Effect Of Metal Doping Research Articles

Producing aromatic‐rich oil through microwave‐assisted catalytic pyrolysis of low‐density polyethylene over Ni/Co/Cu‐doped Ga/ZSM‐5 catalysts

AbstractMicrowave (MW)‐assisted catalytic pyrolysis represents a promising method for transforming petroleum‐based plastic waste into valuable chemicals, offering a pathway towards more sustainable circular economy. In this study, catalytic pyrolysis of low‐density polyethylene (LDPE) was conducted under MW irradiation. The influence of various catalyst types (HZSM‐5, Ga/ZSM‐5, Ga/Ni/ZSM‐5, Ga/Co/ZSM‐5, and Ga/Cu/ZSM‐5) on product yield and distribution was examined. The results revealed that the Ga/ZSM‐5 catalyst yielded the maximum liquid oil, approximately 41%. Ga/Ni/ZSM‐5 performed excellently in the production of long‐chain olefins, constituting about 27% of the liquid fraction. However, Ga/Co/ZSM‐5 led to the production of heavy pyrolysis oil containing nearly 25% long‐chain paraffins, rendering it unsuitable for producing high‐value chemicals. Conversely, the Ga/Cu/ZSM‐5 catalyst yielded an aromatic‐rich pyrolysis oil, with benzene derivatives constituting approximately 90% of the liquid oil fraction, thus proving to be a suitable catalyst for the intended application. The liquid product distribution was compared with a petroleum assay by SimDist, and this suggested that utilizing the HZSM‐5 catalyst could yield an 86.4% naphtha fraction. The study also revealed that the Ga/Cu/ZSM‐5 catalyst generated the largest amounts of hydrogen and syngas, as determined by a MicroGC analysis of the gas products. This catalyst also exhibited the maximum coke deposition (1.35%) postreaction, which was attributed to its high aromatic hydrocarbon content in the pyrolysis oil and maximal hydrogen release. A comparison of fresh and spent catalyst properties was conducted to gain insights into catalyst activity and to correlate the effects of metal doping on product distribution. These findings underscore the potential of MW‐assisted catalytic pyrolysis, particularly with the Ga/Cu/ZSM‐5 catalyst, for the efficient conversion of plastic waste into valuable chemicals, thereby contributing to sustainable resource utilization and environmental conservation.

Efficient low-temperature CO removal from high-humidity sintering flue gas by combination Cu and OMS-2

The non-precious metal manganese-based catalysts currently show insufficient CO catalytic oxidation performance in actual sintering flue gas conditions, with increased water vapor levels causing catalyst deactivation. This study utilized a high-performance manganese dioxide octahedral molecular sieve (OMS-2). The effect of metal doping on the catalytic CO oxidation performance was investigated in preparing OMS-2 using the co-precipitation method. The experiments showed that Cu doping increased CO conversion efficiency more than other metals (Co, Ag, Zn, and Fe), with optimal performance achieved at a 1.91 wt% doping level. Besides, Cu doping significantly enhanced water resistance of the catalyst, enabling effective CO removal in high-humidity conditions. The study observed that Cu ions infiltrated the catalyst framework by substituting some of the Mn ions, creating additional active sites in the form of oxygen vacancies and improving surface oxygen mobility, thereby enhancing the performance of CO catalytic oxidation. Furthermore, Cu doping demonstrated selective absorption of water vapor, with CuxO in the catalyst, effectively adsorbing water vapor and protecting the initial active sites, thereby mitigating water vapor-induced poisoning. Even in 15 vol% H2O at 150 °C, 1.91%Cu-OMS-2 maintained total catalytic activity. Therefore, the co-precipitation method-prepared 1.91%Cu-OMS-2 catalyst holds excellent potential for CO removal in sintering flue gas and shows promise for practical applications.

Thiacalix[4]arene-Stabilized Sb/Ag Bimetallic Nanoclusters: Elucidating the Effects of Sb Doping on Electrocatalytic CO2 Reduction in Ag Clusters.

Accurately identifying the metal doping effects within heterogeneous catalysts presents a formidable challenge due to the complex nature of controlling the interfacial chemistry at the molecular level. Herein, we use two sets of atomically precise nanoclusters to demonstrate the impact of Sb doping on the electrocatalytic CO2 reduction activity in Ag nanoclusters. Leveraging the unique properties of the thiacalix[4]arene, we have pioneered a methodology for incorporating catalytic Ag1+ and Sb3+ sites, culminating in the synthesis of the pioneering Sb-Ag bimetallic cluster, Sb2Ag11. We refined this structure by replacing the two Sb3+ sites with Na+ sites, resulting in a Na2Ag10 cluster. Broadening our investigative scope, we isolated the core components from both Sb2Ag11 and Na2Ag10 and obtained two clusters: Sb2Ag4 and Ag4. The subtle compositional variations between two pairs of structurally analogous clusters, Sb2Ag11 and Na2Ag10, as well as Sb2Ag4 and Ag4, create opportunities to investigate how the Sb doping impacts the catalytic activity of Ag clusters. Clearly, compared to the undoped clusters, those doped with Sb exhibit higher catalytic current densities and enhanced CO selectivity. The theoretical calculations suggest that Sb doping can enhance the adsorption barrier of *H, thereby inhibiting hydrogen evolution activity and conversely promoting eCO2RR to CO activity.

Study on the homologous effects on the performance of alkali metal-doping MgO-based adsorbents for CO2 capture

In this article, MgO-based adsorbents with different structure and surface property were prepared by combustion of the colloids containing Mg and alkali metal. At the same time, CO2 adsorption performance tests are conducted to compare the doping effect of alkali metal on MgO adsorbents. As confirmed, the introduction of lithium, sodium, and potassium can reduce the grain size of MgO and enhance the basicity, especially increasing the concentration of oxygen vacancies on MgO surface which exposed more basic adsorption active sites and was more conducive to CO2 adsorption. Among them, the one doped with 0.5 % K which had more electron shell numbers showed larger surface area and smaller crystal size. Most importantly, it provided more number of basic sites along with the improved strength of surface basicity due to the more oxygen vacancies. As a result, the maximum CO2 uptake (1.09 mmol/g) at the adsorption time of 60 min can be obtained which still remained at 0.67 mmol/g after 16 cycles of CO2 adsorption–desorption. With the aid of N2 physical adsorption, inductively coupled plasma-optical emission spectroscopy, powder X-ray diffraction, scanning electron microscope, X-ray photoelectron spectroscopy, electron paramagnetic resonance, and chemical adsorption, the relationship between CO2 adsorption capacity of MgO-based adsorbent and homologous regularity of alkali metal was disclosed. In other words, by comparing the CO2 adsorption performance of MgO adsorbents prepared by doping different alkali metals, CO2 adsorption capacity increased with the increase of electron shell numbers. Such a configuration is in favor of the electron supply of the p-orbitals and weakens the Mg–O bonds which promoted the formation of oxygen vacancies. The found will provide in-depth understanding for the modification and performance improvement of MgO-based adsorbents.

Effect of metal doping (M = Sc, V, Ti, Fe and Mn) on the sensing performance of the Si12C12 nanocage towards the penicillamine drug molecule: a DFT study

In this work, we have investigated the electronic properties of the pristine and metal(M)-doped Si12C12 (M = Sc, V, Ti, Fe and Mn) nanocages and their sensing performances towards the penicillamine (PCE) molecule using DFT calculations at the B3LYP/LanL2DZ/6-311G(d,p) method. The results reveal that the doping of the Si12C12 nanocage with a metal atom significantly improves its reactivity, therefore their interaction with the nucleophilic centres of the PCE molecule becomes easy. The most stable complexes were obtained when the PCE molecule was chemisorbed onto the MSi12C12 nanocages through its oxygen atom with adsorption energies which vary from –18.0 to –40.2 kcal mol−1. The results also demonstrate that the MSi12C12 possess high sensitivity towards the PCE molecule. The presence of solvent sharply reduces the adsorption energy of the PCE molecule over the clusters surface, resulting in a substantial decrease in the recovery time. A comparative study between the values of the sensitivity of the studied clusters in liquid phase suggests that the FeSi12C12 and MnSi12C12 clusters present high sensing performances compared with the other clusters, so they are regarded as the best sensors to detect the PCE drug molecule.

Effect of metal (Cr, Sr, Ag, Cu) doping on the performance of lead-free RbSnI3 based perovskite solar cells: A theoretical approach

Perovskite solar cells based on lead have witnessed unprecedented growth over the past decade, achieving an impressive power conversion efficiency (PCE) of 26.1%. However, lead toxicity remains a concern for commercialization. In order to resolve the matter, scientists have been investigating alternative materials; in this context, rubidium-based lead-free perovskites like RbSnI3 may be a promising alternative because it has a high optical conductivity and absorption coefficient. Density Functional Theory (DFT)-based first-principles studies are used in this work to examine the effect of metal doping (specifically Cr, Sr, Ag, and Cu) on the optoelectronic and structural characteristics of orthorhombic RbSnI3 perovskite. In addition, we conducted a comprehensive study to investigate the impact of metal doping on the formation energy, structural stability, and HOMO–LUMO energy levels of RbSnI3 perovskite. Introducing transition metal cations (Cr2+, Ag+, and Cu+) at the Rb site results in a flat band in the conduction band region, transforming the RbSnI3’s indirect band gap into a direct one and significantly affecting the optoelectronic properties. The DFT results are then integrated into the Solar Cell Capacitance Simulator (SCAPS-1D) to estimate the effectiveness of the modeled device. The Cu-doped RbSnI3 device exhibits the highest PCE of 20.2%. Furthermore, Ag and Cu doping in RbSnI3 increases bond length, which reduces exciton binding energy and helps with charge carrier generation.

Effect of metal doping on the microwave absorption performance of multi-element (metal, N, and Cl) doped carbon composites

Multi-element-doped carbons are actively being pursued as efficient lightweight microwave absorbers. In this work, metal, nitrogen and chlorine codoped carbons (metal,N,Cl–C, where metals = Ni, Co, Mn, or Zn) were synthesized through the high-temperature carbonization of polypyrrole doped with hydrochloric acid (PPy-HCl) and prepared in the presence of certain metal chloride salts (NiCl2, CoCl2, MnCl2, or ZnCl2). The dielectric parameters and microwave absorption properties of the metal,N,Cl–C composites could be regulated by simply altering the type of metal salt. Compared with N,Cl–C, it was discovered that Co,N,Cl–C and Ni,N,Cl–C possessed higher graphitization degrees, smaller particle sizes and more surface chemical functional groups (metal−N), which significantly improved the conduction loss and polarization loss effects including interfacial polarization and dipole polarization. At a filler ratio of 9.0 wt%, Ni,N,Cl–C displayed a wide effective absorption bandwidth (EAB, RL ≤ −10 dB) of 7.1 GHz at a thickness of 2.5 mm and a minimum reflection loss (RLmin) of −29.7 dB at 9.7 GHz and 3.5 mm thickness. Similarly, Co,N,Cl–C offered an RLmin value of −48.2 dB at 11.3 GHz and a thickness of 3.0 mm and an EAB of 6.0 GHz at a thickness of 2.5 mm. These results showcase the advantages of metal,N,Cl–C composites as microwave absorbers.

A Systematic Study and Biomedical Investigation on O‐Terphenyl Incorporated Copper(II) Chloride Crystal via Slow Evaporation Technique

AbstractCurrent research trends emphasize the need to characterize and analyze the biomedical applications and antibacterial/fungal activity and anticancer studies of O‐terphenyl incorporated copper (II) chloride (OTCC) single crystals by the method of slow evaporation. For this research, a brand‐new inorganic competitive coordination approach is used for crystal formation. As a result, single crystal X‐ray diffraction examination validated the growth of phase in the OTCC crystal. A powder X‐ray diffraction (PXRD) study confirmed the crystalline purity. Fourier transform infrared spectroscopy (FT‐IR) analysis is used to identify the functional groups of organic substances contained in the sample. This sample's optical transparency is assessed using a UV‐Vis‐NIR between 200 and 800 nm in wavelength. In these recent trends, emphasized chemically supported investigation into OTCC crystals and their antibacterial activity and anticancer activity against pathogens are revealed. The outcome of this work will be the effect of metal doping with organic‐based materials, which could be an important reliable weapon in the field of cancer treatment. Many researchers during recent years has done tremendous work exploring and developing drug designs, whereas attention has been drawn to metal‐based organic crystals, metal‐based crystals have the most effect on drug resistance and treat cancer cells. The biological efficacy of this crystal is tested, and it is discovered to have pharmacological qualities such as antibacterial and anticancer capabilities.

Effect of metal doping on the laser induced damage of KDP crystals: A first-principles study

KH2PO4 (KDP) crystal is a kind of widely used nonlinear optical material, but its manufacturing process produces various defects which influence the laser induced damage threshold (LIDT) of the KDP crystal. This work studies the influence of the metal doping defects (Na, Cr, Co, Ni, Zn and Pb) on the stability, electronic structure, optical and mechanical properties of KDP crystal by the density functional theory (DFT) calculation. Results show that the change of lattice parameters and bond lengths, and the formation energies of the metal doped KDP have close relationship with the radius of the doped metal atoms. The electronic and optical calculations show that the Na doping defects have little effect on the energy band and optical properties of KDP crystals, but Cr, Zn and Pb doping defects show large optical absorption peaks. Meanwhile, the Cr, Co, Ni and Pb atoms have great influence on the mechanical properties of the KDP. Therefore, the KDP synthesis process needs to pay particular attention to control Cr and Pb doping defects to avoid decreasing the LIDT of KDP. This work explains the effect of metal doping on the laser damage resistance of KDP crystals and provides a theoretical basis for enhancing the performance of KDP crystals.

Photovoltaic properties of alkali metal X (X=Li, Na, K, Rb, Cs) doped defective molybdenum diselenide structures: First principles study

The electronic structure, work function, complex dielectric function, absorption coefficient and reflectivity of defective MoSe2 models containing point defects as well as alkali metal doping have been calculated based on the first principles of density flood theory. The effect of alkali metal doping on the optoelectronic properties of MoSe2 under defect conditions is investigated. Alkali metal elements were doped separately on the basis of a single Se atom defect, and the results show that the doped systems can all be stable. The introduction of the defect decreases the band gap of MoSe2 from 1.498 eV to 0.816 eV. The alkali-metal-doped defective MoSe2 systems have semiconductor-metal transitions with collisions between the bottom of the conduction band and the top of the valence band for each of the systems, except for the K doping. The K-doped defective MoSe2 is a narrow band gap semiconductor with a band gap of 0.202 eV. Overall, alkali metal doping under defective conditions improves the electrical conductivity of MoSe2, resulting in enhanced conductivity of the crystal. The work function analysis reveals that the work function of the alkali metal doped defective MoSe2, except for K doping, decreases gradually with the increase of its atomic radius, while the electrical conductivity of each system is enhanced. Optical property analyses revealed that the absorption coefficient of alkali-metal doped defective MoSe2 was significantly higher than that of intrinsic MoSe2 in the infrared light region, which compensated for the lack of zero absorption of the intrinsic material in the infrared light region, and enhanced its light-absorbing ability in the infrared light region and part of the visible light region. The reflectivity of each defective MoSe2 system doped by alkali metals is much smaller than that of the intrinsic, and the reflection peaks are red-shifted in the direction of the low-energy region. Overall, the doping of alkali metal atoms reduces the average reflectivity of the defective MoSe2 materials, which is conducive to the enhancement of light absorption and photoelectron emission from the materials. It is hoped that the research results in this paper will contribute to expanding the potential applications of MoSe2 materials in solar cells, photovoltaic devices, and photodetectors.

First-principles study of the effect of alkaline-earth metal doping on the intrinsic MoSe2 photovoltaic properties

In this study, the effect of alkaline-earth metal element doping on the photoelectric properties of intrinsic MoSe2 is systematically investigated based on the first-principles approach, and it is believed that the findings of this work will give some theoretical guidance for future research on MoSe2 doping modification. The results show that all the doping systems exhibit good stability, and Be atom doping has the lowest formation energy value, making the doping easier to produce. The doping of alkaline-earth metal elements resulted in some lattice distortion of MoSe2. Intrinsic MoSe2 is a semiconductor with a direct bandgap of 1.498[Formula: see text]eV, and the doping of alkaline-earth metal elements causes the bandgap value to decrease in each system, and the bandgap is the smallest when Be is doped. All doped systems exhibit P-type conducting properties. Compared with the intrinsic MoSe2, all doped systems have their conduction band fraction moved to the low-energy direction overall, and new density of states peaks appear near the Fermi energy level. These state density peaks mainly originate from the results contributed by the s-orbitals of each doping system Mo-4d, Se-4p, and each dopant atom. The analysis of the work function reveals that the work function of each doped system is smaller than the intrinsic MoSe2, then the energy required for the occurrence of electron leaps is reduced, which improves the electron mobility of the doped system. The Mulliken Population analysis shows that stable chemical bonds are formed between the doped alkaline-earth metal elements and the surrounding Se atoms. The examination of the optical characteristics demonstrated that, in comparison to the intrinsic MoSe2, all doped systems’ greatest dielectric absorption peaks were attenuated and moved toward the low-energy region; the doping of alkaline-earth metal elements broadened the light absorption edge of the intrinsic MoSe2. The absorption peaks of each doping system are shifted toward the low-energy region with the red-shift phenomenon, and the light absorption is good in the ultraviolet region.

Investigation of the adsorption and sensor properties of resorcinol (RSL) on X9N9 (X = Al, B, Ga, In) nanorings by DFT and QTAIM analysis with solvent effects

De-aromative oxygenation of resorcinol is recognized as an important process that produces a variety of bioactive chemicals. Hence, we evaluated the sensing application by utilizing density functional theory to study the resorcinol (RSL)-X9N9 (X = Al, B, Ga, and In) nanoring interaction. We saw that RSL had a strong interaction with every ring. A charge transfer occurs between nanorings and RSL, causing dipole moment to be induced. The band gap energies of all complexes are less than that of RSL. In vacuum the band gap energies of the complexes are less than that of pristine rings while in water, RSL-Ga/In-N complexes, the band gap energies are higher than that of pristine rings. In vacuum all the complexes, except B9N9-RSL have higher adsorption energies. In water phase, Al9N9/Ga9N9-RSL complexes have higher adsorption energies. These values suggest they are good dopants for RSL. The electrical conductivity and work function are significantly altered as a result of the alteration in the Frontier Molecular Orbitals (FMOs) energies of the nanorings following interaction. It is possible to use the X9N9 nanorings for RSL as both an electronic sensor and a work function-based sensor. The extended recovery time of RSL with X9N9, however, indicates that it can be used to store RSL or remove it from a specific environment. Atom in Molecules (AIM) analysis predicts the comprehension reactivity, chemical bonding, and the creation of compounds. The present work can be extended to investigate the effect of coinage metal doping with nanorings to study doping effects and drug delivery carrier properties.

Effect of solution chemistry on the sedimentation, dissolution, and aggregation of the bimetallic Fe/Cu nanoparticles pre- and post-grafted with carboxymethyl cellulose

The suitability of iron-based nanomaterials or composites for in-situ remediation hinges on their physicochemical stability. Introducing surface modifications like metal doping or polymer grafting can regulate interparticle forces, influencing particle stability. Thus, probing how grafting methods (i.e., pre- or post-grafting) tune material properties controlling interparticle forces, comprehend the synergistic effect of metal doping and polymer grafting, and evaluate stability under varying geochemical conditions are the way forward in designing sustainable remediation strategies. To this end, time-dependent sedimentation, dissolution, and aggregation of four synthesized iron-based nanoparticles (bare iron (Fe), copper doped bimetallic iron/copper (Fe/Cu), pre- and post-grafted Fe/Cu with carboxymethyl cellulose (CMC) – CMCpre-Fe/Cu and CMCpost-Fe/Cu, respectively) were carried out as a function of solution chemistry (i.e., pH – 5 to 10, ionic strength, IS – 0 to 100 mM NaCl, initial particle concentration, C0–20 to 200 mg.L−1) mimicking geoenvironmental conditions. CMCpre-Fe/Cu exhibited markedly higher particle availability (> 91 %) against sedimentation than others (bare Fe/Cu (11.28 %) > bare Fe (7.33 %) > CMCpost-Fe/Cu (6.09 %)) – suggesting the pivotal role of grafting method on particle stability. XDLVO energy profiles revealed pre-grafting altered magnetic properties favoring surface charge-driven electrostatic repulsion over magnetic attraction, thereby limiting aggregation-induced particle settling. In contrast, superior magnetic force overrides the electrostatic behavior for bare and post-grafted particles. Unlike bare and post-grafted nanoparticles, CMCpre-Fe/Cu aggregate size correlated positively with [H+] and IS, consistent with their settling behavior. Rise in C0 showed a visible negative effect on particle aggregation and, thereby, sedimentation except for CMCpre-Fe/Cu by facilitating particle collision through Brownian movement. Both acidic pH and copper doping promoted nanoparticle dissolution, whereas pre-grafting can provide a plausible solution against nanoparticle toxicity and loss of reactivity due to ionic release. To recapitulate, these findings are imperative in building a sustainable framework for environmental remediation application.

Micro-mechanism investigation of hydrogen evolution reaction on anti-perovskite Ni3InN considering doping and strain effects

Anti-perovskites are considered as promising high-efficiency catalysts for hydrogen evolution reaction (HER) due to their low cost, adjustable composition, and small water dissociation kinetic barriers. Accounting strain effects, transition metal doping effects and solvent effects, we calculate HER micro-mechanism on anti-perovskite Ni3InN and conclude that HER on Ni3InN can be divided into two steps, rapid proton adsorption at the Bridge site and favorable H2 desorption at the Hollow site. We obtained 2 doping elements (Pt and Ir) from 20 transition metal elements that can enhance HER catalytic performance of Ni3InN. It is worth noting that applying a certain strain is beneficial for the catalytic performance of some doped Ni3InN (e.g. +2 %, +1% for Pt), while harmful for others (e.g. Ir). Our work provides a new perspective for the application of anti-perovskites in HER, which is meaningful for the development of HER catalysts.

Synthesis of Cu/Mn/Ce polymetallic oxide catalysts and catalytic ozone treatment of wastewater.

Non-homogeneous ozone-catalyzed oxidation technology is one of the effective ways of treating wastewater, the core of which lies in the development of efficient ozone oxidation catalysts. This work proposes the design and synthesis of an efficient Cu/Mn/Ce multi-metal composite oxide catalyst by metal salt precursor mixing-direct granulation. The effect of metal doping on the catalyst properties was compared using Density function theory (DFT) calculations, and the Cu/Mn/Ce co-doping showed significant charge accumulation effect with a low ozonolysis energy barrier, which is more favorable for the generation of reactive oxygen species. The successful loading of the main active metal components, such as Mn, Cu, and Ce, was clarified by systematic characterization by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and Brunauer-Emmett-Teller's test (BET), and the chemical oxygen demand (COD) removal could reach more than 60% for the simulated wastewater. The electron paramagnetic resonance (EPR) characterization clarified that the degradation of organic pollutants was mainly dominated by the combination of single-linear oxygen and superoxide radicals in the catalytic process, and the possible catalytic oxidation mechanism was proposed. This work advances the development of non-homogeneous ozone oxidation technology.

Waste iron-based disposable chemical warmer derived electrocatalyst for water splitting

The waste chemical heat pack was recycled into a mixed-phase Fe/Fe3O4/NC catalyst. This catalyst demonstrates excellent performance in both the OER and HER, attributed to the synergistic effects of metallic iron, magnetite, and nitrogen doping.

Doping effect on a two-electron silver nanocluster.

This study investigates the effects of metal addition and doping of a 2-electron silver superatom, [Ag10{S2P(OiPr)2}8] (Ag10). When Ag+ is added to Ag10 in THF solution, [Ag11{S2P(OiPr)2}8(OTf)] (Ag11) is rapidly formed almost quantitatively. When the same method is used with Cu+, a mixture of alloys, [CuxAg11-x{S2P(OiPr)2}8]+ (x = 1-3, CuxAg11-x), is obtained. In contrast, introducing Au+ to Ag10 leads to decomposition. The structural and compositional analysis of Ag11 was characterized by single-crystal X-ray diffraction (SCXRD), ESI-MS, NMR spectroscopy, and DFT calculations. While no crystal structure was obtained for CuxAg11-x, DFT calculations provide insights into potential sites for copper location. The absorption spectrum exhibits a notable blue shift in the low-energy band after copper doping, contrasting with that of the slight shift observed in 8-electron Cu-doped Ag nanoclusters. Ag11 and CuxAg11-x are strongly emissive at room temperature, and solvatochromism across different organic solvents is highlighted. This study underscores the profound influence of metal addition and doping on the structural and optical properties of silver nanoclusters, providing important contributions to understanding the nanoclusters and their photophysical behaviors.

Influence of ‘period four’ transition metal doping in graphene on adsorption and transduction characteristics for CO gas- A detailed ab-initio perspective

This work analyses the comparative effects of period-four transition metal (TM) dopants for CO molecular adsorption on the monolayer Graphene (Gr) supercell using the density functional theory (DFT) based ab initio method for the first time. Ten different TM dopant species (Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cr, Zn) have been incorporated and extensively studied in the context of Carbon Monoxide (CO) adsorption. The study elaborates on the effects of metallic doping in Gr on structural stability, electronic properties, adsorption strength, transduction efficacy, and CO recovery time. The study reveals that introducing each period-four TM dopant in the Gr lattice changes the semi-metallic nature, wherein distinct modulations in the energy band structure and the total density of state profiles can be observed after CO adsorption in each doped Gr matrix. The C atom of the polar CO molecule preferentially adsorbed on the doped TM, forming physical C-X (X: metal) bonds and resulting in slight vertical displacement of the dopant towards adsorbed CO. The results exhibit that depending on the strength of CO adsorption, the metallic dopants can be placed in the following order: Ti > V > Cr > Mn > Fe > Co > Ni > Cu > Zn > Sc, with a significant improvement in charge transfer during CO adsorption after Sc, Co, Ni, V, and Zn doping in Gr. Specifically, the Ni, Zn, and Sc-doped Gr ensures an efficient trade-off between adsorption stability and recovery time with high selectivity in CO2 and N2 environments.

Highly efficient MnCe/Ti catalyst for NH3-SCR of NO from sintering flue gas at low temperature: CO tolerance and reaction mechanism assessed by in situ DRIFTS

The effect of metal doping (Ce, Fe, and Co) on CO tolerance of Mn/Ti catalyst used for eliminating NO from sintering flue gas has been investigated. The best MnCe/Ti catalyst achieves a NOx conversion of 80 % from 125 to 250 °C at a GHSV of 80,000 h−1. NOx conversion dropped by only 4 % below 200 °C and N2 selectivity slightly increased after introduction of CO, indicating strong resistance of MnCe/Ti catalyst to CO. XPS results suggest that CO oxidation does not alter surface content of Mn4+ and Ce3+ sites of used MnCe/Ti catalyst while it reduces the surface adsorbed oxygen of used MnCe/Ti catalyst because surface adsorbed oxygen consumed by CO oxidation cannot be readily replenished owing to the insufficient capacity in oxygen and electron transport. This is primarily accountable for the slight decrease in NOx conversion. Furthermore, NH3 can completely restrain CO adsorption on MnCe/Ti catalyst while CO cannot hinder the adsorption of NH3 and NO on the catalyst because the interaction between CO and MnCe/Ti catalyst significantly weakened in the presence of NH3, leading to the strong CO tolerance of MnCe/Ti. On MnCe/Ti Eley-Rideal mechanism governs the NH3-SCR involving gaseous NO and adsorbed NH3, while Mars-van Krevelen mechanism describes the oxidation of CO, indicating its reaction with gaseous CO and surface adsorbed oxygen. The findings in this paper can provide modification strategy for low-temperature SCR catalysts which are expected to be applied for sintering flue gas.

Effect of p-block metal doping on the optical properties of blue-phosphorene phase monolayer GeSe

Expanding the optical absorption of blue-phosphorene phase GeSe and designing it as infrared light driven photocatalysts and photodetectors is of particular significance. In this work, the mechanism of p-block metals (Al, Ga, In, An, Pb, Sb and Bi) doping enhancing the optical performance of monolayer blue-phosphorene phase GeSe was investigated. The effect of all p-block metal doping on the lattice constant of GeSe is very weak. Pb doped system has the smallest formation energy (−4.82 eV). Except for Sn and Pb, other p-block metal doping can introduce deep impurity levels into the band gap of monolayer GeSe, and they can significantly absorb infrared light, especially Ga doped systems. This is due to the emergence of impurity levels that assist the photon transition. The results of this work provide guidance for promoting the application of blue-phosphorene phase GeSe in the field of photocatalysts and photodetectors.