Computational Study of Reactive and Coke-Resistant Catalysts for the Dry Reforming Reaction of Methane

The dry reforming reaction of methane (DRR) is one of the solutions utilized to deal with the global warming via the catalyzed reaction of the main greenhouse gas: carbon dioxide (COv2) with methane (CHv4), to produce the syngas of carbon monoxide (CO) and hydrogen (Hv2). Although it is a promising process, catalyst deactivation via coking shortens the life of catalysts and increases the cost of catalyst regeneration/replacement, both of which are important concerns. Hence, the search for catalysts of high activity and coke-resistance is the main goal. In this work, we feature a two-step procedure comprising the analysis and design of active and coke-resistant Ni-based DRR catalysts by employing computational techniques. These techniques include density functional theory (DFT) coupled to the ratings concept developed as a catalysts screening tool. The approach aims to investigate reaction and coking schemes prior to the setup of design criteria for such catalysts. The ratings concept is introduced as a screening tool to identify active and stable DRR catalysts via the interpretation of stability and reactivity ratings (RT-S and RT-R). The concept was then extended for practical applications, where reliable predictions of coke formation and removal rates are demonstrated. Such predictions emerge from the interpretation of experimental apparent activation energy values of Pt and Rh supported catalysts. The predicted trend of coking agrees well with the trend of coke deposition measured via temperature-programmed hydrogenation and temperature-programmed oxidation of these catalysts. Furthermore, optimal operating conditions are determined. Four strategies are proposed based on four types of DRR catalysts. In addition, the surface transformation entailing the interchange between Ni metallic, oxide and carbide during the DRR is studied since the control over these transformations is proposed to be the key factor for tuning the performance of DRR catalysts. Ternary contour plots are used for determining reactive and coke-resistant surface compositions. It is concluded that the surface composition for coke-resistant Ni-based DRR catalysts should consist of less than 10 % carbide and at least 75 % metallic. Finally, the design procedure and criteria for high performance DRR catalysts are discussed, where the control synthesis towards the Ni(111) as the dominant surface together with the control of surface transformation from metallic to carbide is proposed to be the main key

Electrocatalytic overall water splitting based on (ZnNiCoFeY)xOy high-entropy oxide supported on MoS2

Hydrogen energy is a sustainable and clean source that can meet global energy demands without adverse environmental impacts. High-entropy oxides (HEOs), multielement (5 or more) oxides with an equiatomic or near-equatomic elemental composition, offer a novel approach to designing bifunctional electrocatalysts. This work explores (ZnNiCoFeY)xOy over MoS2 as a bifunctional electrocatalyst (HEO–MoS2) in an alkaline medium. The HEO was synthesized using a combustion process and loaded over MoS2 using an ultrasonic method. The synthesized HEO over MoS2 exhibits excellent performance, including long-term stability for over 24 h, an overpotential of 214 mV vs the reversible hydrogen electrode (RHE) for the hydrogen evolution reaction (HER), and 308 mV for the oxygen evolution reaction (OER) at 10 mA cm−2. This bifunctional electrocatalyst exhibits low overpotential for both the HER and the OER at high current densities. Additionally, HEO–MoS2 demonstrates smaller solution and charge transfer resistance values. The electrolyzer was assembled using bifunctional HEO–MoS2 electrodes for overall water splitting. These electrodes exhibited a low cell voltage of 1.65 V at 10 mA cm−2. The novel electrocatalyst was fabricated using a facile and scalable method that appeals to industrial applications

Computational Study of Reactive and Coke-Resistant Catalysts for the Dry Reforming Reaction of Methane

The dry reforming reaction of methane (DRR) is one of the solutions utilized to deal with the global warming via the catalyzed reaction of the main greenhouse gas: carbon dioxide (COv2) with methane (CHv4), to produce the syngas of carbon monoxide (CO) and hydrogen (Hv2). Although it is a promising process, catalyst deactivation via coking shortens the life of catalysts and increases the cost of catalyst regeneration/replacement, both of which are important concerns. Hence, the search for catalysts of high activity and coke-resistance is the main goal. In this work, we feature a two-step procedure comprising the analysis and design of active and coke-resistant Ni-based DRR catalysts by employing computational techniques. These techniques include density functional theory (DFT) coupled to the ratings concept developed as a catalysts screening tool. The approach aims to investigate reaction and coking schemes prior to the setup of design criteria for such catalysts. The ratings concept is introduced as a screening tool to identify active and stable DRR catalysts via the interpretation of stability and reactivity ratings (RT-S and RT-R). The concept was then extended for practical applications, where reliable predictions of coke formation and removal rates are demonstrated. Such predictions emerge from the interpretation of experimental apparent activation energy values of Pt and Rh supported catalysts. The predicted trend of coking agrees well with the trend of coke deposition measured via temperature-programmed hydrogenation and temperature-programmed oxidation of these catalysts. Furthermore, optimal operating conditions are determined. Four strategies are proposed based on four types of DRR catalysts. In addition, the surface transformation entailing the interchange between Ni metallic, oxide and carbide during the DRR is studied since the control over these transformations is proposed to be the key factor for tuning the performance of DRR catalysts. Ternary contour plots are used for determining reactive and coke-resistant surface compositions. It is concluded that the surface composition for coke-resistant Ni-based DRR catalysts should consist of less than 10 % carbide and at least 75 % metallic. Finally, the design procedure and criteria for high performance DRR catalysts are discussed, where the control synthesis towards the Ni(111) as the dominant surface together with the control of surface transformation from metallic to carbide is proposed to be the main key

Computational Study of Reactive and Coke-Resistant Catalysts for the Dry Reforming Reaction of Methane

The dry reforming reaction of methane (DRR) is one of the solutions utilized to deal with the global warming via the catalyzed reaction of the main greenhouse gas: carbon dioxide (COv2) with methane (CHv4), to produce the syngas of carbon monoxide (CO) and hydrogen (Hv2). Although it is a promising process, catalyst deactivation via coking shortens the life of catalysts and increases the cost of catalyst regeneration/replacement, both of which are important concerns. Hence, the search for catalysts of high activity and coke-resistance is the main goal. In this work, we feature a two-step procedure comprising the analysis and design of active and coke-resistant Ni-based DRR catalysts by employing computational techniques. These techniques include density functional theory (DFT) coupled to the ratings concept developed as a catalysts screening tool. The approach aims to investigate reaction and coking schemes prior to the setup of design criteria for such catalysts. The ratings concept is introduced as a screening tool to identify active and stable DRR catalysts via the interpretation of stability and reactivity ratings (RT-S and RT-R). The concept was then extended for practical applications, where reliable predictions of coke formation and removal rates are demonstrated. Such predictions emerge from the interpretation of experimental apparent activation energy values of Pt and Rh supported catalysts. The predicted trend of coking agrees well with the trend of coke deposition measured via temperature-programmed hydrogenation and temperature-programmed oxidation of these catalysts. Furthermore, optimal operating conditions are determined. Four strategies are proposed based on four types of DRR catalysts. In addition, the surface transformation entailing the interchange between Ni metallic, oxide and carbide during the DRR is studied since the control over these transformations is proposed to be the key factor for tuning the performance of DRR catalysts. Ternary contour plots are used for determining reactive and coke-resistant surface compositions. It is concluded that the surface composition for coke-resistant Ni-based DRR catalysts should consist of less than 10 % carbide and at least 75 % metallic. Finally, the design procedure and criteria for high performance DRR catalysts are discussed, where the control synthesis towards the Ni(111) as the dominant surface together with the control of surface transformation from metallic to carbide is proposed to be the main key

Computational Study of Reactive and Coke-Resistant Catalysts for the Dry Reforming Reaction of Methane

The dry reforming reaction of methane (DRR) is one of the solutions utilized to deal with the global warming via the catalyzed reaction of the main greenhouse gas: carbon dioxide (COv2) with methane (CHv4), to produce the syngas of carbon monoxide (CO) and hydrogen (Hv2). Although it is a promising process, catalyst deactivation via coking shortens the life of catalysts and increases the cost of catalyst regeneration/replacement, both of which are important concerns. Hence, the search for catalysts of high activity and coke-resistance is the main goal. In this work, we feature a two-step procedure comprising the analysis and design of active and coke-resistant Ni-based DRR catalysts by employing computational techniques. These techniques include density functional theory (DFT) coupled to the ratings concept developed as a catalysts screening tool. The approach aims to investigate reaction and coking schemes prior to the setup of design criteria for such catalysts. The ratings concept is introduced as a screening tool to identify active and stable DRR catalysts via the interpretation of stability and reactivity ratings (RT-S and RT-R). The concept was then extended for practical applications, where reliable predictions of coke formation and removal rates are demonstrated. Such predictions emerge from the interpretation of experimental apparent activation energy values of Pt and Rh supported catalysts. The predicted trend of coking agrees well with the trend of coke deposition measured via temperature-programmed hydrogenation and temperature-programmed oxidation of these catalysts. Furthermore, optimal operating conditions are determined. Four strategies are proposed based on four types of DRR catalysts. In addition, the surface transformation entailing the interchange between Ni metallic, oxide and carbide during the DRR is studied since the control over these transformations is proposed to be the key factor for tuning the performance of DRR catalysts. Ternary contour plots are used for determining reactive and coke-resistant surface compositions. It is concluded that the surface composition for coke-resistant Ni-based DRR catalysts should consist of less than 10 % carbide and at least 75 % metallic. Finally, the design procedure and criteria for high performance DRR catalysts are discussed, where the control synthesis towards the Ni(111) as the dominant surface together with the control of surface transformation from metallic to carbide is proposed to be the main key

Antimicrobial properties dependence on the composition and architecture of copper-alumina coatings prepared by plasma electrolytic oxidation (PEO)

This study presents environmentally friendly and low-cost synthetic routes to produce antimicrobial coatings over 5052 Al alloy based on plasma electrolytic oxidation (PEO) technology. Two methodologies were explored: the decoration with copper and anodic doping with copper ions. The porous oxide layers produced in silicate media presented two porous layers consisting of γ-Al2O3 crystalline phase and amorphous phases of aluminosilicate, silica, and Al(OH)3. Small amounts of copper (&lt;0.3 at.%) were detected in the PEO films. In the Cu-decorated film, copper clusters composed of Cu0 and Cu2+ species were observed visually as small black dots on the surface. In the Cu-doped film, the Cu2+ and Cu+ species were homogeneously distributed on the surface. The copper content affected the corrosion performance in aggressive corrosive media. The PEO coatings showed a remarkable antimicrobial activity after 24 h in standard tests. The antimicrobial effectiveness of the Cu-decorated sample was higher against S. aureus, while the Cu-doped sample was more effective against E. coli. The results demonstrated that differences in the PEO coating architecture can affect the material composition and, consequently, the bacterial inactivation mechanism. These findings can serve as a guide to tailor aluminum alloys for specific antimicrobial surfaces.</p

Photooxidation and Virus Inactivation using TiO2(P25)–SiO2 Coated PET Film

This study chemically modified PET film surface with P25 using silicate as a binder. Different P25–binder ratios were optimized for the catalyst performance. The modified samples were analyzed by scanning electron microscopy-energy-dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy. Diffuse reflectance UV-vis spectra revealed significant reductions in the band gaps of the P25 solid precursor (3.20 eV) and the surface-modified PET–1.0Si–P25 (2.77 eV) with visible light. Accordingly, under visible light conditions, catalyst activity on the film will occur. Additionally, the film’s performance was evaluated using methylene blue (MB) degradation. Pseudo-first-order-rate constants (min−1), conversion percentages, and rates (µg.mL−1.gcat−1.h−1) were determined. The coated films were evaluated for viral Phi–X 174 inactivation and tested with fluorescence and UV-C light illumination, then log (N/N0) versus t plots (N = [virus] in plaque-forming units [PFUs]/mL) were obtained. The presence of nanosilica in PET showed a high adsorption ability in both MB and Phi–X 174, whereas the best performances with fluorescent light were obtained from PET–1.0Si–P25 and PET–P25–1.0Si–SiO2 equally. A 0.2-log virus reduction was obtained after 3 h at a rate of 4×106 PFU.mL−1.gcat−1.min−1. Additionally, the use of this film for preventing transmission by direct contact with surfaces and via indoor air was considered. Using UV light, the PET–1.0Si–P25 and PET–1.0Si–P25–SiO2 samples produced a 2.5-log inactivation after 6.5 min at a rate of 9.6×106 and 8.9×106 PFU.mL−1.gcat−1.min−1, respectively. Copyright © 2022 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Simple, controllable and environmentally friendly synthesis of FeCoNiCuZn-based high-entropy alloy (HEA) catalysts, and their surface dynamics during nitrobenzene hydrogenation

High-entropy alloys (HEAs) have rapidly become one of the hottest research topics in several fields, including materials science, corrosion technology, and catalysis because of their multiple advantages and their potential applications. In this study, using a novel straightforward electroless deposition method, multi-elemental alloys (FeCoNiCuZn) supported on graphite were prepared with controlled metal loading (HEA/g-X; X = 40, 80, 100) without any high temperature post-treatments. These materials were characterized using scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction, and showed a composition ranging from 11 at.% to 31 at.% for each metallic element, a total metal loading varying from 1.3 to 5.2 at.% (5.9 to 21.5 wt.%), homogeneous distribution, and an amorphous structure. Electrochemical impedance spectroscopy, cyclic voltammetry, linear sweep voltammetry, and chronoamperometry were used to evaluate the surface dynamics and the effect of the solution pH during the electrochemical hydrogenation of nitrobenzene using the HEA/g-40 material. The nitrobenzene conversion (&gt;9 mmolNB gcat-1 h−1) and aniline production (≈ 4 mmolAN gcat-1 h−1) rates in Na2SO4 solution (at −1.0 V vs. Ag/AgCl) demonstrated a strong dependence on the applied potential. After comparing the results in alkaline medium (KOH), a competitive adsorption of species (nitrobenzene and H2O) was observed, showing a synergistic effect that greatly improved the selectivity of the nitrobenzene hydrogenation to aniline, from 23% in Na2SO4 to an outstanding 94% in KOH at the same applied potential, surpassing the results of a platinum electrode (34% in KOH). These results provide insightful information regarding the nature of the active sites involved in each step of the reaction mechanism, and gives useful means to develop new, tailored multifunctional HEA electrocatalyst materials.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Micro and Nano Engineerin

On the CO2 photocatalytic reduction over indium tin oxide (ITO) ultra-thin films in water vapor: Experimental and theoretical study

Artificial photosynthesis that converts CO2 and H2O into compounds with added value is a viable method for reducing atmospheric CO2 concentration. In this study, we investigated the photocatalytic activity of ultrathin indium tin oxide (ITO) films on rigid and flexible substrates for CO2 reduction in water vapor and batch and flow setups. To explain a viable reaction mechanism for the 2760 ± 10 % μmol.gcat-1.hr-1 production rate achieved in a continuous reaction system, several theoretical models were developed. According to DFT simulation results, oxygen vacancy might be regarded as the main reaction site for CO2 to CO conversion. Moreover, a viable reaction pathway leading to CH4 formation is proposed. The catalyst’s lower rate of CO2 reduction in the batch reactor as compared with the flow reactor was justified via surface affinity simulation. Our findings highlight the significance of the catalyst’s structural design and reaction media configuration for stability and high activity

First-Principles Density Functional Theory and Machine Learning Technique for the Prediction of Water Adsorption Site on PtPd-Based High-Entropy-Alloy Catalysts

The water-gas shift reaction (WGSR) is employed in industry to obtain high-purity H-2 from syngas, where H2O adsorption is an important step that controls H2O dissociation in WGSR. Therefore, exploring catalysts exhibiting strong H2O adsorption energy (E-ads) is crucial. Also, high-entropy alloys (HEA) are promising materials utilized as catalysts, including in WGSR. The PtPd-based HEA catalysts are explored via density functional theory (DFT) and Gaussian process regression. The input features are based on the microstructure data and electronic properties: d-band center (epsilon(d)) and Bader net atomic charge (delta). The DFT calculation reveals that the epsilon(d) and delta of each active site of all HEA surfaces are broadly scattered, indicating that the electronic properties of each atom on HEA are non-uniform and influenced by neighboring atoms. The strong H2O-active-site interaction determined by a highly negative E-ads is used as a criterion to explore good PtPd-based WGSR catalyst candidates. As a result, the potential candidates are found to have Co, Ru, and Fe as an H2O adsorption site with Ag as a neighboring atom, that is, PtPdRhAgCo, PtPdRuAgCo, PtPdRhAgFe, and PtPdRuAgFe.Funding Agencies|Second Century Fund (C2F); Thailand Science Research and Innovation Fund Chulalongkorn University [CU_FRB65_ind (15)_163_21_29, IND66210011]; Research Grants for Talented Young Researchers, National Research Council of Thailand 2022; National Science and Technology Development Agency, Thailand; Asahi Glass Foundation; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoeping University, Faculty Grant SFOMatLiU [2009 00971]; Swedish Foundation for Strategic Research through the Future Research Leaders 6 program [FFL 15-0290]; Swedish Research Council (VR) [2019-05403]; Knut and Alice Wallenberg Foundation, Sweden (Wallenberg Scholar Grant) [KAW-2018.0194]; Swedish Research Council, Sweden [2018-05973]; NSTDA Supercomputer Center (ThaiSC), Thailand</p