Increase In Cu Research Articles

Influence of solvent on aggregation of metallic Cu in Cu/MgO during hydrogenation in liquid phase

Cu/MgO catalysts generally could selectively hydrogenate C=O in unsaturated aldehydes, but they often suffer from aggregation of Cu species in liquid-phase reactions. In this study, structural change of Cu/MgO catalyst was investigated during the catalysing conversion of ethyl levulinate (EL) to γ-valerolactone (GVL) and 1,4-pentanediol (1,4-PDO) in varied medium. Water as medium could achieve GVL yield of ca. 99%, while ethanol promoted ring-opening of GVL to 1,4-PDO. However, water and ethanol impacted structure of Cu/MgO in distinct ways. Water led to transformation of MgO into Mg(OH)2, destroying interaction of metallic Cu species with MgO. This led to the increase of Cu (111) crystal planes size by ca. 300% and Cu (220) crystal planes size by ca. 200%. The use of water-ethanol as reaction medium further enhanced aggregation of Cu species. Morphology of the Cu/MgO catalyst changed to rope-like structure and abundant additional meso to large pores were created in water or ethanol-water medium. In comparison, ethanol as medium alone suppressed aggregation of metallic Cu and formation of Mg(OH)2, but re-structure of MgO by enlarging pore size also occurred. The aprotic reaction medium such as acetone, tetrahydrofuran and N,N-dimethyl formamide also affected aggregation of metallic Cu species in different ways.

Surface preparation of metal films by gas cluster ion beams using organic acid vapor for Cu–Cu bonding

Surface-activated bonding (SAB) of Cu by gas cluster ion beam (GCIB) irradiation with acetic acid vapor was studied. GCIB irradiation realizes surface smoothing and surface reaction enhancement without severe damage. Therefore, it is promising for SAB. In this study, acetic acid vapor was introduced during Ar-GCIB irradiation to assist the removal of surface oxides on the Cu surface. XPS results showed that Cu(OH)2 was effectively removed by reaction with adsorbed acetic acid, and there was no residue by acetic acid adsorption. In addition, surface roughness decreased by Ar-GCIB irradiation with acetic acid because of the preferential removal of protrusion. Preliminary bonding experiments showed an increase of Cu–Cu bond strength by Ar-GCIB irradiation with acetic acid vapor.

Microstructure and Its Effect on the Intergranular Corrosion Properties of 2024-T3 Aluminum Alloy

Intergranular corrosion is the main corrosion type of Al-Cu-Mg aluminum alloys, which seriously reduce the lifetime of aircraft structural parts. In this paper, the microstructure and the intergranular corrosion behavior of 2024 alloy with varying Cu and Mg content were studied by using a scanning electron microscope (SEM), transmission electron microscope (TEM), and three-dimensional atom probe (3DAP). The results show that nano-scale θ (Al2Cu) and S (Al2CuMg) particles precipitate along grain boundaries after quenching. The nano-cluster is the main strengthening phase in the 2024 alloy after natural aging for 96 h. The intergranular corrosion susceptibility is greatly affected by the presence of θ (Al2Cu) and S (Al2CuMg) phases along grain boundaries. Specifically, Cu-rich precipitates and intermetallics are known to act as local cathodes, which facilitates the action of oxygen reduction and ultimately drives anodic dissolution of the surrounding matrix material. The intergranular corrosion resistance of the alloy decreases with the increase in Cu and Mg contents. The alloy with a lower Mg content shows better corrosion resistance than the commonly used one with a Cu to Mg mass ratio of 2.9. The relationship between the observed corrosion behavior and various contents of Cu and Mg elements is discussed, which has potential to benefit the composition design of 2xxx aluminum alloy with high corrosion resistance.

The microstructures and mechanical properties of a highly alloyed Al-Zn-Mg-Cu alloy: The role of Cu concentration

The influence of Cu content on microstructures and mechanical properties of a highly alloyed Al-10.0Zn-2.6Mg-xCu-0.15Zr alloy with the Cu content in the range of 0 to 3.0 was studied by OM, SEM, TEM, tensile tests, XRD, and DSC. We determined that the Mg(Zn,Al,Cu)2 (σ) and Al2Mg3Zn3 (T) phases presented in all as-cast alloys, and Al2Cu (θ) phase was found in the alloys with Cu higher than 2.5 wt.%. Also, it is found that the volume fraction of the primary phase increased with the Cu increase. Further, the volume fraction of the residual eutectic phase (REP) increased gradually with the increase of Cu after solid solution, mainly attributed to the low diffusion coefficient of Cu and thus suppressed the dissolution of the second phase. The tensile testing of the aged alloys indicates that the strength of the studied alloys increased significantly with the Cu increase when Cu is lower than 1.0 wt.%, whereas further increase Cu content it decreases. The elongation increases to a peak value fast at low Cu content. After a critical Cu content (1.5 wt.%), a slight decrease is followed. The elongation of highly alloyed Al-Zn-Mg-Cu alloys should consider the coupling effect of grain refinement and REP.

A 600 years sediment record of heavy metal pollution history in the Danube Delta

Heavy metal pollution in the Danube Delta (in sediments, water and living organisms) has recently received increasing attention due to its impact on ecosystems health and water quality. However, long term records of heavy metal contamination are not available to date. In this study radiometric dating and geochemical analyses for major elements (Al, Fe, Ca and S) and metals (Cu, Zn, Pb, Ni, Cr and Cd) were performed on the top 4 m of a 9-m sediment core retrieved from the alluvial plain of Sulina distributary channel aiming to reconstruct the heavy metal geological background and contamination history and discuss the possible origins (natural vs. anthropogenic) of metals and the main factors driving their temporal variation. Chronological analysis revealed that the top 4 m of the core span the last ~600 years. Three distinct sediment units (U1: 400–200, U2: 200–140, U3: 140–15) were identified based on the downcore element concentration variation. The lower unit (400–200 cm, ~1450–1700 CE) shows an upward increase of Cu, Zn, Pb, Ni, Cr and Cd metal contents, which are strongly correlated with Al. Enrichment factor (EF) analysis indicates that metals detected in this unit are derived primarily from natural sources. In contrast, metals show elevated EF values within the middle (200–140 cm, ~1700–1770 CE) and upper unit (140–15 cm, ~1770 CE to present). The highest degrees of enrichment of Cu, Zn and Cd occur in the peat layer of the middle unit (U2) which displays higher organic carbon and sulfur contents, indicating that diagenetic enrichment of detected metals occurs under reducing condition. Overall, sediment contamination is moderate while the level increases with time. This study provides new insights into the metal contamination history of deltaic environments and yields baseline values for heavy metal contents in pristine sediments deposited prior to the onset of anthropogenic impact.

Photo-activated proflavine degrades protein and impairs enzyme activity: Involvement of hydroxyl radicals

Proflavine is a well-known antiseptic and bacteriostatic drug, however, it has the potential to be hazardous and mutagenic. Proflavine enters cells and intercalates between DNA base pairs, resulting in mutation and replication inhibition. Previously several investigators demonstrated that photo-activated proflavine generated double-stranded DNA breakage and protein structural alterations. The present study investigated the role of hydroxyl radical (·OH) due to activation of proflavine in the breakdown of protein and enzyme by photo-activated proflavine. The results show that the formation of hydroxyl radicals increased as the photo-illumination period increased, as did the concentrations of proflavine and Cu (II). As demonstrated by SDS-PAGE, the excess of free radicals due to proflavine resulted in oxidative modifications and degradation of BSA protein and trypsin enzyme. Additionally, with an increase in Cu (II) concentration, photo-illuminated proflavine induced a considerable loss of enzyme activity and also accelerated the degradation of the enzyme. Bathocuproine, a particular Cu (I)-sequestering agent, prevented protein degradation and enzyme inactivation. Hydroxyl radical scavengers inhibited the protein-damaging process, indicating that hydroxyl radicals play a substantial role in protein damage. The tryptophan moiety was quenched by proflavine, demonstrating that it binds to proteins and enzymes, changing their structure and activity. As a result, this study helps to better understand proflavine's deleterious influence on protein and enzyme degradation by oxygen-free radicals.

Enhanced effect of H<sub>2</sub> pretreatment on CuO<sub><italic>x</italic></sub>/CeO<sub>2</sub> catalyst for the CO plasma catalytic oxidation

<p indent="0mm">The catalytic oxidation of carbon monoxide (CO) at low temperature has attracted more and more attention since it causes serious impacts on public health and the environment. Non-thermal plasma (NTP) has great potential to lower the temperature of catalytic oxidation of CO. In this study, CuO_{<italic>x</italic>}/CeO₂ catalyst was prepared by incipient wetness impregnation method and activated by H₂ reduction. The catalytic performances of CuO_{<italic>x</italic>}/CeO₂ catalysts before and after H₂ pretreatment in NTP catalytic system under different humidity conditions were compared, and the influences of H₂ pretreatment on the catalyst structure and the reaction mechanism were discussed. The results showed that H₂ pretreatment could improve the plasma catalytic activity of the CuO_{<italic>x</italic>}/CeO₂ catalysts and inhibit the emission of plasma-induced byproducts (O₃ and NO_{<italic>x</italic>}). Enhanced performance of plasma catalytic oxidation of CO over the H₂-pretreated CuO_{<italic>x</italic>}/CeO₂ catalysts was mainly ascribed to the increase of Cu⁺ active sites and oxygen vacancies on the catalyst surface. This study revealed the effect of H₂ pretreatment on the plasma catalytic oxidation of CO over the CuO_{<italic>x</italic>}/CeO₂ catalysts, which provided valuable information for the development of multifunctional catalysts in non-thermal plasma catalytic systems.

Response of Prosopis farcta to gradually increased soil copper and cadmium levels based on an integrated investigation

The impact of gradually increased soil levels of copper (Cu) and cadmium (Cd) on the medicinal plant, Prosopis farcta, irrigated with metal-enriched water was determined. Plants were treated with 2.54, 5.08, 10.16, and 20.32 µg mL−1 for Cu2+ and 6.13, 12.26, 24.52, and 49 µg mL−1 for Cd2+. The rate of phytoremediation was measured by bioconcentration factor (BCF) and the relative bioconcentration factor (RBCF). The movement of metal ions from roots to shoots was calculated as the Translocation Factor (TF). The exposure of plants to Cd or Cu decreased plant growth and increased Cd and Cu concentration in their shoots and roots. The weight of both shoots and roots decreased linearly with the increase of Cu and Cd contents in roots and shoots. Cd was more toxic than Cu as expected. The water content of shoots and roots decreased linearly as heavy metal levels increased. Prosopis farcta can take up Cu and Cd in both Cu- and Cd-contaminated soils but was more capable for transporting Cd from roots to shoots rather than Cu although more Cu is taken up by roots. Prosopis farcta is a natural accumulator of Cu and Cd and can be used in phytoremediation. CONCISE NOVEL ASPECTS OF THIS STUDY This is the first report to show that the medicinal plant Prosopis farcta is an accumulator for Cu and Cd. This was determined by gradual addition of the metals to the soil via irrigation by heavy metal-polluted water which can provide an opportunity for the plant to develop a metal-resistance mechanism. Choosing suitable plant species for heavy metal accumulation is a critical step for successful phytoremediation of heavy metal pollutants. CORE IDEAS Prosopis farcta is of interest as a medicinal plant. P. farcta can take up Cu and Cd in both Cu- and Cd-contaminated soils. P. farcta transports more Cd from roots to shoots but more Cu is taken up.

The Residual Copper and Zinc in Tropical Soil over 21 Years after Amendment with Heavy Metal Containing Waste, Lime, and Compost

This research aimed to evaluate the residual Cu and Zn in tropical soil over 21 years after amendment with industrial waste, lime, and compost. Soil samples were collected from a well-maintained experimental field amended one time with industrial waste high in Cu and Zn set in 1998 at about 1.5–20 years after amendment. Treatments were arranged in a randomized block design with a metal-wares industrial waste at rates 0, 15, and 60 Mg·ha−1, lime at 0 and 5 Mg·ha−1, and compost at 0 and 5 Mg·ha−1. Soil samples were also taken vertically in the exact plot centers at depths of 0–75 cm of plots not amended with lime and compost and also from topsoils (0–15 cm) at 90 points with distances 50 cm between each other in each of the respective plots 21 years after amendment. Significant increases in Cu and Zn caused by waste were observed over 21 years. The increase in soil pH by lime was observed over 10 years but its effect in decreasing Cu and Zn was observed only at 1.5 years, particularly in topsoils. However, the effect of lime in lowering Cu and Zn was observed over 20 years when waste and/or compost were also given. Similarly, the effect of compost was absent over 20 years but significant when waste and/or lime were also given. The relative concentration of Cu and Zn in the 60 Mg waste ha−1 plots decreased over 20 years to 17–53% for Cu and to 12–33% for Zn; their concentrations were, in general, lower with lime and/or compost addition. The relative concentrations of Cu and Zn significantly decreased over 21 years in plots with 15 or 60 Mg·ha−1 and increased in the control plots. Heavy metals moved in soil significantly through soil tillage and erosion and partially by leaching.

Trace metal geochemical and Zn stable isotope data as tracers for anthropogenic metal contributions in a sediment core from Lake Biwa, Japan

The catchment of Lake Biwa, the largest freshwater lake in Japan, has experienced rapid urbanization and industrialization in the second half of the 20th century; yet little is known about the historical trend of metal pollution. We analyzed the elemental concentrations and zinc stable isotope ratios (δ66Zn) in a sediment core from the Northern basin of the lake. The goals were 1) to reconstruct the historical trend of trace metals in the lake and 2) to understand whether the range of Zn concentrations was derived from natural or anthropogenic sources. The first increase in Cu and Zn concentrations from the late 1910s until approximately 1940 could be due to human-induced higher contributions from the surrounding mafic igneous rocks. A second increase in the Zn concentrations accompanied by a slight decrease in the δ66Zn values from the late 1950s coincided with the period of the industrialization and urbanization. The δ66Zn values fell in a binary mixing process between a lithogenic (∼+0.28‰) and an anthropogenic endmember (∼+0.14‰). Although industrial effluents were strictly regulated by law from the late 1960s, constant Zn concentrations throughout the 1980s indicated contributions from domestic wastewaters and diffusive sources such as runoff from paddy fields, roads, and industrial areas. Zinc, Ni, and Co were still enriched in recent surface sediment compared to the pre-industrial times. The metal fractions obtained by the BCR sequential extraction procedure showed that Pb was mainly hosted in the reducible fraction, and Cu and Zn were mainly hosted in the residual fraction. The increasing trace metal concentrations in the acid-labile and reducible fractions towards the surface indicate these fractions were the primary host for anthropogenic trace metals. We conclude it is unlikely that the natural condition of the lake sediment will be recovered owing to the continuing urbanization around Lake Biwa.

Circulating trace elements for the prediction of preeclampsia and small for gestational age babies.

Poor gestational outcomes due to placental insufficiency can have lifelong consequences for mother and child. There is a need for better methods of diagnosis, and elemental metabolomics may provide a means to determine the risk of gestational disorders. This study used blood plasma samples collected at 36weeks' gestation from women who later developed preeclampsia (n = 38), or small-for-gestational age babies (n = 91), along with matched controls (n = 193). Multi-element analysis was conducted by inductively coupled plasma mass spectrometer (ICP-MS), allowing simultaneous measurement of 28 elements. Women who later developed PE, exhibited significantly increased concentrations of K, Rb and Ba. For SGA pregnancies, there was a significant increase in Cu and a decrease in As concentrations. Despite significant differences in single elements, the elemental profile of groups indicated no clustering of control, PE, or SGA samples. Positive predicative values correctly identified approximately 60% of SGA and 70% of PE samples. This is the first-time elemental metabolomics has been used to predict SGA and PE at 36weeks. Though significant changes were identified, routine clinical use may be limited but may contribute to a multi marker test. Future analysis should include other biomarkers, metabolic data or clinical measurements made throughout gestation.

The effects of copper (Cu) or zinc (Zn) on fluidity of A357 alloy

Excellent fluidity is an essential condition for Al-Si-Mg alloy (like A357) to make large thin-walled and complex structure castings, but there is no research about the effects of Cu or Zn on the fluidity of Al-Si-Mg alloys. Under sand casting conditions, the effects of Cu or Zn on the fluidity of A357 were investigated through spiral fluidity resin sand molds, DSC, polarizing microscope and SEM. The results showed that with increase of Cu or Zn content, the solidification temperature range (T) of A357 alloy increased, and the fluidity decreased. With Cu or Zn addition, the grain size of A357 alloy increased, but the coarse grain is not the main reason for the fluidity to deteriorate.

SERS-based copper-mediated signal amplification strategy for simple and sensitive detection of telomerase activity

Simple and sensitive detection of telomerase activity is of vital importance for both early diagnosis and therapy of malignant tumors. Inspired by DNA-biobarcode amplification reported by Chad A. Mirkin, we developed a facile DNA-biobarcode-like SERS-based copper-mediated signal amplification strategy for sensitive detection of telomerase activity. In this strategy, a duplex DNA constructed by hybridization of a copper oxide nanoparticle (CuO NP)-labeled reporting sequence (RS) with the telomerase primer sequence (TS) is ingeniously designed, and anchored on the magnetic bead (MB) to build the CuO NPs-encoded magnetic bead (MB-CuO NPs) detection probe. Upon selective sensing of telomerase, telomerase elongation reaction and structure change of TS products make the CuO NP-RS displace and separate from MB. The separated CuO NPs are dissolved into a mass of Cu2+, which prompt monodisperse dopamine-functionalized AgNPs (D-AgNPs) signal probe into aggregation, resulting in color changes and significantly enhancing of SERS signal. The SERS signal increases with the increase of Cu2+, which is directly proportional to the telomerase. Benefiting from the transformation of CuO NP to Cu2+ with a high amplification effect, this strategy could realize the telomerase activity measurement down to 3 HeLa cells and a dynamic range of 10–10000 cells. It shows a significant improvement of sensitivity without need for other enzymes and elaborate design, which escapes from the complicated manipulations and design in polymerase chain reaction (PCR) and DNA amplification techniques. Moreover, with this strategy, telomerase activities of different cell lines and telomerase inhibitors screening were successfully performed. Significantly, it can also be utilized for visual detection of telomerase, which validates the potential on-site application and its application as point-of-care testing (POCT) for efficient monitoring. Given the high-performance for telomerase analysis, the strategy has a promising application in biological detection and clinical diagnosis, as well as point-of-care tests.

Effect of root surface charge on the absorption and accumulation of Cu(II) by different japonica and indica rice varieties under acidic conditions

Excessive amounts of copper (Cu) in soils causes toxic effects on plants. In this study, 58 rice cultivars were classified into tolerant, moderately tolerant, and susceptible types for Cu(II) toxicity based on 50% germination (LC50). Nine japonica rice varieties (three each from the tolerant, moderately tolerant, and susceptible groups) and six indica rice varieties (three from the moderately tolerant and susceptible groups) were selected for the hydroponics experiments. In the short-term adsorption experiment, Cu(II) adsorbed on rice roots was differentiated into exchangeable, complexed, and precipitated forms. Similarly, it was done for long-term culture. Absorption of Cu(II) by rice roots and shoots was also measured. The results indicated that adsorbed Cu(II) mainly existed as complexed and exchangeable forms on rice roots in the short-term adsorption experiment, and the exchangeable and complexed Cu(II) levels were greater for indica rice than for japonica rice due to the larger negative charge on the indica rice roots. The adsorbed Cu(II) mainly existed as a complexed form in the long-term culture experiment, and the exchangeable Cu(II) level was much lower than that in the short-term adsorption experiment due to the absorption of Cu(II) by rice plants. The indica varieties absorbed more Cu(II) than the japonica varieties. Furthermore, the absorption and accumulation of Cu(II) by the susceptible varieties were greater than by the tolerant and moderately tolerant varieties for both the japonica and indica rice. The absorption and accumulation of Cu(II) in rice roots were much greater than in the shoots. Chlorophyll content, and the lengths and dry matter weights of the rice roots and shoots decreased with increasing Cu(II) concentration. The Cu(II) showed greater toxicity toward indica varieties than japonica varieties, and the greater negative charge on indica roots was one of reasons for the greater exchangeable Cu(II) on the roots, the increase in Cu(II) toxicity, and the higher uptake of Cu(II) by indica rice varieties compared to japonica rice varieties.

N2O Formation Mechanism During Low-Temperature NH3-SCR over Cu-SSZ-13 Catalysts with Different Cu Loadings

Based on the in situ DRIFTS studies, the mechanism of formation and decomposition of NH4NO3 (decomposition to N2O) over Cu-SSZ-13 with different Cu loadings was investigated. Under standard SCR conditions, NH4NO2 can form over all catalysts, which can be more easily oxidized to NH4NO3 over higher Cu content catalysts because of their stronger oxidative ability resulting from the elevation of Cu(OH)+. Hence, a higher Cu content leads to more low-temperature N2O formation, while N2O barely occurred over Cu-0 and Cu-0.7 catalysts. When NO2 exists, NO3– forms from the disproportionation reaction of NO2 first, then reacts with NH3 to form NH4NO3, leading to N2O formation over all catalysts. Nevertheless, Cu2+ is active for the reaction between NH4NO3 and NO. The increase of Cu2+ allows more NH4NO3 consumption, and the self-inhibition of NH4NO3 alleviates, which allows NH4NO3 to decompose to N2O at lower temperatures, and N2O formation peak shifts toward lower temperatures.

Ruddlesden-Popper-based lanthanum cuprate thin film cathodes for solid oxide fuel cells: Effects of doping and structural transformation on the oxygen reduction reaction

Highly textured, c-axis oriented thin films of undoped, Ba-doped, and Sr-doped La2CuO4 are successfully prepared on YSZ (100) substrates by using pulsed laser deposition. Intriguingly, the films undergo a structural transformation from T′(square-planar) to T (octahedral) crystal structure with partial substitution of Ba and Sr ions on La site. Meanwhile, the addition of both Ba and Sr dopants lead to reducing in polarization resistance and alternative kinetics of oxygen reduction reaction (ORR), hereinto La1·8Ba0·2CuO4 film presents superior electrochemical properties because it can accommodate much more oxygen vacancies than the other two films. First-principles calculations reveal that much lower O-defect formation energy originate fundamentally from the increase of Cu–O bond length along c-axis orientation after structural transformation from T′-phase to T-phase. These findings unveil the relationship between the structural transformation and ORR activity, and provide a novel approach to rational design film cathodes for higher electrochemical performance.

Paleolimnological evidence of environmental changes in seven subtropical reservoirs based on metals, nutrients, and sedimentation rates

Paleolimnological research can shed light on a broad range of environmental concerns; however, such studies are scarce in reservoirs. To address this lack of knowledge, a paleolimnological investigation was conducted to determine historical changes in sedimentation rates (SR), using 210Pb geochronology, and concentrations of nutrients and metals (Cr, Cu, Ni, Pb, Zn, Al, Mn,Fe) in seven subtropical reservoirs (São Paulo,Brazil). Sediment cores were collected in the dam areas. Increasing SR was observed in all reservoirs and was mainly attributed to eutrophication and changes in land use and occupation. Considering the total nitrogen and/or phosphorus, the sediment could be considered polluted at the Broa, Barra Bonita, Salto Grande, and Rio Grande reservoirs. Decreasing values were observed for Pb when the use of tetraethyl lead as an additive in gasoline was forbidden (1990). According to the applied indices, no significant enrichment, contamination, or ecological risk for metals were registered, except at the Rio Grande reservoir. At this reservoir, a moderate enrichment of Mn was observed since 1999, which was mainly associated with municipal wastewater and erosive processes, as indicated by a significant correlation between Mn and SR (r = 0.73, p < 0.0001). A very high enrichment of Cu was observed. The accumulation of Cu in this reservoir peaked in 2006 to 6183.0 mgCu/kg, a value 412-fold higher than the background. Even during a period before intense industrialisation, concentrations of Cu were 49-fold higher than background levels. The increase of Cu in bottom sediments could be attributed to vertical migration according to a series of complex mechanisms; however, further research will be needed to improve the understandingof Cu dynamics.This work makes an important contribution to understanding the paleolimnology of reservoirs, and the findings could also be applied in other contexts, since the impact of metal contamination in water bodies is a global-scale problem.

A gradation-dependent particle shape factor for characterizing small-strain shear modulus of sand-gravel mixtures

In this study, a series of shear wave velocity tests were conducted on two types of sand-gravel mixtures with a wide range of particle size distributions. The effect of the particle shape on the small-strain shear modulus (Gmax) was investigated using a customized, large-scale triaxial apparatus. The results showed that Gmax increases with the decrease in particle roundness when the uniformity coefficient (Cu) is less than a certain value. However, this increasing trend gradually flattens with the further increase of Cu. Thus, the effect of particle shape on the Gmax varies with the particle gradation. The performances of six relationships proposed in the literature for predicting Gmax were compared and evaluated in terms of their predictive capabilities. An empirical Gmax model based on the Hardin and Black equation was proposed by including a Fourier-based shape factor modified by Cu. The model can characterize the difference in the variation of Gmax with Cu due to different particle shapes and was thereafter validated. Furthermore, the model serves as a reference guide for estimating the Gmax of soils with various particle size distributions through their particle characteristics.

In-situ self-assembled Cu2O/ZnO core-shell catalysts synergistically enhance the durability of methanol steam reforming

The CuZnO catalyst with excellent low-temperature catalytic activity is widely used in methanol steam reforming (MSR). Here, a series of CuZnO/γ-Al2O3/Al catalysts were prepared by a two-step impregnation method using structured γ-Al2O3/Al support. The unique synergistic effect of Cu2O/ZnO on MSR was found by the experimental and numerical investigation. The experimental characterization results show that the decoration of ZnO can regulate the content of Cu+ on the catalytic surface, and the increase of Cu+ shortens the self-activation response time of the catalyst. During the self-activation process, ZnO-encapsulated Cu nanoparticles (Cu NPs) surface induced by strong metal-support interaction (SMSI) was observed. The encapsulation not only inhibited the agglomeration of Cu NPs but also formed a large number of new Cu2O/ZnO synergistic sites. Furtherly, the numerical calculation show that the Cu2O/ZnO synergistic sites significantly reduced the activation energy of methoxy dehydrogenation (the rate-determining step of MSR).

Analysis of the indium insertions in non-stoichiometric copper sulfide roxbyte, and their effect on the localized surface plasmon resonance of the nanocrystals

After operating what is thought to be an incomplete catalyst-assisted growth of copper indium sulfides, we obtain roxbyite (indium hole-filled non-stoichiometric copper sulfide, Cu $$_7$$ S $$_4$$ , Cu $$_x$$ S, x = $$1.75 -1.78$$ ) with a higher Cu:S ratio in view of its carrier density. This apparent increase of Cu:S ratio and decrease of carrier density is due to the “counterdoping” of the non-stoichiometric copper sulfides by indium atoms. Here, we propose a relatively easy way to synthesize copper sulfides quantum dots with low carrier densities. We rely on the well-known indium as way to decrease the carrier density of the copper sulfide Cu $$_7$$ S $$_4$$ , making the semiconductor suitable for multiple applications (reducing the indium and easily preventing the secondary phase formation). Moreover, we provide an original and practical way to estimate the carrier density of our particles using their localized plasmon resonance. In this paper, we conduct comparative quantitative analyses of the localized surface plasmon resonance (LSPR) of “counterdoped” roxbyite and doped roxbyite synthesized in similar conditions to gauge the effectiveness of the “counterdoping.” Finally, we hope to propose a picture of and focus on a phenomenon that is overlooked in the growth of copper indium sulfide and to offer a pathway for the proposed doping (“counterdoping”) of the copper sulfides.