Ternary Nanohybrid of Ni3S2/CoMoS4/MnO2 on Nickel Foam for Aqueous and Solid-State High-Performance Supercapacitors

To overcome the issues related to supercapacitor (SC) electrodes, such as high cost, low specific capacitance (C_s), low energy density (ED), requirements for expensive binder, etc., binderless electrodes are highly desirable. Here, a new ternary nanohybrid is presented as a binder-free SC electrode based on Ni₃S₂, CoMoS₄, and MnO₂. A facile two-step hydrothermal route, followed by a short thermal annealing process, is developed to grow amorphous polyhedral structured CoMoS₄ and further wrap MnO₂ nanowires on Ni foam. This rationally designed binder-free electrode exhibited the highest C_s of 2021 F g⁻¹ (specific capacity of 883.8 C g⁻¹ or 245.5 mAh g⁻¹) at a current density of 1 A g⁻¹ in 1 M KOH electrolyte with a highly porous surface morphology. This electrode material exhibited excellent cycling stability (90% capacitance retention after 4000 cycles) due to the synergistic contribution of individual components and advanced surface properties. Furthermore, an aqueous binder-free asymmetric SC based on this ternary composite exhibited an ED of 20.7 Wh kg⁻¹, whereas a solid-state asymmetric SC achieved an ED of 13.8 Wh kg⁻¹. This nanohybrid can be considered a promising binder-free electrode for both aqueous and solid-state asymmetric SCs with these remarkable electrochemical properties.

Recent advances and perspectives in the resistance of SO2 and H2O of cerium-based catalysts for NOx selective catalytic reduction with ammonia

This review emphasizes the aspects related to cerium-based catalysts at different levels: metal modification, preparation methods, structures, and reaction mechanisms.

Low temperature performance and sulfur resistance enhancement of Mn-Ce oxides supported on W-modified MWCNT for NH3-SCR removal of NOx

To eliminate nitrogen oxides (NO_x), composite carrier-supported catalysts (Mn-Ce/MWCNT-W) and traditional catalysts (Mn-Ce/MWCNT and W-Mn-Ce/MWCNT) were prepared using an ultrasonic impregnation method that preformed low-temperature ammonia-selective catalytic reduction (SCR) removal of NO_x. The promotion effects of MWCNT-W composite carriers for low temperature SCR activities and SO₂ tolerance of the catalysts were systematically investigated. Compared to traditional catalyst, Mn-Ce/MWCNT-W catalyst, with a 30% WO_x/MWCNT mass ratio, demonstrated improved SCR activity and high N₂-selectivity from 100°C to 200°C. A series of characterizations were carried out and it was found that there were more redox sites and the stronger the NH₃ adsorption capacity over the composite carrier-supported catalysts than traditional catalysts. Also, with this composite carrier-supported catalyst, the improvement of SCR reaction was considered to be from the abundance of high valence state Mn and well dispersed active components. Notably, compared to traditional catalyst, the composite carrier-supported catalyst exhibited the stronger sulfur resistance. Thus, using MWCNT-W composite carriers to prepare Mn-Ce/MWCNT-W catalysts resulted in excellent NO_x conversion and SO₂ resistance at low temperatures.Implications: LT NH₃-SCR of NO_x is an effective way to remove NO_x from stationary sources. The physicochemical properties of the support not only affect a catalyst's LT SCR activity but also affect the catalyst's anti-poisoning performance. The modified carriers could promote active component dispersion, which is conducive to SCR reaction. However, for LT SCR reactions, few reports have addressed the design and preparation of composite carrier-supported catalysts. The goal of this study was to design and synthesize Mn-Ce/MWCNT-W catalysts and to observe the influence of composite support in Mn-based catalysts on LT SCR activity and sulfur resistance.

Improvement of the activity and SO2 tolerance of Sb-modified Mn/PG catalysts for NH3-SCR at a low temperature

A series of MnM/palygorskite (PG) (M = La, W, Mo, Sb, Mg) catalysts was prepared by the wetness co-impregnation method for low-temperature selective catalytic reduction (SCR) of NO with NH₃. Conversion efficiency followed the order Sb > Mo > La > W > Mg. A combination of various physico-chemical techniques was used to investigate the influence of Sb-modified Mn/PG catalysts. MnSb_0.156/PG catalyst showed highest NO conversion at low temperatures in the presence of SO₂ which reveals that addition of Sb oxides effectively enhances the SCR activity of catalysts. A SO₂ step-wise study showed that MnSb_0.156/PG catalyst displays higher durable resistance to SO₂ than Mn/PG catalyst, where the sulfating of active phase is greatly inhibited after Sb doping. Scanning electron microscopy and X-ray diffraction results showed that Sb loading enhances the dispersion of Mn oxides on the carrier surface. According to the results of characterization analyses, it is suggested that the main reason for the deactivation of Mn/PG is the formation of manganese sulfates which cause the permanent deactivation of Mn-based catalysts. For Sb-doped Mn/PG catalyst, SO_x ad-species formed were mainly combined with SbO_x rather than MnO_x. This preferential interaction between SbO_x and SO₂ effectively shields the MnO_x as active species from being sulfated by SO₂ resulting in the improvement of SO₂ tolerance on Sb-added catalyst. Multiple information support that, owing to the addition of Sb, original formed MnO_x crystallite has been completely transformed into highly dispersed amorphous phase accounting for higher SCR activity.

CO2 reforming of methane to syngas over multi-walled carbon nanotube supported Ni-Ce nanoparticles: effect of different synthesis methods

Several multi-walled carbon nanotubes supported Ni-Ce catalysts were synthesized, and their performance in carbon dioxide reforming of methane (CDRM) for syngas production was evaluated. The attachment of Ni-Ce nanoparticles to the functionalized carbon nanotube (fCNT) support was carried out using four synthesis routes, i.e., impregnation (I), sol-gel (S), co-precipitation (C), and hydrothermal (H) methods. Results indicated that synthesis method influences the properties of the NiCe/fCNT catalysts in terms of homogeneity of metal dispersion, size of crystallites, and metal-support interaction. The activity of the catalysts followed the order of NiCe/fCNT(H) > NiCe/fCNT(S) > NiCe/fCNT(C) > NiCe/fCNT(I). The NiCe/fCNT(H) catalyst exhibited the highest catalytic activity with CH₄ and CO₂ conversions of 92 and 96%, respectively, and resulted in syngas product with consistent H₂/CO ratio of 0.91 at reaction temperature of 800 °C without notable deactivation up to 30 h of reaction. Moreover, the growth of carbon on the spent catalyst was only 2% with deposition rate of 4.08 mg/g_cat·h; this was plausibly due to the well-dispersed distribution of nanoparticles on fCNT surface and abundant presence of oxygenated groups on the catalyst surface.

Hierarchical Manganese-Nickel Sulfide Nanosheet Arrays as an Advanced Electrode for All-Solid-State Asymmetric Supercapacitors

In this work, hierarchical manganese-nickel sulfide nanosheet arrays (Mn-Ni-S NAs) were designed through a cost-effective hydrothermal method, followed by an ion-exchange technique. Among the various electrode samples prepared, Mn-Ni-S NAs with a Mn/Ni feeding ratio of 1:2 (denoted Mn-Ni-S NAs (1:2)) were found to possess outstanding electrochemical properties, including a superb areal capacity of 0.687 mAh cm^-2 (286.3 mAh g^-1 specific capacity) and a splendid cycling stability. Furthermore, Mn-Ni-S NAs (1:2) can be coupled with iron oxide embedded in reduced graphene oxides (Fe₂O₃@rGO) to assemble all-solid-state asymmetric supercapacitor devices. The resultant device demonstrated superior volumetric capacity and a superb energy density of 76.6 W h kg^-1 with a prominent cycling stability. The current synthesis protocol provides a meritorious reference for the synthesis of other kinds of transition-metal sulfide electrode materials for energy storage applications.

The influence of support composition on the activity of Cu:Ce catalysts for selective catalytic reduction of NO by CO in the presence of excess oxygen

Excellent catalytic performance for NO reduction by CO in the presence of 5% O₂ over Cu1:Ce3/Al₂O₃.

Full water splitting by a nanoporous CeO2 nanowire array under alkaline conditions

CeO₂ nanowire array was derived from MnO₂–CeO₂/TM via an acid etching strategy, and MnO₂ acts as a pore-forming agent through selective etching with oxalic acid, it shows excellent OER and HER performance.

A review of carbon-based and non-carbon-based catalyst supports for the selective catalytic reduction of nitric oxide

Various types of carbon-based and non-carbon-based catalyst supports for nitric oxide (NO) removal through selective catalytic reduction (SCR) with ammonia are examined in this review. A number of carbon-based materials, such as carbon nanotubes (CNTs), activated carbon (AC), and graphene (GR) and non-carbon-based materials, such as Zeolite Socony Mobil-5 (ZSM-5), TiO2, and Al2O3 supported materials, were identified as the most up-to-date and recently used catalysts for the removal of NO gas. The main focus of this review is the study of catalyst preparation methods, as this is highly correlated to the behaviour of NO removal. The general mechanisms involved in the system, the Langmuir-Hinshelwood or Eley-Riedeal mechanism, are also discussed. Characterisation analysis affecting the surface and chemical structure of the catalyst is also detailed in this work. Finally, a few major conclusions are drawn and future directions for work on the advancement of the SCR-NH3 catalyst are suggested.

Selective catalytic reduction of NO with NH3 over MnO2/PDOPA@CNT catalysts prepared via poly(dopamine) functionalization

MnO₂/PDOPA@CNT catalysts were for the first time prepared via poly(dopamine) functionalization and applied in low-temperature NO reduction with NH₃.

Influence of transition metal (Fe, Co, and Ag) doping on the MnOx–CeO2/Ti-bearing blast furnace slag catalyst for selective catalytic reduction of NOx with NH3 at low temperature

Mn–Ce based catalysts supported on Ti-bearing blast furnace slag (industrial solid waste) and the doping of transition metals were studied.

Efficient 2-Nitrophenol Chemical Sensor Development Based on Ce2O3 Nanoparticles Decorated CNT Nanocomposites for Environmental Safety

Ce₂O₃ nanoparticle decorated CNT nanocomposites (Ce₂O₃.CNT NCs) were prepared by a wet-chemical method in basic medium. The Ce₂O₃.CNT NCs were examined using FTIR, UV/Vis, Field-Emission Scanning Electron Microscopy (FESEM), X-ray electron dispersive spectroscopy (XEDS), X-ray photoelectron spectroscopy (XPS), and powder X-ray diffraction (XRD). A selective 2-nitrophenol (2-NP) sensor was developed by fabricating a thin-layer of NCs onto a flat glassy carbon electrode (GCE, surface area = 0.0316 cm²). Higher sensitivity including linear dynamic range (LDR), long-term stability, and enhanced electrochemical performances towards 2-NP were achieved by a reliable current-voltage (I-V) method. The calibration curve was found linear (R² = 0.9030) over a wide range of 2-NP concentration (100 pM ~ 100.0 mM). Limit of detection (LOD) and sensor sensitivity were calculated based on noise to signal ratio (~3N/S) as 60 ± 0.02 pM and 1.6×10⁻³ μAμM^-1cm^-2 respectively. The Ce₂O₃.CNT NCs synthesized by a wet-chemical process is an excellent way of establishing nanomaterial decorated carbon materials for chemical sensor development in favor of detecting hazardous compounds in health-care and environmental fields at broad-scales. Finally, the efficiency of the proposed chemical sensors can be applied and utilized in effectively for the selective detection of toxic 2-NP component in environmental real samples with acceptable and reasonable results.

Band gap energies for white nanosheets/yellow nanoislands/purple nanorods of CeO2

The photon band gap energies and spin–orbit coupling states of white nanosheets, purple nanorods and yellow nanoislands of CeO₂.

Fabrication and formation mechanism of Ce2O3–CeO2–CuO–MnO2/CNTs catalysts and application in low-temperature NO reduction with NH3

Ce₂O₃–CeO₂–CuO–MnO₂/CNTs catalysts were synthesized via a redox strategy, and presented 58–85% NO conversion at 80–180 °C.

Non-pitch coal-based activated coke introduced CeOx and/or MnOx for low temperature selective catalytic reduction of NOx by NH3

On the modified activated coke, the CeO_x species, promoting NO_x adsorption, significantly increased the starting denitrification activity and the Mn species, helping NH₃ adsorption, showed a gradual increase in activity after a time delay.

Preparation of novel CeMo(x) hollow microspheres for low-temperature SCR removal of NOx with NH3

A series of novel Mo doped CeO₂ hollow microspheres have been successfully synthesized using carbon microspheres as templates, which were characterized by XRD, SEM, TEM, BET and used to remove NO_x upon NH₃-SCR at lower temperature.

In situ and ex situ NO oxidation assisted by sub-microsecond pulsed multi-pin-to-plane corona discharge: the effect of pin density

Pin-to-plane corona reactor for NO to NO₂ conversion at ambient conditions.

Enhanced electroactivity and substrate affinity of microperoxidase-11 attached to pyrene-linkers π–π stacked on carbon nanostructure electrodes

An exceptionally large electroactively connected microperoxidase-11 (MP-11) with strong affinity for organic peroxide and offering a high electrocatalytic reduction current density of 7.5 mA cm⁻² is achieved for the first time.

Fabrication of Mn–CeOx/CNTs catalysts by a redox method and their performance in low-temperature NO reduction with NH3

Highly active Mn–CeO_x/CNTs catalysts were first fabricated by a novel redox method, and a formation mechanism was proposed.

Fe2O3 nanoparticles anchored in situ on carbon nanotubes via an ethanol-thermal strategy for the selective catalytic reduction of NO with NH3

Fe₂O₃ nanoparticles anchored in situ on carbon nanotubes via an ethanol-thermal strategy present an excellent DeNO_x performance.

Highly efficient removal of NO with ordered mesoporous manganese oxide at low temperature

Highly ordered mesoporous MnO₂ was prepared using KIT-6 as a hard template, for selective catalytic reduction (SCR) of NO with NH₃ at low temperature, which was characterized using TEM, XRD, BET, XPS, H₂-TPR, NH₃-TPD and in situ DRIFT.

Promoted performance of a MnOx/PG catalyst for low-temperature SCR against SO2poisoning by addition of cerium oxide

Loading of cerium oxide inhibits the formation of manganese sulfates at temperatures higher than 150 °C.

Interfacial properties and impact toughness of dendritic hexamethylenetetramine functionalized carbon fiber with varying chain lengths

In order to understand the effects of chain length on the interfacial adhesion of PAN-based carbon fiber (CF)/epoxy composites, dendritic hexamethylenetetramine (HMTA) was functionalized on carbon fibers through quaternary ammonium salt reaction using alkyl dihalide of varying chain length [Cl(CH₂)_nCl, n = 2, 6 and 12].

Nitric oxide decomposition using atmospheric pressure dielectric barrier discharge reactor with different adsorbents

An NO removal rate of 99% and energy efficiency of 99.4 g NO per kW h were obtained on NaY zeolite using the adsorption–desorption and decomposition process in a self-made coaxial cylinder-type dielectric barrier discharge reactor.

Influence of aging on in situ hydrothermally synthesized Cu-SSZ-13 catalyst for NH3-SCR reaction

Cu-SSZ-13 crystallized for 72 h shows excellent hydrothermal stability, NO_x removal activity and N₂ selectivity even under high space velocity (640 000 h⁻¹). Aging treatments lead to the transform of some Cu species from isolated Cu²⁺ to new complexes and dealuminization of the zeolites framework, contributing to catalyst deactivation.

Low-temperature NO reduction with NH3 over Mn–CeOx/CNT catalysts prepared by a liquid-phase method

Mn–CeO_x/CNTs prepared by a liquid-phase method showed excellent low-temperature activity for NO reduction with NH₃.

Design of meso-TiO2@MnO(x)-CeO(x)/CNTs with a core-shell structure as DeNO(x) catalysts: promotion of activity, stability and SO2-tolerance

Developing low-temperature deNOx catalysts with high catalytic activity, SO2-tolerance and stability is highly desirable but remains challenging. Herein, by coating the mesoporous TiO2 layers on carbon nanotubes (CNTs)-supported MnOx and CeOx nanoparticles (NPs), we obtained a core-shell structural deNOx catalyst with high catalytic activity, good SO2-tolerance and enhanced stability. Transmission electron microscopy, X-ray diffraction, N2 sorption, X-ray photoelectron spectroscopy, H2 temperature-programmed reduction and NH3 temperature-programmed desorption have been used to elucidate the structure and surface properties of the obtained catalysts. Both the specific surface area and chemisorbed oxygen species are enhanced by the coating of meso-TiO2 sheaths. The meso-TiO2 sheaths not only enhance the acid strength but also raise acid amounts. Moreover, there is a strong interaction among the manganese oxide, cerium oxide and meso-TiO2 sheaths. Based on these favorable properties, the meso-TiO2 coated catalyst exhibits a higher activity and more extensive operating-temperature window, compared to the uncoated catalyst. In addition, the meso-TiO2 sheaths can serve as an effective barrier to prevent the aggregation of metal oxide NPs during stability testing. As a result, the meso-TiO2 overcoated catalyst exhibits a much better stability than the uncoated one. More importantly, the meso-TiO2 sheaths can not only prevent the generation of ammonium sulfate species from blocking the active sites but also inhibit the formation of manganese sulfate, resulting in a higher SO2-tolerance. These results indicate that the design of a core-shell structure is effective to promote the performance of deNOx catalysts.