive determination of carbendatim (CRB) is reportedutilizing a well-designed sensing architecture based on vanadium diselenide-multiwalled carbon nanotube (VSMC). FTIR, XRD, FESEM, EDS, and EIS were employed to evaluate the sensor's structural integrity, and the results demonstrated the successful integration of nanomaterials, resulting in a robust and sensitive electrochemical sensor. Cyclic voltammetry (CV) and chronoamperometric (CA) investigations showed that the sensor best performed at pH 8.0 (BRB) with an excellent detection limit of 9.80nM with a wide linear range of 0.1 to 10.0µM. A more thermodynamically viable oxidation of CRB was observed at the VSMC/GCE, with a shift of 200mV in peak potential towards the less positive side compared with the unmodified GCE. In addition, the sensor demonstrated facile heterogeneous electron transfer, favorable anti-fouling traits in the presence of a wide range of interferents, good stability, and reproducible analytical performance. Finally, the developed sensor was validated for real-time quantification of CRB from spiked water, food, and bio-samples, which depicted acceptable recoveries (98.6 to 101.5%) with RSD values between 0.35 and 2.23%. Further, to derive the possible sensing mechanism, the valence orbitals projected density of states (PDOS) for C, H, and N atoms of an isolated CRB molecule, VSe2 + CNT and VSe2 + CNT + CRB were calculated using density functional theory (DFT) calculations. The dominant charge transfer from the valence 2p-orbitals of the C and N atoms of CRB to CNT is responsible for the electrochemical sensing of CRB molecules.

Coinage Metal Complexes of a Sterically Encumbered Anionic Pyridylborate.

Sterically loaded, anionic pyridine has been synthesized and utilized successfully in the stabilization of a isoleptic series of coinage metal complexes. The treatment of [4-(Ph3B)-2,6-Trip2Py]K (Trip=2,4,6-iPr3C6H2) with CuBr(PPh3), AgCl(PPh3) or AuCl(PPh3) (Py=pyridine) afforded the corresponding [4-(Ph3B)-2,6-Trip2Py]M(PPh3) (M=Au, Ag, Cu) complexes, via salt metathesis, as isolable, crystalline solids. Notably, these reactions avoid the facile single electron transfer chemistry reported with the less bulky ligand systems. The X-ray structures revealed that they are two-coordinate metal adducts. The M-N and M-P bond distances are longest in the silver and shortest in the copper adduct among the three group 11 family members. Computational analysis revealed an interesting stability dependence on steric bulk of the anionic pyridine (i. e., pyridyl borate) ligand. A comparison of structures and bonding of [4-(Ph3B)-2,6-Trip2Py]Au(PPh3) to pyridine and m-terphenyl complexes, {[2,6-Trip2Py]Au(PPh3)}[SbF6] and [2,6-Trip2Ph]Au(PPh3) are also provided. The Au(I) isocyanide complex, [4-(Ph3B)-2,6-Trip2Py]Au(CNBut) has been stabilized using the same anionic pyridylborate illustrating that it can support other gold-ligand moieties as well.

Unbiased overall photoelectrocatalytic water-splitting over micropyramid Si/In2O3/CuO/ZnO photocathode and Ni/BiVO4 photoanode under simulated solar-light illumination

Micropyramid Si/In2O3/CuO/ZnO photocathode and Ni/BiVO4 photoanode have been synthesized using a magnetron sputtering method with different conditions and characterized for a photoelectrochemical water-splitting process. The as-designed heterojunction of Si/In2O3/CuO/ZnO photocathode successfully induces a facile electron transfer to generate hydrogen in 0.5 M H2SO4. Similarly, Ni/BiVO4 photoanode evolves oxygen in 0.1 M Na2B4O7. Both photoreactions are done under concentrated solar-light irradiation (AM 1.5G, 500 mA/cm2). The analysis shows that IPCE values of photocathode and photoanode reached 40 and 60 % at 300 and 400 nm wavelengths, respectively. Furthermore, the ABPE of photocathode and photoanode achieved 14.9% and 0.8% at 0.21 and 1.15 VRHE, respectively. Photoelectrochemical analysis indicates that half cells of the photocathode and photoanode can reach photocurrents of ∼120 and ∼20 mA/cm2 at 0 and 1.23 VRHE, respectively. The outstanding performances indicate a facile charge transfer during redox reactions at the photocathode and photoanode. In addition, combining the photoelectrodes to form a cell configuration of Si/In2O3/CuO/ZnO//Ni/BiVO4 with a proton exchange membrane generates an unbiased photocurrent of 0.26 mA/cm2 at 0.55 VRHE. The combined cell has been tested for its stability in splitting water molecules into hydrogen and oxygen, indicating a promising result to overcome energy and environmental issues.

Direct observation of electron transfer in solids through X-ray crystallography

Nanoscale electron transfer (ET) in solids is fundamental to the design of multifunctional nanomaterials, yet its process is not fully understood. Herein, through X-ray crystallography, we directly observe solid-state ET via a crystal-to-crystal process. We first demonstrate the creation of a robust and flexible electron acceptor/acceptor (A/A) double-wall nanotube crystal ([(Zn2+)4(LA)4(LA=O)4]n) with a large window (0.90 nm × 0.92 nm) through the one-dimensional porous crystallization of heteroleptic Zn4 metallocycles ((Zn2+)4(LA)4(LA=O)4) with two different acceptor ligands (2,7-bis((1-ethyl-1H-imidazol-2-yl)ethynyl)acridine (LA) and 2,7-bis((1-ethyl-1H-imidazol-2-yl)ethynyl)acridin-9(10H)-one (LA=O)) in a slow-oxidation-associated crystallization procedure. We then achieve the bottom-up construction of the electron donor incorporated-A/A nanotube crystal ([(D)2⊂(Zn2+)4(LA)4(LA=O)4]n) through the subsequent absorption of electron donor guests (D = tetrathiafulvalene (TTF) and ferrocene (Fc)). Finally, we remove electrons from the electron donor guests inside the nanotube crystal through facile ET in the solid state to accumulate holes inside the nanotube crystal ([(D•+)2⊂(Zn2+)4(LA)4(LA=O)4]n), where the solid-state ET process (D – e– → D•+) is thus observed directly by X-ray crystallography.

Urchin-Like Mesoporous TiN Hollow Sphere Enabling Promoted Electrochemical Kinetics of Bromine-Based Flow Batteries.

Bromine-based flow batteries (BFB) have always suffered from poor kinetics due to the sluggish Br3 -/Br- redox, hindering their practical applications. Developing cathode materials with high catalytic activity is critical to address this challenge. Herein, the in-depth investigation for the free energy of the bromine redox electrode is conducted initially through DFT calculations, establishing the posterior desorption during oxidation as the rate-determining step. An urchin-like titanium nitride hollow sphere (TNHS) composite is designed and synthesized as the catalyst for bromine redox. The large difference in Br- and Br3 - adsorption capability of TNHS promotes rapid desorption of generated Br3 - during the oxidation process, liberating active sites timely to enable smooth ongoing reactions. Besides, the urchin-like microporous/mesoporous structure of TNHS provides abundant active surface for bromine redox reactions, and ample cavities for the bromine accommodation. The inherently high conductivity of TNHS enables facile electron transfer through multiple channels. Consequently, zinc-bromide flow batteries with TNHS catalyst exhibit significantly enhanced kinetics, stably operating at 80mAcm-2 with 82.78% energy efficiency. Overall, this study offers a solving strategy and catalyst design approach to the sluggish kinetics that has plagued bromine-based flow batteries.

Computational Insights on Structural Sensitivity of Cobalt in NO Electroreduction to Ammonia and Hydroxylamine.

It has been reported that it was selective to produce ammonia on metallic cobalt in the electrocatalytic nitric oxide reduction reaction (eNORR), where hexagonal close-packed (hcp) cobalt outperforms face-centered cubic (fcc) cobalt. However, hydroxylamine is more selectively produced on a cobalt single-atom catalyst (Co-SAC). Herein, we uncover the structural sensitivity over hcp-Co, fcc-Co, and Co-SAC in eNORR by employing a recently developed constant potential simulation method and microkinetic modeling. It was found that the superior activity for ammonia production on hcp-Co can be attributed to its facile electron and proton transfer and a stronger lateral suppression effect from NO* over fcc-Co. The exceptional hydroxylamine selectivity on Co-SAC is due to the modified electronic structure, namely, a positively charged active center. It was found that it is more favorable to produce NOH* over hcp-Co and fcc-Co, while HNO* is more preferable on Co-SAC, which are firmly correlated with the vertical and strong NO adsorption on the former and the moderate adsorption on the latter. In other words, a key factor for selectivity control is the first step of NO* protonation. Therefore, the local structure and electronic structure of the catalysts can be critical in regulating the activity and selectivity in eNORR.

Visible-Light [4+2] Homodimerization of Decomposition-Prone Styrenes via Electron Transfer Catalysis of Diaryl Diselenides.

The facile electron transfer catalysis of diaryl diselenides was utilized for the visible-light [4+2] homodimerization of decomposition-prone styrenes. The reaction required only 0.5 mol % TPT+BF4- photocatalyst and 1.5 mol % electron transfer catalyst (ArSe)2. The spontaneous electron transfer capability of diaryl diselenides was demonstrated for the first time, leading to the sequestration of redox-prone radical cation intermediates via electron transfer processes. A variety of polymerization-prone styrenes smoothly underwent the visible-light-promoted [4+2] homodimerization to tetralin derivatives.

Approaching high rate All-Solid-State Lithium-Sulfur batteries via promoted sulfur conversion with nickel oxide nanoparticle electrocatalyst

All-solid-state lithium-sulfur battery (ASLSB) is deemed a promising next-generation energy storage device owing to its combination of high theoretical specific energy (2600 Wh kg−1) derived from the sulfur active material, and exceptional safety characteristics and the ability to suppress the polysulfide shuttle effect through the use of solid electrolyte (SE). However, the low electronic and ionic conductivity of sulfur, coupled with the poor solid–solid interfacial contact inherent in all-solid-state configuration, has resulted in poor electrochemical performance. Herein, NiO electrocatalyst supported on N-doped sites of super-p was synthesized and incorporated as a carbon additive in the composite cathode of the ASLSB. The direct growth of nanosized NiO electrocatalyst on the N-doped sites of super-p ensures facile electron transfer to the electrocatalyst surface, while maximizing the electrocatalyst’s surface area. As a result, the overpotential during charging and discharging of the ASLSB was significantly reduced, as assessed through galvanostatic intermittent titration technique and cyclic voltammetry, indicating enhanced redox conversion of sulfur. Furthermore, the Li6PS5Cl sulfide SE induces solid–solid conversion of sulfur, eliminating the dissolution issue of polysulfide intermediates and ensuring good cycle performance. The assembled ASLSB exhibits a high reversible capacity of 1845 mAh g−1 at 0.05C at room temperature and enhanced rate capability at high C-rates, operated at 60 °C. Even at a substantially high sulfur loading level of 6.65 mg cm−2, a maximum areal capacity of 9.48 mAh cm−2 was achieved at room temperature, highlighting the important role of electrocatalyst in realizing high performance ASLSBs.

QM/MM Study Into the Mechanism of Oxidative C=C Double Bond Cleavage by Lignostilbene-α,β-Dioxygenase.

The enzymatic biosynthesis of fragrance molecules from lignin fragments is an important reaction in biotechnology for the sustainable production of fine chemicals. In this work we investigated the biosynthesis of vanillin from lignostilbene by a nonheme iron dioxygenase using QM/MM and tested several suggested proposals via either an epoxide or dioxetane intermediate. Binding of dioxygen to the active site of the protein results in the formation of an iron(II)-superoxo species with lignostilbene cation radical. The dioxygenase mechanism starts with electrophilic attack of the terminal oxygen atom of the superoxo group on the central C=C bond of lignostilbene, and the second-coordination sphere effects in the substrate binding pocket guide the reaction towards dioxetane formation. The computed mechanism is rationalized with thermochemical cycles and valence bond schemes that explain the electron transfer processes during the reaction mechanism. Particularly, the polarity of the protein and the local electric field and dipole moments enable a facile electron transfer and an exergonic dioxetane formation pathway.

Titanium Nanotubes as an Effective Electrocatalyst Support for Hydrogen Evolution Reaction

Developing proper support for hydrogen evolution reaction (HER) electrocatalysts is important for enhancing the HER efficiency and reducing the cost of green hydrogen production. TiO2-based-catalyst support has attracted considerable attention due to its commercial availability, high stability, low cost, and its unique electronic and ionic properties [1]. TiO2 is commonly utilized in various applications involving, photocatalysis, solar cells, and photoelectrochemical water splitting [2]. The ease of the synthesis of TiO2 with different morphologies and crystal structures makes it promising support to replace carbon in electrochemical applications [3]. Recently, anatase TiO2 nanoparticles decorated with PtOx clusters showed benchmark activity toward hydrogen evolution from the acidic medium with an overpotential of –125 mV at –10 mA cm–2 [4]. Furthermore, Pt clusters supported on porous TiO2 nanoparticles achieved higher stability compared with that of the benchmark Pt/C catalyst due to the facile electron transfer from TiO2 to PtOx [4]. Despite the TiO2-supported Pt nanoclusters have been recently investigated, the characteristic of HER electrocatalysts loaded on highly ordered TiO2 nanotube arrays (TNTs) is still unexplored. TNTs are expected to be an optimal support architecture owing to their large internal surface area and excellent electron mobility [5, 6]. Moreover, they can be readily synthesized and have robust mechanical stability. Therefore, in our work, highly ordered TNTs on Ti substrate have been synthesized and investigated as a support for different types of HER electrocatalysts (i.e. PtOx [7], MoS2 [8], and CoOP [9]). The PtOx clusters supported on TNTs (Ti/TNTs/PtOx) showed excellent performance for HER. An overpotential of –30 mV was sufficient to deliver –10 mA cm–2 from the acidic medium. The electrocatalytic mass activity of Ti/TNTs/PtOx (i.e. 204 mA mgPt –1) is enhanced by 12 and 1.7-fold compared to those of Pt/C and titanium nanoparticles (TNPs) supported PtOx electrocatalysts, respectively. The superior activity of the Ti/TNTs/PtOx is mainly due to its large electrochemically active surface area and the excellent electron mobility in the TNTs support. The immobilizing of MoS2 on TNTs resulted in enhanced electrocatalytic HER activity. An overpotential of –200 mVRHE was ample to deliver –10 mA cm–2 from 0.5 M H2SO4 aqueous solution. A synergy between the in-situ immobilized MoS2 and TNTs is proposed to explain the enhanced HER performance. In an alkaline medium, the Ti/TNTs/CoOP electrode fabricated by incorporating CoOP spheres into the TNTs exhibited only –130 mV overpotential to deliver –10 mA cm–2. This value is superior to that of CoOP deposited on bare Ti foil (–165 mV), FTO (–185 mV), and glassy carbon (–214 mV). In general, our study revealed that the TNTs support improves the electrochemical surface area and accessibility of active sites while reducing the charge transfer resistance at the electrode/electrolyte interface. Acknowledgments T.A.K. thanks the Deanship of Research Oversight and Coordination at KFUPM for the conference attendance support.

Extent of carbon nitride photocharging controls energetics of hydrogen transfer in photochemical cascade processes

Graphitic carbon nitride is widely studied in organic photoredox catalysis. Reductive quenching of carbon nitride excited state is postulated in many photocatalytic transformations. However, the reactivity of this species in the turn over step is less explored. In this work, we investigate electron and proton transfer from carbon nitride that is photocharged to a various extent, while the negative charge is compensated either by protons or ammonium cations. Strong stabilization of electrons by ammonium cations makes proton-coupled electron transfer uphill, and affords air-stable persistent carbon nitride radicals. In carbon nitrides, which are photocharged to a smaller extent, protons do not stabilize electrons, which results in spontaneous charge transfer to oxidants. Facile proton-coupled electron transfer is a key step in the photocatalytic oxidative-reductive cascade – tetramerization of benzylic amines. The feasibility of proton-coupled electron transfer is modulated by adjusting the extent of carbon nitride photocharging, type of counterion and temperature.

Pore-Confined π-Chromophoric Tetracene as a Visible Light Harvester toward MOF-Based Photocatalytic CO2 Reduction in Water.

Integrating photoactive π-chromophoric guest molecules inside the MOF nanopore can result in the emergence of light-responsive features, which in turn can be utilized for developing photoactive materials with inherent properties of MOF. Herein, we report the confining of π-chromophoric tetracene (TET) molecules inside the nanospace of postmodified Zr-MOF-808 (Zr-MOF) with MBA molecules (MBA = 2-(5'-methyl-[2,2'-bipyridine]-5-yl)acetic acid) for effectively utilizing its light-harvesting properties toward photocatalytic CO2 reduction. The confinement of the TET molecules as a photosensitizer and the covalent grafting of a catalytically active [Re(MBA)(CO)3Cl] complex, postsynthetically, result in a single integrated catalytic system named Zr-MBA-TET-Re-MOF. Photoreduction of CO2 over Zr-MBA-TET-Re-MOF showed the evolution of 805 μmol g-1 CO with 99.9% selectivity after 10 h of continuous visible light irradiation in water without any additional sacrificial electron donor and having the apparent quantum efficiency of 1.3%. In addition, the catalyst demonstrated an appreciable activity even under direct sunlight irradiation in aqueous medium with a maximum production of 362.7 μmol g-1 CO, thereby mimicking artificial photosynthesis. Moreover, electron transfer from TET to the catalytic center was supported by the formation of photoinduced TET radical cation, as inferred from in situ UV-vis spectra, electron paramagnetic resonance (EPR) analysis, and transient absorption (TA) studies. Additionally, the in situ diffuse reflectance infrared Fourier transform (DRIFT) measurements support that the photoreduction of CO2 to CO proceeds via *COOH intermediate formation. The close proximity of the light-harvesting molecule and catalytic center facilitated facile electron transfer from the photosensitizer to the catalyst during the CO2 reduction.

Intramolecular Electron Transfer in Multi-Redox Systems Based on Cyclic [3]Spirobifluorenylene Compound.

Cyclic [3]spirobifluorenylene with bulky alkyl groups at the ends (1) was designed and synthesized to investigate the electron transfer phenomena in a π-conjugated system including orthogonal π-conjugated chains. The three bifluorenyl units in 1 are conjugated to each other via spiro-conjugation, resulting in the splitting of the HOMO levels to a small extent. Therefore, the SOMO-HOMO gap of the radical cation species is small, which is considered to allow the facile intramolecular electron transfer. In the TD-DFT calculations for the radical cation species of 1, the geometry-featured interchain electronic transitions were visualized by NTO calculations. The radical cation species of 1 generated by chemical oxidation with SbCl5 exhibited a broadened and lower-energy shifted NIR absorption band compared to those of its partial structures. Considering the results of the TD-DFT calculations, the NIR band of the radical cation of 1 was attributed to the intramolecular electron transfer processes among the bifluorenyl units in the macrocycle. ESR experiments also indicated the delocalization of a spin of 1·+ in the whole molecule via hole hopping in the ESR time scale at room temperature. This work demonstrates the usefulness of spiro-conjugation as a bridging unit in molecular wires to facilitate smooth electron transfer.

Preparation of nickel–iron sulfide/oxide nanocomposites by biomineralization of sulfate-reducing bacterium for efficient oxygen evolution

Efficient electrolysis of water is critical for renewable energy technologies, and achieving this goal through low-cost, low-energy, and environmentally-friendly methods is imperative. The nanomaterials prepared by biomineralization have the characteristics of small particle size, strong stability, low cost, clean and environmental protection. This study utilized sulfate-reducing bacteria (SRB) to prepare oxygen evolution reaction (OER) catalysts based on the principles of biomineralization. To enhance its OER activity, three distinct doping methods were employed based on bacterial biomineralization products (BPs), and a possible biomineralization mechanism of SRB in the preparation of metal sulfides and iron compounds has been proposed. Our investigations demonstrated that Ni-doped biomineralized products hydrothermal treatment yielded an electrocatalyst having outstanding catalytic activity and performance, and it exhibited a small overpotential of 230 mV at a current density of 10 mA cm−2 as well as a Tafel slope down to 46 mV dec−1 in alkaline solution. This electrode material outperformed the commercial RuO2 electrocatalyst. The high catalytic activity of the prepared electrocatalyst is ascribed to the additional active sites introduced by the doping of Ni, facile electron transfer, enhanced conductivity, and wettability. Overall, the utilization of the biomineralization method for the catalytic material preparation can considerably facilitate the development of energy conversion and storage processes.

Green functionalization for chelating ligand-like and π-conjugated active sites on carbon nanotubes and its use for vanadium redox flow batteries

An imide bond-based functional group is proposed for the catalyst's active site in vanadium redox flow batteries (VRFBs). Based on the functional group's inherent property produced by the optimized process, the catalytic activity toward vanadium ion redox reaction (VIRR) on both sides was increased sixfold without adversely affecting VIRR reversibility in comparison to the raw material, carboxylic acid-functionalized carbon nanotubes. These advantages were attributed to the imide bond-based functional groups acting as a chelating ligand to form strong interactions with vanadium redox couples while also inducing facile electron transfer by the π-conjugated bonds, resulting in increased catalytic activity and reversibility. Moreover, the treatment used an eco-friendly process comprising low-cost precursors (citric acid and urea) and mild conditions (80 °C, 2 h), thereby improving the commercial availability of VRFBs. In VRFB driving tests, the fabricated electrode outperformed the electrode with a polymer-like structure in terms of catalytic activity and long-term stability due to leaching of the active sites from the latter. Overall, the proposed catalyst could be a practical option for enhancing VRFB performance based on a low-cost and eco-friendly treatment method.

Selenized Binary Transition Metals-Mxene Composite for the High-Performance Asymmetric Supercapacitors

The exploration of novel and efficient energy storage materials is crucial for the development of high-performance supercapacitors. Herein, we develop a new composite with multilayered MXene (Ti3C2Tx) nanoparticles and porous NiCo2Se4 nanosheets. The unique accordion-like nanostructure and strong interfacial interactions of MXene introduce the favorable nanocomposite with a larger surface area and reasonable cycling stability. The substitution of Se for the oxyhdryl in the Ni-Co based hydroxides modulates the orbital hybridization with the corresponding metallic cations, which effectively improves the electrochemical activity of Ni/Co and reduces the adsorption/desorption energy barrier of electrolyte ions. Based on the above considerations, we proposed a new Ni-Co TMSe and multilayer Ti3C2Tx MXene nanocomposite on NF (denoted as MXene-NiCo2Se4@NF) that could act as a binder-free electrode for SCs. In this regard, compared with the directly grown pure NiCo2Se4 electrode, the composite electrode exhibits a larger surface area, higher mass-loading, and lower internal resistance by the introduced MXene particles. The well-designed hierarchical structures make it possible for facilitated electrolyte diffusion, more active sites, fast electron transport, and improved nanostructure stability for a longer lifespan. Owing to such multifold attributes, the fabricated composite electrodes enable to attain a specific capacity of 786.25 C/g and 589.22 C/g at the current density at 1 A/g and 20 A/g with a good rate capability, respectively. The selenization improved the inherent conductivity of active materials and contributed to the lower deprotonation energy barrier, resulting in facile electron transfer in the Faradaic reaction process. Furthermore, the composite structure retained over 90% of capacity after 8000 cycles. The assembled asymmetrical device displays a high specific energy density of 64.36 Wh/kg, at a power density of 0.8kW/kg. These results suggest that the proposed composite structure can potentially be used as active material in various practical applications.

(Cu3-x Nix)Co2-Layered Double Hydroxide Nanosheets for Enhanced Electrocatalytic Activity Towards Overall Water Splitting

The exploration of transition metal based electrocatalyst for overall water splitting is becoming important as hydrogen becomes integral part of energy landscape. Recently, a new class of compounds i.e. layered double-hydroxides (LDHs), also known as anionic clays, are have shown tremendous promise for use as electrocatalyst. The lamellar morphology of LDHs accommodates higher active sites, that contributes to the facile electron transfer and thus attracts a great deal of interest in catalysis application. Moreover, the high catalytic activity of LDHs are also linked to their facile anion exchange, specific electronic structures, and versatile chemical compositions.Herein, we have developed a series of ternary layered double hydroxide (LDH) using pH-adjusted co-precipitation method with varying ratio of Cu, Ni and Co, which are used as an electrocatalyst for overall water splitting. (CuxNi1)Co1-LDHs (x = 0.5 1, 1.5, and 2 ) were systematically characterized using XRD, XPS, SEM, FTIR, TEM and BET techniques. The synergistic contributions from the electrocatalytically active metals and lamellar morphology of LDHs promotes water dissociation, facilitates faster release of H2-O2 gas bubbles, ameliorate electrolyte ion diffusion and improves electron transfer rate. It is further observed that the (CuxNi1)Co1-LDHs showed excellent electrocatalytic activity for both hydrogen evolution (HER) and oxygen evolution reaction (OER) with an overpotential of 147 and 218 mV for HER and OER, respectively at 10 mA cm-2. Tafel slope was found to be lowest for (Cu1Ni1)Co1-LDH. Further, the durability of the materials was also analysed by performing chronoamperometry for over 12 h. The overall water electrolytic cell using (Cu1Ni1)Co1-LDH as both electrodes can reach 50 mA cm−2 at 1.9V with outstanding durability.