Ultrafast Reduction Research Articles

Construction of durable antibacterial cellulose textiles through grafting dynamic disulfide-containing amino-compound and nanosilver deposition

Cotton textile is very comfortable to wear, and also provides an ideal environment for bacterial propagation, easily causing harm to human health. In order to address this issue, various antibacterial techniques are employed for cotton finishing. However, some processes are complex and involve the use of environmentally unfriendly chemicals. In this work, a durable and efficient antibacterial cotton fabric was prepared via grafting of an amino-compound containing dynamic disulfide bonds, and then in-situ deposition of silver nanoparticles (AgNPs). Briefly, the reactive α-lipoic acid-modified polyethyleneimine (mPEI) was introduced to the cotton fibers via thiol-ene click reaction. Subsequently, the amino groups and dynamically-generated sulfhydryl groups in the mPEI molecules were used to initiate the ultrafast reduction of silver ions without the participation of additional reductant, constructing a stable antibacterial layer on fiber surface. The results reveal that the amino and thiol groups of mPEI could form coordination bonds with the deposited silver nanoparticles, and the antibacterial ability of AgNP@cotton-g-mPEI fabric remains at a high level even after 20 washing cycles. After 30 min of contact with Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), the antibacterial rates against both bacteria reached 99.99 %. Meanwhile, the network matrix constructed by the recombination of the dynamic disulfide bonds in mPEI endows the cotton fabric with detectable wrinkle resistance and encouraging anti-ultraviolet effect. The present work provides a novel alternative for preparation of durable and efficient antibacterial textiles.

Precise redox strategy to fabricate CuO/Cu2O hetero-electrodes for ultrafast electrochemical nitrate reduction into valuable ammonia resources

Electrochemical reduction of nitrate is a highly promising method for removing nitrate from water bodies. However, slow reaction rates have been a major challenge in its practical application. In this study, a novel CuO/Cu2O@CC hetero-electrode was developed by using a precise redox strategy, where CuO and Cu2O were simultaneously introduced to provide catalytic active sites for the reduction of nitrate into ammonia. This compositing design could significantly enlarge the electrochemically active surface area, reduce the electron transfer resistance and increase hydroxyl oxygen content on the electrode surface. The effect of operating parameters (cathodic potential, initial pH, supporting electrolyte concentration, initial NO3–−N concentration and coexisting Cl– concentration) on nitrate reduction was studied to optimize the reduction efficiency. Under −1.4 V (vs. Ag/AgCl) cathodic potentials and initial pH = 7 parameters, CuO/Cu2O@CC 3 achieved a remarkable 92.9% removal of 100 mg L–1 initial nitrate and a high ammonia selectivity of 78.33% in 1 h using 0.5 mol L–1 K2SO4 as supporting electrolyte, with a pseudo-first-order kinetic constant of 2.5856 h–1. Additionally, based on the experimental results, a reaction mechanism for the heterostructures electrode was proposed. The successful construction of CuO/Cu2O hetero-electrode provides a unique insight into the electrochemical reduction of nitrate.

Quantifying the ultrafast and steady-state molecular reduction potential of a plasmonic photocatalyst.

Plasmonic materials are promising photocatalysts as they are well suited to convert light into hot carriers and heat. Hot electron transfer is suggested as the driving force in many plasmon-driven reactions. However, to date, there are no direct molecular measures of the rate and yield of plasmon-to-molecule electron transfer or energy of these electrons on the timescale of plasmon decay. Here, we use ultrafast and spectroelectrochemical surface-enhanced Raman spectroscopy to quantify electron transfer from a plasmonic substrate to adsorbed methyl viologen molecules. We observe a reduction yield of 2.4 to 3.5% on the picosecond timescale, with plasmon-induced potentials ranging from [Formula: see text]3.1 to [Formula: see text]4.5 mV. Excitingly, some of these reduced species are stabilized and persist for tens of minutes. This work provides concrete metrics toward optimizing material-molecule interactions for efficient plasmon-driven photocatalysis.

Ultrafast photoinduced conductivity reduction by bonding orbital control in an incommensurate crystal

Ultrafast photoinduced conductivity reduction by bonding orbital control in an incommensurate crystal

Coeffect of Co-Mn in bimetallic oxide catalyst for ultrafast electrochemical reduction of nitrate: Insight into ion interaction

Co3O4 has been considered as promising catalysts for electroreduction of nitrate (ERN), which is an emerging tactic to close the nitrogen cycle on earth. However, the nitrate reduction efficiency of Co3O4 is less than satisfactory, which could be enhanced by assistance of Mn element. Herein, we synthesized Co3O4, Mn2O3 and Mn1.5Co1.5O4 nanoparticles for electrodes via a simple sol–gel method using metal nitrates. Moreover, a special electrode 3-Mn/Co was fabricated by physical mixed Co3O4 and Mn2O3. Mn1.5Co1.5O4 and 3-Mn/Co electrodes presented 78.6 % and 64.09 % nitrate removal efficiency after 3 h, 115.46 % and 75.68 % higher than that of Co3O4, proving the existence of Co-Mn coeffect. The optimum Mn1.5Co1.5O4 endures operating parameters experiments of applied potential, level of NO3– concentration, pH value and Cl- concentration and maintains solid stability through ten batches of reaction. Eventually, the ion valence changes of electrodes before and after electrocatalysis verifies that both Co and Mn function in the reaction. The ERN performance variation between electrodes, doped and physically mixed with Mn, and Co3O4 further elucidates that Mn3+ takes major effect in ERN process, while Mn4+ would blocks the electrons transferred to NO3–. In general, a novel process of Co3+/Mn3+- Co2+/Mn4+ reaction cycle in Co and Mn bimetallic and monometallic oxides for ERN performance is proposed as a clue for electrode fabrication.

Rational design of zero-valence and well-dispersed copper nanocluster stabilized by carbon-coated SiO2 for highly effective and ultrafast reduction of nitroarenes

In this work, we present a ligand modification strategy that allows for the regulation of the valence and dispersion state of Cu clusters in the final obtained Cu@C/SiO2 catalyst. Specifically, the phthalic acid (PA) ligand promotes the uniform anchoring of zero-valence Cu nanoclusters on Cu@C/SiO2, resulting in excellent catalytic activity in the selective reduction of toxic 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) with a rate constant (k) of 19.06×10-3 s-1. This value was approximately 2.4- and 31.2-fold higher than that of the CuO/SiO2 and bare CuO catalysts, respectively. Additionally, no significant decline in activity was detected during six successful cycles. Through systematic analysis of structural and electronic properties of the catalyst, we confirmed that the coordination effect of the PA ligand and the carbothermic effect of its carbon derivatives effectively prevent particle aggregation and modulate the valence state of copper species in Cu@C/SiO2, resulting in superior catalytic performance.

Organics Recovery from Waste Activated Sludge In-Situ Driving Efficient Nitrogen Removal from Mature Landfill Leachate: An Innovative Biotechnology with Energy Superiority

The sustainable recovery and utilization of sludge bioenergy within a circular economy context has drawn increasing attention, but there is currently a shortage of reliable technology. This study presents an innovative biotechnology based on free nitrous acid (FNA) to realize sustainable organics recovery from waste activated sludge (WAS) in-situ, driving efficient nitrogen removal from ammonia rich mature landfill leachate by integrating partial nitrification, fermentation, and denitrification process (PN/DN–F/DN). First, ammonia ((1708.5 ± 142.9) mg·L−1) in mature landfill leachate is oxidized to nitrite in the aerobic stage of a partial nitrification coupling denitrification (PN/DN) sequencing batch reactor (SBR), with nitrite accumulation ratio of 95.4% ± 2.5%. Then, intermediate effluent (NO2−–N = (1196.9 ± 184.2) mg·L−1) of the PN/DN-SBR, along with concentrated WAS (volatile solids (VSs) = (15 119.8 ± 2484.2) mg·L−1), is fed into an anoxic reactor for fermentation coupling denitrification process (F/DN). FNA, the protonated form of nitrite, degrades organics in the WAS to the soluble fraction by the biocidal effect, and the released organics are utilized by denitrifiers to drive NOx− reduction. An ultra-fast sludge reduction rate of 4.89 kg·m−3·d−1 and nitrogen removal rate of 0.46 kg·m−3·d−1 were realized in the process. Finally, F/DN-SBR effluent containing organics is refluxed to PN/DN-SBR for secondary denitrification in the post anoxic stage. After 175 d operation, an average of 19 350.6 mg chemical oxygen demand organics were recovered per operational cycle, with 95.2% nitrogen removal and 53.4% sludge reduction. PN/DN–F/DN is of great significance for promoting a paradigm transformation from energy consumption to energy neutral, specifically, the total benefit in equivalent terms of energy was 291.8 kW·h·t−1 total solid.

Sulfonic Acid Functionalization-Boosted Ultrafast, Durable, and Selective Four-Electron Oxygen Reduction Reaction: Evidenced by EC-SHINERS and DFT Studies

Sulfonic Acid Functionalization-Boosted Ultrafast, Durable, and Selective Four-Electron Oxygen Reduction Reaction: Evidenced by EC-SHINERS and DFT Studies

In situ formation of gold nanoparticles@supramolecular hydrogels with ultra-fast catalytic reduction of dyes and excellent anti-bacterial properties

2-QY-Au NPs@metallohydrogel could catalyze and degrade a variety of organic dyes with an excellent catalytic activity and presented good biocompatibility and antibacterial activity.

Porous carbon-encapsulated CuxO/Cu catalyst derived from N-coordinated MOF for ultrafast 4-nitrophenol reduction in batch and continuous flow reactors

The preparation of reactors with high performance noble metal-free catalysts as the core is important research in catalytic hydrogenation. Herein, a novel multi-crystalline nitrogen-doped porous carbon-encapsulated CuxO/Cu Catalyst (CuxO/Cu/NC) was successfully synthesized by simple pyrolysis of N-coordinated metal organic frameworks (Cu2(BDC)2(DABCO)) and applied to construct a continuous flow reactor. The effects of N-coordination doping in MOF precursors on morphology, size and oxidation states of Cu species in the derived catalysts were systematically investigated by comparing with Cu/C (from Cu(BDC)) and Cu/NC (from Cu(BDC-NH2)). The significantly increased LUMO energy calculated by density functional theory (DFT) revealed that the introduction of coordination nitrogen-doped MOF precursor was beneficial to inhibit Cu2+ reduction during the calcination process and promote the formation of a carbon-supported multi-crystalline CuxO/Cu structure with rich defect sites and small size (13 nm). An enhanced catalytic activity was obtained for 4-nitrophenol (4-NP) reduction with the rate constant (k) of 0.1507 s−1, outperforming Cu/NC and Cu/C catalysts (5–11 folds), even many reported catalysts (1.2–95 folds). Ultrafast degradation of 4-NP was completed within 25 s. In addition, an online continuous flow reactor-high performance liquid chromatography system was also constructed, realizing real-time and automatic monitoring of the degradation reaction. It can remove 98.4 % of 4-NP within 50 s and maintain exceed 97 % degradation rate for 12 h. Highly dispersed catalyst, synergistic effect of copper species and the accelerated mass transfer endow the packed-bed reactor with superior activity and durability, it is expected to offer a great opportunity for contaminants reduction in water treatment.

PtO Nanoparticles Decorated on Mesoporous Cobalt Selenite Networks as a Novel Photocatalyst for Ultrafast Reduction of Cr(VI)

It is a troublesome and urgent issue to design novel photocatalysts for Cr(VI) reduction in wastewater with highly photoactive under visible exposure. A novel mesoporous PtO/CoSeO3 photocatalyst was constructed through a sol-gel procedure by incorporating the non-ionic surfactant F108 for photoreduction of Cr(VI). TEM and XRD data of the synthesized CoSeO3 nanoparticles are quite uniform in size and the monoclinic crystal shape, with particle size of 10 nm. The optimized 1.2%PtO/CoSeO3 photocatalyst exhibited almost 100% reduction efficiency within 30 min, and the apparent rate constant was found at about 0.0803 min−1, which was fostered 3.5 folds greater than the bare CoSeO3. The enhanced photocatalytic ability of PtO/CoSeO3 photocatalyst was ascribed to their fostered separation efficiency of carriers and promoted the absorption of visible light than bare CoSeO3. The photoelectrochemical and photoluminescent responses indicated that the obtained PtO/CoSeO3 inhibited the recombination of carriers, thus promoting the Cr(VI) photoreduction. The present work highlights new insights over PtO/CoSeO3 photocatalysts for the Cr(VI) photoreduction under visible illumination.

Ultrafast metal oxide reduction at Pd/PdO2 interface enables one-second hydrogen gas detection under ambient conditions

Ultrafast metal oxide reduction at Pd/PdO2 interface enables one-second hydrogen gas detection under ambient conditions

Preparation of core/shell-structured ZnFe2O4@ZnIn2S4 catalysts and its ultrafast microwave catalytic reduction performance for aqueous Cr(VI)

Irresponsible discharge of hexavalent chromium (Cr(VI)) containing industrial wastewater is a serious environmental issue, and a great risk to human health. In this work, a novel class of microwave (MW) responsive core/shell-structured ZnFe2O4@ZnIn2S4 (ZFO@ZIS) catalysts were prepared for aqueous Cr(VI) reduction. These catalysts exhibited “unexpectedly” high MW catalytic activity. The one with the ZFO:ZIS molar ratio = 1:3 led to 100 % Cr(VI) reduction within 15 min in a solution with the Cr(VI) concentration as high as 100 mg/L, which is superior to in the cases of using other photocatalysts previously reported. More significantly, the ZFO@ZIS catalysts exhibited an excellent Cr(VI) reduction ability even at a pH value as high as 6, close to that of industrial wastewater, demonstrating additionally their great feasibility. The excellent MW catalytic activity of the composite catalysts can be attributed to the MW induced “hot spots” effect. The MW responsive ZFO@ZIS core/shell-structured catalysts developed in this work can be a promising candidate for high efficiency catalytic reduction of Cr(VI) in wastewater.

Construction of novel Cu-based bimetal polycrystal@carbon catalyst prepared from bimetal HKUST-1 type MOFs (MOF-199s) for ultrafast reduction of 4-nitrophenol via interfacial synergistic catalysis

The novel Cu-based bimetal polycrystal@carbon (C-HK(Cu/M)) composites derived from metal (Ni, Zn and Co) in-situ substituted Cu-based HKUST-1 were successfully fabricated by partial reduction strategy and employed for the reduction of 4-nitrophenol (4-NP). Systematic characterization demonstrated that Ni showed stronger orbital hybridization with Cu than Zn and Co, thereby significantly improving the catalytic properties of the C-HK(Cu/Ni) composite. The presence of Ni in HKUST-1 efficiently inhibited the reduction of adjacent Cu clusters, leading to the generation of unique polycrystal NiO/Cu/CuO nanohybrids (2.4–8.0 nm) with high dispersion (Cu exposure reaching 88.5%). While, the MOF ligands were catalyzed by doping Ni into the conductive and porous carbons, and finally engineered interfacial synergistic catalysis for enhancing the kinetics and stability for the reduction of 4-NP. The porous support accelerated 4-NP diffusion and adsorption in the composite, and as a consequence, the surrounding polycrystal nanohybrids on conductive carbon were responsible for producing hydrogen reducing species for 4-NP reduction. Therefore, C-HK(Cu/Ni) exhibited ultrafast kinetics and turnover frequency (TOF) for 4-NP reduction, which were up to 179 and 14 times higher than parent C-HK(Cu), surpassing the current state-of-the-art noble metal catalysts. Moreover, the activity of C-HK(Cu/Ni) was evaluated for six consecutive runs with minimal loss, demonstrating the high reusability and practicability of the catalyst on an industrial scale.

Role of Lewis Acid Metal Centers in Metal–Organic Frameworks for Ultrafast Reduction of 4-Nitrophenol

Metal–Organic Frameworks (MOFs) can be a good alternative to conventional catalysts because they are non-toxic and can be selective without compromising efficiency. Nano MOFs such as UiO-66 have proven themselves to be competitive in the catalytic family. In this study, we report the excellent catalytic behavior of UiO-66 MOF in the reduction of a model reaction: 4-Nitrophenol (4-NP) to 4-Aminophenol (4-AP) over MOF-5 (Zn-BDC) and MIL-101 (Fe-BDC). Nano UiO-66 crystals were synthesized by a hydrothermal process and characterized by Powder X-ray Diffraction, Diffused Reflectance UV-Vis spectroscopy, Scanning Electron Microscopy, and Transmission Electron Microscopy. The catalysts’ performance during the hydrogenation reduction reaction from 4-NP to 4-AP was investigated in the presence of a reducer, NaBH4. The UiO-66 nano crystals exhibited excellent catalytic behavior owing to its large surface area and Lewis acidic nature at the metal nodes. Furthermore, UiO-66 showed excellent recyclability behavior, verified during repeated consecutive use in a sequence. The catalyst yielded similar catalytic behavior during the reduction of nitrophenols at each cycle, which is a novel finding.

Noble metal nanoparticles (Mx = Ag, Au, Pd) decorated graphitic carbon nitride nanosheets for ultrafast catalytic reduction of anthropogenic pollutant, 4-nitrophenol

We report an effective facile immobilization of noble nanoparticles (Mx = Ag, Au and Pd) assembled on g-C3N4 (g-CN) prepared via a simple ultra-sonication strategy. The Mx assembled g-CN nanocomposites were applied for the effective conversion of 4-nitrophenol (4-NP). As prepared nanocomposites were characterized by techniques of XRD, SEM-EDS, TEM, XPS, and FT-IR analysis to gain crystallographic structural, and morphological insights. The Pd@g-C3N4 (Pd@g-CN) nanocomposite exhibited best catalytic performance (kapp = 1.141 min−1) toward the conversion of 4-NP to 4-aminophenol (4-AP), almost 100% within 4 min using aqueous sodium borohydride (NaBH4). The higher catalytic efficiency of Pd@g-CN could be attributed to the surface electron density on the Pd and rapid electron transfer capacity. Interestingly, g-CN not only role as a stabilizer but also provided compatibility for noble metal deposition, which improves the chemical and morphological stability of noble metal nanoparticles. Different reaction parameters including concentrations of 4-NP, and catalyst amount were studied. These unique combinations make noble metal nanoparticles anchored g-CN nanosheets an ideal platform for catalysis applications and environmental remediation.

Surface chemistry and porosity engineering through etching reveal ultrafast oxygen reduction kinetics below 400 °C in B-site exposed (La,Sr)(Co,Fe)O3 thin-films

Oxides are critical materials for energy devices like solid oxide cells, catalysts, and membranes. Their performance is often limited by their catalytic activity at reduced temperatures. In this work, a simple etching process with acetic acid at room temperature was used to investigate how oxygen exchange is influenced by surface chemistry and mesoporous structuring in single-crystalline epitaxial (La0.60Sr0.40)0.95(Co0.20Fe0.80)O3. Using low energy ion scattering and electrical measurements, it is shown that increasing the B-site transition metal cation surface exposure (most notably with Fe) leads to strongly reduced activation energy from Ea ≈ 1 eV to Ea ≈ 0.4 eV for oxygen exchange and an order of magnitude increased oxygen exchange kinetics below 400 °C. Increasing the active area by ∼200% via mesoporous structuring leads to increased oxygen reduction rates by the same percentage. Density functional calculations indicate that a B-site exposed surface with high oxygen vacancy concentration can explain the experimental results. The work opens a pathway to tune surfaces and optimize oxygen exchange for energy devices.

Myrica Rubra-like MnFe2O4 Microsphere: A high efficiency microwave reduction catalyst for Cr(VI) removal from water

Aqueous hexavalent chromium (Cr(VI)) is easy to enter the biological system, causing serious threat to human and aquatic environment health. In this paper, a myrica rubra-like MnFe2O4 catalyst with average diameter of 200–300 nm were prepared by a simple solvothermal method. Benefiting from the knobby surface and the considerable microwave absorption ability, the as-prepared MnFe2O4 microsphere exhibited excellent microwave catalytic reduction ability for Cr(VI) in water, and the catalysts dosage, initial Cr(VI) concentration, solution pH value and temperature showed crucial effect on the catalytic reduction process. When the pH value of the solution was 2, the amount of catalysts was 2 g/L, and the temperature was 100 ℃, the myrica rubra-like MnFe2O4 catalysts could remove as high as 96% of Cr(VI) from a 50 mg/L aqueous solution only after 10 min microwave irradiation, which is much higher than the commercial one. The enhanced catalysis performance could be ascribed to the surface “knob” with a size of ∼ 17 nm, which accelerated the generation of e– under microwave irradiation, finally promoted the catalytic reduction performance. The microwave catalytic reduction strategy is a hopeful alternative for ultrafast reduction of Cr(VI) in sewage with high efficiency.

Solar light-responsive CdS/UiO-66-NH2 for ultrafast uranium reduction from uranium-containing mine wastewater without external sacrificial agents

• 40 CUN achieved a record kinetic reaction rate reduction efficiency in air atmosphere and absence of sacrificial agents; • Cd 2+ ions are absorbed on UiO-66-NH 2 by the coordination bonds of Cd-N. • The photogenerated holes are consumed by oxidizing S 2− to SO 4 2− . • 85.62% of U(VI) in the uranium contained real mine wastewater could be removed under solar. As the nuclear industry ushered in a historical opportunity for rapid development, the massive discharge of nuclear waste liquids posed health risks to humans and environmental pollutant due to its combined chemotoxicity and radiotoxicity. Therefore, how to effectively treat uranium-containing mine wastewater is full of challenges. In this work, the CdS/UiO-66-NH 2 nanoparticles photocatalysts were prepared and applied for reduction of uranium hexavalent in the absence of any sacrificial agents. The kinetic photoreaction rate reaches 3.78 mmol/(g·h), which is a record among the reported rate. Excitingly, 85.62% of U(VI) in the mine wastewater could be removed under sunlight irradiation in the air condition. The results show that the photogenerated electrons rapidly transport from CdS to UiO-66-NH 2 due to the formation of heterojunction structure, whereas the photo-generated holes are consumed by oxidizing S 2− to SO 4 2− . This work represents an important step towards the remediation of the radioactive environment from mine wastewater, and promotes the extensive application of photocatalysis technology.

Ultrafast Graphitization and Reduction of Spongy Graphene Oxide by Low-Energy Electromagnetic Radiation to Boost the Performance and Stability of Carbon-Based Supercapacitors

Ultrafast Graphitization and Reduction of Spongy Graphene Oxide by Low-Energy Electromagnetic Radiation to Boost the Performance and Stability of Carbon-Based Supercapacitors