Variable Valence Research Articles

Study on the mechanism of methane activation on Co-based catalysts with variable valence

Study on the mechanism of methane activation on Co-based catalysts with variable valence

Effect of variable valence elements Se on Ti and P sites of LATP solid electrolyte

The NASICON solid electrolyte Li1.3Al0.3Ti1.7(PO4)3 (LATP) has garnered significant attention owing to its low cost, excellent air stability, and high ionic conductivity. However, it exhibits low density and elevated grain boundary resistance due to suboptimal sintering performance. In order to improve the sintering performance and further increase the ionic conductivity, LATP solid electrolyte was synthesized by introducing Se4+ ion doping by solid phase method. The effects of different doping amounts of Se4+ ions on the structure and properties of solid electrolyte were systematically studied. It was observed that a low doping amount of Se4+ ion replaces Ti4+ ion which increases the crystal density and inhibits the formation of secondary phase LiTiPO5. While the doping amount is high, part of Se4+ ion transforms into Se6+ ion and replaces P5+ ion, causing lattice distortion and broadening the Li+ ion migration channel, but at the same time, it also promotes the precipitation of secondary phase LiTiPO5 and impedes the Li + transfer. The prepared sample with 2 wt% of SeO2 exbihits the total ionic conductivity of 0.41 mS/cm at room temperature and an improved bulk density of 2.93 g/cm3.

Pre-existing mobile Zn2+ ions in ZnZr4(PO4)6 for capacitive- and battery- type energy storage systems

Zinc-ion based energy storage systems with a pure intrinsic Zn2+ ion conductor, ZnZr4(PO4)6 (ZnZrP), and consisting of variable valence Zr sites, are fabricated for the first time. Zn2+ ions are loosely held within the voids of the Zr-phosphate framework enabling ionic conduction in the solid matrix. By combining with activated carbon (AC), the resulting ZnZrP-AC composite exhibits a high mixed ionic-electronic conductivity of 1.25 mS cm−1. Benefitting from the high conductivity, fast charge transfer and transport across the ZnZrP-AC cross-section are enabled through short diffusion pathways in the resulting hybrid supercapacitor (HSC) or Zn-ion battery (ZIB). The HSC (ZnZrP-AC/ZnCl2-γ-butyrolactone/Zn-AC) delivers a specific capacitance of 275F g−1, energy and power density maxima of 153 Wh kg−1 and 7.2 kW kg−1 and a cycling life of 10,000 cycles, with 87.2 % capacitance retention. In the ZIB configuration of ZnZrP-AC/Zn(CF3SO3)2-acetonitrile/Zn-AC, a capacity of 136 mAh/g (at 50 mA g−1), with capacity retention of 95 % after 100 cycles is achieved, with a mixed diffusive and surface-confined fast charge storage mechanism. The active materials remain largely intact after cycling confirming the durability of the cell architecture with potential for scale-up and practical applications.

Programmable Circular Multivalent Nanobody‐Targeting Chimeras (mNbTACs) for Multireceptor‐Mediated Protein Degradation and Targeted Drug Delivery

Multispecific therapeutics hold significant promise in drug delivery, protein degradation, and cell recruitment to address clinical issues of tumor heterogeneity, resistance, and immune evasion. However, their modular engineering remains challenging. We developed a targeted degradation platform, termed multivalent nanobody‐targeting chimeras (mNbTACs), by encoding diverse nanobody codons on a circular template using DNA printing technology. The homo‐ or hetero‐ mNbTACs specifically recognized membrane targets in a multivalent manner and simultaneously recruited scavenger receptors to favor clathrin‐/caveolae‐dependent endocytosis and lysosomal degradation of multiple proteins with high efficiency and selectivity. We demonstrated that a bispecific doxorubicin‐loaded mNbTAC, named Doxo‐mvNbsPPH, passively accumulated at tumor sites, specifically interacted with PD‐L1 and HER2 targets, and was rapidly transported into lysosome, inducing potent immunogenic cell death and alleviating immune checkpoint evasion. The synergistic boosting of innate and adaptive immunity promoted the infiltration and proliferation of CD8+ T cells in tumor microenvironment (an 11‐fold increase) with high toxicity and low exhaustion, eventually enhancing antitumor efficacy. Our mNbTAC platform provides multispecific therapeutics with variable valences and programmed species, whereas it induces targeted protein degradation through multireceptor‐mediated endocytosis and lysosomal degradation without the need for lysosome‐targeting receptors, representing a general and modular tool to harness extracellular proteome for disease treatment.

Programmable Circular Multivalent Nanobody-Targeting Chimeras (mNbTACs) for Multireceptor-Mediated Protein Degradation and Targeted Drug Delivery.

Multispecific therapeutics hold significant promise in drug delivery, protein degradation, and cell recruitment to address clinical issues of tumor heterogeneity, resistance, and immune evasion. However, their modular engineering remains challenging. We developed a targeted degradation platform, termed multivalent nanobody-targeting chimeras (mNbTACs), by encoding diverse nanobody codons on a circular template using DNA printing technology. The homo- or hetero- mNbTACs specifically recognized membrane targets in a multivalent manner and simultaneously recruited scavenger receptors to favor clathrin-/caveolae-dependent endocytosis and lysosomal degradation of multiple proteins with high efficiency and selectivity. We demonstrated that a bispecific doxorubicin-loaded mNbTAC, namedDoxo-mvNbsPPH, passively accumulated at tumor sites, specifically interacted with PD-L1and HER2targets, and was rapidly transported into lysosome, inducing potent immunogenic cell death and alleviating immune checkpoint evasion. The synergistic boosting of innate and adaptive immunity promoted the infiltration and proliferation of CD8+T cells in tumor microenvironment (an 11-fold increase) with high toxicity and low exhaustion, eventually enhancing antitumor efficacy. Our mNbTAC platform provides multispecific therapeutics with variable valences and programmed species, whereas it induces targeted protein degradation through multireceptor-mediated endocytosis and lysosomal degradation without the need for lysosome-targeting receptors, representing a general and modular tool to harness extracellular proteome for disease treatment.

Transition Metal (Molybdenum)-Doped Drug-like Conformational Nanoarchitectonics with Altered Valence States (Mn2+/Mn4+ and Mo5+/Mo6+) for Augmented Cancer Theranostics.

Despite the advancements in cancer therapy, delivering active pharmaceutical ingredients (APIs) using nanoparticles remains challenging due to the failed conveyance of the required drug payload, poor targeting ability, and poor biodistribution, hampering their clinical translation. Recently, the appropriate design of materials with intrinsic therapeutic functionalities has garnered enormous interest in the development of various intelligent therapeutic nanoplatforms. In this study, we demonstrate the fabrication of transition metal (molybdenum, Mo)-doped manganese dioxide (MnO2) nanoarchitectures, exhibiting diagnostic (magnetic resonance imaging, MRI) and therapeutic (chemodynamic therapy, CDT) functionalities. The facile hydrothermal approach-assisted Mo-doped MnO2 flower-like nanostructures offered tailorable morphologies in altered dimensions, precise therapeutic effects, exceptional biocompatibility, and biodegradability in the tumor microenvironment. The resultant defects due to doped Mo species exhibited peroxidase and oxidase activities, improving glutathione (GSH) oxidation. The two sets of variable valence metal ion pairs (Mn2+/Mn4+ and Mo5+/Mo6+) and their interplay could substantially improve the Fenton-like reaction and generate toxic hydroxyl radicals (•OH), thus achieving CDT-assisted antitumor effects. As inherent T1-MRI agents, these MnO2 nanoparticles displayed excellent MRI efficacy in vitro. Together, we believe that these conformational Mo-doped MnO2 nanoarchitectures with two pairs of variable valence states could potentiate drugless therapy in pharmaceutics.

Visible-light-response organic-inorganic hybrid CdS/MIL-101-NH2 S-scheme heterostructures for high-efficient photo-Fenton application

Developing artificial-photosynthesized heterostructures for solar energy conversion has inspired extensive interest, but the organic-inorganic hybrid Fe-based MOF photocatalyst is still in shortage. Here we report a visible-light response CdS/MIL-101-NH2 hybrid S-scheme heterostructure to exhibit efficient photocatalytic and photo-Fenton functionalities under the simulated solar-driven irradiation. In our work, the 0D CdS nanoparticles have in-situ anchored on the 3D NM101 octahedron to form well interface connection by a mild and simple co-precipitation method, which effectively promoted to shorten the carrier transfer distance as well as to promote charge separation. The whole photo-physics process has been revealed by systemically characterizations and the artificial-photosynthesized S-scheme heterostructure has been confirmed by the results of electrochemical measurements and density functional theory (DFT) calculations. By comparison, the as-prepared CdS/MIL-101-NH2 photocatalysts have more potential applications in Fenton-like advanced oxidation techniques considering their stability and element with variable valency, furthermore, the corresponding mechanism has been discussed. Our work extends the territory of organic-inorganic hybrid heterostructures and hopes to provide a new viewpoint for fabricating efficient artificial-photosynthesized photocatalysts.

Design and synthesis of high-entropy A2B2O7-type pyrochlore ceramics for the immobilization of molten salt radwastes

Pyrochlore-based high-entropy ceramics can encapsulate multiple elements with different valences, making them promising for immobilizing high-level radioactive nuclides in molten salt radwaste. This approach addresses key challenges in dry reprocessing and molten salt reactor waste management. In this study, a single-phase pyrochlore-based high-entropy ceramic is synthesized to incorporate NdF3 and CeF3 as simulated molten salt radwastes. Various synthesis components have been explored, and the ceramics were characterized using x-ray diffraction (XRD) and Raman spectroscopy. Comparative analysis revealed that the size disorder is the critical factor to synthesize single-phase pyrochlore-based high-entropy ceramics. The effects of elemental ratio and the presence of variable valence elements on the synthesis of single-phase pyrochlore-based high-entropy ceramics are elucidated through the concept of size disorder. Two single-phase pyrochlore compositions have been successfully synthesized: #HE4 (Nd2(Ti0.25Zr0.25Hf0.25Sn0.25)2O7) and #HECe0.1 (Nd2(Zr0.3Hf0.2Sn0.2Nb0.2Ce0.1)2O7). These samples were tested with a 7-day leaching experiment using the Product Consistency Test Method PCT-B. The normalized release rates of all elements in #HE4 ranged from 10-7 to 10-9 g·m-2·d-1, indicating excellent chemical durability. These findings suggest that medium- and high-entropy pyrochlore-based ceramics are effective for immobilizing radioactive nuclides in molten salt radwastes.

Synergistic removal of NO and CO in industrial waste gas by Fe-modified Cu/TiO2 catalysts: The synergistic effect of metal oxides interaction

NH3-based selective catalytic reduction (NH3-SCR) combined with carbon monoxide (CO) catalytic oxidation is a productive way to synergistically remove nitrogen oxides (NOx) and CO from industrial waste gas. Catalyst is the undoubtedly centerpiece of the synergistic removal technology, which has aroused tremendous attention. Herein, in this investigation a variety of Cu/TiO2 catalysts modified by various metal oxides were prepared by impregnation method, and the excellent synergistic removal performance of Fe-modified Cu/TiO2 catalyst was observed. The Cu/TiO2 catalyst with a 7 wt% Fe doping amount exhibited the highest NO and CO removal efficiency (86 % for NO at 300 °C and over 98 % for CO from 300 ∼ 400 °C). Through a series of characterization techniques, it was discovered that Cu and Fe oxides interacted to evenly distribute them throughout the surface of TiO2 support, resulting in smaller particle size and abundant variable valence species (Cu+/Cu2+ and Fe2+/Fe3+) to enhance the redox performance of the catalysts. Moreover, the creation of additional surface chemisorbed oxygen, the adsorption of NO and CO, and the improvement of surface acidity were all facilitated by the electron transfer between various Cu and Fe species. In addition, in-situ diffuse reflectance infrared transform spectroscopy (in situ DRIFTS) results revealed the interaction between NH3-SCR and CO oxidation. This study proposes a viable approach to develop efficient catalysts for the synergistic removal of NO and CO in industrial applications.

Nanostructured bi-metallic biochar: An innovative approach for arsenic (III) removal from contaminated water

Possessing variable valence states, the element Arsenic (As) is intimidating the quality of the ecology and human health severely. In this study, eliminating As (III) from water-based solutions with great efficiency was done using Bagasse-Mn-Al, a sugarcane bagasse-derived biochar impregnated with Mn and Al. The Bagasse-Mn-Al composite yielded higher removal efficiency towards As (III) than the biochar itself. About 89.53 % of As (III) was removed within 65 min maintaining the very first concentration of As (III) at 400 μg/L, initial pH at 2–2.5, and adsorbent dosage at 0.625 g/L. The Bagasse-Mn-Al composite showed an adsorption potential maximum of 54.945 mg/g which is superior to most of the cheaply synthesized metal-impregnated biochar reported. Results from a variety of characterization techniques indicated that the •OH free radical in the Bagasse-Mn-Al composite mainly contributed to the removal of As (III) where oxidation and complexation were the major mechanisms. With high catalytic efficiency, this cost effectively produced metal-coated biochar showed easy and effective separation of As (III) from aqueous solution. Further, this study focuses on the high potential of Bagasse-Mn-Al adsorbent in the treatment of both ground and wastewater.

Synergistic enhancement of electro-Fenton redox processes by iron-molybdenum dual sites for synchronous removal of Cr (VI) and emerging organic pollutants

Synergy removal of heavy metals and emerging organic pollutants (EOPs) poses a formidable challenge in heterogeneous electro-Fenton processes. Here, we present a three-dimensional iron-doped molybdenum disulfide hierarchical microsphere/graphite felt (Fe-MoS2 HS/GF) system. This system exhibits exceptional electrocatalytic redox activity, achieving a 9.75-fold and 18.96-fold increase in Cr (VI) (2.38 × 10-2 min−1) and BPA (8.29 × 10-2 min−1) removal rates compared to the MoS2 HS/GF system, respectively. And it also exhibited a significantly enhanced mineralization efficiency (59.28 %) for BPA, surpassing that of the MoS2/GF system (5.75 %) by a factor of 10.31. Mechanistic insights indicate that the Fe-Mo dual catalytic sites effectively lower reaction barriers of H2O2 dissociation, generating significant amounts of ·OHsurface and 1O2 species for BPA degradation. Moreover, an electric field-driven the variable valence state of the Fe-Mo dual sites facilitates Fe (II) regeneration and Cr (VI) reduction. Notably, this system shows broad applicability for synchronous removal of Cr (VI) and diverse EOPs, exhibiting robust stability under unsteady-state continuous-flow operation (2 L reactor) with reduced biotoxicity in actual wastewater. This study highlights the synergistic benefits of the dual catalytic sites in the heterogeneous electro-Fenton processes for treating multicomponent wastewater.

Defect Structure, Oxygen Ion Conduction, and Conducting Mechanism in Ruddlesden-Popper Sr3Zr2-xMxO7-0.5x (M = Ga, Y, In).

Ruddlesden-Popper (RP)-structured materials based on transition metals with a variable valence, such as Fe, Mn, Ni, and so on, have been well documented for their potential of being used as electrodes in solid-oxide fuel cells. However, RP materials with pure or dominant ionic conduction are rare. Here, a series of Zr-based RP materials Sr3Zr2-xMxO7-0.5x (M = Ga, Y, In) with electrical conductivity as high as 3.25 × 10-3 S cm-1 at 900 °C in air was reported, which represents the highest conductivity for the Zr-based RP materials and is comparable to that of the recently reported In-based RP oxide-ion conductors, such as NdBaInO4-based and La2BaIn2O7-based materials. Under low oxygen partial pressure (pO2), the doped samples show pure ionic conducting behaviors without n-type electronic conductivity. The defect formation energies, local structure around the oxygen vacancies, and oxide-ion-conducting mechanism of the acceptor-doped Sr3Zr2O7-based materials were studied for the first time. The results revealed a two-dimensional oxide ion migration characteristic within the perovskite slabs. This work therefore provides a good reference for developing new oxide-ion conductors in the Zr-based RP-structured materials.

Influence of variable valence metal oxides on physico-chemical and antibacterial properties of semi-coated glazes

The paper presents the results of studies on the production of semi-coated glazes with antibacterial activity by introducing variable valence oxides CeO2, WO3, Bi2O3, Fe2O3, MnO2 and MoO3 into their composition. The raw polycomponent compositions were comprised of aluminosilicate multi-calcium glass frit, dolomite powder, feldspar, alumina, quartz sand, wet-enriched kaolin and refractory clay. The coatings were obtained by single firing on a ceramic-based porcelain stoneware at a temperature of 1 200 ± 5 °C in a high-speed mode for 60 ± 2 minutes. The study focused on the processes of glaze formation of coatings and the influence of the components of glaze charges on decorative and aesthetic characteristics of coatings (color, texture, gloss and whiteness). Parameters of physical and chemical properties were determined in accordance with the existing specification for the products, i. e. temperature coefficient of linear expansion, heat resistance, chemical resistance, microhardness, frost resistance, wear resistance, etc. Antibacterial activity of the coatings towards Escherichia coli ATCC 8739 and Staphylococcus aureus ATCC 6538 test strains was studied.

Hierarchical nanostructure engineering endows ammonium vanadate as high capacity and ultra-long cycle cathode for wide-temperature aqueous zinc-ion batteries

Vanadium-based materials are the most promising cathode materials for Zinc-Ion batteries (ZIBs) due to their rich crystal structures and variable valence states. However, the structural collapse during multiple cycles leads to poor cycle life. Therefore, this work develops a 3-dimensional (3D) hierarchical nanostructure NH4V4O10 microspheres composed of nanosheets by a simple hydrothermal method, which are composed of nanosheets, this hierarchical nanostructure can promote the diffusion kinetics of Zn2+ and effectively mitigate the volume change of NH4V4O10 during the charging and discharging processes. As a result, the ZIBs assembled by the NH4V4O10 cathode exhibits high specific capacity of 522.9 mAh g−1 at 0.1 A g−1 and energy density of 348.96 Wh kg−1 at 215.12 W kg−1. At 20 A g−1, the NH4V4O10//Zn aqueous ZIB has 87.2 % capacity retention after 20,000 cycles. In addition, it exhibits excellent specific capacity and cycling performance over a wide-temperature range. At 10 A g−1, the NH4V4O10//Zn aqueous ZIB only loses 5.1 % capacity after 3500 cycles at −20 °C. Even at a high temperature of 50 °C, the capacity of NH4V4O10 battery is able to maintain 95.8 % after 450 cycles. This work informs the development of aqueous ZIBs for long cycle stability in a wide temperature range.

Biocompatible and capacitive PDA-Ov-Co3O4@CC anode augmented exoelectrogens enrichment and extracellular electron transfer in microbial fuel cells

Metal oxides rich in oxygen vacancies (Ov) possess excellent intrinsic conductivity, variable valence metal center and high capacitance, which were potential candidates as microbial fuel cells anode. However, their high bacterial toxicity greatly hindered the activity of biofilm. To solve this issue, in this work, polydopamine (PDA) covered capacitive Ov doped Co3O4 nanosheets were designed and successfully grown on carbon cloth (CC). The introduction of Ov significantly promoted the charge storage, the net charge and the accumulated charge were 217.1 and 2680.3 C/m2, respectively, surpassed Co3O4 anode without Ov. In addition, Ov also decreased the charge-transfer resistance (Rct), effectively accelerating EET. The Rct of PDA/Ov-Co3O4@CC was 29.51 Ω, lower than CC (382.10 Ω). The cover of PDA prevented the direct contact between metal ions and microorganisms, greatly enhanced the bacterial viability. The power density of MFCs with PDA/Ov-Co3O4@CC anode was 2.77 W/m2, 1.45 times higher than that of bare CC (1.90 W/m2). In addition, PDA/Ov-Co3O4@CC anode displayed excellent coulombic efficiency and daily COD removal amount (23.5 % and 147.6 mg/L/d), higher than the control groups. The community analysis showed the abundance of Geobacter on PDA/Ov-Co3O4@CC anode was 91 %, higher than other anodes. Present study developed a facile and effective PDA coating strategy to simultaneously enhance the biocompatibility and capacitance of Ov-rich metal oxides, which will be a promising method for the preparation of high performance MFCs anode.

Modulation of electron transfer behavior on Fe2P-Co2P/NPC oxygen electrocatalyst by lattice cation substitution engineering and charge transport network design for rechargeable Zn-air batteries

Crystal structure modulation engineering on the lattice scale and charge transport network design on the micro/nano scale work together to endow oxygen electrocatalysts with high reactivity to fully release the capacity of Zn-air batteries (ZABs) as the next-generation green energy storage devices. Metal phosphide-based oxygen reduction reaction (ORR)/oxygen evolution reaction (OER) electrocatalysts with tunable electronic structures, variable valence states, and moderate overpotentials are recognized as the most promising and ideal candidates for air cathodes. The cation substitution strategy overcomes the drawback that single metal phosphides with fewer active sites and high adsorption barriers are not sufficient to achieve satisfactory electrocatalytic performance. In this paper, the Fe2P-Co2P/NPC oxygen electrocatalyst employing lattice cation site substitution engineering and three-dimensional (3D) conductive network encapsulation strategies are constructed to successfully ensure fast electron transfer behavior and safe charge/discharge energy storage. Noteworthy, the presence of Schottky barriers at the interface of the two materials hinders the electron reflux, which promotes a unidirectional flow of electrons, and increases the electron condensation in the OER and ORR processes. Relying on these features, the Fe2P-Co2P/NPC-assembled liquid ZABs achieved power densities, specific capacities, and energy densities of 175.18 mW cm-2, 805.75 mAh gZn-1, and 958.84 Wh kg-1, respectively, and importantly good rate performances and stability were exhibited even under high-current-density operation. The corresponding flexible solid-state ZABs also possesses superior electrochemical activity and mechanical flexibility. This work paves the way for the construction of bifunctional oxygen electrocatalysts with high-speed electron transfer channels, thus advancing the development of wearable electronic devices.

Variable valence I3−/I− ionic bridge assisting CuI nanoparticle/BiOI nanosheet S-scheme photocatalyst with hydrophobic surface for boosting CO2 conversion with 100 % CO selectivity

The photocatalyst film, composed of tetragonal BiOI nanosheets and cubic phase CuI nanoparticles, was synthesized on the FTO substrate by a simple electro-deposition method. The orderly crisscrossed nanosheet structure caused exterior hydrophobic property, resisting the excess H2O molecules and further inhibiting the competitive H2O reduction process. The novel BiOI/CuI catalyst exhibited excellent photocatalytic ability of CO2 reduction into CO with 100 % selectivity in H2O vapor. Typically, the optimal 150BiOI/CuI photocatalyst exhibited CO yield of 7237.65 μmol/cm2 after 11 h of simulated sunlight illumination, achieving quantum efficiency of 2.5 % at 380 nm. The excellent performance of the BiOI/CuI composite film in photocatalytic CO2 reduction can be attributed to the construction of hydrophobic surface and S-scheme heterojunction with I3−/I− redox mediator, as confirmed by the in-situ XPS, hole injection test and cyclic voltammetry results. This study lays the groundwork for employing highly efficient iodide-based photocatalysts in gas-liquid-solid triphase catalytic systems.

Ru-Mn pair-site triggers key oxygen intermediate for enhanced acidic oxygen evolution reaction kinetics

Charge and spin regulation of electrons are identified as a vital factor in improving the oxygen evolution reaction (OER) catalytic activity. Nevertheless, the influence of surface reconstruction on charge and spin structure under complex catalytic reaction conditions has been unintentionally neglected. Correct understanding and targeted regulation of surface reconstruction are the key to prepare high active catalysts. Herein, variable valence states Mn is adopted to regulate Ru-NC, which serves as a model to reduce the localization of Ru 4d structure and stimulate facile charge transfer, achieving accelerated surface reconstruction to generate Ru-O active ingredient with high active to acidic water oxidation. Doping Mn not only accelerates surface reconstruction, but also improves durability by eliminating Ru peroxidation due to Mn-buffered charge compensation. The enhancement of OER activity results from the Mn and O induced Ru spin states to change from intermediate spin to low spin, thereby weakening the interaction with *O intermediates, and promoting *OH adsorption, which benefits the initial step of OER. This study not only provides a strategy to achieve directional reconstruction with the help of metal site asymmetry, but also provides a thorough comprehension of charge and spin dependent acidic OER kinetics.

Rationally Designed S-Scheme CeO2/g-C3N4 Heterojunction for Promoting Visible Light Driven CO2 Photoreduction into Syngas.

Exploring low-cost visible light photocatalysts for CO2 reduction to produce proportionally adjustable syngas is of great significance for meeting the needs of green chemical industry. A S-Scheme CeO2/g-C3N4 (CeO2/CN) heterojunction was constructed by using a simple two-step calcination method. During the photocatalytic CO2 reduction process, the CeO2/CN heterojunction can present a superior photocatalytic performance, and the obtained CO/H2 ratios in syngas can be regulated from 1 : 0.16 to 1 : 3.02. In addition, the CO and H2 production rate of the optimal CeO2/CN composite can reach 1169.56 and 429.12 μmol g-1 h-1, respectively. This superior photocatalytic performance is attributed to the unique S-Scheme photogenerated charge transfer mechanism between CeO2 and CN, which facilitates rapid charge separation and migration, while retaining the excellent redox capacity of both semiconductors. Particularly, the variable valence Ce3+/Ce4+ can act as electron mediator between CeO2 and CN, which can promote electron transfer and improve the catalytic performance. This work is expected to provide a new useful reference for the rational construction of high efficiency S-Scheme heterojunction photocatalyst, and improve the efficiency of photocatalytic reduction of CO2, promoting the photocatalytic reduction of CO2 into useful fuels.

In-situ interconnected 1D/2D/3D architectures of CNT/MoS2/Fe3O4 membranes for increasing degradation efficiency of penetrative electro-Fenton under low energy consumption

The electro-Fenton oxidation process for the degradation of organic pollutants in recalcitrant wastewater has garnered significant attention and research efforts in the field of advanced water treatment. This is primarily due to its highly effective degradation capabilities and the advantages it offers, including the avoidance of unsafe transportation and storage of hydrogen peroxide (H2O2). However, challenges such as relatively high energy consumption, complex operational requirements, and limited operational stability continue to pose significant economic constraints on the widespread application of electro-Fenton technology in water purification. In this study, we employed a secondary hydrothermal method to construct a multi-layered CNT/MoS2/Fe3O4 composite heterostructure in situ. Leveraging the synergistic effects of the introduced variable valence elements, Fe and Mo, and the interconnected multi-layered membrane structure, the CNT/MoS2/Fe3O4 electro-Fenton membrane holds promise in a permeable filtration system. Under the conditions of a current density of 1.50 mA/cm² and an electrolyte concentration of 0.50 mol/L, the CNT/MoS2/Fe3O4 composite membrane exhibited a degradation efficiency of over 90.00 % for 100.00 mg/L RhB within 10 minutes, and the degradation rate approached nearly 99.00 % at 60 minutes. Furthermore, the degradation efficiency for various recalcitrant organic dye wastewaters, including phenol, methyl orange, and methylene blue, could be maintained at levels ranging from 80.00 % to 97.00 %. Particularly, under optimized operating conditions, the specific energy consumption (EC) for the CNT/MoS2/Fe3O4 membrane process was measured at 0.60±0.01 kWh/m³, showcasing exceptionally low energy consumption characteristics. In conclusion, it is expected to contribute to the reduction of the overall consumption of heterogeneous electro-Fenton oxidation systems and enhance their operational efficiency. This innovative approach represents a significant advancement in the field, offering the potential to address the economic limitations associated with electro-Fenton technology in water quality purification.