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16 pages, 3576 KiB

Open AccessFeature PaperArticle

Direct Evidence of Dynamic Metal Support Interactions in Co/TiO₂ Catalysts by Near-Ambient Pressure X-ray Photoelectron Spectroscopy

by Davide Salusso, Canio Scarfiello, Anna Efimenko, Doan Pham Minh, Philippe Serp, Katerina Soulantica and Spyridon Zafeiratos

Nanomaterials 2023, 13(19), 2672; https://doi.org/10.3390/nano13192672 - 29 Sep 2023

Cited by 1 | Viewed by 1157

Abstract

The interaction between metal particles and the oxide support, the so-called metal–support interaction, plays a critical role in the performance of heterogenous catalysts. Probing the dynamic evolution of these interactions under reactive gas atmospheres is crucial to comprehending the structure–performance relationship and eventually [...] Read more.

The interaction between metal particles and the oxide support, the so-called metal–support interaction, plays a critical role in the performance of heterogenous catalysts. Probing the dynamic evolution of these interactions under reactive gas atmospheres is crucial to comprehending the structure–performance relationship and eventually designing new catalysts with enhanced properties. Cobalt supported on TiO₂ (Co/TiO₂) is an industrially relevant catalyst applied in Fischer−Tropsch synthesis. Although it is widely acknowledged that Co/TiO₂ is restructured during the reaction process, little is known about the impact of the specific gas phase environment at the material’s surface. The combination of soft and hard X-ray photoemission spectroscopies are used to investigate in situ Co particles supported on pure and NaBH₄-modified TiO₂ under H₂, O₂, and CO₂:H₂ gas atmospheres. The combination of soft and hard X-ray photoemission methods, which allows for simultaneous probing of the chemical composition of surface and subsurface layers, is one of the study’s unique features. It is shown that under H₂, cobalt particles are encapsulated below a stoichiometric TiO₂ layer. This arrangement is preserved under CO₂ hydrogenation conditions (i.e., CO₂:H₂), but changes rapidly upon exposure to O₂. The pretreatment of the TiO₂ support with NaBH₄ affects the surface mobility and prevents TiO₂ spillover onto Co particles. Full article

(This article belongs to the Special Issue Transition Metal Complexes and Nanomaterials for Catalysis Application)

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15 pages, 3114 KiB

Open AccessArticle

Nanoparticulate Perovskites for Photocatalytic Water Reduction

by Sven A. Freimann, Catherine E. Housecroft and Edwin C. Constable

Nanomaterials 2023, 13(14), 2094; https://doi.org/10.3390/nano13142094 - 18 Jul 2023

Viewed by 773

Abstract

SrTiO₃ and BaTiO₃ nanoparticles (NPs) were activated using H₂O₂ or aqueous HNO₃, and pristine and activated NPs were functionalized with a 2,2′-bipyridine phosphonic acid anchoring ligand (1), followed by reaction with RuCl₃^. [...] Read more.

SrTiO₃ and BaTiO₃ nanoparticles (NPs) were activated using H₂O₂ or aqueous HNO₃, and pristine and activated NPs were functionalized with a 2,2′-bipyridine phosphonic acid anchoring ligand (1), followed by reaction with RuCl₃^.3H₂O and bpy, RhCl₃^.3H₂O and bpy, or RuCl₃^.3H₂O. The surface-bound metal complex functionalized NPs were used for the photogeneration of H₂ from water, and their activity was compared to related systems using TiO₂ NPs. The role of pH during surface complexation was found to be important. The NPs were characterized using Fourier transform infrared (FTIR) and solid-state absorption spectroscopies, thermogravimetric analysis mass spectrometry (TGA-MS), and matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS), and the dihydrogen generation was analyzed using gas chromatography–mass spectrometry (GC-MS). Our findings indicate that extensively functionalized SrTiO₃ or BaTiO₃ NPs may perform better than TiO₂ NPs for water reduction. Full article

(This article belongs to the Special Issue Transition Metal Complexes and Nanomaterials for Catalysis Application)

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8 pages, 3462 KiB

Open AccessArticle

Photochemical Method for Laser Absorption

by Weiwei Tang, Yinuo Zhang, Xingyu Qi, Yu Duanmu and Yue Yao

Nanomaterials 2022, 12(24), 4384; https://doi.org/10.3390/nano12244384 - 09 Dec 2022

Viewed by 873

Abstract

During the laser application process, laser energy is usually converted into heat energy, causing high temperature, which affects the (high-speed) aircraft in routine flight. A completely novel photochemical method was investigated to potentially minimize the energy effect of the laser beam. Ag nanoparticles/ [...] Read more.

During the laser application process, laser energy is usually converted into heat energy, causing high temperature, which affects the (high-speed) aircraft in routine flight. A completely novel photochemical method was investigated to potentially minimize the energy effect of the laser beam. Ag nanoparticles/

C_{3} N_{4}

were synthesized by an ultra-low temperature reduced deposit method with Ag mean diameters of 5–25 nm for photofixation of

N_{2}

. The absorption performance of laser can be improved by using appropriate charge density and small size Ag metal particles. The energy absorption rate was 7.1% over Ag/

C_{3} N_{4}

(−40) at 5

mJ / {cm}^{2}

of laser energy. Full article

(This article belongs to the Special Issue Transition Metal Complexes and Nanomaterials for Catalysis Application)

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10 pages, 4561 KiB

Open AccessArticle

Revealing the Real Role of Etching during Controlled Assembly of Nanocrystals Applied to Electrochemical Reduction of CO₂

by Tingting Yue, Ying Chang, Haitao Huang, Jingchun Jia and Meilin Jia

Nanomaterials 2022, 12(15), 2546; https://doi.org/10.3390/nano12152546 - 24 Jul 2022

Cited by 1 | Viewed by 1311

Abstract

In recent years, the use of inexpensive and efficient catalysts for the electrocatalytic CO₂ reduction reaction (CO₂RR) to regulate syngas ratios has become a hot research topic. Here, a series of nitrogen-doped iron carbide catalysts loaded onto reduced graphene oxide [...] Read more.

In recent years, the use of inexpensive and efficient catalysts for the electrocatalytic CO₂ reduction reaction (CO₂RR) to regulate syngas ratios has become a hot research topic. Here, a series of nitrogen-doped iron carbide catalysts loaded onto reduced graphene oxide (N-Fe₃C/rGO-H) were prepared by pyrolysis of iron oleate, etching, and nitrogen-doped carbonization. The main products of the N-Fe₃C/rGO-H electrocatalytic reduction of CO₂ are CO and H₂, when tested in a 0.5 M KHCO₃ electrolyte at room temperature and pressure. In the prepared catalysts, the high selectivity (the Faraday efficiency of CO was 40.8%, at −0.3 V), and the total current density reaches ~29.1 mA/cm² at −1.0 V as demonstrated when the mass ratio of Fe₃O₄ NPs to rGO was equal to 100, the nitrogen doping temperature was 800 °C and the ratio of syngas during the reduction process was controlled by the applied potential (−0.2~−1.0 V) in the range of 1 to 20. This study provides an opportunity to develop nonprecious metals for the electrocatalytic CO₂ reduction reaction preparation of synthesis and gas provides a good reference Full article

(This article belongs to the Special Issue Transition Metal Complexes and Nanomaterials for Catalysis Application)

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8 pages, 2590 KiB

Open AccessArticle

The Construct CoSe₂ on Carbon Nanosheets as High Sensitivity Catalysts for Electro-Catalytic Oxidation of Glucose

by Di Wang and Ying Chang

Nanomaterials 2022, 12(3), 572; https://doi.org/10.3390/nano12030572 - 07 Feb 2022

Cited by 6 | Viewed by 1642

Abstract

Seeking an efficient, sensitive, and stable catalyst is crucial for no-enzyme glucose sen-sors to detect glucose content accurately. Herein, we constructed a catalyst of selenide cobalt (CoSe₂) on carbon nanomaterials by auxiliary pyrolysis of sodium chloride. The CoSe₂ on carbon [...] Read more.

Seeking an efficient, sensitive, and stable catalyst is crucial for no-enzyme glucose sen-sors to detect glucose content accurately. Herein, we constructed a catalyst of selenide cobalt (CoSe₂) on carbon nanomaterials by auxiliary pyrolysis of sodium chloride. The CoSe₂ on carbon nanosheets possesses good selectivity and a wide linear range up to 5 mM. Based on its good detection per-formance, the CoSe₂ nanomaterial is expected to be an emerging catalyst for no-enzyme sensors. Full article

(This article belongs to the Special Issue Transition Metal Complexes and Nanomaterials for Catalysis Application)

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17 pages, 5586 KiB

Open AccessArticle

Preparation of Amine-Modified Cu-Mg-Al LDH Composite Photocatalyst

by Qining Wang, Quanwang Yan, Yu Zhao, Jie Ren and Ning Ai

Nanomaterials 2022, 12(1), 127; https://doi.org/10.3390/nano12010127 - 30 Dec 2021

Cited by 6 | Viewed by 2448

Abstract

Cu-Mg-Al layered double hydroxides (LDHs) with amine modification were prepared by an organic combination of an anionic surfactant-mediated method and an ultrasonic spalling method using N-aminoethyl-γ-aminopropyltrimethoxysilane as a grafting agent. The materials were characterized by elemental analysis, XRD, SEM, FTIR, [...] Read more.

Cu-Mg-Al layered double hydroxides (LDHs) with amine modification were prepared by an organic combination of an anionic surfactant-mediated method and an ultrasonic spalling method using N-aminoethyl-γ-aminopropyltrimethoxysilane as a grafting agent. The materials were characterized by elemental analysis, XRD, SEM, FTIR, TGA, and XPS. The effects of the Cu²⁺ content on the surface morphology and the CO₂ adsorption of Cu-Mg-Al LDHs were investigated, and the kinetics of the CO₂ adsorption and the photocatalytic reduction of CO₂ were further analyzed. The results indicated that the amine-modified method and appropriate Cu²⁺ contents can improve the surface morphology, the increase amine loading and the free-amino functional groups of the materials, which were beneficial to CO₂ capture and adsorption. The CO₂ adsorption capacity of Cu-Mg-Al N was 1.82 mmol·g⁻¹ at 30 °C and a 0.1 MPa pure CO₂ atmosphere. The kinetic model confirmed that CO₂ adsorption was governed by both the physical and chemical adsorption, which could be enhanced with the increase of the Cu²⁺ content. The chemical adsorption was suppressed, when the Cu²⁺ content was too high. Cu-Mg-Al N can photocatalytically reduce CO₂ to methanol with Cu²⁺ as an active site, which can significantly improve the CO₂ adsorption and photocatalytic conversion. Full article

(This article belongs to the Special Issue Transition Metal Complexes and Nanomaterials for Catalysis Application)

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15 pages, 4866 KiB

Open AccessArticle

Boron Modified Bifunctional Cu/SiO₂ Catalysts with Enhanced Metal Dispersion and Surface Acid Sites for Selective Hydrogenation of Dimethyl Oxalate to Ethylene Glycol and Ethanol

by Deliang Yang, Runping Ye, Ling Lin, Rong Guo, Peiyu Zhao, Yanchao Yin, Wei Cheng, Wenpeng Yuan and Yuangen Yao

Nanomaterials 2021, 11(12), 3236; https://doi.org/10.3390/nano11123236 - 29 Nov 2021

Cited by 5 | Viewed by 2001

Abstract

Boron (B) promoter modified Cu/SiO₂ bifunctional catalysts were synthesized by sol-gel method and used to produce ethylene glycol (EG) and ethanol (EtOH) through efficient hydrogenation of dimethyl oxalate (DMO). Experimental results showed that boron promoter could significantly improve the catalytic performance by [...] Read more.

Boron (B) promoter modified Cu/SiO₂ bifunctional catalysts were synthesized by sol-gel method and used to produce ethylene glycol (EG) and ethanol (EtOH) through efficient hydrogenation of dimethyl oxalate (DMO). Experimental results showed that boron promoter could significantly improve the catalytic performance by improving the structural characteristics of the Cu/SiO₂ catalysts. The optimized 2B-Cu/SiO₂ catalyst exhibited excellent low temperature catalytic activity and long-term stability, maintaining the average EG selectivity (Sel._EG) of 95% at 190 °C, and maintaining the average EtOH selectivity (Sel._EtOH) of 88% at 260 °C, with no decrease even after reaction of 150 h, respectively. Characterization results revealed that doping with boron promoter could significantly increase the copper dispersion, enhance the metal-support interaction, maintain suitable Cu⁺/(Cu⁺ + Cu⁰) ratio, and diminish metallic copper particles during the hydrogenation of DMO. Thus, this work introduced a bifunctional boron promoter, which could not only improve the copper dispersion, reduce the formation of bulk copper oxide, but also properly enhance the acidity of the sample surface, so that the Cu/SiO₂ sample could exhibit superior EG selectivity at low temperature, as well as improving the EtOH selectivity at high temperature. Full article

(This article belongs to the Special Issue Transition Metal Complexes and Nanomaterials for Catalysis Application)

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Review

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20 pages, 42671 KiB

Open AccessReview

Transition Metal Nitrides for Electrocatalytic Application: Progress and Rational Design

by Zihan Meng, Shuhong Zheng, Ren Luo, Haibo Tang, Rui Wang, Ruiming Zhang, Tian Tian and Haolin Tang

Nanomaterials 2022, 12(15), 2660; https://doi.org/10.3390/nano12152660 - 03 Aug 2022

Cited by 11 | Viewed by 2404

Abstract

The energy crisis and environmental issues are becoming more severe due to the long-term consumption of fossil fuels. Therefore, novel energy-conversion devices with high energy density and environmental friendliness are expected to provide reliable alternatives to traditional fossil-based energy systems. However, because of [...] Read more.

The energy crisis and environmental issues are becoming more severe due to the long-term consumption of fossil fuels. Therefore, novel energy-conversion devices with high energy density and environmental friendliness are expected to provide reliable alternatives to traditional fossil-based energy systems. However, because of the inevitable use of costly precious metals as the electrode catalysts for such devices, their popularization is seriously hindered. Transition metal nitrides (TMNs) exhibit similar surface and adsorption properties to noble metals because the atomic distance between metal atoms increases and the d-band center of metal atoms downshifts after nitrogen atoms enter the metal lattice. TMNs have become one of the best electrode materials to replace noble metal-based electrocatalysts in next-generation energy-storage and energy-conversion devices. In this review, the recent developments in the electrocatalytic application of TMNs are covered. First, we discuss the structure and activity origin of TMNs and introduce the common synthesis methods for the preparation of TMNs. Subsequently, we illustrate the applications of mono-metallic TMNs and multi-metallic TMNs in oxygen-reduction reaction, oxygen-evolution reaction, and bifunctional oxygen reduction and evolution reactions. Finally, we summarize the challenges of TMNs encountered at the present stage, and expect their future development. Full article

(This article belongs to the Special Issue Transition Metal Complexes and Nanomaterials for Catalysis Application)

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