Precursor Composition Research Articles

Single-fibre coating and additive manufacturing of multifunctional papers.

Paper-based materials with precisely designed wettabilities show great potential for fluid transport control, separation, and sensing. To tune the wettability of paper, paper sheets are usually modified after the paper manufacturing process. This limits the complexity of the local wettability design. We combined the wettability design of the individual fibres with subsequent paper sheet fabrication through either fibre deposition or fibre printing. Using silica-based cellulose fibre functionalization, the wettability of the paper sheets, containing only one specific fibre type, could be gradually tuned from highly hydrophilic to highly hydrophobic, resulting in water exclusion. The development of a silica-functionalized fibre library containing mesoporous or dense silica coatings, as well as silica with varying precursor compositions, further enabled the variation of the paper wettability and fluid flow. By combining this fibre library with the paper fabrication process by (i) fibre deposition or (ii) fibre printing, the paper wettability architecture and thus the local fibre composition were adjusted without any further processing steps. This enabled the fabrication of papers with wettability integration, such as a wettability pattern or a Janus paper design, containing wettability gradients along the paper sheet cross section. This asymmetric wettability along all three spatial dimensions enabled side-selective oil-water separation.

Understanding the nanoscale phenomena of nucleation and crystal growth in electrodeposition.

Electrodeposition is used at the industrial scale to make coatings, membranes, and composites. With better understanding of the nanoscale phenomena associated with the early stage of the process, electrodeposition has potential to be adopted by manufacturers of energy storage devices, advanced electrode materials, fuel cells, carbon dioxide capturing technologies, and advanced sensing electronics. The ability to conduct precise electrochemical measurements using cyclic voltammetry, chronoamperometry, and chronopotentiometry in addition to control of precursor composition and concentration makes electrocrystallization an attractive method to investigate nucleation and early-stage crystal growth. In this article, we review recent findings of nucleation and crystal growth behaviors at the nanoscale, paying close attention to those that deviate from the classical theories in various electrodeposition systems. The review affirms electrodeposition as a valuable method both for gaining new insights into nucleation and crystallization on surfaces and as a low-cost scalable technology for the manufacturing of advanced materials and devices.

40-meter-long REBCO tapes with critical current over 4,000 A/12 mm at 4.2 K and 13 T by advanced MOCVD

REBa2Cu3O7−δ (REBCO, RE = rare earth) tapes doped with 5% and 15% Zr have been scaled up to lengths more than 40 m in a pilot-scale advanced metal organic chemical vapor deposition (A-MOCVD) tool. The precursor compositions used for the long tapes were guided by a study of the influence of (Ba + dopant)/Cu content on the critical current density (Jc) of 5 and 15 mol.% Hf- and Zr-added tapes at 4.2 K and 13 T. The 40-m-long tapes exhibited a critical current (Ic) over 4,000 A/12 mm at 4.2 K and 13 T as well as over 1,400 A/12 mm at 20 K and 20 T. The critical current densities of a 40-m-long tape doped with 5% Zr at 4.2 K measured at the National High Magnetic Field Laboratory (NHMFL) were > 10 MAcm−2 and >5 MAcm−2 at 14 T and 30 T, respectively, which are over three times those of commercial REBCO tapes. The infield Jc of 5% Zr-added 40-m-long tapes was similar to those of previously-reported high-performance short samples made with 15% Zr or Hf. These results demonstrate the excellent potential of A-MOCVD for manufacturing high Ic REBCO tapes for use in ultrahigh-field magnet applications.

Ketjen Black@Ce-MOF derived KB@CeO2-C as separator coating for lithium sulfur batteries

Lithium‑sulfur batteries (LSBs) have received wide attention because of their advantages of high theoretical specific capacity. However, shuttle effect of lithium polysulfides need to be solved urgently, which makes the commercial application of LSBs difficult. To solve these problems, Ce-MOF and conductive carbon material Ketjen Black (KB) are used to compound to obtain a composite precursor, and then further calcined at a high temperature to obtain KB@CeO2-C derivative. After applying KB@CeO2-C to commercial separators, the performance of LSBs is improved because of its excellent adsorption and catalytic capability. Through experimental analysis, when the sulfur areal density on the cathode electrode is 2.8 mg cm−1, the discharge specific capacity of the KB@CeO2-C separator battery in the first cycle at 0.5C is 835 mAh g−1, and after 900 cycles, the discharge specific capacity can still maintain 400.1 mAhg−1. When the sulfur loading of the electrode is added to 5 mg cm−1, the initial specific capacity at 0.1C can reach 1090.3 mAh g−1, and it can be stabilized for 120 cycles, which demonstrates its application potential.

Novel approach for manufacture of single‐grain EuBCO/Ag bulk superconductors via modified single‐direction melt growth

AbstractDespite the success of top‐seeded melt growth (TSMG) and TSIG, some key aspects of their manufacture need to be addressed including the presence of microstructural defects, inhomogeneities in trapped field and the difficulty of growing large‐diameter bulk monoliths. Recently, a promising new method single‐direction melt growth (SDMG) appears to address the majority of the shortcomings of TSMG and TSIG. Single‐grain EuBCO/Ag bulk with the highest peritectic temperature to date was grown by modified SDMG. This remarkable achievement was made possible by lowering the peritectic temperature of the precursor composition by the addition of silver and by using single‐grain EuBCO fabricated by TSMG as a seed. The EuBCO/Ag bulk grown by SDMG has demonstrated significant improvements in comparison to a reference TSMG sample. A reduction of approximately 30% in defect area (associated primarily with porosity), as well as a significantly enhanced homogeneity of trapped field and critical temperature, was observed. Furthermore, the critical current density curves exhibit a considerable improvement, particularly in the 2–5 T field range. The SDMG technique has considerable potential for scale‐up for the fabrication of large‐diameter bulk single grains, with only growth along the c‐axis involved during the thermal process.

Physical, mechanical and microstructural properties of one-part semi-lightweight geopolymers based on metakaolin modified with gypsum and lime

The elemental composition of precursors is crucial for the performance development of geopolymers. Metakaolin (MK) was used to produce one-part geopolymers (OPG), and the influence of calcium-based components (lime and gypsum) on their properties was investigated. The experimental results show that the use of lime instead of MK increases the fluidity of the mixture, while the addition of gypsum decreases the fluidity. Meanhwlie, the use of lime to replace a small amount of MK increases the concentration of activator by consuming water and the dissolution of calcium ions also participates in the geopolymerization reaction, which enhances the mechanical properties and durability of OPG. When 10 % lime is applied, the 7-d and 28-d compressive strengths of OPG are increased by 210 % and 157.14 % compared with the plain sample, respectively. The addition of gypsum generates AFt in OPG, which reduces the compactness of the microstructure, which is not conducive to the development of the strength and durability of OPG. When 10 % gypsum is applied, the 28-d compressive and flexural strengths of OPG are decreased by 32.14 % and 26.67 % compared with plain samples, respectively. As the lime content increases, further addition of gypsum to OPG has a more negative effect on OPG due to the plundering of calcium ions in the lime. The 28-d dry density of OPG is between 1585 and 1729 kg/m3, which makes it have a lower thermal conductivity (0.87–0.94 W/m·K).

Valorization of Agricultural Waste Lignocellulosic Fibers for Poly(3-Hydroxybutyrate-Co-Valerate)-Based Composites in Short Shelf-Life Applications.

Biocircularity could play a key role in the circular economy, particularly in applications where organic recycling (composting) has the potential to become a preferred waste management option, such as food packaging. The development of fully biobased and biodegradable composites could help reduce plastic waste and valorize agro-based residues. In this study, extruded films made of composites of polyhydroxybutyrate-co-valerate (PHBV) and lignocellulosic fibers, namely almond shell (AS) and Oryzite® (OR), a polymer hybrid composite precursor, have been investigated. Scanning electron microscopy (SEM) analysis revealed a weak fiber-matrix interfacial interaction, although OR composites present a better distribution of the fiber and a virtually lower presence of "pull-out". Thermogravimetric analysis showed that the presence of fibers reduced the onset and maximum degradation temperatures of PHBV, with a greater reduction observed with higher fiber content. The addition of fibers also affected the melting behavior and crystallinity of PHBV, particularly with OR addition, showing a decrease in crystallinity, melting, and crystallization temperatures as fiber content increased. The mechanical behavior of composites varied with fiber type and concentration. While the incorporation of AS results in a reduction in all mechanical parameters, the addition of OR leads to a slight improvement in elongation at break. The addition of fibers improved the thermoformability of PHBV. In the case of AS, the improvement in the processing window was achieved at lower fiber contents, while in the case of OR, the improvement was observed at a fiber content of 20%. Biodisintegration tests showed that the presence of fibers promoted the degradation of the composites, with higher fiber concentrations leading to faster degradation. Indeed, the time of complete biodisintegration was reduced by approximately 30% in the composites with 20% and 30% AS.

Feasibility study of engineered geopolymer composites based high-calcium fly ash and micromechanics analysis

Engineered geopolymer composites (EGC) have attracted much attention as green construction materials, characterized by strain-hardening behavior and multiple cracking capabilities. Nevertheless, the current utilization of low-calcium fly ash in EGC preparation poses a challenge in terms of long hardening time, which substantially affects the feasibility of applying EGC in engineering projects. The purpose of this study is to assess the potential for developing EGCs using high-calcium fly ash (HFA), explore the impact of sodium silicate (SS)-to-sodium hydroxide (SH) ratio on material properties, and perform a comparative analysis between EGCs fabricated with low-calcium fly ash (LFA) and HFA. SEM analysis elucidates that an increase in the SS-to-SH ratio exerts a favorable influence on matrix density, thereby augmenting overall strength. Nevertheless, this enhancement is accompanied by a notable reduction in tensile strain capacity. It was observed that EGC based on HFA (HFA-EGC) outperforms LFA-based EGC (LFA-EGC) in various aspects of mechanical properties. The effects of SS-to-SH ratio, LFA, and HFA on the mechanical properties were analyzed at the microscale using XRD and SEM, and combined with micromechanical parameters, establishing a multi-scale connection for material performance. The study offers a comprehensive analysis of how varying precursor and activator compositions affect the tensile properties.

Remarkably boosting ethanol upgrading to higher alcohols through cooperative catalysis of surface-interface multiple-active sites on nitrogen-doped carbon decorated copper-based catalysts

Upgrading biomass-derived ethanol to higher alcohols is a significantly promising process involving multi-step tandem reactions finely regulated by multiple active sites. However, the role of multiple active sites in addressing activity and selectivity toward alcohols still remains unclear. Herein, we developed supported copper catalysts decorated with surface trace-level nitrogen-doped carbon (NC) derived from melamine/Cu-Mg-Al layered double hydroxide composite precursors and studied their catalytic performance for converting ethanol to higher alcohols. As-constructed NC-decorated Cu-based catalyst, which was obtained by calcination of the precursor with a melamine/Cu molar ratio of 2:1 at 550 °C, achieved an 82% selectivity to higher alcohols at 63% ethanol conversion under reaction conditions (250 °C, 2 MPa pressure), along with unprecedentedly high ethanol conversion rate of 38.9 mmol·gcat−1·h−1 and production rate of higher alcohols (31.9 mmol·gcat−1·h−1), which are the highest standard among previously reported catalysts to date. By performing comprehensive structural characterizations and density functional theory calculations, it was revealed that surface modification of NC component promoted the dispersion of Cu particles and modulated the electronic structures of Cu species, facilitating the formation of Cu+ sites at metal-support interfaces and surface oxygen vacancies. Moreover, the significantly enhanced catalytic efficiency of Cu catalysts was mainly attributed to the favorable cooperative catalysis of multiple surface-interface active sites (Cu0, Cu+, oxygen vacancies, and acid-base sites), thereby accelerating tandem processes to produce higher alcohols during ethanol conversion. The present findings afford a new strategy for the rational design of high-performance supported copper catalysts for biomass-derived ethanol coupling to higher alcohols.

PHASE FORMATION IN ALKALINE TITANOSILICATE SYSTEMS DURING HYDROTHERMAL SYNTHESIS

The investigations in the polycomponent high alkaline systems – TiO2–H2SO4–Na2SiO3–NaOH–H2O and TiO2–H2SO4–(NH4)2SO4–Na2SiO3–NaOH–H2O under hydrothermal synthesis conditions have been carried out to provide new products with the given technical properties. It has been shown that by directed selection of structure-forming components, in particular titanium compounds, together with optimal parameters of hydrothermal treatment of the obtained precursor, it is possible to form compounds with the given phase and chemical composition, morphology and particle size. It was found that the rate of structural transformations during synthesis depends on the phase composition of titanosilicate precursors. During their hydrothermal treatment, alkaline and thermal hydrolysis with subsequent dehydration of hydrolyzed phases of titanium (IV) and silicon take place. The process is accompanied by localization of free bonds providing formation of Ti–O–Si–O-bridges and their subsequent transformation into structured new formations.

DEVELOPMENT OF SUPPORTED NICKEL-CERIUM CATALYSTS FOR RESOURCE-SAVING CONVERSION OF METHANE INTO HYDROGEN-CONTAINING GAS

To develop an effective catalyst for the resource-saving conversion of coal-industry methane into hydrogen-containing gas, the materials Ce0.2Ni0.8O1.2/Al2O3 were synthesized, their physicochemical and functional properties were studied depending on the nature of the precursors of active components (nickel(II) nitrate hexahydrate, nickel(II) ammonium oxide) and promoters (cerium(III) nitrate hexahydrate, ammonium cerium(IV) nitrate). It is shown that the nature of the precursor affects the textural and structural characteristics of the samples, their catalytic activity in the steam-carbon dioxide reforming of methane and resistance to the formation of carbon deposits. The optimal composition of precursors (nickel (II) nitrate hexahydrate, cerium(III) nitrate hexahydrate) has been established, the use of which in the synthesis of the Ce0.2Ni0.8O1.2/Al2O3 catalyst ensures a decrease in the average particle size of the Ni active component (25 → 6.5 nm) and the degree of catalyst carbonisation (2.9 → 0.5%), high hydrogen yield (95%) at 800 °C in the steam-carbon dioxide reforming of methane.

Different bonding modes modulate the structure and properties of g-C3N4-Based materials

Composite precursors with hydrogen bonding interactions (Fe(OH)3/DCDA) and chemical bonding interactions (Fe(OH)3/PA/DCDA) were constructed by simple hydrothermal method, respectively, and then the corresponding photocatalysts (Fe2O3/g-C3N4 and Fe2O3/C/g-C3N4) were calcined under N2 atmosphere to study the effect of different bonding types of precursors on the structure and performance of the photocatalysts. It is shown that the strong chemical bonding interaction between -CHO in Fe(OH)3/PA and -NH2 in DCDA causes the calcined Fe2O3/C/g-C3N4 to exhibit a lower density of terminal amino defects compared to the weak hydrogen bonding interaction, which greatly facilitates the photogenerated electron-hole separation. In addition, the strong chemical bonding interactions in the precursors would also cause incomplete polymerization during calcination, leading to the formation of porous structures in the catalyst Fe2O3/C/g-C3N4, which increases the specific surface area on the one hand and enhances the photoavailability on the other. Therefore, the prepared Fe2O3/C/g-C3N4 has good photocatalytic activity and can degrade 51.28 % of MB solution after 60 min of continuous irradiation under visible light, which is 2.8 times higher than that of g-C3N4.

Systematic Mix Design Study on Geopolymers—Prediction of Compressive Strength

Due to the demand for decarbonization of the construction sector, research on alkali-activated binders and material-minimized carbon-reinforced structures has gained momentum in recent years. Most of the research into alkali-activated binders is focused on developing market-ready alternatives, mainly using a trial-and-error approach. In this study, an attempt is made to identify and quantify the factors influencing compressive strength development. Due to their worldwide availability, investigations are being carried out into binders based on calcined clays and natural pozzolans. The goal is to develop a method to produce tailor-made AAB for continuous manufacturing methods to combine carbon reinforcement and alkali-activated materials. For this purpose, an experimental matrix with 20 variation parameters was set up, in which the activator solution and the precursor composition varied. The design of the experiments was used to minimize the number of experiments. It was shown that no single factor is responsible for the development of compressive strength but instead involves several interacting factors. It was possible to find empirical formulas for predicting the compressive strength after 2, 7, and 28 days.

The Singhbhum Craton (India) records a billion year of continental crust formation and modification

The petrogenesis of continental crust from its ultimate mantle source can be reconstructed from the element abundances and radiogenic isotope compositions of ideally pristine igneous rocks. The initial isotope compositions of igneous rocks provide geochemical constraints on the age, composition and evolution of their source(s). Determining initial isotope ratios for rock samples can be challenging, especially in rocks with a long and protracted thermal history. The Rb-Sr system is highly sensitive to parent-daughter element fractionation during magma differentiation. This makes the Rb-Sr isotope systematics ideal to trace the precursor composition of Archean felsic crust and constrain the time of element fractionation during the formation and subsequent modification of continental crust. Initial isotope compositions can be obtained directly from minerals that strongly prefer the daughter element and effectively exclude the parent element of the radio-isotope system of interest. Apatite, having a near zero Rb/Sr ratio, is ideal for preserving its initial 87Sr/86Sr and zircon records initial 176Hf/177Hf compositions. Combined modelling of Sr and Hf isotope data from granitoids of the Archean Singhbhum Craton, indicates that the older Paleoarchean granitoids, emplaced between 3.53 Ga and 3.44 Ga, were derived from a mafic precursor (∼52–54 wt% SiO2) sourced from a depleted mantle at ∼3.71 Ga. Initial 87Sr/86Sr isotope signatures of matrix apatite and apatite inclusions in zircon from the younger Paleoarchean granitoids (3.4–3.2 Ga) of the Singhbhum Craton indicate these younger granitoids were produced by mixing of magma generated from an older mafic source and partial melts derived from the older granitoids. The combined Sr-Hf isotope modelling links the timing of mantle extraction of the precursor material for Paleoarchean Singhbhum granitoids with a known mafic crust extraction event at ∼3.71 Ga. In combination, the new Sr isotope data from apatite combined with whole rock and zircon Hf isotope data from the literature reveal a ∼1 Ga protracted crustal growth and differentiation history of the nucleus of the Singhbhum Craton. By combining radio-isotope systems like 87Rb-87Sr and 176Lu-176Hf, the petrogenesis of Archean felsic crust from the extraction of mafic material from the mantle to reworking in an orogenic cycle to emplacement can be reconstructed. This approach can be applied to other greenstone-gneiss terranes to quantify the spatio-temporal and compositional evolution of voluminous felsic crust and the formation of cratons in the Archean.

Trace amount Pt anchored on nitrogen-doped carbon nanoparticle with hollow capsule structure for efficient electrocatalytic oxygen reduction

The utilization of sustainable green energies requires the energy conversion devices to enhance the convenience of use and storage. The oxygen reduction reaction (ORR), as one of the necessary steps in the operation of these devices, exhibits a slow reaction kinetic rate that seriously affects energy conversion and output efficiency. Due to the low abundance and poor stability of Pt, it is essential to develop high-performance oxygen reduction catalysts with low Pt loading. In this work, a composite precursor consisting of ZIF-8 coupled with ferrocene and chloroplatinic acid was prepared, and subsequently derived to obtain nitrogen-doped carbon nanoparticles with hollow capsule morphology on the surface. These hollow capsule structure formed with the assistance of Pt and Fe significantly enhances the performance of Pt/FC@ZIF-8-C nanoparticles as the ORR electrocatalyst, exhibiting superior catalytic activity and stability compared to Pt/C at a low Pt loading (0.7 wt%). This is very important for promoting the design and preparation of Pt-based catalysts, as well as the application of energy conversion and storage devices in the field of green energy sources.

Computationally Guided Synthesis of MXenes by Dry Selective Extraction.

MXenes are a rapidly growing family of 2Dtransition metal carbides and nitridesthatare promising for various applications, including energy storage and conversion, electronics, and healthcare. Hydrofluoric-acid-based etchants are typically used for large-scale and high-throughput synthesis of MXenes, which also leads to a mixture of surface terminations that impede MXene properties. Herein, a computational thermodynamic model with experimental validation is presented to explore the feasibility of fluorine-free synthesis of MXenes with uniform surface terminations by dry selective extraction (DSE) from precursor MAX phases using iodine vapors. A range of MXenesand respective precursor compositions are systematically screened using first-principles calculations to find candidates with high phase stability and low etching energy. A thermodynamic model based on the "CALculation of PHAse Diagrams" (CALPHAD) approach is further demonstrated, using Ti3 C2 I2 as an example, to assess the Gibbs free energy of the DSE reaction and the state of the byproducts as a function of temperature and pressure. Based on the assessment, the optimal synthesis temperature and vapor pressure are predicted and further verified by experiments. This work opens an avenue for scalable, fluorine-free dry synthesis of MXenes with compositions and surface chemistries that are not accessible using wet chemical etching.

The effect of Ir and Sc on the emission capacity of W–Ir matrix scandate cathodes prepared via a novel in situ method

The size and distribution of Sc2O3 in the composite powder precursor has great effect on the emission property of scandate cathode. By one-step in-situ synthesis method, the composite powder exhibits the structure of quasi-spherical Sc2O3 nanoparticles grown in situ on the surface of W/Ir grains, and the obtained W–Ir cathode with 3wt % Sc2O3 could provide the emission current density of 83.43 A/cm2 at 900 °Cb, which is higher than other W–Ir mixed matrix scandate cathodes and W matrix scandate cathode. The XRD results showed that the high emission ability depended on the high content of active phase α-Ba2ScAlO5 and low content of non-active phase BaAl2O4. In-situ TEM has been applied to observe the microstructure evolution of the cathode surface at high temperature for the first time. A serial change in the microstructural features of cathode surface and the migration of Ba, Sc and O on the substrate surface has been found, confirming the formation of Ba-Sc-O active layer. The first-principles calculations indicate that the active substances (Sc) are more stable (low adsorption energy of − 8.58 eV) on the IrW matrix cathode surface than on the tungsten matrix cathode surface, which is consistent with the low evaporation rate of the active substance detected by TFMS technique. Besides, the interaction between the active substance and the matrix was strengthened due to more electron transfer of Sc (1.88 e) and Ba (1.45 e), therefore lowering the work function. The feasible preparation technique makes such a cathode promising for applications in high-power microwave devices.

Evolution of Glassy Carbon Derived from Pyrolysis of Furan Resin.

Glassy carbon (GC) material derived from pyrolyzed furan resin was modeled by using reactive molecular dynamics (MD) simulations. The MD polymerization simulation protocols to cure the furan resin precursor material are validated via comparison of the predicted density and Young's modulus with experimental values. The MD pyrolysis simulations protocols to pyrolyze the furan resin precursor is validated by comparison of calculated density, Young's modulus, carbon content, sp2 carbon content, the in-plane crystallite size, out-of-plane crystallite stacking height, and interplanar crystallite spacing with experimental results from the literature for furan resin derived GC. The modeling methodology established in this work can provide a powerful tool for the modeling-driven design of next-generation carbon-carbon composite precursor chemistries for thermal protection systems and other high-temperature applications.

Synthesis of strontium oxide-zinc oxide nanocomposites by Co-precipitation method and its application for degradation of malachite green dye under direct sunlight

Photocatalysts workable under direct sunlight are the safe and cost-effective option for water purification. The nanocomposites of strontium oxide and zinc oxide (SZ NCs) were synthesized using coprecipitation method. The respective precursors of SZ NCs were subjected to alkaline hydrolysis and subsequently thermally treated to yield SZ NCs. The SZ NCs with different ZnO composition was synthesized by varying the concentration of ZnO precursor from 0.2 to 1 M. The structural properties of SZ NCs evaluated using X-Ray diffraction (XRD), Thermogravimetric analysis (TGA), and Differential thermal analysis DTA). The optical properties of SZ NCs studied using ultraviolet–visible (UV–Vis) spectroscopic study. The trend observed in the intensity of XRD peaks indicated the occurrence of Zn doping in the crystalline lattice of SrO and the formation of SrO–ZnO composite. Upon incorporation of 1 M of ZnO precursor, the grain size of the SrO was decreased from 49.3 to 27.6 nm. The weight loss in the thermal analysis indicates the removal of carbonates from the sample upon heating and shows the formation of an oxide structure. UV–Vis spectra confirmed that the presence of SrO enhanced the sunlight absorption of SZ NCs. The increase in the composition of ZnO precursors increased the bandgap of SrO (2.09 eV) to the level of ZnO (3.14 eV). SZ NCs exhibited heterostructure morphology, where the nanosized domains with varying shapes (layered and rod-like) were observed. Under direct sunlight conditions, SZ NCs prepared using 1 M/0.6 M of SrO/ZnO precursors exhibited 15–20 % higher photocatalytic efficiency than neat SrO and ZnO. In precise, 1 mg of this SZ NC was degraded 98 % of malachite green dye dissolved in water (10 ppm) under direct sunlight. Additionally, the thermal stability results showed that 18 % decomposition was obtained due to the degradation impurities in SrO/ZnO catalysts and the XRD results revealed that no structural change is obtained in SrO/ZnO photocatalysts after stability test. The SZ NCs can be effectively used as safe and economic sunlight photocatalysts for water purification in remote areas without the electricity.

Hydrogen Production via Methanol Steam Reforming over CuO/ZnO/Al2O3 Catalysts Prepared via Oxalate-Precursor Synthesis

CuO/ZnO/Al2O3 catalysts are commonly used for the methanol steam reforming reaction. The oxalate precursor of CuO/ZnO/Al2O3 catalysts were prepared via the co-precipitation method using oxalic acid as the precipitator, deionized water and ethanol as the solvent, and microwave radiation and water baths as aging heating methods, respectively. This suggests that ethanol selects the crystalline phase composition of oxalate precursors and limits their growth. Microwave irradiation prompted the isomorphous substitution between Cu2+ of CuC2O4 and Zn2+ of ZnC2O4 in the mother liquid; Zn2+ in ZnC2O4·xH2O was substituted with Cu2+ in CuC2O4, forming the master phase (Cu,Zn)C2O4 in the precursor. Moreover, the solid solution Cu-O-Zn formed after calcination, which exhibited nano-fibriform morphology. It has the characteristics of small CuO grains, a large surface area, and strong synergistic effects between CuO and ZnO, which is conducive to improving the catalytic performance of methanol steam reforming. The conversion rate of methanol reached 91.2%, the space time yield of H2 reached 516.7 mL·g−1·h−1, and the selectivity of CO was only 0.29%.