Accessible Surface Research Articles

Computational exploration of novel ketoprofen derivatives: Molecular dynamics simulations and MM-PBSA calculations for COX-2 inhibition as promising anti-inflammatory drugs

Computer-aided drug design is widely employed to identify novel compounds for therapeutic applications. Ketoprofen (KTP), a commonly used and marketed nonsteroidal anti-inflammatory drug (NSAID), is effective in treating pain, fever, inflammation, and some cancers. In this research, we explored the behavior of six analogues designed by structurally modifying the KTP molecule. Specifically, KTP-A and KTP-B contain a –CN group at the ortho position, KTP-C and KTP-D have a –CN group at the meta position, and KTP-E and KTP-F feature a –CF3 group at the meta position. To assess these analogues, we conducted molecular dynamics simulations (MD) to study their inhibitory effects on human cyclooxygenase 2 (COX-2), providing detailed insights into the structure and dynamics of the protein both with and without ligands. MD simulation, enhanced by technological advances, has proven to be a powerful tool for new drug discovery. We further quantified the binding affinity of these drug molecules toward COX-2 using molecular mechanics Poisson-Boltzmann surface area (MM-PBSA) binding free energy calculations. The dynamic properties were evaluated through analyses of root mean square deviations (RMSD), root mean square fluctuations (RMSF), radius of gyration (Rg), solvent-accessible surface area (SASA), covariance matrix, principal component analysis (PCA), and Gibbs free energy landscapes (FEL). Ultimately, this study confirms that the six KTP derivatives are promising candidates for the treatment of inflammation, with KTP-B standing out as particularly effective.

Inhibiting Emulative Oxygen Adsorption via Introducing Pt-Segregated Sites into the Pd Surface for Enhanced H2 Sensing in Air.

Pd-modified metal sulfide gas sensors exhibit excellent hydrogen (H2) sensing activity through spillover effects. However, the emulative oxygen adsorption often occupies an exposed Pd surface and thus limits the effective Pd-H interaction, impeding the H2 sensing performance in air. Herein, we develop an edge-rich Pt-shell/Pd-core structure to adjust the selective adsorption between oxygen and hydrogen for effective H2 sensing in an air atmosphere. Detailedly, through accurately regulating the rate of Pt deposition onto the icosahedron Pd surface, an edge-rich Pt-shell/Pd-core structure can be first achieved. It has been found that marginal Pt aggregations can segregate the oxygen molecules around the Pt species and induce easier Pt-O bonding, further guiding accessible Pd surfaces for effective Pd-H interactions, which can be verified by 1H ssNMR, in-situ Raman, ex-situ XPS, and density functional theory analyses. The final ZnS/PdPt sensor exhibits an ultrasensitive response (8608 to 4% H2) and a wide detected range (0.5 ppm-4%) in air, exceeding most reported hydrogen sensors.

Calixarene incorporated molecular imprinting on covalent organic framework for supramolecular recognition and specific extraction of citrinin

Specific recognition and selective extraction of mycotoxin in environmental and food matrixes is significant to guarantee public health. Covalent organic frameworks (COFs) are promising adsorbents with tailorable functionality, but their low binding affinity and poor selectivity hamper their wide application for selective extraction of trace mycotoxin from complex matrix. Herein, we report calixarene incorporated molecular imprinting on COF to prepare molecularly imprinted calix[4]arene-containing COF (MICOF-CX4) for supramolecular recognition and specific adsorption of citrinin. Calixarene with host-guest chemistry was used as a functional monomer, while amine units with different topologies and function groups were selected to regulate MICOF-CX4 to match with citrinin. The complementary shape and supramolecular interactions of MICOF-CX4 gave highly selective recognition for citrinin. Moreover, MICOF-CX4 with vast accessible surface and plentiful imprinting sites exhibited faster adsorption kinetics and 4-fold higher adsorption capacity for citrinin adsorption than no-imprinted COF-CX4. Combination of MICOF-CX4 based solid-phase extraction with high-performance liquid chromatography-mass spectrometry allowed interference free determination of trace citrinin in real samples with a low detection limit of 0.03 ng mL−1, good precision of 4.5 % and quantitative recovery of 88.2 %−101.4 %. The cooperative functions of calixarene and molecular imprinting make COF promising adsorbent for specific adsorption of trace targets in complex matrixes.

Fluorine-doped carbon dots decorated on iron-cobalt selenide nanosheets as superior electrocatalysts for oxygen evolution in seawater

Developing oxygen evolution reaction (OER) catalysts that can efficiently and stably operate at high current densities in seawater electrolysis is urgently demanded but challenging. In this study, selenium-vacancies-rich iron-cobalt selenide nanosheets (FeCoSe-VSe) decorated with fluorine-doped carbon dots (FCDs) are rationally designed and prepared on nickel foams (NF) through the successive processes of hydrothermal treatment and selenization. Benefiting from the large accessible surface area and abundant active sites provided by FCDs and selenium vacancy defects, as well as the coupled interface between FCDs and FeCoSe-VSe that optimizes the oxygen adsorption energy and accelerates the kinetic process, the FCDs/FeCoSe-VSe/NF composite exhibits excellent OER catalytic activities with a low overpotential of 258 mV at a current density of 200 mA cm−2 in 1 M KOH and a small Tafel slope of 34.7 mV dec–1. In the electrolytes of simulated and natural seawater, the overpotentials of the FCDs/FeCoSe-VSe/NF electrode are slightly higher, measured to be 264 and 297 mV, respectively. More profoundly, the introduction of FCDs enhances the corrosion resistance of the catalyst in alkaline electrolytes, ensuring the long-term stability. This work offers a guidance to improve the electrochemical performances of catalysts for high-efficiency seawater oxidation.

Destabilisation of Alzheimer's amyloid-β protofibrils by Baicalein: mechanistic insights from all-atom molecular dynamics simulations.

Alzheimer's disease (AD) is the most common form of dementia and the fifth leading cause of death globally. Aggregation and deposition of neurotoxic Aβ fibrils in the neural tissues of the brain is a key hallmark in AD pathogenesis. Destabilisation studies of the amyloid-peptide by various natural molecules are highly relevant due to their neuroprotective and therapeutic potential for AD. We performed molecular dynamics (MD) simulation to investigate the destabilisation mechanism of amyloidogenic protofilament intermediate by Baicalein (BCL), a naturally occurring flavonoid. We found that the BCL molecule formed strong hydrophobic contacts with non-polar residues, specifically F19, A21, V24, and I32 of Chain A and B of the pentameric protofibril. Upon binding, it competed with the native hydrophobic contacts of the Aβ protein. BCL loosened the tight packing of the hydrophobic core by disrupting the hydrogen bonds and the prominent D23-K28 inter-chain salt bridges of the protofibril. The decrease in the structural stability of Aβ protofibrils was confirmed by the increased RMSD, radius of gyration, solvent accessible surface area (SASA), and reduced β-sheet content. PCA indicated that the presence of the BCL molecule intensified protofibril motions, particularly affecting residues in Chain A and B regions. Our findings propose that BCL would be a potent destabiliser of Aβ protofilament, and may be considered as a therapeutic agent in treating AD.

Computer-Aided Site-Specific PEGylation of PET Hydrolases for Enhanced PET Degradation.

The enormous accumulation of poly(ethylene terephthalate) (PET) waste has posed a serious threat to the environment and human health, and biodegradation with PET hydrolase (PETase) can be a possible solution. Herein, we propose site-specifically modifying PETase with amphiphilic polymers to improve the enzyme performance at ambient temperature. For this purpose, we devise a computer-aided strategy to prioritize the conjugation site, and polyethylene glycol (PEG) preparations of 0.55 to 10 kDa are site-specifically conjugated to PETase. The most active conjugate PETase-PEG 5k (PETase-5K) shows an increase of melting temperature (3.88 °C) and significantly improves PET degradation performance (3.5- and 3.1-fold increases at 30 and 40 °C, respectively). Experimental investigation and molecular dynamics simulations reveal that the site-specific PEGylation increases the hydrophobic solvent-accessible surface area and the binding capability to the PET surface, thickens the hydration layer, increases the intramolecular hydrogen bonding, reduces the interactions between water and the conjugated enzyme surface, and rigidifies the enzyme structure via hydrogen bonding and hydrophobic interactions between the polymer and the enzyme, thus leading to improved enzymatic performance of PETase-5K. We further validate the versatility of the site-specific PEGylation in one of the most evolved variants of PETase, FAST-PETase, by 1.8-fold improvement in PET degradation at 30 °C. The presented computer-aided site-specific conjugation strategy has opened a new avenue to enhancing PETase performance at ambient temperature, and the contribution of PEGylation to PETase unraveled in this work laid a foundation for the rational engineering of PET hydrolases.

Capacitive deionization and electrochemical performance of a hierarchical porous electrodes enabled by nitrogen and phosphorus doped CNTs and removable NaCl template

Capacitive Deionization (CDI) is an electrochemical desalination technique based on the electrical double layer, which accumulate salts from the water stream; however, achieving higher salt adsorption for low-concentration salt is hindered due to several obstacles, such as low adsorption capacity and slow kinetics on the electrode surface. In this study, we reported a novel electrode fabrication method designed to enhance the hydrophilicity of the electrode material and activate hierarchical porosity, making a more accessible adsorption surface area. This modification enables more than 210 % improvement in salt adsorption capacity, achieving 17.5 mg g-1 in a single pass process with good stability in an 850 mg/L NaCl solution at 1.2 V, surpassing most reported carbon-based electrodes under similar operating conditions. Electrode formulation consists of Nitrogen (N) and Phosphorus (P) doped hierarchical carbon nanotubes (CNTs) network blended with additional NaCl as a green and removable template to reach higher levels of porosity. The electrochemical sorption behavior of the sample was characterized over a voltage range of –0.5 to 0.7 V. Furthermore, the electrode materials were characterized utilizing various characterization methods, including Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-ray Diffraction (XRD), Raman Spectroscopy, Fourier Transformed Infrared (FTIR), X-ray Photoelectron Spectroscopy (XPS), and Brunauer-Emmett-Teller (BET) to explore the correlation between microstructure, morphology, and properties. Our finding reveals that not only N and P can affect adsorption, but also the novel cathode preparation method, which employs a removable NaCl templated hierarchical porous electrode, has a profound effect on the electrochemical and CDI results. This finding will open a new perspective in designing electrodes for all electrochemical systems.

Molecular insights into 5-hydroxymethylfurfural: a computational, spectroscopic, and docking investigation

The quantum chemical properties of 5-hydroxymethylfurfural were investigated using Density Functional Theory alongside vibrational spectroscopy. Key outcomes included optimizing molecular structure, vibrational frequencies, and various molecular parameters. By comparing DFT results with experimental infrared spectra, molecular motion was clarified. Reactive sites were identified through Molecular Electrostatic Potential and Fukui function analyses. Hirshfeld surface analysis revealed insights into the crystal structure’s intermolecular interactions and hydrogen bonding. Time-dependent Density Functional Theory combined with the Polarizable Continuum Model provided Ultraviolet spectra, highlighting charge transfer between the highest occupied and lowest unoccupied molecular orbitals. The compound’s electronegativity (4.7239) and electron affinity were assessed. Biological studies, including drug-likeness evaluations and molecular docking, also demonstrated potential physiological benefits, mainly through the compound’s low binding energy. A 100-nanosecond molecular dynamics simulation of the 5-HMF-4LB4 complex revealed its stability and dynamic behavior through analyses of Root Mean Square Deviation, Root Mean Square Fluctuation, hydrogen bonding, Solvent Accessible Surface Area, and radius of gyration.

Unveiling the structural and physico-chemical properties of glutenin macropolymer under frozen storage: Studies on experiments and molecular dynamics simulation

Glutenin macropolymer (GMP) plays an important role in wheat gluten fractions, and extensively presents in the frozen dough. However, the effects of freezing treatment on GMP remain not abundantly understood. In this study, we investigated the structure and physico-chemical properties of GMP under frozen storage through experimental methods and bioinformatics algorithms. Results revealed that freezing treatment weakened the structure and properties of GMP to varying degrees, and GMP might have tolerance to short-term freezing storage. During frozen storage, portions of α-helix in GMP were converted into β-turn and random coil, slight changes in the tertiary structure, and its surface hydrophobicity increased by 4.8 %. SDS-PAGE profiles indicated that the depolymerization behavior mainly occurred above the Mw of 70.0 kDa. Slight changes were observed in the content of free thiol groups and disulfide bonds during frozen storage. Combination of fluorescence spectroscopy and intermolecular interactions suggested that hydrogen bonds and hydrophobic interactions were probably important indicators for evaluating the deterioration of GMP. Frozen storage resulted in an unfolded and open protein network. Moreover, freezing treatment led to a main conversion from strongly bond water to weakly bond water. However, no significant changes in water distribution were observed during the first 7 days of frozen storage. The viscoelastic loss of GMP primarily occurred in the first fourteen days, but tan δ did not significantly increased, indicating that protein has not been seriously deteriorated. Molecular dynamics simulation further supplemented and validated these experimental results from molecular level through analysis of root mean square deviation, root mean square fluctuation, solvent-accessible surface area, radius of gyration and the number of hydrogen bonds.

High-Performance Methanol Oxidation via Ni12-Metal8/CNF Catalyst for Fuel Cell Applications

In this work, non-precious electrocatalysts were synthesized using the electrospinning technique. Ni12M8/CNF (M = Cd, Co, and Cu) catalysts were successfully prepared in a fixed ratio to withstand the optimum transition metal co-catalyst in addition to the role of CNFs as support in ion-charge movement through the catalyst surface. The prepared catalysts were physically studied by XRD, SEM, and TEM. The electrochemical activity was verified using different fuel concentrations, different sweeping scan rates, and electrochemical impedance. Ni12Cu8/CNFs showed the highest electrochemical activity reaching 152 mA/cm2 through different methanol concentrations. The outstanding performance is attributed to the large active surface area provided by carbon nanofibrous that eases the charge carrier transfer through the untrapped surface of the catalyst. The electrochemical tests suggest that Ni12Cu8/CNFs have the lowest ohmic impedance resistance ensuring the highest efficiency of the designed catalyst. The obtained results serve as an efficient catalyst for direct methanol electrooxidation reactions and suggest a possible application of a low-cost, easily accessible, and large surface area established via the preparing method.

An orientational graphene/bamboo evaporator for efficient solar-powered steam generation and desalination

Solar-powered steam generation and desalination by interfacial solar steam generation (ISSG) are promising techniques for addressing the freshwater shortage. However, the insufficient conversion efficiency and complex pollutant components confine its further extension and application. This study innovatively constructs an orientational graphene/bamboo evaporator (GBE), maintaining a solvent-accessible surface area and reducing vaporization enthalpy by selective delignification and torrefaction. The GBE device features a channel oriented from bamboo, consolidating the parallel architecture with multilayer biofilm filtration that guides efficient bulk-water pumping, steam release, and pollutant interception. The GBE demonstrates full-spectrum optical absorption at 90.5 % and 33.4 s response time while maintaining operational stability across different salt concentrations and natural water environments. The GBE achieved an evaporation rate of 1.53 kg m-2h-1as 4.34 enhancement factor under 1 kW/m−2(−|-) illumination, surpassing microplastics (99.84 %) and tetracycline (99.87 %) desalination. This work provides a high-performance and innovative approach to bamboo evaporator design, offering a viable and alternative method to address freshwater shortage.

Green self-templated synthesis of P-doped mesoporous carbon from dual sodium salts with improved average pore size for capacitive deionization

Mesoporous carbon materials hold significant potential in capacitive deionization (CDI) technology owing to expansive accessible surface area, more adaptable pore structure, excellent conductivity properties and effective surface modification and functionalization. While templating is a common method for synthesizing mesoporous carbons, the commonly used hard and soft templating approaches among them suffer from the challenges of expensive precursors and templating agents, complex procedures, secondary contaminants and difficulties in template removal. In contrast, the self-templating method not only circumvents the traditional template removal or combustion steps but also eliminates the use of organic solvents and hazardous chemicals, thus minimizing environmental impact. In this paper, we have successfully synthesized phosphorus-doped mesoporous carbon with a large average pore size (paver) using a green and convenient self-templating method employing dual sodium salts of sodium alginate (SA) and sodium phytate (SP). Compared to single SA (6.76 nm) or SP (3.74 nm) self-templated carbonization, the average pore size of carbon materials obtained from dual self-templated carbonization with a proportional mixture (12.97 nm) is significantly improved. The larger average pore size provides a greater surface area for electrode-electrolyte interactions, allowing for easier access and faster diffusion of ions into the pores, thereby enhancing the electrochemical and capacitive deionization properties of the material. The resulting material demonstrates promising electrochemical and desalination performance as evidenced by possessing a specific capacitance of 175.8 A/g and an adsorption capacity of 19.65 mg/g, underlining its potential for application in capacitive deionization utilizing mesoporous carbon materials with large average pore size.

Radical Protein Footprinting in Mammalian Whole Blood.

Hydroxyl Radical Protein Footprinting (HRPF) is a powerful method to probe the solvent-accessible surface area of proteins. It is mostly used to study the higher-order structure of proteins, as well as protein-protein and protein-carbohydrate interactions. Hydroxyl radicals are generated by the photolysis of hydrogen peroxide and these radicals modify the surface amino acids. Bottom-up proteomics is then applied and peptide oxidation is calculated and correlated with solvent accessibility. It is mainly performed in vitro ; however, it has been recently used in living systems, including live cells, live nematodes, and 3D cell cultures. Mammalian tissues are still out of reach as they absorb UV strongly, hindering radical generation. Here, we describe the first example of RPF in mammalian stabilized whole blood. Using photoactivation of persulfate with a commercially available FOX Photolysis System modified for sample handling and inline mixing, we demonstrate the first labeling of proteins in whole blood. We demonstrate that the RPF protocol does not alter the blood cell gross morphology outside of a moderate hypertonicity equivalent to sodium chloride exposure prior to labeling. We detail an improved quenching protocol to limit background labeling in persulfate RPF. We describe the labeling of the top ten most abundant proteins in the blood. We demonstrate the equivalence of ex vivo labeling in whole blood with labeling of the same structure in vitro using hemoglobin as a test system. Overall, these results now open the possibility of performing RPF-based structural proteomics in pre-clinical models and using readily available clinical samples.

Co2P/CoP embedded in N, P, S triply-doped hollow carbon towards enhanced oxygen electrocatalysis

Simultaneously dispersing phosphide crystallites and multiple heteroatoms in hollow carbon is a significant yet challenging task for achieving high-performance oxygen electrocatalysts of zinc-air batteries. Herein, a simple wrapping-pyrolysis strategy is proposed to prepare Co2P/CoP embedded in N, P, S triply-doped hollow carbon (Co2P/CoP@NPS-HC). Co2P/CoP@NPS-HC composite features hollow polyhedral structure populated with numerous catalytically active Co2P/CoP nanoparticles and N, P, S heteroatoms. This optimized catalyst exhibits excellent activity for oxygen reduction reaction, with a half-wave potential of 0.82 V vs. RHE, and impressive enhancement for oxygen evolution reaction, indicated by an overpotential of 400 mV at 10 mA cm−2. Moreover, Co2P/CoP@NPS-HC catalyst exhibits greater durability and superior methanol tolerance compared to commercial Pt/C. The excellent bifunctional electrocatalytic performance of Co2P/CoP@NPS-HC catalyst is attributed to the synergistic effect of uniformly dispersed Co2P/CoP nanoparticles and N, P, S triply-doped hollow carbon structure. The former provides abundant catalytically active sites, while the latter offers a high accessible specific surface area, as well as enhances catalytic activity and electronic conductivity due to its altered charge distribution.

Correlation-Based Predictions of Gas Solute Diffusivity in Ionic Liquid Solvents Based on Solvent-Accessible Surface Area.

In our prior study [Olowookere, F. V.; Turner, C. H. J. Phys. Chem. B 2023, 127(42), 9144-9154], we introduced a new scaling relationship to predict gas solute diffusion at challenging conditions, focusing on CO2 and SO2 diffusion in multivalent ionic liquid (IL) solvents. This work extends our initial exploratory study into a much broader array of systems, encompassing additional solutes (N2, CH4, C2H6, C3H8, C3H8O, and H2O) and a variety of different ionic liquid species ([Bzmim3]3+, [Bzmim4]4+, [BMIM]+, [EMIM]+, [HMIM]+, [NapO2]2-, [BzO3]3-, [BF4]-, [Tf2N]-, and [PF6]-). Our study demonstrates a remarkably robust logarithmic correlation between solute diffusion and solvent accessible surface area (SA) across 20 different additional systems. We perform comprehensive analyses of the underlying molecular phenomena responsible for this correlation, including solute lifetime distributions, void space dynamics, and Voronoi tessellation, in order to elucidate a stronger mechanistic understanding of this behavior. Our findings highlight a direct link between the solvent accessible SA and the size of the void domains. Overall, our scaling approach provides an efficient and reliable approach for predicting diffusion from analyses of short simulations at higher temperatures.

Highly branched Pt-Ni-Co core-shell nano-dendrites anchored on N-doped carbon aerogel: Synergism between meso-porosity and surface morphology for enhanced ORR performance

Dendritic nanostructures are seizing growing interest in electrocatalysis owing to their unique structural features and low density. Under unique branched structures with the symbiotic effect of N-doped carbon aerogel (N-AC), the obtained core-shell nano-dendrites (NDs) showed excellent oxygen reduction performance. In detail, the mass and specific activities of Pt-Ni-Co/N-AC were found to be 1.88 A mgPt−1 / 0.78 mA cm−2 which is 9.9/2.5 times greater than commercial Pt/C. Furthermore, Pt-Ni-Co/N-AC demonstrated the best performance with the lowest activity loss across 1k, 3k, and 5k cycles and 40k sec testing, (40k testing repeated 4 times). At the 5k cycle and 40k sec testing, the ECSA loss is 13.47 % and the current loss is 10.1 %, the smallest among all tested NDs. This indicates that they exhibit superior stability and durability over extended cycles. The catalyst's large surface area, effective exposure and accessibility of active sites in NDs, high Pt-N/Ni-Co content, and predominance of pyridinic-N over pyrrolic-N collectively add to ND's activity. Highly branched, porous interconnected structures supported by chemical active sites of N-AC and sustained performance of Pt-Ni-Co/N-AC NDs make them a reliable choice for fuel cell technology.

Modulating allergenicity of prawn tropomyosin (penaeus chinensis) via pulsed electric field-induced conformational changes

The effect of electric field intensities (EFIs, 5–20 kV/cm) and treatment times (0.5–2 h) on allergenicity and spatial conformation of prawn tropomyosin was evaluated. The results demonstrated that the IgG and IgE binding capacity of tropomyosin maximally increased by 24.34 % and 29.16 % respectively, followed by a subsequent decrease after 20 kV/cm treatment for 1 h. Interestingly, 5–10 kV/cm treatments significantly decreased the α-helix content (P < 0.05) and fluorescence intensity, while 20 kV/cm treatment promoted extensive spiralization, resulting in a tightly packed structure. The increased flexibility further exposed the hydrolysis sites and strengthened the gastrointestinal digestibility of tropomyosin. Additionally, molecular dynamic simulation indicated that extended EFIs increased structural flexibility and depolymerized the tropomyosin dimers through destroying intermolecular hydrogen bonds (formed within arginine and glutamate), which allowed tropomyosin to be easily recognized by IgG/IgE. Whereas, decrease of solvent-accessibility surface area (SASA), hydrophobic surface area induced conformation folded and caused epitopes masked.

A First Principles Study of Lithium Adsorption in Nanoporous Graphene

Recently, nanoporous graphene has attracted great interest in the scientific community. It possesses nano-sized holes; thus, it has a highly accessible surface area for lithium adsorption for energy storage applications. Defective graphene has been extensively studied. However, the lithium adsorption mechanism of nanoporous graphene is not clearly understood yet. Here, we present theoretical investigations on the lithium-ion adsorption mechanism in nanoporous graphene. We perform ab initio electronic structure calculations based on density functional theory. Lithium adsorption in a graphene nanopore is studied and adsorption sites are determined. We also study different lithium-ion distributions in graphene nanopores to determine the best lithium–nanoporous graphene structures for lithium-ion batteries. We show that lithium ions can be adsorbed in a graphene nanopore, even in a single layer of graphene. It is also shown that adding more nanopores to multilayer nanoporous graphene can result in higher Li storage capacity for new-generation lithium-ion batteries.

Coexistence of Redox‐Active Metal and Ligand Sites in Copper‐based 2D Conjugated Metal‐Organic Frameworks for Battery‐Supercapacitor hybrid systems

Two‐dimensional (2D) conjugated metal‐organic frameworks (c‐MOFs) are promising materials for supercapacitor (SC) electrodes due to their high electrochemically accessible surface area coupled with superior electrical conductivity compared to traditional MOFs. Here, porous and non‐porous HHB‐Cu (HHB=hexahydroxybenzene), derived through surfactant‐assisted synthesis, are studied as representative 2D c‐MOF models, showing different reversible redox reactions with Na+ and Li+ in aqueous and organic electrolytes, respectively. We deployed these redox activities to design negative electrodes for hybrid SCs (HSCs), combining the battery‐like property of HHB‐Cu as negative electrode and the high capacitance and robust cyclic stability of activated carbon (AC) as positive electrode. In organic electrolyte, porous HHB‐Cu‐based HSC achieves a maximum cell specific capacity (Cs) of 22.1 mAhg‐1 at 0.1 Ag‐1, specific energy (Es) of 15.55 Whkg‐1 at specific power (Ps) of 70.49 Wkg‐1, and 77% cyclic stability after 3000 gravimetric charge‐discharge (GCD) cycles at 1 Ag‐1 (calculated on the mass of both electrode materials). In the aqueous electrolyte, porous HHB‐Cu‐based HSC displays a Cs of 13.9 mAhg‐1 at 0.1 Ag‐1, Es of 6.13 Whkg‐1 at 44.05 Wkg‐1, and 72.3% Cs retention after 3000 GCD cycles. The non‐porous sample shows lower Es performance but better rate capability compared to the porous one.

Regulation of extracellular electron transfer by sustained existence of Fe²⁺/Fe³⁺ redox couples on iron oxide-functionalized woody biochar anode surfaces in bioelectrochemical systems

Sluggish extracellular electron transfer between the exoelectrogens and anode interface limits the application of bioelectrochemical systems (BECs) for energy generation. In this study, an innovative anode coated with oxidized biochar and co-functionalized with iron nanoparticles (FBC/Fe2O3) was developed to enhance microbial reactions through tuned physicochemical and electrical properties. The designed anode features a highly porous, heterogeneous structure with a large accessible surface area of 10.141 m²/g, promoting better habitation and metabolism of exoelectrogens. The synergistic effect of iron nanoparticles and oxidized functional groups increased the hydrophilicity of the anode surface, augmenting its affinity for bacterial outer membrane c-cysts and facilitating microbial adhesion at a density of 3.106 × 10⁹ CFU/cm². The iron moieties on the FBC/Fe2O3 electrode surface act as electron mediators, utilizing Fe²⁺/Fe³⁺ redox couples, as evidenced by X-ray photoelectron spectroscopy (XPS) data. This enhancement improved extracellular electron transfer (EET) between bacterial cells and the anode surface, resulting in a faster and bifurcated EET process through both direct transfer via outer membrane c-cysts and mediated transfer via the redox couples of Fe moieties. The assembled double-chamber microbial fuel cell (DC-MFC) with the FBC/Fe2O3 anode achieved a maximum power density of 528.75 mW/m² and a chemical oxygen demand (COD) removal efficiency of 47.5 % within 24 h of operation.