Reductive Conversion Research Articles

A novel Pd-doped perovskite-based LaCo0·9Pd0·1O3–Ba/Al2O3 catalyst enhances NOx to ammonia reaction

The effect of Pd doping on the NOx removal efficiency and NH3 selectivity was studied over lean NOx trap LaCo1-xPdxO3-Ba/Al2O3-type catalysts. Two catalysts were prepared by the sequential impregnation of 15 wt% of LaCo1-xPdxO3-type perovskites and 20 wt% of barium over alumina. The results of X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, temperature programmed techniques, UV–vis diffuse reflection absorption spectroscopy, and X-ray photoelectron spectroscopy demonstrated that perovskite and barium grains uniformly distribution over the alumina surface. Cobalt partial substitution by palladium changed the chemical coordination environment, thus leading to the redox properties of perovskites getting different. Moreover, the LaCoO3–Ba/Al2O3 catalyst exhibited a high reduction on NOx by H2 between 450 and 550 °C. Whereas Pd-doped LaCo0·9Pd0·1O3–Ba/Al2O3 catalyst decreased the best activity interval around 100 °C, as well as improved the NH3 selectivity. The NOx reduction conversion of the LaCo0·9Pd0·1O3–Ba/Al2O3 catalyst increased significantly from 72.9% to around 100% at H2/NO ratio = 1, and the production of NH3 was increased from 20.1% to 58.6% at H2/NO ratio = 3.

Rational Design of Non-Noble Metal Single-Atom Catalysts in Lithium-Sulfur Batteries through First Principles Calculations.

Lithium-sulfur (Li-S) batteries with a high theoretical energy density of 2600 Wh·kg-1 are hindered by challenges such as low S conductivity, the polysulfide shuttle effect, low S reduction conversion rate, and sluggish Li2S oxidation kinetics. Herein, single-atom non-noble metal catalysts (SACs) loaded on two-dimensional (2D) vanadium disulfide (VS2) as the potential host materials for the cathode in Li-S batteries were investigated systematically by using first-principles calculations. Based on the comparisons of structural stability, the ability to immobilize sulfur, electrochemical reactivity, and the kinetics of Li2S oxidation decomposition between these non-noble metal catalysts and noble metal candidates, Nb@VS2 and Ta@VS2 were identified as the potential candidates of SACs with the decomposition energy barriers for Li2S of 0.395 eV (Nb@VS2) and of 0.162 eV (Ta@VS2), respectively. This study also identified an exothermic reaction for Nb@VS2 and the Gibbs free energy of 0.218 eV for Ta@VS2. Furthermore, the adsorption and catalytic mechanisms of the VS2-based SACs in the reactions were elucidated, presenting a universal case demonstrating the use of unconventional graphene-based SACs in Li-S batteries. This study presents a universal surface regulation strategy for transition metal dichalcogenides to enhance their performance as host materials in Li-S batteries.

A Synthetic Microbiome Based on Dominant Microbes in Wild Rice Rhizosphere to Promote Sulfur Utilization

Sulfur (S) is one of the main components of important biomolecules, which has been paid more attention in the anaerobic environment of rice cultivation. In this study, 12 accessions of rice materials, belonging to two Asian rice domestication systems and one African rice domestication system, were used by shotgun metagenomics sequencing to compare the structure and function involved in S cycle of rhizosphere microbiome between wild and cultivated rice. The sulfur cycle functional genes abundances were significantly different between wild and cultivated rice rhizosphere in the processes of sulfate reduction and other sulfur compounds conversion, implicating that wild rice had a stronger mutually-beneficial relationship with rhizosphere microbiome, enhancing sulfur utilization. To assess the effects of sulfate reduction synthetic microbiomes, Comamonadaceae and Rhodospirillaceae, two families containing the genes of two key steps in the dissimilatory sulfate reduction, aprA and dsrA respectively, were isolated from wild rice rhizosphere. Compared with the control group, the dissimilatory sulfate reduction in cultivated rice rhizosphere was significantly improved in the inoculated with different proportions groups. It confirmed that the synthetic microbiome can promote the S-cycling in rice, and suggested that may be feasible to construct the synthetic microbiome step by step based on functional genes to achieve the target functional pathway. In summary, this study reveals the response of rice rhizosphere microbial community structure and function to domestication, and provides a new idea for the construction of synthetic microbiome.

Life cycle assessment as a prospective tool for sustainable agriculture and food planning at a local level

Owing to the far-reaching environmental consequences of agriculture and food systems, such as their contribution to climate change, there is an urgent need to reduce their impact. International and national governments set sustainability targets and implement corresponding measures. Nevertheless, critics of the globalized system claim that a territorial administrative scale is better suited to address sustainability issues. Yet, at the sub-national level, local authorities rarely apply a systemic environmental assessment to enhance their action plans. This paper employs a territorial life cycle assessment methodology to improve local environmental agri-food planning. The objective is to identify significant direct and indirect environmental hotspots, their origins, and formulate effective mitigation strategies. The methodology is applied to the administrative department of Finistere, a strategic agricultural region in North-Western France. Multiple environmental criteria including climate change, fossil resource scarcity, toxicity, and land use are modeled. The findings reveal that the primary environmental hotspots of the studied local food system arise from indirect sources, such as livestock feed or diesel consumption. Livestock reduction and organic farming conversion emerge as the most environmentally efficient strategies, resulting in a 25% decrease in the climate change indicator. However, the overall modeled impact reduction is insufficient following national objectives and remains limited for the land use indicator. These results highlight the innovative application of life cycle assessment led at a local level, offering insights for the further advancement of systematic and prospective local agri-food assessment. Additionally, they provide guidance for local authorities to enhance the sustainability of planning strategies.

Effective Reduction of CO2 with Aromatic Amines into N-Formamides Triggered by Noble-Free Metal-Organic Framework Catalysts Under Mild Conditions.

The reductive transformation of carbon dioxide (CO2) into high-valued N‑formamides matches well with the atom economy and the sustainable development intention. Nevertheless, developing a noble-free metal catalyst under mild reaction conditions is desirable and challenging. Herein, a caged metal-organic framework (MOFs) [H2N(CH3)2]2{[Ni3(µ3-O)(XN)(BDC)3]·6DMF}n (1) (XN = 6″-(pyridin-4-yl)-4,2″:4″,4″'-terpyridine), H2BDC = terephthalic acid) is harvested, presenting high thermal and chemical stabilities. Catalytic investigation reveals that 1 as a renewable noble-free MOFs catalyst can catalyze the CO2 reduction conversion with aromatic amines tolerated by broad functional groups at least ten times, resulting in various formamides in excellent yields and selectivity under the mildest reaction system (room temperature and 1bar CO2). Density functional theory (DFT) theoretical studies disclose the applicable reaction path, in which the CO2 hydrosilylation process is initiated by the [Ni3] cluster interaction with CO2 via η2-C, O coordination mode. This work may open up an avenue to seek high-efficiency noble-free catalysts in CO2 chemical reduction into high value-added chemicals.

Statistical Design-Guided Synthesis of Nanoarchitectonics of High-Performance NiFeMoN Electrocatalyst through Facile One-Step Magnetron Sputtering.

This study presents an innovative, statistically-guided magnetron sputtering technique for creating nanoarchitectonics of high-performing, NiFeMoN electrocatalysts for oxygen evolution reaction (OER) in water splitting. Using a central composite face-centered (CCF) design, 13 experimental conditions are identified that enable precise optimization of synthesis parameters through response surface methodology (RSM), confirmed by analysis of variance (ANOVA). The statistical analysis highlighted a interaction between Mo% and N% in the nanostructured NiFeMoN and found optimizing values at 31.35% Mo and 47.12% N. The NiFeMoN catalyst demonstrated superior performance with a low overpotential of 216mV at 10mA cm-2 and remarkable stability over seven days, attributed to the modifications in electronic structure and the creation of new active sites through Mo and N additions. Furthermore, the NiFeMoN coating, when used as a protective layer for a Si photoanode in 1m KOH, achieved an applied-bias photon-to-current efficiency (ABPE) of 5.2%, maintaining stability for 76 h. These advancements underscore the profound potential of employing statistical design for optimizing synthesis parameters of intricate catalyst materials via magnetron sputtering, paving the way for accelerated advancements in water splitting technologies and also in other energy conversion systems, such as nitrogen reduction and CO2 conversion.

Mutual conversion mechanisms for environmental interest products to jointly enhance synergistic effect between power, CET and TGC markets in China

The construction of mutual conversion mechanisms for environmental interest products (EIP) is crucial to enhance connectivity and promote the synergistic development among multiple market systems including power, carbon emissions trading (CET) and tradable green certificate (TGC). In this paper, static and dynamic TGC‑carbon allowance (CA)-Chinese certified emission reduction (CCER) conversion mechanisms are designed from the perspective of physical and economic values. Based on the multi-agent dynamic game model considering Weber-Fechner's law, the transaction behavior for various generation companies (GENCOs) and power purchasers in power, CET and TGC markets under different conversion mechanisms are analyzed. The results demonstrate that TGC-CA-CCER conversion mechanisms further expand the transaction space for low-carbon GENCOs, and effectively reflect the differentiated value of each EIP in diverse scenarios and time periods. Compared with other conversion mechanisms, the dynamic TGC-CA-CCER conversion mechanism based on physical values has better economic as well as environmental benefits, and enhances the competitiveness and liquidity of markets, which is the optimal solution to realize the mutual conversion of EIP. These insights can make up for the research gap of mutual conversion mechanisms on different EIP and provide mechanism options for realizing favorable interaction among power, CET and TGC markets.

Undersizing of the tibial component in Oxford unicompartmental knee arthroplasty (UKA) increases the risk of periprosthetic fractures.

Tibial periprosthetic fractures (TPF) after unicompartmental knee arthroplasty (UKA) are a rare condition that affects about 1% of cases. Known risk factors include age, sex, body mass index (BMI), and bone density, as well as surgical technique and prosthesis design. The purpose of the study was to determine if undersizing of the tibial component in relation to the femoral component increases the risk of tibial periprosthetic fractures. Over a 6-year-period 1542 patients with cemented (n = 363) and uncemented (n = 1179) medial UKA were retrospectively evaluated. Tibial periprosthetic fractures were identified and classified, and epidemiologic data were documented at follow-up. Undersizing was defined as a smaller tibial component compared to the femoral implant. The association of potential risk factors for TPF with the incidence of TPF was investigated with binominal logistic regression. Fourteen patients (0.9%) suffered from TPF at a median of 1month after surgery. The mean follow-up period was 5.9 ± 1.7years. Fractures were more common in cases with undersized tibial components [odds ratio (OR) 3.2, p < 0.05]. Furthermore, older age (OR 1.1, p < 0.05) and female sex (OR 6.5, p < 0.05) were identified as significant risk factors, while BMI (p = 0.8) and cemented implantation (p = 0.2) had no effect on fracture rate. Revision surgery included open reduction and internal fixation or conversion to total knee arthroplasty. Undersizing of implant sizes in UKA increases the risk for TPF especially in patients with small tibial implants. Therefore, mismatched implants should be avoided for UKA particularly when risk factors like obesity, older age, or female gender are present. Tibial periprosthetic fractures were successfully treated by open reduction and internal fixation or conversion to total knee arthroplasty.

Reductive hydrothermal conversion of uranyl oxalates into UO2+x monitored by in situ XANES analyses.

Hydrothermal conversion of actinide oxalates has recently gained attention as an innovative fabrication route for nuclear fuels but has remained mainly limited to tetra- or tri-valent cations. We report herein the reductive conversion of mixtures of uranyl and oxalate ions into UO2+x oxides under mild hydrothermal conditions (T = 250 °C). A multi-parametric study first led to specifying the optimal conditions in terms of pH, oxalate/U ratio and duration to provide a quantitative precipitation of uranium in the hyper-stoichiometric dioxide form with pH = 0.8; R = noxalate/nU = 3, and t = 72 hours. Particularly, pH was evidenced as a key parameter, with 3 different compounds obtained over a range of only 0.4 units. The mechanism leading to the formation of UO2+x was then investigated thanks to an in situ XANES study. Analysis of the supernatant showed that U(VI) was quickly reduced into U(IV) thanks to the presence of oxalates and/or their decomposition products in solution, following first-order kinetics. Tetravalent uranium was then hydrolysed, leading to the precipitation of UO2+x as the only crystalline phase. This study thus demonstrates that the hydrothermal conversion of actinide oxalates into oxides is an extremely versatile tool that can be implemented in a large variety of chemical systems, particularly in terms of the oxidation state of the cations initially present in solution.

Dual-3DM3AD: Mixed Transformer Based Semantic Segmentation and Triplet Pre-Processing for Early Multi-Class Alzheimer's Diagnosis.

Alzheimer's Disease (AD) is a widespread, chronic, irreversible, and degenerative condition, and its early detection during the prodromal stage is of utmost importance. Typically, AD studies rely on single data modalities, such as MRI or PET, for making predictions. Nevertheless, combining metabolic and structural data can offer a comprehensive perspective on AD staging analysis. To address this goal, this paper introduces an innovative multi-modal fusion-based approach named as Dual-3DM3-AD. This model is proposed for an accurate and early Alzheimer's diagnosis by considering both MRI and PET image scans. Initially, we pre-process both images in terms of noise reduction, skull stripping and 3D image conversion using Quaternion Non-local Means Denoising Algorithm (QNLM), Morphology function and Block Divider Model (BDM), respectively, which enhances the image quality. Furthermore, we have adapted Mixed-transformer with Furthered U-Net for performing semantic segmentation and minimizing complexity. Dual-3DM3-AD model is consisted of multi-scale feature extraction module for extracting appropriate features from both segmented images. The extracted features are then aggregated using Densely Connected Feature Aggregator Module (DCFAM) to utilize both features. Finally, a multi-head attention mechanism is adapted for feature dimensionality reduction, and then the softmax layer is applied for multi-class Alzheimer's diagnosis. The proposed Dual-3DM3-AD model is compared with several baseline approaches with the help of several performance metrics. The final results unveil that the proposed work achieves 98% of accuracy, 97.8% of sensitivity, 97.5% of specificity, 98.2% of f-measure, and better ROC curves, which outperforms other existing models in multi-class Alzheimer's diagnosis.

Design of a gold nanoparticles site in an engineered lipase: an artificial metalloenzyme with enantioselective reductase-like activity.

The conjugation of gold complexes with proteins has proved to be interesting and effective in obtaining artificial metalloenzymes as catalysts with improved properties such as higher stability, activity and selectivity. However, the design and precise regulation of their structure as protein nanostructured forms level remains a challenge. Here, we have designed and constructed a gold nanoparticles-enzyme bioconjugate, by tailoring the in situ formation of gold nanoparticles (AuNPs) at two specific sites on the structure of an alkalophilic lipase from Geobacillus thermocatenulatus (GTL). For this purpose, two genetically modified variants of GTL were created by inserting a unique cysteine residue into the catalytic active site by replacing the active serine (GTL-114) and into the lid site (GTL-193). The enzyme, after a first protein-gold coordination, induced the in situ formation of AuNPs, generating a homogeneous artificial enzyme. The size and morphology of the nanoparticles in the AuNPs-enzyme conjugate have been controlled by specific pH conditions in synthesis and the specific protein region where they are formed. Reductase activity of all of them was confirmed in the hydrogenation of nitroarenes in aqueous media. The protein area seemed to be key for the AuNPs, with the best TOF values obtained for the bioconjugates with AuNPs in the lid site. Finally, the protein environment and the asymmetric properties of the AuNPs were tested in the reduction of acetophenone to 1-phenylethanol in aqueous medium at room temperature. A high reductive conversion and an enantiomeric excess of up to 39% towards (R)-1-phenylethanol was found using Au-Mt@GTL-114 pH 10 as a catalyst. Moderate enantioselectivity towards the opposite isomer was also observed using the Au-Mt@GTL-193 pH 10 conjugate.

From copper concentrate to Cu-based metal oxides for thermochemical heat storage: Impurity impact analysis and redox performance optimization

Copper oxide is a promising material for thermochemical heat storage, but its high cost remains a challenge for large-scale applications. To address this issue, we explore using relatively cheap copper concentrate as a starting material. We heat treat the concentrate and find that it mainly consists of CuO and CuFe2O4. Our thermogravimetric analysis shows that the re-oxidation performance of the concentrate is poor, with only 12.5 % reaction, which is about 32.5 % lower than that of commercial copper oxide (≥99.5 %). Our investigation reveals that impurities in the concentrate inhibit the re-oxidation of copper oxide, and their removal is essential to improve performance. Based on these findings, we optimize the existing purification process that removes impurities to less than 0.1–0.5 wt%. The resulting copper oxide has a content above 99 % and an extraction rate of over 97 %, which can minimize the waste of raw materials and reduce the influence of impurities. The redox properties of the purified copper oxide are comparable to those of commercially available copper oxide. On this basis, the self-made CuO was modified by doping with cheap MgO and Al2O3, whose reduction conversion rate and reoxidation rate could still reach 97.0 % and 96.3 % after 250 redox cycles.

(Invited) Plasmonic Aerogels for Gas-Phase Photocatalytic Reactions

As a special form of material, aerogel has emerged as a promising type of photocatalyst. Owing to the large specific surface area and the developed pore texture, it would be suitable to drive various gas-phase reactions such as CO2 reduction and CH4 conversion. More importantly, the size of the fundamental building blocks in an aerogel, which is typically 5-20 nm, is approaching that of the noble metals with the surface plasmon resonance (SPR) effect. Innovated by Rolison and Niederberger(1, 2), aerogels with plasmonic effect have been extensively studied as photocatalysts for hydrogen evolution and dye degradation in liquid mediumThis talk then aims to introduce some of our recent results on the construction and evaluation of plasmonic noble metal/ceria composite aerogels, which cover the content from the synthesis to new applications. Modified synthesis methods are developed for the rational incorporation of plasmonic metal nanoparticles such as Ag and Au into an aerogel backbone in one step, which offers an alternative route to tune the composition and size of these nanoparticles, or even building single-atom composite aerogels in the conventional sol-gel methodology(3). When these plasmonic aerogel photocatalysts are applied for gas-phase CO2 reduction and non-oxidative CH4 coupling reaction, good performance is observed. The synergistic effect of plasmonic sensitizer and co-catalyst is discussed and is responsible for the performance enhancement. P. A. DeSario, J. J. Pietron, A. Dunkelberger, T. H. Brintlinger, O. Baturina, R. M. Stroud, J. C. Owrutsky and D. R. Rolison, Langmuir, 33, 9444 (2017). F. Rechberger and M. Niederberger, Nanoscale Horizons, 2, 6 (2017). M. Wu, C. Ouyang, Z. Ye, S. Li, Z. Hong and M. Zhi, ACS Applied Energy Materials, 5, 7335 (2022).

Nickel foam supported non-noble Co3O4 as monolithic membrane catalyst for the reduction of p-nitrophenol

Catalytic reduction of p-nitrophenol (PNP) into p-aminophenol (PAP) is regarded as an effective detoxification approach. However, high cost and difficulty in recycling of the powdery noble metal catalyst limit the practicality of this method to a great extent. Hence, the development of non-noble metal catalysts with easy recovery nature is very desirable. In this study, we prepared a Co3O4@nickel foam (NF) monolithic membrane catalyst by coating Co3O4 onto nickel foam via a hydrothermal-calcination method. Moreover, its catalytic performance towards PNP reduction was assessed in the presence of NaBH4. The results showed that a PNP reduction conversion of 87.61 % could be achieved within 25 min under the reaction conditions: two pieces of 3 × 3 cm2 Co3O4@NF, NaBH4 dosage of 0.02 mol L−1, PNP concentration of 0.108 mmol L−1, a total reaction volume of 500 mL and reaction temperature of 25 °C. Additionally, Co3O4@NF monolithic membrane exhibited stable catalytic performance. After 10 consecutive catalytic cycles, a PNP reduction conversion of more than 85 % could be maintained. Therefore, it is expected that such kind of NF supported non-noble Co3O4 monolithic membrane catalyst has promising applications in nitrophenol wastewater treatment.

Nitrogen removal characteristics of novel bacterium Klebsiella sp. TSH15 by assimilatory/dissimilatory nitrate reduction and ammonia assimilation

A novel strain with heterotrophic nitrification and aerobic denitrification was screened and identified as Klebsiella sp. TSH15 by 16S rRNA. The results demonstrated that the ammonia-N and nitrate-N removal rates were 2.99 mg/L/h and 2.53 mg/L/h under optimal conditions, respectively. The analysis of the whole genome indicated that strain TSH15 contained the key genes involved in assimilatory/dissimilatory nitrate reduction and ammonia assimilation, including nas, nar, nir, nor, glnA, gltB, gdhA, and amt. The relative expression levels of key nitrogen removal genes were further detected by RT-qPCR. The results indicated that the N metabolic pathways of strain TSH15 were the conversion of nitrate or nitrite to ammonia by assimilatory/dissimilatory nitrate reduction (NO3−→NO2−→NH4+) and further conversion of ammonia to glutamate (NH4+-N → Glutamate) by ammonia assimilation. These results indicated that the strain TSH15 had the potential to be applied to practical sewage treatment in the future.

Valorization of cattle manure via a thermo-chemical process

World population growth and improvements in income levels have led to an increase in the global consumption of animal-sourced proteins. However, the massive production of animal manure has resulted in significant environmental burdens, such as increasing greenhouse gas emissions, eutrophication, and water and soil contamination. As such, this study proposed a sustainable and rapid disposal platform for animal manure as a precautionary approach to attenuate the environmental burdens caused by manure. A pyrolysis process was used to convert cattle manure into value-added products with the aim of achieving both rapid volume reduction and sustainable conversion. CO2 was fed into the process to increase the green/sustainable benefits and the results were compared with pyrolysis with the addition of N2 (inert gas). Pyrolysis oil was the major product of cattle manure pyrolysis. However, because of its complicated composition, pyrolysis oil cannot be considered a beneficial product. Thus, pyrolysis oil was converted into value-added syngas (H2/CO). Under pyrolysis with an introduction of CO2, the homogeneous reaction converted the volatile compounds and CO2 into CO at ≥ 510 ˚C. However, the reaction rate leading the CO2 reactivity was insufficient. To improve CO2 reactivity, supported Ni catalyst was introduced for catalytic pyrolysis. The concentration of CO from CO2-induced pyrolysis jumped 3.5 times (42.0 wt%) when the supported Ni catalyst was loaded in comparison with catalyst free pyrolysis setup. The increase in CO generation led to a decrease in the pyrolysis oil content (benzene analogs and polycyclic aromatic hydrocarbons) because the carbon was mostly reallocated to CO. The results of this study offer a strategic means of valorizing manure into syngas by tailoring the carbon length of the pyrogenic products.

Mushroom‐based biocatalysts for the synthesis of aroma and flavours from exogenous organic molecules: a review of two decades

SummaryMushroom species, rich in lignolytic oxidoreductases are promising biocatalysts for the functionalization or degradation of small molecules to produce aroma and/or flavours. These macrofungi, sources of thermostable extracellular enzymes are often safer as biocatalysts, produce aromatic flavours similar to plant‐origin and capable of using a wide range of recalcitrant lignocellulosic substrates. The current review summarises the research on mushroom‐mediated production of aroma and aromatic flavours from organic molecules (pure or extract) in the last two decades. It mainly includes oxidative conversion or degradation of small molecules such as mono and sesquiterpenoids, phenylpropanoids, aromatic or linear alcohols and carbonyls, alkenes, carotenoids, fatty acids and amino acids into oxygenated aroma/flavours using the whole‐cells or purified enzymes of mushroom‐origin. Allylic or alcohol oxidation, alkene cleavage and degradation of unsaturated long‐chains were the major pathways of oxidative transformations. Reductive conversions of aromatic and linear carbonyls were also exemplified. However, slow biomass growth, low‐substrate load, conversion, product titre and selectivity, long fermentation time, difficult/low expression of enzymes, cost‐effective and efficient upscaling, insufficient genomic data are major challenges in utilising the diversity of mushroom species for aroma and bioflavour production in industrial scale.

Reductive roasting of red mud with carbon and sulfuric acid dissolution of iron and aluminum: Transformation phases and leaching characteristics

A novel approach is proposed, combining pyrometallurgical and hydrometallurgical processes, to enhance the recovery of Fe and Al while effectively breaking down the mineral composition of red mud. The study delves into the roasting reduction behavior and conversion mechanism of red mud, utilizing thermodynamic analysis and conducting roasting experiments. Extensive investigations were conducted to analyze the impact of roasting temperature and time on the carbothermal reduction of red mud. The results indicate that the most favorable leaching effect of iron and aluminum from red mud was achieved after roasting at 1000 °C for 45 min. The behavior of roasted red mud during acid leaching was meticulously explored. During the roasting process, the majority of hematite in the red mud underwent reduction to wustite (FeO) and zero-valent iron, while the aluminum-bearing minerals melted and decomposed to form NaAlSiO4 and Ca2Al2SiO7, along with other substances. The formation of low-valent and independently present iron products played a role in achieving high Fe leaching efficiency. The presence of Ca and Al-containing compounds such as Ca2Al2SiO7 in the product of roasting proved difficult to leach, leading to poor Al leaching efficiency. The acid leaching process exhibited promising results, with maximum leaching efficiency of iron and aluminum reaching 95.7% and 72.5%, respectively. This success can be attributed to the control over experimental conditions, which allowed for the generation of desired iron oxides with various valence states.

Functional Graphdiyne for Emerging Applications: Recent Advances and Future Challenges

AbstractGraphdiyne (GDY) is regarded as an exceptional candidate to meet the growing demand in many fields due to its rich chemical bonds, highly π‐conjugated structure, uniformly distributed pores, large surface area, and high inhomogeneity of charge distribution. The extensive research efforts bring about a rapid expansion of GDY with a variety of functionalities, which significantly enhance performance including photocatalysis, energy, biomedicine, etc. In this review, the synthetic strategies (in situ and ex situ approaches) that are designed to rationally functionalize GDY, including optimizing their nanostructures by surface/interface engineering with dopants or functional groups (heteroatoms/small molecules/macromolecules), and building up hierarchical GDY‐based heterostructures are highlighted. Theoretical calculations on the structural evolution and electronic characteristics after the functionalization of GDY are briefly discussed. With elaborate functionalization and rational structure engineering, functional GDY applied in a variety of emerging applications (e.g., hydrogen evolution reaction, CO2 reduction reaction, nitrogen reduction reaction, energy storage and conversion, nanophotonics, sensors, biomedical applications, etc.) are comprehensively discussed. Finally, challenges and prospects concerning the future development of GDY‐based nanoarchitectures are also presented.

On the reduction of NiFe/Al2O3 oxygen carrier in high-pressure chemical looping applications

Chemical looping represents a promising technology with various applications ranging from clean power production to alternative syngas production. In this work, two oxygen carriers with different Ni loadings (4.3% wt. and 12% wt.) and similar Fe loadings (9.9% wt. and 8.5% wt.) are synthesized through a co-precipitation/impregnation route and tested in two thermogravimetric analyzers. Firstly, the effect of temperature (700–900 °C) on the oxygen transport capacity and reduction conversion of both materials is assessed at ambient pressure (0.5 nl/min with 20% H2/N2). The influence of material loading is also studied, and it is shown that higher Ni loadings provide a significant improvement in material activity. A complete reduction conversion is achieved at 900 °C and ambient pressure. At high pressure (10–20 bar), tests are carried out in a temperature range of 700–850 °C. The effect of flow rate (2 nl/min to 6 nl/min with 50% H2/N2) is first assessed to prevent external mass transfer limitations. Higher total pressures have a negative effect on reduction kinetics, while higher Ni loadings demonstrate increased final reduction conversion also at high pressure, reaching about 75% conversion after 20 min. The long-term cyclability of the material is also investigated both at low (100 cycles) and high pressure (80 cycles) conditions and a conversion gain is observed throughout the cycles in both cases. No changes in the material microstructure are observed after 80 high-pressure cycles.