Electron Donor Research Articles

Pop-Up Paper-Based Biosensor for a Dual-Mode Lung Cancer ctDNA Assay Based on Novel CoB Nanosheets with Dual-Enzyme Activities and a Portable Smartphone/Barometer for Readout.

Timely monitoring of circulating tumor DNA (ctDNA) in serum is meaningful for personalized diagnosis and treatment for lung cancer. Cheap and efficient point-of-care testing (POCT) has emerged as a promising method, especially in a low-resource setting. Herein, (i) a 3D pop-up paper-based POCT device was designed and manufactured via a cheap method; it was used for saving time and efficiently building a biosensor; (ii) a novel cobalt boride nanosheet (CoB NS) nanozyme with abundant groups was used for POCT dual-mode signal transduction and then a portable smartphone/pressure meter to readout; (iii) a user-friendly smartphone app was fabricated for achieving more convenient POCT. Detailly, the dual-mode signal generated was based on the CoB NS with peroxidase activity to catalyze a chromogenic agent to develop color and with catalase activity to catalyze decomposition of H2O2 to O2. Density functional theory (DFT) and experimental results showed a good catalysis performance of the CoB NS via studying its five possible catalytic pathways, in which the metal Co is the catalytic active site center that acts as the electron donor and promotes electron transfer between the CoB NS and the adsorbed substrates. Benefiting from that, the proposed method showed good analytical ability in detecting ctDNA. Besides, its accuracy was valued by comparing it with the standard qPCR method to detect real samples from tumor cells and tumor-bearing mice, which showed a consistent result and potential practical applicability of the proposed method for POCT ctDNA. In general, this work not only provided a dual-mode POCT platform that could also be applied for other analytes but also first revealed the nanozyme properties of the CoB NS and inspired its new application from electrocatalysis, energy, etc. to biomedicine.

Cu3P/CoP Heterostructure for Efficient Electrosynthesis of Ammonia from Nitrate Reduction Reaction.

Electrocatalytic nitrate reduction (ENO3RR) for ammonia production is one of the potential alternatives to Haber-Bosch technology for the realization of artificial ammonia synthesis. However, efficient ammonia production remains challenging due to the complex electron transfer process in ENO3RR. In this study, we fabricated a Cu3P/CoP heterostructure on carbon cloth (CC) by electrodeposition and vapor deposition, which exhibits an exceptional ENO3RR performance in alkaline medium, and showcases a Faradaic efficiency of ammonia (FENH3) and an ammonia yield rate as high as 97.95% and 17,637.3 μg h-1 cm-2 at -0.9 V vs RHE. Moreover, Cu3P/CoP also has excellent catalytic activity for nitrite reduction to ammonia, with an FENH3 up to 98.31% at -0.7 V vs RHE. The experimental and theoretical calculations reveal and confirm that the formation of a heterogeneous interface between Cu3P and CoP effectively promotes the electron transfer, where Cu3P as an electron donor induces the decrease of electron density around Cu and results in an enhancement of NO2- adsorption, thereby accelerating the ENO3RR process while inhibiting the competitive hydrogen evolution reaction (HER). Moreover, the metal phosphide catalyst facilitates the water dissociation, which accelerates the abundant *H generation, thus enhancing the subsequent hydrogenation process toward ENO3RR.

Cucurbit[8]uril-stabilized charge transfer: An efficient supramolecular approach toward a heterogeneous organic photocatalyst for aerobic oxidation reactions.

Host-stabilized charge transfer (HSCT) has been widely utilized in macrocycle-derived supramolecular assemblies and architectures. However, there has been less research attention focused on the direct fabrication of pure organic photocatalysts using HSCT. Herein, four viologen derivatives (m-PV2+, m-BPV2+, d-PV2+, and d-BPV2+) with different electron donor-acceptor (D-A) structures were synthesized. Their host-guest complexes with cucurbit[8]uril (Q[8]) in an aqueous solution could be switched using the substituted electron donor moieties, in which the host-guest complexes of m-BPV2+@Q[8] andd-BPV2+@Q[8] exhibited HSCT interactions. Control experiments revealed that the d-BPV2+@Q[8] complex had the strongest ability to sensitize singlet oxygen (1O2). This was ascribed to the increased π-conjugation of d-BPV2+@Q[8], which led to more effective HSCT upon encapsulation by the Q[8] host. Consequently, the d-BPV2+@Q[8] complex could be easily employed as a heterogeneous photocatalyst for the photooxidation reaction of thioether com-pounds with high selectivity. In particular, d-BPV2+@Q[8] was successfully applied to the synthesis of sulfoxide drugs, such as the con-version of inexpensive Iberverin ($7.0 per gram) to the expensive bioactive inhibitor Iberin ($19500.0 per gram) in high yield (94%).

Spatial Conformation Engineering of Aromatic Ketones for Highly Efficient and Stable Perovskite Solar Cells.

Carbonyl-containing materials employed in state-of-the-art hybrid lead halide perovskite solar cells (PSCs) exhibit a strong structure-dependent electron donor effect that predominates in defect passivation. However, the impact of the molecular spatial conformation on the efficacy of carbonyl-containing passivators remains ambiguous, hindering the advancement of molecular design for passivating materials. Herein, we show that altering the spatial torsion angle of aromatic ketones from twisted to planar configurations, as seen in benzophenone (BP, 27.2°), anthrone (AR, 15.3°), and 9-fluorenone (FO, 0°), leads to a notable increment of the electron cloud density around the carbonyl group, thus improving the passivation ability for lead-based defects. Consequently, the PSC performance also relies on the torsion angle of the aromatic ketones, with the coplanar FO-based PSC achieving a highest power conversion efficiency (PCE) of 25.13% and retaining 92% of its initial efficiency after 1000 h of operation at the maximum power point under continuous 1-sun illumination (ISOS-L-1I). Moreover, a perovskite mini-module (14.0 cm2) containing FO exhibits a PCE of 20.19%. Our findings highlight the influence of molecular conformation on the passivation effect of the carbonyl group, offering deeper insight into the design and development of aromatic ketones as passivators for highly efficient and stable PSCs.

Steric and Distance Effect on Electron Transfer in Dibenzo-Fused BODIPY-Based Photoredox Catalysts.

π-Extended BODIPY compounds are a compelling class of fluorophores known for their red or near-infrared (NIR) emission and high quantum yields, which are crucial for applications in materials science, solar cells, and biomedical imaging. Our recent study shows that we can use a dibenzo-fused BODIPY as a singlet-driven red photoredox catalyst by installing a simple electron donor group. Despite their potential in these applications, knowledge of electron transfer reactions involving dibenzo-fused BODIPY is still scarce. This paper presents the synthesis and systematic photophysical investigations of donor-acceptor (D-A) and donor-bridge-acceptor (D-bridge-A) series of dibenzo-fused BODIPY with N,N'-diethylaniline fragments serving as an electron donor. We examined the effects of methyl substituents and bridge length on the rates of photoinduced electron transfer (PeT). Through steady-state and time-resolved optical spectroscopy, electrochemistry, and density functional theory calculations, we elucidated how these simple structural modifications controlled the PeT rates and examined their impacts on catalytic activities in atom transfer radical addition (ATRA) reactions. Our results support previous studies on the (D-A) design of red heavy atom-free photocatalysts.

Neutral Phosphorus-Based Beryllium Scorpionate Complexes as Spectroscopic Probes for Base Strength and Electron Donation.

The synthesis and properties of tris(diisopropylphosphanylmethyl)phenylborate ([TP(iPr)]-) beryllium complexes [TP(iPr)]BeL with L = Cl, Br, I, CN, SCN, OCN, N3, and CF3SO3 are described. In these compounds, the 1JPBe NMR coupling constant can be used as a sensitive probe for the basicity and electron-donating properties of the L- anions in solution.

Nitrous oxide is the main product during nitrate reduction by a novel lithoautotrophic iron(II)-oxidizing culture from an organic-rich paddy soil.

Microbial nitrate reduction coupled to iron(II) oxidation (NRFeOx) occurs in paddy soils due to high levels of dissolved iron(II) and regular application of nitrogen fertilizer. However, to date, there is no lithoautotrophic NRFeOx isolate or enrichment culture available from this soil environment. Thus, resulting impacts on greenhouse gas emissions during nitrate reduction (i.e., nitrous oxide [N2O]) and on toxic metalloid (i.e., arsenic) mobility can hardly be investigated. We enriched a lithoautotrophic NRFeOx culture, culture HP (Huilongpu paddy, named after its origin), from a paddy soil (Huilongpu Town, China), which was dominated by Gallionella (71%). The culture reduced 0.45 to 0.63 mM nitrate and oxidized 1.76 to 2.31 mM iron(II) within 4 days leading to N2O as the main N-product (62%-88% N2O-N of total reduced NO3--N). Nitrite was present as an intermediate at a maximum of 0.16 ± 0.1 mM. Cells were associated with, but mostly not encrusted by, poorly crystalline iron(III) minerals (ferrihydrite). Culture HP performed best below an iron(II) threshold of 2.5-3.5 mM and in a pH range of 6.50-7.05. In the presence of 100 µM arsenite, only 0%-18% of iron(II) was oxidized. Due to low iron(II) oxidation, arsenite was not immobilized. However, the proportion of N2O-N of total reduced NO3--N decreased from 77% to 30%. Our results indicate that lithoautotrophic NRFeOx occurs even in organic-rich paddy soils, resulting in denitrification and subsequent N2O emissions. The obtained novel enrichment culture allows us to study the impact of lithoautotrophic NRFeOx on arsenic mobility and N2O emissions in paddy soils.IMPORTANCEPaddy soils are naturally rich in iron(II) and regularly experience nitrogen inputs due to fertilization. Nitrogen fertilization increases nitrous oxide emissions as it is an intermediate product during nitrate reduction. Microorganisms can live using nitrate and iron(II) as electron acceptor and donor, respectively, but mostly require an organic co-substrate. By contrast, microorganisms that only rely on nitrate, iron(II), and CO2 could inhabit carbon-limited ecological niches. So far, no isolate or consortium of lithoautotrophic iron(II)-oxidizing, nitrate-reducing microorganisms has been obtained from paddy soil. Here, we describe a lithoautotrophic enrichment culture, dominated by a typical iron(II)-oxidizer (Gallionella), that oxidized iron(II) and reduced nitrate to nitrous oxide, negatively impacting greenhouse gas dynamics. High arsenic concentrations were toxic to the culture but decreased the proportion of nitrous oxide of the total reduced nitrate. Our results suggest that autotrophic nitrate reduction coupled with iron(II) oxidation is a relevant, previously overlooked process in paddy soils.

Dynamic-Cycling Zinc Sites Promote Ruthenium Oxide for Sub-Ampere Electrochemical Water Oxidation.

Although iridium-based electrocatalysts are commonly regarded as the sole stable operating acidic oxygen evolution reaction (OER) catalysts in proton-exchange membrane water electrolysis (PEMWE) devices, their exorbitant cost and scarcity severely restrict their widespread application. Herein, we introduce a promising alternative to iridium: zinc-doped ruthenium dioxide (TE-Zn/RuO2), which exhibits remarkable and enduring activity for acidic OER. In situ characterizations elucidate that the dynamic cycling of zinc dopants serves as both electron acceptors and donors, facilitating the activation of Ru sites at low overpotentials while thwarting peroxidation at high overpotentials, thus concurrently achieving heightened activity and robust stability. Additionally, the incorporation of zinc induces weakened Ru-O covalency, thereby stabling *OOH intermediates and instigating a sustained adsorbate evolution mechanism, dramatically stabilizing the RuO2 lattice. Importantly, the TE-Zn/RuO2 catalyst as an anode exhibits good stability over 300 h at a water-splitting current of 500 mA cm-2 in the PEMWE device, underscoring its considerable promise for practical applications.

Recent Advances in the Hydroxylation of Boronic Acids

Hydroxylated compounds represent a significant and diverse class of substances in the field of chemistry. These compounds play critical roles in various chemical reactions and are essential components in numerous industrial applications. Recent years have witnessed remarkable advancements in the synthesis of hydroxylated compounds, especially those derived from boronic acids. The synthesis of hydroxylated compounds from boronic acids typically involves the utilization of various types of catalysts, which are essential for enhancing reaction rates and selectivity, including metal catalysts such as CuFe₂O₄, Cu@C₃N₄, AgNPs, and Ti0.97Ni0.3O1.97, as well as non‐metal catalysts like polycaprolactone (PCL), TFB‐BMTH COF materials, C70, and graphene oxide (GO). These catalytic reactions often require the addition of oxidants such as hydrogen peroxide (H₂O₂) or molecular oxygen, which serve as critical reagents in the hydroxylation process. In certain cases, organic bases act as electron donors to propel the reaction. Furthermore, some studies have reported oxidative hydroxylation reactions that are catalyst‐free.This review aims to summarize the recent advancements and breakthroughs in the synthesis of hydroxylated compounds from boronic acids, with a particular focus on research conducted from 2014 to 2024.

Co-occurrence of direct and indirect extracellular electron transfer mechanisms during electroactive respiration in a dissimilatory sulfate reducing bacterium.

Understanding the extracellular electron transfer mechanisms of electroactive bacteria could help determine their potential in microbial fuel cells (MFCs) and their microbial syntrophy with redox-active minerals in natural environments. However, the mechanisms of extracellular electron transfer to electrodes by sulfate-reducing bacteria (SRB) remain underexplored. Here, we utilized double-chamber MFCs with carbon cloth electrodes to investigate the extracellular electron transfer mechanisms of Desulfovibrio vulgaris Hildenborough (DvH), a model SRB, under varying lactate and sulfate concentrations using different DvH mutants. Our MFC setup indicated that DvH can harvest electrons from lactate at the anode and transfer them to cathode, where DvH could further utilize these electrons. Patterns in current production compared with variations of electron donor/acceptor ratios in the anode and cathode suggested that attachment of DvH to the electrode and biofilm density were critical for effective electricity generation. Electron microscopy analysis of DvH biofilms indicated DvH utilized filaments that resemble pili to attach to electrodes and facilitate extracellular electron transfer from cell to cell and to the electrode. Proteomics profiling indicated that DvH adapted to electroactive respiration by presenting more pili- and flagellar-related proteins. The mutant with a deletion of the major pilus-producing gene yielded less voltage and far less attachment to both anodic and catholic electrodes, suggesting the importance of pili in extracellular electron transfer. The mutant with a deficiency in biofilm formation, however, did not eliminate current production indicating the existence of indirect extracellular electron transfer. Untargeted metabolomics profiling showed flavin-based metabolites, potential electron shuttles.IMPORTANCEWe explored the application of Desulfovibrio vulgaris Hildenborough in microbial fuel cells (MFCs) and investigated its potential extracellular electron transfer (EET) mechanism. We also conducted untargeted proteomics and metabolomics profiling, offering insights into how DvH adapts metabolically to different electron donors and acceptors. An understanding of the EET mechanism and metabolic flexibility of DvH holds promise for future uses including bioremediation or enhancing efficacy in MFCs for wastewater treatment applications.

Anaerobic Faecalicatena spp. degrade sulfoquinovose via a bifurcated 6-deoxy-6-sulfofructose transketolase/transaldolase pathway to both C2- and C3-sulfonate intermediates

Plant-produced sulfoquinovose (SQ, 6-deoxy-6-sulfoglucose) is one of the most abundant sulfur-containing compounds in nature and its bacterial degradation plays an important role in the biogeochemical sulfur and carbon cycles and in all habitats where SQ is produced and degraded, particularly in gut microbiomes. Here, we report the enrichment and characterization of a strictly anaerobic SQ-degrading bacterial consortium that produces the C2-sulfonate isethionate (ISE) as the major product but also the C3-sulfonate 2,3-dihydroxypropanesulfonate (DHPS), with concomitant production of acetate and hydrogen (H2). In the second step, the ISE was degraded completely to hydrogen sulfide (H2S) when an additional electron donor (external H2) was supplied to the consortium. Through growth experiments, analytical chemistry, genomics, proteomics, and transcriptomics, we found evidence for a combination of the 6-deoxy-6-sulfofructose (SF) transketolase (sulfo-TK) and SF transaldolase (sulfo-TAL) pathways in a SQ-degrading Faecalicatena-phylotype (family Lachnospiraceae) of the consortium, and for the ISE-desulfonating glycyl-radical enzyme pathway, as described for Bilophila wadsworthia, in an Anaerospora-phylotype (Sporomusaceae). Furthermore, using total proteomics, a new gene cluster for a bifurcated SQ pathway was also detected in Faecalicatena sp. DSM22707, which grew with SQ in pure culture, producing mainly ISE, but also 3-sulfolacate (SL) 3-sulfolacaldehyde (SLA), acetate, butyrate, succinate, and formate, but not H2. We then reproduced the growth of the consortium with SQ in a defined co-culture model consisting of Faecalicatena sp. DSM22707 and Bilophila wadsworthia 3.1.6. Our findings provide the first description of an additional sulfoglycolytic, bifurcated SQ pathway. Furthermore, we expand on the knowledge of sulfidogenic SQ degradation by strictly anaerobic co-cultures, comprising SQ-fermenting bacteria and cross-feeding of the sulfonate intermediate to H2S-producing organisms, a process in gut microbiomes that is relevant for human health and disease.

Two-stage binding of mitochondrial ferredoxin-2 to the core iron-sulfur cluster assembly complex

Iron-sulfur (FeS) protein biogenesis in eukaryotes begins with the de novo assembly of [2Fe-2S] clusters by the mitochondrial core iron-sulfur cluster assembly (ISC) complex. This complex comprises the scaffold protein ISCU2, the cysteine desulfurase subcomplex NFS1-ISD11-ACP1, the allosteric activator frataxin (FXN) and the electron donor ferredoxin-2 (FDX2). The structural interaction of FDX2 with the complex remains unclear. Here, we present cryo-EM structures of the human FDX2-bound core ISC complex showing that FDX2 and FXN compete for overlapping binding sites. FDX2 binds in either a ‘distal’ conformation, where its helix F interacts electrostatically with an arginine patch of NFS1, or a ‘proximal’ conformation, where this interaction tightens and the FDX2-specific C terminus binds to NFS1, facilitating the movement of the [2Fe-2S] cluster of FDX2 closer to the ISCU2 FeS cluster assembly site for rapid electron transfer. Structure-based mutational studies verify the contact areas of FDX2 within the core ISC complex.

Redox‐Neutral Carboxylation of Benzylic Tertiary C−H Bonds with Carbon Dioxide

AbstractThe direct catalytic carboxylation of benzylic tertiary C−H bonds with CO2 for the synthesis of all‐carbon quaternary carboxylic acids represents a significant challenge. Here, we present a redox‐neutral approach to address this difficulty by leveraging the synergistic interplay between photocatalysis and cascade hydrogen abstraction cycles. Remarkably, this strategy eliminates the need for sacrificial electron donors, electron acceptors, or stoichiometric additives, offering enhanced atom economy and environmental sustainability. It is particular that the combination of α‐amino alkyl radicals with sulfur radicals generated in situ from the decomposition of DMSO was employed to realize the abstraction of benzylic tertiary C−H bonds. Our method enables the direct synthesis of a diverse array of benzylic quaternary carboxylic acids with excellent functional group tolerance as well as the derivatization of bioactive molecules and the gram‐scale synthesis of pharmaceuticals under mild reaction conditions.

Doped hexa-peri-hexabenzocoronene as anode materials for lithium- and magnesium-ion batteries.

The adsorption processes of Li+, Li, Mg2+, and Mg on twelve adsorbents (pristine and N/BN/Si-doped hexa-peri-hexabenzocoronene (HBC) molecules) were studied using density functional theory. The molecular electrostatic potential (MESP) analyses show that the replacement of C atoms of HBC by N/BN/Si units can provide a more electron-rich system than the parent HBC molecule. Li+ and Mg2+ exhibit strong adsorption on pristine and doped HBC molecules. The adsorption energy of cations on these nanoflakes (Eads-1) was in the range of -247.44 (Mg2+/m-C40H18N2 system) to -47.65 kcal mol-1 (Li+/B21H18N21 system). Importantly, our results suggest the weaker interactions of Li+ and Mg2+ with the nanoflakes as the MESP minimum values of the nanoflakes became less negative. In all studied systems, we observed electron donation from the nanoflakes to Li+ and Mg2+. For the metal/nanoflake systems, the adsorption energy of metals on the nanoflakes (Eads-2) was in the range of -33.94 (Li/C38H18B2N2 system) to -2.14 kcal mol-1 (Mg/B21H18N21 system). Among the studied anode materials for lithium-ion batteries (LIBs), the highest cell voltage (Vcell) of 1.90 V was obtained for B21H18N21. Among the studied anode materials for magnesium-ion batteries (MIBs), the highest Vcell value of 5.29 V was obtained for m-C40H18N2. Eads-2 has a significant effect on the variation of Vcell of LIBs, while Eads-1 has a significant effect on the variation of Vcell of MIBs.

Helical π‐Extended Terrylene Diimide Dimer Based on Ring‐Fused Ethylene Bridge for Organic Solar Cells

AbstractTerrylene diimides (TDIs), as the higher homologues of perylene diimide (PDI) in the series of rylene diimides (RDIs), exhibit several especial properties including enhanced absorption ability in the near infrared (NIR) region, higher fluorescence quantum yields as well as stronger π–π stacking in comparison to naphthalene diimides (NDIs) and perylene diimides (PDIs). However, TDIs have been largely overlooked in terms of their photovoltaic applications because of the chemical inaccessibility and poor solubility. In this contribution, a helical π‐extended terrylene diimide dimer based on ring‐fused ethylene bridge, namely FTDI2 is designed and synthesized. The photovoltaic performances of FTDI2 and the parent TDI are investigated using the commercially available PTB7‐Th as the electron donor. A significantly improved power‐conversion efficiency (PCE) of 5.11 % compared to that of TDI based ones (0.5 %) is achieved for FTDI2‐based device, demonstrating the potential of terrylene dyes in the photovoltaics field.

Photocatalytic water splitting for large-scale solar-to-chemical energy conversion and storage

Sunlight-driven water splitting allows renewable hydrogen to be produced from abundant and environmentally benign water. Large-scale societal implementation of this green fuel production technology within energy generation systems is essential for the establishment of sustainable future societies. Among various technologies, photocatalytic water splitting using particulate semiconductors has attracted increasing attention as a method to produce large amounts of green fuels at low cost. The key to making this technology practical is the development of photocatalysts capable of splitting water with high solar-to-fuel energy conversion efficiency. Furthermore, advances that enable the deployment of water-splitting photocatalysts over large areas are necessary, as is the ability to recover hydrogen safely and efficiently from the produced oxyhydrogen gas. This lead article describes the key discoveries and recent research trends in photosynthesis using particulate semiconductors and photocatalyst sheets for overall water splitting, via one-step excitation and two-step excitation (Z-scheme reactions), as well as for direct conversion of carbon dioxide into renewable fuels using water as an electron donor. We describe the latest advances in solar water-splitting and carbon dioxide reduction systems and pathways to improve their future performance, together with challenges and solutions in their practical application and scalability, including the fixation of particulate photocatalysts, hydrogen recovery, safety design of reactor systems, and approaches to separately generate hydrogen and oxygen from water.

Investigation of Nonmetal F‐doped Co3O4 as Catalyst for N2O Catalytic Decomposition

AbstractAn effective nonmetal F‐doped Co3O4 (F‐Co3O4) catalyst was prepared using co‐precipitation method, and its catalytic performance was investigated for N2O decomposition comparing with pure Co3O4 catalyst. The catalytic activity test indicates that F‐Co3O4 catalyst exhibits better activity with 100% N2O conversion at a reaction temperature of 380 °C, which is 80 °C lower than that of pure Co3O4. The characterization results show that F is successfully doped into the lattice of Co3O4 and replaces part of O sites, which enlarges the surface area, enhances the surface basicity, and leads to higher basic sites density on the surface of Co3O4. Moreover, F doping promotes the electron donation capacity of Co2+, weakening of Co─O bond and generation of more oxygen vacancies. The synergy of the above factors results in reduction of activation energy over F‐Co3O4 catalyst, thus F‐Co3O4 catalyst exhibits better catalytic performance than pure Co3O4 for N2O decomposition, even in the existence of O2 or H2O as impurity gas. Meanwhile, F‐Co3O4 catalyst also exhibits better stability than pure Co3O4. This work will provide practical reference for constructing efficient nonmetal‐doped Co3O4 catalysts for N2O decomposition.

Fe3O4@Fe2O3 carbon aerogel particle electrodes for three-dimensional electro-Fenton oxidation: A novel mechanism promoted by non-radical pathway

Three-dimensional electro-Fenton (3D-EF) has exhibited strengths over traditional electro-Fenton (EF) process for water decontamination, but recent researches on 3D-EF are focused on the decontamination mechanism driven by the radical pathway which was environmentally sensitive and poor in anti-interference capability. This study explored the non-radical mechanism in the 3D-EF process by preparing a novel Fe3O4@Fe2O3/carbon aerogel-700 (FFCA-700) particle electrode (PE) to construct a 3D-EF system promoted by non-radical pathway. The electrodes induced electric field spontaneously polarized FFCA-700 into PEs which led to higher active surface areas of electrodes and the enhancement of mass transfer. Numerous polarized FFCA-700 served as electron donor for dissolved O2 to obtain electron to form ·O2– while the increase in positive charge of the graphitized carbon, caused by the functional group containing electron-rich oxygen, was conducive for ·O2– to transform to 1O2 thus promoting the non-radical pathway. Tetracycline (TC) was selected as the model pollutant to evaluate and compare the remediation performance of different systems. The results suggested that FFCA-700-3D-EF system performed well for pollutant removal in real wastewater. Overall, this study provided a reference for the design and optimization of CPEs and the guidance for the mechanism studies on remediation of organically contaminated wastewater by 3D-EF process.

Polyol-Intermediated Facile Synthesis of B5-Site-Rich Ru-Based Nanocatalysts for COx-Free Hydrogen Production via Ammonia Decomposition.

Herein, a B5-site-rich Ru/MgAl2O4 nanocatalyst for the production of COx-free hydrogen from ammonia (NH3) is synthesized using the polyol method. The polyol method enables size-sensitive Ru-nanoparticle growth and controlled B5-site formation on the catalyst by tuning the carbon-chain length of the polyol solvent used, obviating the use of a separate stabilizer and enhancing electron donation from Ru (with a high surface electron density) and π-back bonding. The Ru/MgAl2O4 (BG) catalyst synthesized using butylene glycol (a long-carbon-chain solvent) contains 2.5nm Ru particles uniformly dispersed on its surface and abundant B5 sites at (0 0 2)/(0 1 1). Moreover, the Ru/MgAl2O4 (BG) catalyst exhibits lower activation energy (48.9kJmol-1) and higher H2 formation rate (565-1,236mmol gcat -1 h-1 at 350-450°C and a weight hourly space velocity of 30,000mL gcat -1 h-1) during the NH3 decomposition reaction than catalysts with a similar Ru particle size and high metal dispersion synthesized by the impregnation and deposition-precipitation methods. This high performance is possibly because the abundant electron-donating B5 sites on the catalyst surface accelerate the recombination-desorption of N2, which is the rate-determining step of the NH3 decomposition reaction at low temperatures. Thus, this study facilitates clean hydrogen production.

Silica-coated nano zero-valent iron as a slow-release electron donor for sustained enhancement of aerobic denitrification in oligotrophic source water: Performance and mechanism

Limited organic carbon in drinking water constrains the removal of nitrate‑nitrogen (NO3−-N) via aerobic denitrification. This paper reports the use of silica-coated nano zero-valent iron (nZVI@SiO2) as a stable and sustainable electron donor to enhance aerobic denitrification. The nZVI@SiO2, synthesized via a one-step method, was resistant to oxidation and exhibited excellent stability. In conjunction with aerobic denitrifying bacteria, nZVI@SiO2 achieved NO3−-N and total nitrogen TN removal efficiencies of 90.64 % and 80.94 %, respectively. This represents an increase of 24.15 % in the efficiency of TN removal compared with that of the nZVI system. The activity of the nZVI system diminished gradually after just three cycles, whereas nZVI@SiO2 maintained NO3−-N and TN removal efficiencies of 89.33 % and 78.08 %, respectively, after four cycles, respectively, indicating its sustainable ability to enhance aerobic denitrification. Cyclic voltammetry and electrochemical impedance spectroscopy demonstrated enhanced electron transfer efficiency of nZVI@SiO2. Furthermore, nZVI@SiO2 significantly promoted the activity of the electron transfer system, ATP levels, nitrate/nitrite reductase activity, contents of complexes I and III, and extracellular polymeric substances. nZVI@SiO2 significantly enhanced electron generation, transfer, and consumption during biological denitrification by functioning as both an electron donor and mediator. The findings implicate nZVI@SiO2 as a means to enhance nitrogen removal by aerobic denitrifying microorganisms in oligotrophic water via sustained donation of electrons.