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1.
Angew Chem Int Ed Engl ; : e202415786, 2024 Sep 26.
Article in English | MEDLINE | ID: mdl-39324519

ABSTRACT

Optimizing the reactivity and selectivity of single-atom catalysts (SACs) remains a crucial yet challenging issue in heterogeneous catalysis. This study demonstrates selective catalysis facilitated by a polyoxometalates-mediated electronic interaction (PMEI) in a Pt single-atom catalyst supported on CeO2 modified with Keggin-type phosphotungstate acid (HPW), labeled as Pt1/CeO2-HPW. The PMEI effect originates from the unique arrangement of isolated Pt atoms and HPW clusters on CeO2 surface. Electrons are transferred from ceria support to the electrophilic tungsten in HPW clusters, and subsequently, Pt atoms donate electrons to the now electron-deficient ceria. This phenomenon enhances the positive charge of Pt atoms, moderating O2 activation and limiting lattice oxygen mobility compared to the conventional Pt1/CeO2 catalyst. The resulting electronic structure of Pt combined with the strong and local acidic environment of HPW on Pt1/CeO2-HPW leads to improved degradation of NH3, N2 selectivity in the NO conversion, and CO2 yield when inputting volatile organic compounds. This study sheds the light on the design of SACs with balanced reactivity and selectivity for environmental catalysis applications.

2.
JACS Au ; 4(8): 2767-2791, 2024 Aug 26.
Article in English | MEDLINE | ID: mdl-39211630

ABSTRACT

Environmental catalysis has attracted great interest in air and water purification. Selective catalytic reduction with ammonia (NH3-SCR) as a representative technology of environmental catalysis is of significance to the elimination of nitrogen oxides (NO x ) emitting from stationary and mobile sources. However, the evolving energy landscape in the nonelectric sector and the changing nature of fuel in motor vehicles present new challenges for NO x catalytic purification over the traditional NH3-SCR catalysts. These challenges primarily revolve around the application limitations of conventional industrial NH3-SCR catalysts, such as V2O5-WO3(MoO3)/TiO2 and chabazite (CHA) structured zeolites, in meeting both the severe requirements of high activity at ultralow temperatures and robust resistance to the wide array of poisons (SO2, HCl, phosphorus, alkali metals, and heavy metals, etc.) existing in more complex operating conditions of new application scenarios. Additionally, volatile organic compounds (VOCs) coexisting with NO x in exhaust gas has emerged as a critical factor further impeding the highly efficient reduction of NO x . Therefore, confronting the challenges inherent in current NH3-SCR technology and drawing from the established NH3-SCR reaction mechanisms, we discern that the strategic manipulation of the properties of surface acidity and redox over NH3-SCR catalysts constitutes an important pathway for increasing the catalytic efficiency at low temperatures. Concurrently, the establishment of protective sites and confined structures combined with the strategies for triggering antagonistic effects emerge as imperative items for strengthening the antipoisoning potentials of NH3-SCR catalysts. Finally, we contemplate the essential status of selective synergistic catalytic elimination technology for abating NO x and VOCs. By virtue of these discussions, we aim to offer a series of innovative guiding perspectives for the further advancement of environmental catalysis technology for the highly efficient NO x catalytic purification from nonelectric industries and motor vehicles.

3.
Environ Sci Technol ; 58(36): 16215-16224, 2024 Sep 10.
Article in English | MEDLINE | ID: mdl-39190430

ABSTRACT

Elimination of dilute gaseous toluene is one of the critical concerns within the field of indoor air remediation. The typical degradation route on titanium-based catalysts, "toluene-benzaldehyde-carbon dioxide", necessitates the oxidation of the methyl group as a prerequisite for photocatalytic toluene oxidation. However, the inherent planar adsorption configuration of toluene molecules, dominated by the benzene rings, leads to significant steric hindrance for the methyl group. This steric hindrance prevents the methyl group from contacting the active species on the catalyst surface, thereby limiting the removal of toluene under indoor conditions. To date, no effective strategy to control the steric hindrance of the methyl group has been identified. Herein, we showed a B-Ti-O interface that exhibits significantly enhanced toluene removal efficiency under indoor conditions. In-depth investigations revealed that, compared to typical Ti-based photocatalysts, the steric hindrance between the methyl group and the catalyst surface decreased from 3.42 to 3.03 Å on the designed interface. This reduction originates from the matching of orbital energy levels between Ti 3dz2 and C 2pz of the benzene ring. The decreased steric hindrance improved the efficiency of toluene being attacked by surface active species, allowing for rapid conversion into benzaldehyde and benzoic acid species for subsequent reactions. Our work provides novel insights into the steric hindrance effect in the elimination of aromatic volatile organic compounds.


Subject(s)
Oxidation-Reduction , Oxygen , Titanium , Toluene , Toluene/chemistry , Titanium/chemistry , Adsorption , Oxygen/chemistry , Boron/chemistry , Catalysis
4.
Environ Sci Technol ; 2024 Jul 16.
Article in English | MEDLINE | ID: mdl-39013630

ABSTRACT

Renewing metal-poisoned NH3-SCR catalysts holds great potential for mitigating environmental pollution and utilizing hazardous wastes simultaneously. Ionic compounds containing heavy metals often exhibit limited solubility due to their high polarizability, making traditional washing techniques ineffective in removing heavy metal poisons. This study presents a gas-based method for regenerating heavy-metal-poisoned V2O5-WO3/TiO2 catalysts employed in NH3-SCR techniques. The regeneration is achieved by employing a masking and reconstruction strategy, which involves the in situ formation of NO2 to mediate the production of SO3. This enables the effective bonding of Pb and triggers the reconstruction of active VOx sites. In situ spectroscopy confirms that the sulfation of PbO restores acidity, while the occupied effect resulting from the sulfation of TiO2 promotes the formation of more polymeric VOx species. Consequently, the regenerated catalyst exhibits enhanced activity and superior resistance to metal poisons compared with the fresh catalyst. The innovative method offers a promising solution for extending the lifespan of poisoned catalysts, reducing waste generation, and enhancing the efficiency of NH3-SCR systems.

5.
Environ Sci Technol ; 58(26): 11781-11790, 2024 Jul 02.
Article in English | MEDLINE | ID: mdl-38877971

ABSTRACT

Synergistic control of nitrogen oxides (NOx) and nitrogen-containing volatile organic compounds (NVOCs) from industrial furnaces is necessary. Generally, the elimination of n-butylamine (n-B), a typical pollutant of NVOCs, requires a catalyst with sufficient redox ability. This process induces the production of nitrogen-containing byproducts (NO, NO2, N2O), leading to lower N2 selectivity of NH3 selective catalytic reduction of NOx (NH3-SCR). Here, synergistic catalytic removal of NOx and n-B via spatially separated cooperative sites was originally demonstrated. Specifically, titania nanotubes supported CuOx-CeO2 (CuCe-TiO2 NTs) catalysts with spatially separated cooperative sites were creatively developed, which showed a broader active temperature window from 180 to 340 °C, with over 90% NOx conversion, 85% n-B conversion, and 90% N2 selectivity. A synergistic effect of the Cu and Ce sites was found. The catalytic oxidation of n-B mainly occurred at the Cu sites inside the tube, which ensured the regular occurrence of the NH3-SCR reaction on the outer Ce sites under the matching temperature window. In addition, the n-B oxidation would produce abundant intermediate NH2*, which could act as an extra reductant to promote NH3-SCR. Meanwhile, NH3-SCR could simultaneously remove the possible NOx byproducts of n-B decomposition. This novel strategy of constructing cooperative sites provides a distinct pathway for promoting the synergistic removal of n-B and NOx.


Subject(s)
Nitrogen Oxides , Catalysis , Nitrogen Oxides/chemistry , Volatile Organic Compounds/chemistry , Oxidation-Reduction
6.
Environ Sci Technol ; 58(17): 7672-7682, 2024 Apr 30.
Article in English | MEDLINE | ID: mdl-38639327

ABSTRACT

The development of efficient technologies for the synergistic catalytic elimination of NOx and chlorinated volatile organic compounds (CVOCs) remains challenging. Chlorine species from CVOCs are prone to catalyst poisoning, which increases the degradation temperature of CVOCs and fails to balance the selective catalytic reduction of NOx with the NH3 (NH3-SCR) performance. Herein, synergistic catalytic elimination of NOx and chlorobenzene has been originally demonstrated by using phosphotungstic acid (HPW) as a dechlorination agent to collaborate with CeO2. The conversion of chlorobenzene was over 80% at 270 °C, and the NOx conversion and N2 selectivity reached over 95% at 270-420 °C. HPW not only allowed chlorine species to leave as inorganic chlorine but also enhanced the BroÌ·nsted acidity of CeO2. The NH4+ produced in the NH3-SCR process can effectively promote the dechlorination of chlorobenzene at low temperatures. HPW remained structurally stable in the synergistic reaction, resulting in good water resistance and long-term stability. This work provides a cheaper and more environmentally friendly strategy to address chlorine poisoning in the synergistic reaction and offers new guidance for multipollutant control.


Subject(s)
Chlorobenzenes , Catalysis , Chlorobenzenes/chemistry , Volatile Organic Compounds/chemistry , Chlorine/chemistry , Cerium/chemistry , Halogenation
7.
Nat Commun ; 15(1): 2901, 2024 Apr 04.
Article in English | MEDLINE | ID: mdl-38575571

ABSTRACT

Simultaneous multi-target detection and multi-site gene editing are two key factors restricting the development of disease diagnostic and treatment technologies. Despite numerous explorations on the source, classification, functional features, crystal structure, applications and engineering of CRISPR-Cas13a, all reports use the contiguous target RNA activation paradigm that only enables single-target detection in vitro and one-site gene editing in vivo. Here we propose a noncontiguous target RNA activation paradigm of Cas13a and establish a CRISPR-Cas13a Gemini System composed of two Cas13a:crRNA binary complexes, which can provide rapid, simultaneous, highly specific and sensitive detection of two RNAs in a single readout, as well as parallel dual transgene knockdown. CRISPR-Cas13a Gemini System are demonstrated in the detection of two miRNAs (miR-155 and miR-375) for breast cancer diagnosis and two small RNAs (EBER-1 and EBER-2) for Epstein-Barr virus diagnosis using multiple diagnostic platforms, including fluorescence and colorimetric-based lateral flow systems. We also show that CRISPR-Cas13a Gemini System can knockdown two foreign genes (EGFP and mCherry transcripts) in mammalian cells simultaneously. These findings suggest the potential of highly effective and simultaneous detection of multiple biomarkers and gene editing of multiple sites.


Subject(s)
Epstein-Barr Virus Infections , MicroRNAs , Animals , Humans , RNA/genetics , Clustered Regularly Interspaced Short Palindromic Repeats/genetics , CRISPR-Cas Systems/genetics , Epstein-Barr Virus Infections/genetics , Herpesvirus 4, Human/genetics , Mammals/genetics
8.
Nano Lett ; 24(10): 3243-3248, 2024 Mar 13.
Article in English | MEDLINE | ID: mdl-38427592

ABSTRACT

Achieving timely, reversible, and long-range remote tunability over surface wettability is highly demanded across diverse fields, including nanofluidic systems, drug delivery, and heterogeneous catalysis. Herein, using molecular dynamic simulations, we show, for the first time, a theoretical design of electrowetting to achieve remotely controllable surface wettability via using a terahertz wave. The key idea driving the design is the unique terahertz collective vibration identified in the vicinal subnanoscale water layer, which is absent in bulk water, enabling efficient energy transfer from the terahertz wave to the rotational motion of the vicinal subnanoscale water layer. Consequently, a frequency-specific alternating terahertz electric field near the critical strength can significantly affect the local hydrogen-bonding network of the contact water layer on the solid surface, thereby achieving tunable surface wettability.

9.
Chem Commun (Camb) ; 60(20): 2700-2715, 2024 Mar 05.
Article in English | MEDLINE | ID: mdl-38352985

ABSTRACT

The development of energy storage material technologies stands as a decisive measure in optimizing the structure of clean and low-carbon energy systems. The remarkable activity inherent in plasma technology imbues it with distinct advantages in surface modification, functionalization, synthesis, and interface engineering of materials. This review systematically expounds upon the principles, classifications, and application scenarios of plasma technology, while thoroughly discussing its unique merits in the realm of modifying electrode materials, solid-state electrolytes, and conductive carbon materials, which are widely used in lithium-ion batteries, sodium ion batteries, metal air batteries and other fields. Finally, considering the existing constraints associated with lithium-ion batteries, some application prospects of plasma technology in the energy storage field are suggested. This work is of great significance for the development of clean plasma technology in the field of energy storage.

10.
J Hazard Mater ; 468: 133722, 2024 Apr 15.
Article in English | MEDLINE | ID: mdl-38367433

ABSTRACT

The synergistic removal of NOx and chlorinated volatile organic compounds (CVOCs) has become the hot topic in the field of environmental catalysis. However, due to the trade-off effects between catalytic reduction of NOx and catalytic oxidation of CVOCs, it is indispensable to achieve well-matched redox property and acidity. Herein, synergistic catalytic removal of NOx and chlorobenzene (CB, as the model of CVOCs) has been originally demonstrated over a Co-doped SmMn2O5 mullite catalyst. Two kinds of Mn-Mn sites existed in Mn-O-Mn-Mn and Co-O-Mn-Mn sites were constructed, which owned gradient redox ability. It has been demonstrated that the cooperation of different active sites can achieve the balanced redox and acidic property of the SmMn2O5 catalyst. It is interesting that the d band center of Mn-Mn sites in two different sites was decreased by the introduction of Co, which inhibited the nitrate species deposition and significantly improved the N2 selectivity. The Co-O-Mn-Mn sites were beneficial to the oxidation of CB and it cooperates with Mn-O-Mn-Mn to promote the synergistic catalytic performance. This work paves the way for synergistic removal of NOx and CVOCs over cooperative active sites in catalysts.

11.
J Hazard Mater ; 465: 133164, 2024 Mar 05.
Article in English | MEDLINE | ID: mdl-38103292

ABSTRACT

In response to the stricter EU VII emission standards and the "150 â„ƒ challenge", selective catalytic reduction by ammonia (NH3-SCR) catalysts for motor vehicles are required to achieve high NO conversion below 200 °C. Compounding metal oxides with zeolites is an important strategy to design the low-temperature SCR catalysts. Here, we original prepared Cu-SSZ-13 @ MnGdOx (Cu-Z @ MGO), which achieved over 90% NO conversion and 95% N2 selectivity at 150 â„ƒ. It has been demonstrated that a uniform mesoporous loaded layer of MGO grows on Cu-Z, and a recrystallization zone appears at the MGO-Cu-Z interface. We discover that the excellent low-temperature SCR activity derives from the strong metal oxide-zeolite interaction (SMZI) effects. The SMZI effects cause the anchor and high dispersion of MGO on the surface of Cu-Z. Driven by the SMZI effects, the Mn3+/Mn4+ redox cycle ensures the low and medium temperature-SCR activity and the Cu2+/Cu+ redox cycle guarantees the medium and high temperature-SCR activity. The introduction of MGO improves the reaction activity of -NH2 species adsorbed at Mn sites at 150 â„ƒ, achieving a cycle of reduction and oxidation reactions at low temperatures. This strategy of inducing SMZI effects of metal oxides and zeolites paves a way for development of high-performance catalysts.

12.
Environ Sci Technol ; 57(50): 21470-21482, 2023 Dec 19.
Article in English | MEDLINE | ID: mdl-38050842

ABSTRACT

NOx and CH3SH as two typical air pollutants widely coexist in various energy and industrial processes; hence, it is urgent to develop highly efficient catalysts to synergistically eliminate NOx and CH3SH. However, the catalytic system for synergistically eliminating NOx and CH3SH is seldom investigated to date. Meanwhile, the deactivation effects of CH3SH on catalysts and the formation mechanism of toxic byproducts emitted from the synergistic catalytic elimination reaction are still vague. Herein, selective synergistic catalytic elimination (SSCE) of NOx and CH3SH via engineering deep oxidation sites over Cu-modified Nb-Fe composite oxides supported on TiO2 catalyst against toxic CO and HCN byproducts formation has been originally demonstrated. Various spectroscopic and microscopic characterizations demonstrate that the sufficient chemisorbed oxygen species induced by the persistent electron transfer from Nb-Fe composite oxides to copper oxides can deeply oxidize HCOOH to CO2 for avoiding highly toxic byproducts formation. This work is of significance in designing superior catalysts employed in more complex working conditions and sheds light on the progress in the SSCE of NOx and sulfur-containing volatile organic compounds.


Subject(s)
Air Pollutants , Oxides , Oxidation-Reduction , Oxides/analysis , Oxides/chemistry , Oxygen , Electron Transport , Catalysis , Ammonia/chemistry
13.
Proc Natl Acad Sci U S A ; 120(52): e2312480120, 2023 Dec 26.
Article in English | MEDLINE | ID: mdl-38134197

ABSTRACT

Tetrafluoromethane (CF4), the simplest perfluorocarbons, is a permanently potent greenhouse gas due to its powerful infrared radiation adsorption capacity. The highly symmetric and robust C-F bond structure makes its activation a great challenge. Herein, we presented an innovated approach that efficiently activates C-F bond utilizing protonated sulfate (-HSO4) modified Al2O3@ZrO2 (S-Al2O3@ZrO2) catalyst, resulting in highly efficient CF4 decomposition. By combining in situ infrared spectroscopy tests and density function theory simulations, we demonstrate that the introduced -HSO4 proton donor has a stronger interaction on the C-F bond than the hydroxyl (-OH) proton donor, which can effectively stretch the C-F bond for its activation. Consequently, the obtained S-Al2O3@ZrO2 catalyst achieved a stable 100% CF4 decomposition at a record low temperature of 580 °C with a turnover frequency value of ~8.3 times higher than the Al2O3@ZrO2 catalyst without -HSO4 modification, outperforming the previously reported results. This work paves a new way for achieving efficient C-F bond activation to decompose CF4 at a low temperature.

14.
Angew Chem Int Ed Engl ; 62(52): e202314303, 2023 Dec 21.
Article in English | MEDLINE | ID: mdl-37942727

ABSTRACT

Transition metal single atom electrocatalysts (SACs) with metal-nitrogen-carbon (M-N-C) configuration show great potential in oxygen evolution reaction (OER), whereby the spin-dependent electrons must be allowed to transfer along reactants (OH- /H2 O, singlet spin state) and products (O2 , triplet spin state). Therefore, it is imperative to modulate the spin configuration in M-N-C to enhance the spin-sensitive OER energetics, which however remains a significant challenge. Herein, we report a local field distortion induced intermediate to low spin transition by introducing a main-group element (Mg) into the Fe-N-C architecture, and decode the underlying origin of the enhanced OER activity. We unveil that, the large ionic radii mismatch between Mg2+ and Fe2+ can cause a FeN4 in-plane square local field deformation, which triggers a favorable spin transition of Fe2+ from intermediate (dxy 2 dxz 2 dyz 1 dz2 1 , 2.96 µB ) to low spin (dxy 2 dxz 2 dyz 2 , 0.95 µB ), and consequently regulate the thermodyna-mics of the elementary step with desired Gibbs free energies. The as-obtained Mg/Fe dual-site catalyst demonstrates a superior OER activity with an overpotential of 224 mV at 10 mA cm-2 and an electrolysis voltage of only 1.542 V at 10 mA cm-2 in the overall water splitting, which outperforms those of the state-of-the-art transition metal SACs.

15.
Environ Sci Technol ; 57(38): 14472-14481, 2023 09 26.
Article in English | MEDLINE | ID: mdl-37695840

ABSTRACT

Catalyst deactivation caused by alkali metal poisoning has long been a key bottleneck in the application of selective catalytic reduction of NOx with NH3 (NH3-SCR), limiting the service life of the catalyst and increasing the cost of environmental protection. Despite great efforts, continuous accumulation of alkali metal deposition makes the resistance capacity of 2 wt % K2O difficult to enhance via merely loading acid sites on the surface, resulting in rapid deactivation and frequent replacement of the NH3-SCR catalyst. To further improve the resistance of alkali metals, encapsulating alkali metals into the bulk phase could be a promising strategy. The bottleneck of 2 wt % K2O tolerance has been solved by virtue of ultrahigh potassium storage capacity in the amorphous FePO4 bulk phase. Amorphous FePO4 as a support of the NH3-SCR catalyst exhibited a self-adaptive alkali-tolerance mechanism, where potassium ions spontaneously migrated into the bulk phase of amorphous FePO4 and were anchored by PO43- with the generation of Fe2O3 at the NH3-SCR reaction temperature. This ingenious potassium storage mechanism could boost the K2O resistance capacity to 6 wt % while maintaining approximately 81% NOx conversion. Besides, amorphous FePO4 also exhibited excellent resistance to individual and coexistence of alkali (K2O and Na2O), alkali earth (CaO), and heavy metals (PbO and CdO), providing long durability for CePO4/FePO4 catalysts in flue gas with multipollutants. The cheap and accessible amorphous FePO4 paves the way for the development and implementation of poisoning-resistant NOx abatement.


Subject(s)
Alkalies , Potassium , Catalysis , Temperature
16.
Environ Sci Pollut Res Int ; 30(48): 105897-105911, 2023 Oct.
Article in English | MEDLINE | ID: mdl-37718365

ABSTRACT

Metal-organic frame (MOF) materials can effectively degrade organic pollutants, whereas the MOF is rapidly hydrolysed in water and has poor stability and low reusability. However, in the current advanced oxidation process (AOP) system, the removal effect of pollutants under alkaline condition is not ideal. In this study, a magnetic composite material derived from MOF was synthesised and used as a new catalyst for rapid degradation of tetrabromobisphenol A (TBBPA). Compared to precarbonisation, FeCo@GC formed a conductive graphite carbon skeleton, retained the complete rhombododecahedron structure, had a larger specific surface area and provided more active sites for peroxymonosulfate (PMS) activation. The target pollutant TBBPA (20 mg/L) was completely degraded within 30 min, and the mineralisation rate reached 40.98% in the FeCo@GC (150 mg/L) and PMS (1 mM) systems, owing to the synergistic interaction between Fe, Co and graphite carbon. The reactive oxygen species (ROS) involved in the reaction were determined to be SO4•-, ·OH, 1O2 and O2•- by electron paramagnetic resonance and free radical scavenging experiments, and the 1O2 played a dominant role. Based on the results of LC-MS analysis results, the main degradation pathways of TBBPA involve three mechanisms: the debromination reaction, hydroxylation and cleavage of the benzene ring. In addition, compared with previous AOP systems, FeCo@GC/PMS overcomes the disadvantage of poor degradation effect of TBPPA under alkaline conditions, has a wide range pH (3-11) application and has the best effect on TBBPA degradation under alkaline conditions. FeCo@GC has an excellent cycle performance, with a removal rate of re-calcined material of 88.52% after five cycles. Therefore, FeCo@GC can be used as a promising and efficient catalyst for removing environmental organic pollutants.


Subject(s)
Environmental Pollutants , Graphite , Peroxides/chemistry , Carbon , Magnetic Phenomena , Hydrogen-Ion Concentration
17.
Langmuir ; 39(25): 8889-8899, 2023 Jun 27.
Article in English | MEDLINE | ID: mdl-37314863

ABSTRACT

Unraveling the dynamics of the active sites upon CeO2-based catalysts in selective catalytic reduction of nitrogen oxides by ammonia (NH3-SCR) is challenging. In this work, we prepared tungsten-acidified and sulfated CeO2 catalysts and used operando spectroscopy to reveal the dynamics of acid sites and redox sites on catalysts during NH3-SCR reaction. We found that both Lewis and Brønsted acid sites are needed to participate in the catalytic reaction. Notably, Brønsted acid sites are the main active sites after a tungsten-acidified or sulfated treatment, and the change of Brønsted acid sites significantly affects the NOx removal. Moreover, acid functionalization promotes the cerium species cycle between Ce4+ and Ce3+ for the NOx reduction. This work is critical to deeply understanding the natural properties of active sites, and it also provides new insights into the mechanism for NH3-SCR over CeO2-based catalysts.

18.
Small ; 19(37): e2301906, 2023 Sep.
Article in English | MEDLINE | ID: mdl-37140102

ABSTRACT

Aqueous zinc-ion batteries (ZIBs) have attracted extensive attention in recent years because of its high volumetric energy density, the abundance of zinc resources, and safety. However, ZIBs still suffer from poor reversibility and sluggish kinetics derived from the unstable cathodic structure and the strong electrostatic interactions between bivalent Zn2+ and cathodes. Herein, magnesium doping into layered manganese dioxide (Mg-MnO2 ) via a simple hydrothermal method as cathode materials for ZIBs is proposed. The interconnected nanoflakes of Mg-MnO2 possess a larger specific surface area compared to pristine δ-MnO2 , providing more electroactive sites and boosting the capacity of batteries. The ion diffusion coefficients of Mg-MnO2 can be enhanced due to the improved electrical conductivity by doped cations and oxygen vacancies in MnO2 lattices. The assembled Zn//Mg-MnO2 battery delivers a high specific capacity of 370 mAh g-1 at a current density of 0.6 A g-1 . Furthermore, the reaction mechanism confirms that Zn2+ insertion occurred after a few cycles of activation reactions. Most important, the reversible redox reaction between Zn2+ and MnOOH is found after several charge-discharge processes, promoting capacity and stability. It believes that this systematic research enlightens the design of high-performance of ZIBs and facilitates the practical application of Zn//MnO2 batteries.

19.
Langmuir ; 39(21): 7434-7443, 2023 May 30.
Article in English | MEDLINE | ID: mdl-37200447

ABSTRACT

Mn-based catalysts are promising for selective catalytic reduction (SCR) of NOx with NH3 at low temperatures due to their excellent redox capacity. However, the N2 selectivity of Mn-based catalysts is an urgent problem for practical application owing to excessive oxidizability. To solve this issue, we report a Mn-based catalyst using amorphous ZrTiOx as the support (Mn/ZrTi-A) with both excellent low-temperature NOx conversion and N2 selectivity. It is found that the amorphous structure of ZrTiOx modulates the metal-support interaction for anchoring the highly dispersed active MnOx species and constructs a uniquely bridged Mn3+ bonded with the support through oxygen linked to Ti4+ and Zr4+, respectively, which regulates the optimal oxidizability of the MnOx species. As a result, Mn/ZrTi-A is not conducive to the formation of ammonium nitrate that readily decomposes to N2O, thus further increasing N2 selectivity. This work investigates the role of an amorphous support in promoting the N2 selectivity of a manganese-based catalyst and sheds light on the design of efficient low-temperature deNOx catalysts.

20.
Environ Sci Technol ; 57(17): 7041-7050, 2023 05 02.
Article in English | MEDLINE | ID: mdl-37078822

ABSTRACT

Ozone catalytic oxidation (OZCO) has gained great interest in environmental remediation while it still faces a big challenge during the deep degradation of refractory volatile organic compounds (VOCs) at room temperature. Hydroxylation of the catalytic surface provides a new strategy for regulating the catalytic activity to boost VOC degradation. Herein, OZCO of toluene at room temperature over hydroxyl-mediated MnOx/Al2O3 catalysts was originally demonstrated. Specifically, a novel hydroxyl-mediated MnOx/Al2O3 catalyst was developed via the in situ AlOOH reconstruction method and used for toluene OZCO. The toluene degradation performance of MnOx/Al2O3 was significantly superior to those of most of the state-of-the-art catalysts, and 100% toluene was removed with an excellent mineralization rate (82.3%) and catalytic stability during OZCO. ESR and in situ DRIFTs results demonstrated that surface hydroxyl groups (HGs) greatly improved the reactive oxygen species generation, thus dramatically accelerating the benzene ring breakage and deep mineralization. Furthermore, HGs provided anchoring sites for uniformly dispersing MnOx and greatly enhanced toluene adsorption and ozone activation. This work paves a way for deep decomposition of aromatic VOCs at room temperature.


Subject(s)
Ozone , Oxides , Temperature , Toluene , Oxidation-Reduction , Hydroxyl Radical , Catalysis
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