Electron Mediator Research Articles

Near-infrared light-driven asymmetric photolytic reduction of ketone using inorganic-enzyme hybrid biocatalyst

Effective photolytic regeneration of the NAD(P)H cofactor in enzymatic reductions is an important and elusive goal in biocatalysis. It can, in principle, be achieved using a near-infrared light (NIR) driven artificial photosynthesis system employing H2O as the sacrificial reductant. To this end we utilized TiO2/reduced graphene quantum dots (r-GQDs), combined with a novel rhodium electron mediator, to continuously supply NADPH in situ for aldo-keto reductase (AKR) mediated asymmetric reductions under NIR irradiation. This upconversion system, in which the Ti-O-C bonds formed between r-GQDs and TiO2 enabled efficient interfacial charge transfer, was able to regenerate NADPH efficiently in 64 % yield in 105 min. Based on this, the pharmaceutical intermediate (R)-1-(3,5-bis(trifluoromethyl)phenyl)ethan-1-ol was obtained, in 84 % yield and 99.98 % ee, by reduction of the corresponding ketone. The photo-enzymatic system is recyclable with a polymeric electron mediator, which maintained 66 % of its original catalytic efficiency and excellent enantioselectivity (99.9 % ee) after 6 cycles.

Electrochemical detection of quinone reduced by Complex I Complex II and Complex III in full mitochondrial membranes

In the last decades enormous advances have been made in characterizing the atomic and molecular structure of respiratory chain supercomplexes [1]. However, it still remains a challenge to stitch this refined spatial atomistic description with functional information provided by biochemical studies of isolated protein material. Development of functional assays that detect respiratory chain complexes in their native membrane environment contribute to address the open questions related to the role played by their association and interactions. We present a characterization assay in which a functionalized gold electrode is modified with mitochondrial membrane fragments that allows monitoring electrochemically the activity of different respiratory chain complexes immersed in the mitochondrial membrane. We measure the intensity of the reducing current of the electron mediator CoQ1 at the electrode surface and its variation upon addition of the corresponding enzymatic substrates. The activities of Complex I, Complex II and Complex III were monitored by the way in which they reduce the current, reflecting the amount of quinone reduced by the complexes in the presence of their substrates. We detect that CoQ1H2 produced by Complex I remains partially trapped within the membrane and is more easily oxidized by Complex III or the electrode than the quinone reduced by Complex II.

Interface engineering of BiVO4/Zn3V2O8 heterocatalysts for escalating the synergism: Impact of Cu electron mediator for overall water splitting

The risk of global warming is increasing due to excessive consumption of fossil fuels. To fill the gap between production and consumption of conventional energy sources, modern societies are searching green and renewable alternatives. In this work, BiVO4/Zn3V2O8 heterocatalysts were synthesized and interfacially engineered for overall water splitting reactions. To obtain the structural and interfacial morphologies, catalysts were characterized by XRD, FTIR, Raman spectroscopy, SEM and AFM techniques. The optical and chemical characteristics of as-synthesized catalysts were evaluated using UV–Vis/DRS, PL, EIS, EDX, XPS and BET analysis. The role of Cu metal, synergism between BiVO4/Zn3V2O8 and mechanistic approaches were further revealed. The results depict that Cu metal exceptionally compete to sustain the synergism as an electron mediator source. The synergistic effect and electron mediator were found as key factors to boost the overall water splitting efficiencies. Due to interfacial engineering of BiVO4/Zn3V2O8 system, charge transfer becomes more feasible for the redox reactions (i.e. water splitting). It was examined that due to presence of Cu metal, rate of overall water splitting reaction was higher than the catalysts having no mediator (i.e. absence of Cu). During photoreaction, two successive rates for H2 and O2 evolution were speculated 17.66 and 8.96 mmol g−1 h−1, respectively which delivers approximately 5.04 kJ g−1 h−1 energy. On the basis of results and activities, it could be concluded that, this research will exhibit exceptional potential and hold promise of an ultimate transition to the water splitting and green energy technologies.

Graphene-decorated novel Z-scheme Bi@MOF composites promote high performance photocatalytic desulfurization

The Z-scheme photocatalyst constructed based on bismuth-based metal oxides (BMO) and metal–organic frameworks (MOF) holds significant potential for effectively degrading odorous Reduced Sulfur Compounds (RSC) due to its robust redox capabilities. However, challenges such as lattice mismatch, interface defects, and rapid recombination of photogenerated charges substantially impede the Z- scheme charge transfer in BMO@MOF photocatalysts. In this research, graphene was introduced into the BiVO4@NH2-UiO-66 system as an electron bridge and co-catalyst to reduce the interfacial transfer resistance and increase the absorption of near-infrared light, resulting in superior degradability of RSCs compared to both the individual components and BiVO4@NH2-UiO-66. The incorporated graphene not only serves as the growth substrate for BiVO4 and NH2-UiO-66 but also plays a crucial role as an electron mediator in enhancing the vectorial charge transfer from BiVO4 to NH2-UiO-66. This strengthens the Z-scheme charge transfer pathway, suppressing bulk charge recombination, increasing overall carrier density, and maintaining robust redox capabilities. Additionally, the investigation of active species and key intermediate products was conducted to explore potential degradation pathways of RSCs. This work demonstrates a novel approach in promoting photocatalytic degradation of RSCs by harnessing the synergistic effects between doping and heterogeneous structures within the photocatalyst.

Robust Oxidase-Mimetic Supramolecular Nanocatalyst for Lignin Biodegradation.

Enzymatic catalysis presents an eco-friendly, energy-efficient method for lignin degradation. However, challenges arise due to the inherent incompatibility between enzymes and native lignin. In this work, we introduce a supramolecular catalyst composed of fluorenyl-modified amino acids and Cu2+, designed based on the aromatic stacking of the fluorenyl group, which can operate in ionic liquid environments suitable for the dissolution of native lignin. Amino acids and halide anions of ionic liquids shape the copper site's coordination sphere, showcasing remarkable catechol oxidase-mimetic activity. The catalyst exhibits thermophilic property, and maintains oxidative activity up to 75 °C, which allows the catalyzed degradation of the as-dissolved native lignin with high efficiency even without assistance of the electron mediator. In contrast, at this condition, the native copper-dependent oxidase completely lost its activity. This catalyst with superior stability and activity offer promise for sustainable lignin valorization through biocatalytic routes compatible with ionic liquid pretreatment, addressing limitations in native enzymes for industrially relevant conditions.

Vis‐NIR Modulation in a Dynamically Reversible Single C‐pBPV Biopolymer Electrolyte for Sustainable Systems in Electrochromism

AbstractIn the pursuit of sustainable technology, the synthesis of a novel biopolymer, C‐pBPV, through the polymerization of carboxymethyl cellulose sodium salt (CMC‐Na) and viologen (BPV), with ammonium persulfate as an initiator is presented. This groundbreaking process not only promises an eco‐friendly approach but also opens avenues for advanced applications in electrochromic devices (ECDs), particularly in smart windows, displays, and beyond. Departing from conventional multi‐layered approaches, the study underscores the significance of a single‐layer material. C‐pBPV serves both as an electro‐chrome and an electrolyte, making it a compelling material for ECDs. It is used to create a gel‐based electrochromic device G1 with exceptional bistable properties. Following, a systematically controllable device, G2 is accomplished, to enhance color‐switching capabilities by adding vitamin C as an electron mediator. Both devices exhibited outstanding electrochromic properties, showcasing dual‐band absorption in the Vis‐NIR region, with color transitions from transparency to a striking purple state at low voltages. Embracing an all‐in‐one layer configuration, this study set the stage for next‐generation smart windows that not only regulate solar light for energy conservation but also pioneer a more compact, user‐friendly design, prioritizing visual comfort, sustainability, and a tailored user experience.

Accelerating Charge Kinetics in Photocatalytic CO2 Reduction by Modulating the Cobalt Coordination in Heterostructures of Cadmium Sulfide/Metal-Organic Layer.

Artificial photocatalytic CO2 reduction (CO2R) holds great promise to directly store solar energy into chemical bonds. The slow charge and mass transfer kinetics at the triphasic solid-liquid-gas interface calls for the rational design of heterogeneous photocatalysts concertedly boosting interfacial charge transfer, local CO2 concentration, and exposure of active sites. To meet these requirements, in this study heterostructures of CdS/MOL (MOL = metal-organic layer) furnishing different redox Co sites are fabricated for CO2R photocatalysts. It is found that the coordination environment of Co is key to photocatalytic activity. The best catalyst ensemble comprising ligand-chelated Co2+ with the bipyridine electron mediator demonstrates a high CO yield rate of 1523µmol h-1 gcat -1, selectivity of 95.8% and TON of 1462.4, which are ranked among the best seen in literature. Comprehensive photochemical and electroanalytical characterizations attribute the high CO2R performance to the improved photocarrier separation and charge kinetics originated from the proper energy band alignment and coordination chemistry. This work highlights the construction of 2D heterostructures and modulation of transition metal coordination to expedite the charge kinetics in photocatalytic CO2 reduction.

Pickering emulsion stabilized with charge separation and transfer modulated photocatalyst for enzyme-photo-coupled catalysis

Biocatalytic reduction is extensively employed in chemical and pharmaceutical industries due to its notable advantages including high activity, selectivity and mild reaction conditions, however, the stoichiometric use of the expensive NADH (reduced form of nicotinamide adenine dinucleotide) hinders its widespread application. Despite the persisting challenges of low charge separation efficiency and limited solubility of organic substrates in aqueous phase, in situ photocatalytic NADH regeneration remains a promising solution. Herein, we report the construction of an enzyme-photo-coupled catalytic system in Pickering emulsion droplet, which was stabilized by a charge separation and transfer modulated photocatalyst. The photocatalyst integrated with visible light driven conjugated polymer, TiO2 and electron mediator greatly enhanced the cascade electron transfer from photocatalyst to NAD+. Consequently, NADH production rate over the integrated photocatalyst reaches as high as 2.4 mmol·g−1·h−1 under visible light irradiation, 12 folds higher than the corresponding physical mixture. Furthermore, the enzyme-photo-coupled catalytic system was constructed with alcohol dehydrogenase/NAD+ confined in the emulsion droplet and photocatalyst assembled at the oil-water interface. The photoactive emulsion continuously catalyzed the n-butyaldehyde reduction to accumulate 16.1 mmol·L−1 butanol, equivalent to 14 cycles for NADH regeneration under visible light irradiation. The primary result demonstrates the potential application prospect of Pickering emulsion in enzyme-photo-coupled catalysis due to the facilitated charge transfer from photocatalyst to NAD+ and fast mass diffusion attributed to the large interfacial area of water and oil.

Fumarate respiration of Fasciola flukes as a potential drug target.

Fascioliasis is a neglected tropical zoonotic disease caused by liver flukes belonging to the genus Fasciola. The emergence of resistance to triclabendazole, the only World Health Organization-recommended drug for this disease, highlights the need for the development of new drugs. Helminths possess an anaerobic mitochondrial respiratory chain (fumarate respiration) which is considered a potential drug target. This study aimed to evaluate the occurrence of fumarate respiration in Fasciola flukes. We analyzed the properties of the respiratory chain of Fasciola flukes in both adults and newly excysted juveniles (NEJs). Fasciola flukes travel and mature through the stomach, bowel, and abdominal cavity to the liver, where oxygen levels gradually decline. High fumarate reductase activity was observed in the mitochondrial fraction of adult Fasciola flukes. Furthermore, rhodoquinone-10 (RQ10 Em'= -63 mV), a low-potential electron mediator used in fumarate respiration was found to be predominant in adults. In contrast, the activity of oxygen respiration was low in adults. Rotenone, atpenin A5, and ascochlorin, typical inhibitors of mitochondrial enzymes in complexes I, II, and III, respectively, inhibit the activity of each enzyme in the adult mitochondrial fraction. These inhibitors were then used for in vitro viability tests of NEJs. Under aerobic conditions, NEJs were killed by rotenone or ascochlorin, which inhibit aerobic respiration (complex I-III), whereas atpenin A5, which inhibits complex II involved in fumarate respiration, did not affect NEJs. Moreover, ubiquinone-10 (UQ10 Em'= +110 mV), which is used in oxidative respiration, was detected in NEJs, in addition to RQ10. In contrast, under anaerobic conditions, rotenone and atpenin A5, which inhibit fumarate respiration (complex I-II), were crucial for NEJs. These findings demonstrate that NEJs have active hybrid respiration, in which they can properly use both oxygen and fumarate respiration, depending on oxygen availability. Thus, fumarate respiration is a promising drug target for Fasciola flukes, because it plays an essential role in both adults and NEJs.

Low-interference and sensitive electrochemical detection of glucose and lactate using boron-doped diamond electrode and electron mediator menadione.

To minimize background interference in electrochemical enzymatic biosensors employing electron mediators, it is essential for the electrochemical oxidation of electroactive interfering species (ISs), such as ascorbic acid (AA), to proceed slowly, and for the redox reactions between electron mediators and ISs to occur at a low rate. In this study, we introduce a novel combination of a working electrode and an electron mediator that effectively mitigates interference effects. Compared to commonly used electrodes such as Au, glassy carbon, and indium tin oxide (ITO), boron-doped diamond (BDD) electrodes demonstrate significantly lower anodic current (i.e., lower background levels) in the presence of AA. Additionally, menadione (MD) exhibits notably slower reactivity with AA compared to other electron mediators such as Ru(NH3)63+, 4-amino-1-naphthol, and 1,4-naphthoquinone, primarily due to the lower formal potential of MD compared to AA. This synergistic combination of BDD electrode and MD is effectively applied in three biosensors: (i) glucose detection using electrochemical-enzymatic (EN) redox cycling, (ii) glucose detection using electrochemical-enzymatic-enzymatic (ENN) redox cycling, and (iii) lactate detection using ENN redox cycling. Our developed approach significantly outperforms the combination of ITO electrode and MD in minimizing IS interference. Glucose in artificial serum can be detected with detection limits of ~ 20μM and ~ 3μM in EN and ENN redox cycling, respectively. Furthermore, lactate in human serum can be detected with a detection limit of ~ 30μM. This study demonstrates sensitive glucose and lactate detection with minimal interference, eliminating the need for (bio)chemical agents to remove interfering species.

Carbon skeleton dispersed nano-jarosite for efficient Cr (Ⅵ) degradation: A bioinspired MFC cathode catalyst

Relevant advancements in microbial fuel cells (MFCs) are impeded by the limited oxygen reduction reactions at the cathode. The challenge prompted the development of a jarosite-biochar catalyst using a straightforward biomineralization method. Through X-ray diffraction (XRD) and scanning electron microscope (SEM) analysis, we observed a reduction in the agglomeration phenomenon of nano jarosite and a decrease in particle size. The biochar-jarosite MFC demonstrated a significant increase in voltage (682.5 mV) and a maximum power density of 1211 mW/m2. Electrochemical impedance spectroscopy (EIS) showed that the charge transfer resistance of the cathode decreased from 2580 Ω to 111 Ω, demonstrating excellent oxygen reduction reaction (ORR) performance. The jarosite-biochar significantly enhanced the MFC degradation of Cr (VI), exhibiting a 5.2-fold increase, while demonstrating exceptional stability. The X-ray photoelectron spectroscopy (XPS) of Fe and Cr on the surface of jarosite-biochar further substantiates the role of jarosite as an electron mediator between biochar and Cr (VI) in the MFC. Our study presents a cost-effective and efficient biomineralization strategy for the modification of cathode materials in MFCs, offering significant potential for enhancing the catalytic performance of iron-containing carbonaceous composites in Cr (VI) environments.

Efficient and stable visible-light-driven Z-scheme overall water splitting using an oxysulfide H2 evolution photocatalyst

So-called Z-scheme systems permit overall water splitting using narrow-bandgap photocatalysts. To boost the performance of such systems, it is necessary to enhance the intrinsic activities of the hydrogen evolution photocatalyst and oxygen evolution photocatalyst, promote electron transfer from the oxygen evolution photocatalyst to the hydrogen evolution photocatalyst, and suppress back reactions. The present work develop a high-performance oxysulfide photocatalyst, Sm2Ti2O5S2, as an hydrogen evolution photocatalyst for use in a Z-scheme overall water splitting system in combination with BiVO4 as the oxygen evolution photocatalyst and reduced graphene oxide as the solid-state electron mediator. After surface modifications of the photocatalysts to promote charge separation and redox reactions, this system is able to split water into hydrogen and oxygen for more than 100 hours with a solar-to-hydrogen energy conversion efficiency of 0.22%. In contrast to many existing photocatalytic systems, the water splitting activity of the present system is only minimally reduced by increasing the background pressure to 90 kPa. These results suggest characteristics suitable for applications under practical operating conditions.

Photo- and electrochemical properties of newly synthesized thioxathone-viologen-fluorene ternary compound and its electrochromic device

External stimuli-responsive materials exhibit widespread potential applications in sensors, smart windows, displays, and opto-electronic molecular devices. In this study, we report light-/electrochemically induced chromic behaviors of newly synthesized ternary compound in the device. This compound is composed of a light-harvesting unit of thioxathone (TX), an electron donor of fluorene (FL), and an electron mediator of viologen (VIO), and thus it can act as a photochromic species with an intramolecular electron transfer under irradiation. The precursors of TX and FL substituents give off broad emissions at approximately 437 and 310 − 330 nm, respectively. Both emissions are largely quenched in the TX-VIO-FL ternary compound, which is caused by an intramolecular transduction of energy from the excited singlet FL and TX to the electroactive VIO substituent. Based on cyclic voltammogram of TX-VIO-FL modified electrodes, two reversible waves are observed at around − 0.44 and − 0.89 V (vs Hg/Hg2Cl2), attributed to the electron transport processes of TX-VIO2+-FL ↔ TX-VIO+•-FL and TX-VIO+•-FL ↔ TX-VIO0-FL, respectively. Sandwiched type of photo-/electrochromic devices are constructed, displaying a good transmittance and reversible viologen color change behavior under irradiation or an applied bias of − 2.6 V.

Perchlorate decomposition on rhodium nanoclusters supported on copper crystallite (RhxCu) electrode in an electrodialysis-assisted bipolar electro-reduction system (ED-ER)

Perchlorate (ClO4−) contamination in the aquatic environments presents challenges for remediation due to its high solubility and chemical inertness. A bimetallic RhxCu/Ti was synthesized by incorporating rhodium (Rh) nanoclusters onto the copper crystallites on a titanium mesh substrate for electro-reduction of perchlorate ions. Characterization, which included voltammetry, Raman spectroscopy, and constant potential electrolysis, elucidated the reduction mechanism of perchlorate. A reversible phase transition of Rh(0)⇌ Rh(II) was found to be an effective electron mediator of adsorbed ClO4−, where the neighboring Cu sites were responsible for hydrogenation of chlorinated intermediates. The dispersity of Rh clusters was influenced by the Rh-to-Cu ratio, thereby enhancing the electrochemical reactivity. The bimetallic electrode with around 30 % Rh coverage, i.e., Rh0.3Cu/Ti, possessed superior removal and faradaic efficiency within a potential range of −0.6 V to −0.8 V (vs. Ag/AgCl, at pH 3), which were 95 % and 78 %, respectively. The electro-reduction (ER) and the associated electrodialysis (ED) divided using ion exchange membrane were demonstrated for the treatment of perchlorate wastewater. The electrical field applied by the ED unit drove the migration of ClO4− ions to the surfaces of Rh0.3Cu/Ti cathode, further improving the removal efficiency of perchlorate and lowering energy consumption.

Modification of an oxyhalide solid-solution photocatalyst with an efficient O2-evolving cocatalyst and electron mediator for two-step photoexcitation overall water splitting.

Two-step photoexcitation overall water splitting based on particulate photocatalysts represents a promising approach for low-cost solar hydrogen production. The performance of an O2-evolution photocatalyst and electron mediator between two photocatalysts crucially influences the construction of an efficient two-step excitation water-splitting system. Bismuth-tantalum oxyhalides are emerging photocatalysts for O2 evolution reactions and can be applied in two-step water-splitting systems. In this study, a highly crystalline Bi4TaO8Cl0.9Br0.1 solid solution with microplatelet morphology was synthesized by the dual flux method. The light absorption intensity and charge transfer efficiency of the Bi4TaO8Cl0.9Br0.1 solid solution were higher than those of Bi4TaO8Cl and Bi4TaO8Br; thus, the sacrificial O2 evolution activity of Bi4TaO8Cl0.9Br0.1 photocatalyst was obviously enhanced. The two-step excitation water splitting with a solid-state electron mediator was successfully constructed using Bi4TaO8Cl0.9Br0.1 as the O2-evolution photocatalyst and Ru/SrTiO3:Rh as the H2-evolution photocatalyst. The CoOx cocatalyst and reduced graphene oxide decorations on the surface of Bi4TaO8Cl0.9Br0.1 promoted the catalytic O2 generation process on Bi4TaO8Cl0.9Br0.1 and electron transfer between CoOx/Bi4TaO8Cl0.9Br0.1 and Ru/SrTiO3:Rh photocatalysts, respectively. As a result, the apparent quantum yield for this overall water-splitting system was 1.26% at 420 nm, which surpassed the present performance of the two-step excitation water-splitting systems consisting of metal oxyhalide photocatalysts. This study demonstrates the validity of high-quality solid-solution photocatalysts with suitable surface modification for efficient solar hydrogen production from water splitting.

Water-soluble fullerenol-mediated electron transfer in molecular systems toward enhanced solar hydrogen production.

We present here that visible-light-induced electron transfer from an excited dye to an in situ generated Pt cocatalyst can be promoted by employing water-soluble fullerenol (C60(OH)24) as an electron mediator, and as a result, the fullerenol-based molecular system shows a 3 times higher H2 evolution activity than C60(OH)24-free system.

Low electric current in a bioelectrochemical system facilitates ethanol production from CO using CO-enriched mixed culture.

Fossil resources must be replaced by renewable resources in production systems to mitigate green-house gas emissions and combat climate change. Electro-fermentation utilizes a bioelectrochemical system (BES) to valorize industrial and municipal waste. Current electro-fermentation research is mainly focused on microbial electrosynthesis using CO2 for producing commodity chemicals and replacing petroleum-based infrastructures. However, slow production rates and low titers of metabolites during CO2-based microbial electrosynthesis impede its implementation to the real application in the near future. On the other hand, CO is a highly reactive gas and an abundant feedstock discharged from fossil fuel-based industry. Here, we investigated CO and CO2 electro-fermentation, using a CO-enriched culture. Fresh cow fecal waste was enriched under an atmosphere of 50% CO and 20% CO2 in N2 using serial cultivation. The CO-enriched culture was dominated by Clostridium autoethanogenum (≥89%) and showed electro-activity in a BES reactor with CO2 sparging. When 50% CO was included in the 20% CO2 gas with 10 mA applied current, acetate and ethanol were produced up to 12.9 ± 2.7 mM and 2.7 ± 1.1 mM, respectively. The coulombic efficiency was estimated to 148% ± 8% without an electron mediator. At 25 mA, the culture showed faster initial growth and acetate production but no ethanol production, and only at 86% ± 4% coulombic efficiency. The maximum optical density (OD) of 10 mA and 25 mA reactors were 0.29 ± 0.07 and 0.41 ± 0.03, respectively, whereas it was 0.77 ± 0.19 without electric current. These results show that CO electro-fermentation at low current can be an alternative way of valorizing industrial waste gas using a bioelectrochemical system.

A high-performance lignin flow fuel cell based on self-generating electricity of lignin at low temperature via a privileged structure and redox chemistry

A lignin flow fuel cell is developed which can self-generate electricity via the privileged structure and redox chemistry of lignin without electron mediators and pre-reaction. It achieves high power density and long-term stability at room temperature.

Augmented photocatalysis induced by 1T-MoS2 bridged 2D/2D MgIn2S4@1T/2H-MoS2 Z-scheme heterojunction: mechanistic insights into H2O2 and H2 evolution.

In the realm of composite photocatalysts, the fusion of the co-catalyst effect with interfacial engineering is recognized as a potent strategy for facilitating the segregation and migration of photo-induced charge carriers. Herein, an innovative mediator-based Z-scheme hybrid, i.e. MIS@1T/2H-MoS2, has been well designed by pairing MIS with 1T/2H-MoS2via a facile hydrothermal strategy as a competent photocatalyst for H2O2 and H2 generation. The co-catalyst, i.e. metallic 1T-phase bridging between semiconducting 2H-MoS2 and MIS, serves as a solid state electron mediator in the heterostructure. Morphological findings revealed the growth of 1T/2H-MoS2 nanoflowers over MIS microflowers, verifying the close interaction between MIS and 1T/2H-MoS2. By virtue of accelerated e-/h+ pair separation and migration efficiency along with a proliferated density of active sites, the MMoS2-30 photocatalyst yields an optimum H2O2 of 35 μmol h-1 and H2 of 370 μmol h-1 (ACE of 5.9%), which is 3 and 2.7 fold higher than pristine MIS. This obvious enhancement can be attributed to photoluminescence and electrochemical aspects that substantiate the diminished charge transfer resistance along with improved charge carrier separation, representing a good example of a noble metal-free photocatalyst. The proposed Z-scheme charge transfer mechanism is aided by time-resolved photoluminescence (TRPL), XPS, radical trapping experiments, and EPR analysis. Overall, this endeavour provides advanced insights into the architecture of noble metal-free Z-scheme heterostructures, offering promising prospects in photocatalytic applications.

Effects of humic electron mediators on reductive dechlorination of polychlorinated biphenyl by consortia enriched from terrestrial and marine environments.

Humic electron mediators can facilitate the reductive dehalogenation of organohalogenated compounds by accelerating electron transfer. To investigate the effect of humic electron mediators on the microbial anaerobic reductive dechlorination of Polychlorinated biphenyls (PCBs), three types of humic electron mediators, humin (HM), humic acid (HA), and anthraquinone-2,6-disulfonic acid (AQDS, HA analogs), were added to PCB dechlorination cultures enriched from different sources in terrestrial and marine environments (T and M cultures). The results showed that meta- and para-site dechlorination occurred in the M culture, while only meta-site dechlorination occurred in the T culture. The dechlorination process N and the dechlorination process H or H' are presented in both cultures. HM enhanced PCB dechlorination metabolic activity in both cultures mainly by promoting meta-site dechlorination. HA showed a weak promoting effect on the M culture by promoting para-chlorine removal but inhibited the dechlorination metabolism of the terrestrial-origin culture, inhibiting meta-chlorine removal. AQDS showed inhibitory effects on both cultures by inhibiting the microbial removal of meta-chlorine. High-throughput sequencing and qPCR results suggest that HM is not a carbon source for the potential dechlorinating metabolism of Dehalococcoides but may promote reductive dechlorination by changing the community structure, and AQDS may inhibit anaerobic reductive dechlorination of PCBs by inhibiting the growth of Dehalococcoides. This study provides insights into the mechanism of enhancing PCB microbial dechlorination mediated by humic substances and plays a significant role in extending the application prospects of PCBs bioremediation technology.