Research

Jump to: Review

12 pages, 2713 KiB

Open AccessFeature PaperArticle

Efficient Photocatalytic Core–Shell Synthesis of Titanate Nanowire/rGO

by Xiaofang Ye, Yang Tian, Mengyao Gao, Fangjun Cheng, Jinshen Lan, Han Chen, Mark Lanoue, Shengli Huang and Z. Ryan Tian

Catalysts 2024, 14(4), 218; https://doi.org/10.3390/catal14040218 - 22 Mar 2024

Viewed by 907

Abstract

Wide bandgap semiconductor-based photocatalysts are usually limited by their low solar energy conversion efficiency due to their limited absorption solar wavelength, their rapid surface recombination of the photogenerated electron–hole pairs, and their low charge-carrier mobility. Here, we report a novel stepwise solution synthesis [...] Read more.

Wide bandgap semiconductor-based photocatalysts are usually limited by their low solar energy conversion efficiency due to their limited absorption solar wavelength, their rapid surface recombination of the photogenerated electron–hole pairs, and their low charge-carrier mobility. Here, we report a novel stepwise solution synthesis for achieving a new photocatalytic core–shell consisting of a titanate nanowire/reduced graphene oxide shell (or titanate/rGO) 1D-nanocomposite. The new core–shell nanocomposite maximized the specific surface area, largely reduced the charge transfer resistance and reaction energy barrier, and significantly improved the absorption of visible light. The core–shell nanocomposites’ large on/off current ratio and rapid photo-responses boosted the photocurrent by 30.0%, the photocatalysis rate by 50.0%, and the specific surface area by 16.4% when compared with the results for the pure titanate nanowire core. Our numerical simulations support the effective charge separation on the new core–shell nanostructure, which can help further advance the novel photocatalysis. Full article

(This article belongs to the Special Issue Surface Microstructure Design for Advanced Catalysts)

► Show Figures

Figure 1

17 pages, 11501 KiB

Open AccessFeature PaperArticle

Estimating the Anti-Viral Performance of Photocatalytic Materials: The Correlation between Air Purification Efficiency and Severe Acute Respiratory Syndrome Coronavirus 2 Inactivation

by Tsuyoshi Ochiai, Takeshi Nagai, Kengo Hamada, Tomoyuki Tobe, Daisuke Aoki, Kayano Sunada and Hitoshi Ishiguro

Catalysts 2024, 14(3), 163; https://doi.org/10.3390/catal14030163 - 23 Feb 2024

Viewed by 1620

Abstract

The coronavirus disease 2019 pandemic has increased the demand for anti-viral products. Photocatalytic materials are used to develop coatings and air purifiers that inactivate severe acute respiratory syndrome coronavirus 2. However, the methods for evaluating the anti-viral performance of photocatalytic materials are time-consuming. [...] Read more.

The coronavirus disease 2019 pandemic has increased the demand for anti-viral products. Photocatalytic materials are used to develop coatings and air purifiers that inactivate severe acute respiratory syndrome coronavirus 2. However, the methods for evaluating the anti-viral performance of photocatalytic materials are time-consuming. To address this problem, herein, we propose a screening test for the anti-viral performance of photocatalytic materials based on the ‘acetaldehyde decomposition test’—an air purification efficiency test used to evaluate the decomposition performance of photocatalytic materials. This test is suitable for screening multiple samples and conditions in a short period. The temporal variation in the acetaldehyde concentration was approximated using an exponential function, similar to the temporal variation in the viral infection values. Thereafter, the slope of the regression line for the acetaldehyde concentration over time was used as an indicator in the screening tests. When the anti-viral performance and acetaldehyde decomposition tests were conducted on the same photocatalytic material, a correlation was observed between the slopes of the regression lines. Overall, the proposed screening test shows good potential for evaluating the anti-viral performance of photocatalytic materials. Full article

(This article belongs to the Special Issue Surface Microstructure Design for Advanced Catalysts)

► Show Figures

Graphical abstract

15 pages, 2794 KiB

Open AccessArticle

Mechanism of Selective Qβ Bacteriophage Inactivation under the Presence of E. Coli Using Ground Rh-Doped SrTiO₃ Photocatalyst

by Sho Usuki, Shingo Machida, Ken-ichi Katsumata, Makoto Ogawa, Sanjay S. Latthe, Shanhu Liu, Kenji Yamatoya and Kazuya Nakata

Catalysts 2024, 14(2), 94; https://doi.org/10.3390/catal14020094 - 24 Jan 2024

Viewed by 954

Abstract

Photocatalysts have recently attracted attention for removing infectious-disease-causing bacteria and viruses. Among such photocatalysts, ground Rh-doped SrTiO₃ (“g-STO:Rh”) has been found to have biospecificity that reduces the Qβ phage infectivity under conditions that did not decrease the E. coli survival rate. Elucidating [...] Read more.

Photocatalysts have recently attracted attention for removing infectious-disease-causing bacteria and viruses. Among such photocatalysts, ground Rh-doped SrTiO₃ (“g-STO:Rh”) has been found to have biospecificity that reduces the Qβ phage infectivity under conditions that did not decrease the E. coli survival rate. Elucidating the mechanism of selective antiphage activation is important for developing photocatalysts that act effectively against specific microorganisms. In this study, SDS-PAGE and quantitative PCR showed that a g-STO:Rh-treated Qβ phage preferentially inactivated the A2 protein involved in attachment to host cells. The analysis of the photocatalyst-treated ovalbumin using g-STO:Rh indicated that the protein’s isoelectric point significantly influenced the initial interaction with g-STO:Rh. However, once the protein is absorbed, it was decomposed without the release of intermediates. Furthermore, an inactivation assay for four different phages by photocatalyst treatment using g-STO:Rh revealed that phages with positively charged proteins are highly susceptible to inactivation, and the accessibility of critical components to g-STO:Rh influences susceptibility. We conclude that the selective antiphage activation of g-STO:Rh depends on the adsorption efficiency of the protein and g-STO:Rh. Full article

(This article belongs to the Special Issue Surface Microstructure Design for Advanced Catalysts)

► Show Figures

Graphical abstract

10 pages, 2211 KiB

Open AccessFeature PaperArticle

Phase Transformation of Zr-Modified LaNiO₃ Perovskite Materials: Effect of CO₂ Reforming of Methane to Syngas

by Tatiparthi Vikram Sagar, Nakka Lingaiah, Potharaju S. Sai Prasad, Nataša Novak Tušar and Urška Lavrenčič Štangar

Catalysts 2024, 14(1), 91; https://doi.org/10.3390/catal14010091 - 22 Jan 2024

Cited by 1 | Viewed by 985

Abstract

Zr-modified LaNiO₃ catalysts (LaNi_xZr_1−xO₃; 0 ≤ x ≤ 1) are synthesized by the sol–gel method. The physio-chemical properties of materials are investigated using different characterization techniques and evaluated for the CO₂ reforming of methane to [...] Read more.

Zr-modified LaNiO₃ catalysts (LaNi_xZr_1−xO₃; 0 ≤ x ≤ 1) are synthesized by the sol–gel method. The physio-chemical properties of materials are investigated using different characterization techniques and evaluated for the CO₂ reforming of methane to syngas. Interestingly, the characterization studies revealed the phase transformation from La-Zr pyrochlore to La-Ni perovskite depending on the Ni:Zr ratio in the material. The formation of the pyrochlore phase is observed for high-Zr-containing catalysts, thus leading to the production of bulk NiO. The formation of La-Ni perovskite is observed for high-Ni-containing catalysts and the ZrO₂ acted as a support. The formation of La-Ni perovskite supported on ZrO₂ enhanced the Ni dispersion of the catalysts. The high dispersion of Ni enhanced the catalytic activity, and LaNi_0.8Zr_0.2O₃ showed the best performance among all of the studied catalysts in terms of conversions and the H₂/CO ratio. Full article

(This article belongs to the Special Issue Surface Microstructure Design for Advanced Catalysts)

► Show Figures

Figure 1

17 pages, 5285 KiB

Open AccessFeature PaperArticle

Lattice Distortion in Co₃O₄/Mn₃O₄-Guided Synthesis via Carbon Nanotubes for Efficient Lean Methane Combustion

by Xinfang Wei, Ke Yang, Qinghan Zhu, Jinlong Li, Jian Qi and Haiwang Wang

Catalysts 2023, 13(7), 1112; https://doi.org/10.3390/catal13071112 - 17 Jul 2023

Viewed by 762

Abstract

In this paper, with the synergistic effect of C, Co and O elements, and with a one-dimensional carbon nanotube (CNT) as the structure guide agent, a two-dimensional Co₃O₄ nano-sheet with high catalytic activity was prepared, and its catalytic activity was [...] Read more.

In this paper, with the synergistic effect of C, Co and O elements, and with a one-dimensional carbon nanotube (CNT) as the structure guide agent, a two-dimensional Co₃O₄ nano-sheet with high catalytic activity was prepared, and its catalytic activity was further improved by adding a manganese element. By controlling the annealing time, a two-dimensional Co₃O₄-based nano-sheet with a regular arrangement of atoms on the surface was gradually formed during the oxidation process of CNT. Then, the lattice distortion of Co₃O₄ was caused by doping manganese. The interaction between Mn and Co promotes the cycle capacity of Mn/Co redox pair and the generation of reactive oxygen species, which is conducive to an improvement in catalytic activity. Finally, under different catalytic conditions, the 2D Co₃O₄-based catalysts all showed stable catalytic performances, among which methane flow rate had a great influence. When the airspeed was controlled within the range of 42,000 mL·g⁻¹·h⁻¹, the methane conversion rate could still reach 90% (450 °C). Full article

(This article belongs to the Special Issue Surface Microstructure Design for Advanced Catalysts)

► Show Figures

Figure 1

16 pages, 6629 KiB

Open AccessFeature PaperArticle

Atmosphere-Dependent Electron Relaxation of the Ag-Decorated TiO₂ and the Relations with Photocatalytic Properties

by Wenhao Zhao, Liping Wen and Baoshun Liu

Catalysts 2023, 13(6), 970; https://doi.org/10.3390/catal13060970 - 02 Jun 2023

Cited by 2 | Viewed by 893

Abstract

In the current research, the atmosphere effects on the photoinduced electron relaxations of the undecorated TiO₂ and Ag-decorated TiO₂ (Ag/TiO₂) were carefully studied by means of the in situ photoconductance and diffuse reflection measurements. In pure N₂ atmosphere, [...] Read more.

In the current research, the atmosphere effects on the photoinduced electron relaxations of the undecorated TiO₂ and Ag-decorated TiO₂ (Ag/TiO₂) were carefully studied by means of the in situ photoconductance and diffuse reflection measurements. In pure N₂ atmosphere, the results showed that the electron relaxation mainly occurs through the transfer to the residual O₂, and the Ag nanoparticles form a fast electron transfer pathway. It was seen that the apparent activation energy of the electron transfer to O₂ was greatly reduced by the Ag decoration. In the methanol-containing N₂ atmosphere, the electron relaxation can still occur via the transfer to residual O₂ in the case of the undecorated TiO₂, while the relaxation mechanism changes for the Ag/TiO₂ as the relaxations are decreased with the temperatures. It is possible that the methanol molecule adsorbed on the Ag/TiO₂ perimeters could act as the bridge for the recombination of the holes and the electrons stored in the Ag nanoparticles. Reducing the Ag nanoparticle size from 15 nm to 3 nm can greatly increase the electron relaxations due to the increase in Ag dispersion and Ag/TiO₂ interconnection. Although the electron transfer to O₂ was increased, both the photocatalytic oxidations of acetone and isopropanol showed a decrease after the Ag decoration. The results indicated that the photocatalytic oxidation was not limited by the electron transfer to O₂. The increased electron transfer to O₂ contributed to the recombination around the Ag/TiO₂ perimeters, and the photocatalytic activities were decreased. Full article

(This article belongs to the Special Issue Surface Microstructure Design for Advanced Catalysts)

► Show Figures

Graphical abstract

16 pages, 7314 KiB

Open AccessArticle

Facile Construction of Three-Dimensional Heterostructured CuCo₂S₄ Bifunctional Catalyst for Alkaline Water Electrolysis

by Shengnan Li, Pengli Ma, Jishuang Yang, Srinivasan Krishnan, Kannan S. Kesavan, Ruimin Xing and Shanhu Liu

Catalysts 2023, 13(5), 881; https://doi.org/10.3390/catal13050881 - 13 May 2023

Cited by 4 | Viewed by 1221

Abstract

Developing an efficient multi-functional electrocatalyst with high efficiency and low cost to replace noble metals is significantly crucial for the industrial water electrolysis process and for producing sustainable green hydrogen (H₂) fuel. Herein, ultrathin CuCo₂S₄ nanosheets assembled into [...] Read more.

Developing an efficient multi-functional electrocatalyst with high efficiency and low cost to replace noble metals is significantly crucial for the industrial water electrolysis process and for producing sustainable green hydrogen (H₂) fuel. Herein, ultrathin CuCo₂S₄ nanosheets assembled into highly open three-dimensional (3D) nanospheres of CuCo₂S₄ (Cu/Co = 33:67) were prepared by a facile one-pot solvothermal approach and utilized as a bifunctional electrocatalyst for efficient overall water splitting. The as-prepared CuCo₂S₄ is characterized structurally and morphologically; the BET surface area of the CuCo₂S₄ (Cu/Co = 33:67) catalyst was found to have a larger specific surface area (21.783 m²g⁻¹) than that of other catalysts with a Cu/Co ratio of 67:33, 50:50, and 20:80. Benefiting from a highly open structure and ultrathin nanosheets with excellent exposure to catalytically active sites, CuCo₂S₄ (Cu/Co = 33:67) is identified as an efficient catalyst for the proton reduction and oxygen evolution reactions in 1 M KOH with an overpotential of 182 and 274 mV at 10 mA cm⁻², respectively. As expected, a low cell voltage of 1.68 V delivers a current density of 10 mA cm⁻². Stability and durability are also greatly enhanced under harsh alkaline conditions. Therefore, this work provides a simple strategy for the rational design of spinel-based transition metal sulfide catalysts for electrocatalysis. Full article

(This article belongs to the Special Issue Surface Microstructure Design for Advanced Catalysts)

► Show Figures

Graphical abstract

12 pages, 4762 KiB

Open AccessArticle

Photocatalytic Degradation of Diclofenac in Tap Water on TiO₂ Nanotubes Assisted with Ozone Generated from Boron-Doped Diamond Electrode

by Daichuan Ma, Xianying Han, Xinsheng Li and Daibing Luo

Catalysts 2023, 13(5), 877; https://doi.org/10.3390/catal13050877 - 12 May 2023

Viewed by 1178

Abstract

Degradation of pharmaceuticals in water by TiO₂ photocatalysis often suffers from low efficiency due to low activity and mass transfer limitation. In this work, diclofenac removal in tap water was performed by photocatalysis on TiO₂ nanotube growth on Ti mesh substrate [...] Read more.

Degradation of pharmaceuticals in water by TiO₂ photocatalysis often suffers from low efficiency due to low activity and mass transfer limitation. In this work, diclofenac removal in tap water was performed by photocatalysis on TiO₂ nanotube growth on Ti mesh substrate assisted by ozone (O₃), which was generated from a hole-arrayed boron-doped diamond (HABDD) film electrode. The vertically oriented TiO₂ nanotubes were used as the heterogeneous photocatalyst. The HABDD, as a self-standing diamond electrode, was designed and custom-made by MWCVD technology. The microstructures and crystalline of the TiO₂ nanotubes and HABDD were characterized by a scanning electronic micrograph (SEM) and X-ray diffraction (XRD). Unlike other ozone generation methods, direct generation of ozone in the flowing water was applied in the photocatalysis process, and its effect was discussed. The diclofenac removal performance of the electrochemical-photocatalytic system was studied depending on O₃ generation efficiency, flowing rate, and the initial diclofenac concentration. The enhanced degradation effect from O₃ molecules on TiO₂ photocatalysis was attributed to the larger active surface area, the increased photo-generated charge separation rate, and the contact area of O₃. The degradation efficiency in the combined electrochemical-photocatalytic TiO₂/O₃/UV system was higher than that of the O₃/UV and TiO₂/UV routes individually. Furthermore, a theoretical calculation was used to analyze the TiO₂/O₃ interface in aqueous media in terms of the final energy. This system created an almost in situ feeding channel of oxidants in the TiO₂ photocatalysis process, thus increasing photocatalytic efficiency. This synergetic system is promising in the treatment of pharmaceuticals in water. Full article

(This article belongs to the Special Issue Surface Microstructure Design for Advanced Catalysts)

► Show Figures

Figure 1

16 pages, 4124 KiB

Open AccessArticle

The Effect of Cu(II) Nanoparticle Decoration on the Electron Relaxations and Gaseous Photocatalytic Oxidations of Nanocrystalline TiO₂

by Binshan Zhao, Liping Wen, Li Xu, Xiujian Zhao and Baoshun Liu

Catalysts 2023, 13(3), 550; https://doi.org/10.3390/catal13030550 - 09 Mar 2023

Cited by 2 | Viewed by 1201

Abstract

A photocatalytic effect arises from the electron relaxation of semiconductors. Directing the electron relaxation toward photocatalytic reactions is the focus of photocatalytic studies. Co-catalyst decoration is a main way to modulate the electron relaxation, and the Cu(II) nanoparticles have been widely studied as [...] Read more.

A photocatalytic effect arises from the electron relaxation of semiconductors. Directing the electron relaxation toward photocatalytic reactions is the focus of photocatalytic studies. Co-catalyst decoration is a main way to modulate the electron relaxation, and the Cu(II) nanoparticles have been widely studied as an important co-catalyst. However, the detailed mechanism is still not well known. The current study is devoted to investigating the effect of the Cu(II) nanoparticle decoration on the electron relaxations for TiO₂ through in situ photochromism and photoconductances, based on which the relation to the photocatalytic properties was discussed. The result shows that the Cu(II)/Cu(0) redox couple assists the double electron transfer from TiO₂ to O₂, while the Cu(I)/Cu(0) redox couple assists the single electron transfer to O₂. Although the Cu(II) decoration changes the mechanism and increases the rate of the electron relaxations, the electron relaxation does not occur via the Cu redox couple assistance. It was found that the electron relaxation kinetics depends on the reduced Cu species, which can be greatly increased when the Cu(II) was reduced to Cu(0). It is also revealed that the electron relaxation corresponds to the electron transfer from TiO₂ to O₂, but it does not occur through the Cu redox couple assistance. The result also shows that the increase in the electron relaxation is mainly directed toward the recombination rather than photocatalytic reactions. The present research gains some insights on the role of the co-catalysts in the electron relaxations and its relation to photocatalysis; this should be meaningful for designing novel photocatalytic materials. Full article

(This article belongs to the Special Issue Surface Microstructure Design for Advanced Catalysts)

► Show Figures

Figure 1

12 pages, 2706 KiB

Open AccessArticle

Efficient and Stable O-Methylation of Catechol with Dimethyl Carbonate over Aluminophosphate Catalysts

by Baoqin Wu, Yao Sheng, Linkai Zhou, Runduo Hong, Lifan Zhang, Xinfeng Ren, Xiujing Zou, Xingfu Shang, Xionggang Lu and Xueguang Wang

Catalysts 2023, 13(1), 150; https://doi.org/10.3390/catal13010150 - 09 Jan 2023

Viewed by 1702

Abstract

The O-methylation of catechol is an effective method for the industrial production of guaiacol used as an important chemical. However, the low catechol conversion and poor catalyst stability are the most critical issues that need to be addressed. Herein, the O-methylation [...] Read more.

The O-methylation of catechol is an effective method for the industrial production of guaiacol used as an important chemical. However, the low catechol conversion and poor catalyst stability are the most critical issues that need to be addressed. Herein, the O-methylation of catechol with dimethyl carbonate was investigated over aluminophosphate (APO) catalysts, using a continuous-flow system to produce guaiacol. APO catalysts were synthesized with varying P/Al molar ratios and calcination temperatures to study their effects on catalytic performance for the reaction. The physico-chemical properties of the APO catalysts were thoroughly investigated using XRD, NH₃-TPD, CO₂-TPD, FTIR, and Py-FTIR. The P/Al molar ratio and catalyst calcination temperature significantly influenced the structure and texture, as well as the surface acid-base properties of APO. Both the medium acid and medium base sites were observed over APO catalysts, and the Lewis acid sites acted as the main active sites. The APO (P/Al = 0.7) exhibited the highest catalytic activity and excellent stability, due to the suitable medium acid-base pairs. Full article

(This article belongs to the Special Issue Surface Microstructure Design for Advanced Catalysts)

► Show Figures

Graphical abstract

Review

Jump to: Research

19 pages, 2597 KiB

Open AccessFeature PaperReview

Research Progress in Fuel Oil Production by Catalytic Pyrolysis Technologies of Waste Plastics

by Liu An, Zonglan Kou, Renjie Li and Zhen Zhao

Catalysts 2024, 14(3), 212; https://doi.org/10.3390/catal14030212 - 21 Mar 2024

Viewed by 851

Abstract

Improper disposal of waste plastic has caused serious ecological and environmental pollution problems. Transforming plastics into high value-added chemicals can not only achieve efficient recycling of waste plastics, but is also an effective way to control white pollution. The catalyst selectively breaks the [...] Read more.

Improper disposal of waste plastic has caused serious ecological and environmental pollution problems. Transforming plastics into high value-added chemicals can not only achieve efficient recycling of waste plastics, but is also an effective way to control white pollution. The catalyst selectively breaks the C–C bond of polyolefin plastic under heat treatment and converts it into liquid fuel, thus realizing sustainable recycling of plastics and has a good development prospect. This review provides a detailed overview of the current development of catalytic pyrolysis, catalytic hydrolysis, solvent decomposition, and supercritical hydrothermal liquefaction for cracking plastics to make fuel oil. The reaction mechanism, influencing factors, and promoting effects of catalysts in various degradation technologies are analyzed and summarized, and the latest proposed tandem reaction for degrading plastics is briefly introduced. Finally, some optimization paths of waste plastic pyrolysis to fuel oil technology are proposed: synergies between mixed raw materials, in-depth exploration of catalysts, design and manufacture of reactors that match the pyrolysis technology. All these are important research directions for promoting the industrialization of plastic pyrolysis to fuel oil. Full article

(This article belongs to the Special Issue Surface Microstructure Design for Advanced Catalysts)

► Show Figures

Graphical abstract

26 pages, 5985 KiB

Open AccessFeature PaperReview

Solution Plasma for Surface Design of Advanced Photocatalysts

by Rui Wang, Changhua Wang, Yanmei Xing and Xintong Zhang

Catalysts 2023, 13(7), 1124; https://doi.org/10.3390/catal13071124 - 19 Jul 2023

Cited by 1 | Viewed by 1149

Abstract

Rational design of the surface of photocatalysts can conveniently modulate the photo-stimulated charge separation, influence the surface reaction kinetics, and other pivotal factors in the photocatalytic processes for efficient photocatalysis. Solution plasma, holding promise for mild modification of the surface structure of materials, [...] Read more.

Rational design of the surface of photocatalysts can conveniently modulate the photo-stimulated charge separation, influence the surface reaction kinetics, and other pivotal factors in the photocatalytic processes for efficient photocatalysis. Solution plasma, holding promise for mild modification of the surface structure of materials, has recently been recognized as an emerging technology for surface engineering of high-performance photocatalysts. In this review, we will briefly introduce the fundamentals of solution plasma and its applications in materials preparation and summarize the recent research progress in the surface design of advanced photocatalysts by solution plasma. Lastly, we will indicate some possible new directions. This review is expected to provide an instructive guideline for the surface design of heterogeneous photocatalysts by solution plasma. Full article

(This article belongs to the Special Issue Surface Microstructure Design for Advanced Catalysts)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Surface Microstructure Design for Advanced Catalysts

Share This Special Issue

Special Issue Editors

Special Issue Information

Keywords

Published Papers (12 papers)

Research

Review

Further Information

Guidelines

MDPI Initiatives

Follow MDPI