Stable Metal Research Articles

Probing the influence of imidazolylidene- and triazolylidene-based carbenes on the catalytic potential of dioxomolybdenum and dioxotungsten complexes in deoxygenation catalysis.

We report the synthesis of dianionic OCO-supported NHC and MIC complexes of molybdenum and tungsten with the general formula (OCO)MO2 (OCO = bis-phenolate benzimidazolylidene M = Mo (1-Mo), bis-phenolate triazolylidene M = Mo (2-Mo), M = W (2-W) and bis-phenolate imidazolylidene, M = Mo (3-Mo), W (3-W)). These complexes are tested in the catalytic deoxygenation of nitroarenes using pinacol as a sacrificial oxygen atom acceptor/reducing agent to examine the influence of the carbene and the metal centre in this transformation. The results show that the molybdenum-based triazolylidene complex 2-Mo is by far the most active catalyst, and TOFs of up to 270 h-1 are observed, while the tungsten analogues are basically inactive. Mechanistic studies suggest that the superiority of the triazolylidene-based complex 2-Mo is a result of a highly stable metal carbene bond, strongly exceeding the stability of the other NHC complexes 1-Mo and 3-Mo. This is proven by the structural isolation of a triazolylidene pinacolate complex (5-Mo) that can be thermally converted to a μ-oxodimolybdenum(V) complex 7-Mo. The latter complex is very oxophilic and stoichiometrically deoxygenates nitro- and nitrosoarenes at room temperature. In contrast, azoarenes are not reductively cleaved by 7-Mo, suggesting direct deoxygenation of the nitroarenes to the corresponding anilines with nitrosoarenes as intermediates. In summary, this work showcases the superior influence of MIC donors on the catalytic properties of early transition metal complexes.

Highly selective catalytic hydrogenation of furfural and acetophenone on S-doped mesoporous carbon Sphere-Supported Pd nanocluster catalyst

The efficient catalytic conversion of the biomass platform molecule furfural into biofuels or other high-value-added chemicals is currently a research hotspot. However, the hydrogenation of furfural possesses challenges due to the occurrence of multiple side reactions that generate various by-products. Herein, S-doped mesoporous carbon spheres (CS-S) with an ordered and accessible structure were precisely designed and synthesized. Subsequently, ∼1.8 nm Pd nanoclusters were immobilized within the radial mesoporous structure of CS-S to obtain a Pd/CS-S catalyst. This catalyst was used for the hydrogenation of furfural and acetophenone into tetrahydrofurfuryl alcohol (THFA) and 1-phenylethanol, respectively, and 99 % conversion and more than 90 % selectivity were achieved. Mechanistic study revealed that the electron-deficient Pd nanoclusters anchored on CS-S exhibit higher adsorption energies for reactant molecules, thus facilitating the pre-adsorption and activation of substrate molecules. Moreover, the Gibbs free energy for each step of the hydrogenation process is lower on the electron-deficient Pd metal surface, leading to excellent catalytic hydrogenation performance. In addition, the Pd/CS-S catalyst also exhibited remarkable recyclability and stability over multiple reaction cycles. This work facilitates the construction of stable metal nanocluster-based catalysts for enabling highly selective catalytic hydrogenation.

Optimizing soil remediation with multi-functional L-PH hydrogel: Enhancing water retention and heavy metal stabilization in farmland soil.

Agricultural soils face severe challenges, including water scarcity and heavy metal contamination. Optimizing soil remediation efficiency while minimizing inputs is essential. This study assessed the water retention and heavy metal adsorption properties of L-PH hydrogel through aqueous experiments. Fourier Transform Infrared (FTIR) and X-ray Photoelectron Spectroscopy (XPS) elucidated the adsorption mechanisms. The results showed that L-PH hydrogel exhibited high water absorption efficiency, with Zn2+ removed via electrostatic interactions and cation exchange, and Cd2+ and Cu2+ adsorbed through coordination complexation. Soil experiments tested water retention and heavy metal leaching under various application methods (M1=0-10cm mixed, M2=10-20cm mixed, T1=5-10cm layered, T2=10-15cm layered) and rates (NL=0%, L1=0.1%, L2=0.2%, L3=0.5%). L-PH reduced water infiltration, enhanced soil water retention, and decreased heavy metal mobility across all treatments. The highest water retention was observed in the M1 method. Under M1L1, cumulative leaching of Cd2+, Cu2+, and Zn2+ decreased by 68.84%, 33.44%, and 83.60%, respectively. Two-way ANOVA revealed that application rate had a greater effect on leaching than the method. FTIR and XRD analyses showed that at low concentrations (L1, L2), L-PH formed coordination bonds with Cd2+ and Cu2+, creating Cd(HCOO)2·2(NH2)2CO and Cu(HCOO)(OH) in the soil. Zn2+ was stabilized through adsorption and precipitation, forming Zn(OH)2, thereby reducing leaching. Higher concentrations of L-PH may have further interacted with Zn, leading to dissolution and adsorption/precipitation processes. Redundancy analysis (RDA) analysis suggests that an increase in organic carbon and moisture content in soil aggregates larger than 2mm, along with a decrease in bioavailable heavy metals, may enhance heavy metal stabilization, reducing their movement and leaching. This study offers valuable insights into addressing the twin challenges of water scarcity and heavy metal pollution.

Recent progress in constructing fluorinated solid-electrolyte interphases for stable lithium metal anodes

Recent progress in constructing fluorinated solid-electrolyte interphases for stable lithium metal anodes

Viscoelastic Soft Solid Electrolytes Enable Fast Zinc Ion Conductance and Highly Stable Zinc Metal Anode

AbstractAchieving both high ionic conductance and stable Zn metal anode simultaneously remains a challenge with current liquid and solid electrolytes. Here, a viscoelastic soft solid electrolyte (VSSE) strategy is presented that effectively balances Zn ion conduction and Zn anode stability. The VSSE is created by nano‐SiO2 inducing a liquid‐to‐solid transition in a liquid solution containing Zn(BF4)2 salt dissolved in an oligomer (glycerol polyoxyethylene‐b‐oxypropylene ether, GPE) and water. The plentiful oxygen functional group in VSSE provides enough hydrogen bonding sites for water molecules to be completely hydrogen‐bonded to form a state without free water. The bound water serves as a Zn‐O coordination modulator that can weaken the strong Zn‐O coordination, lowering the dissociation energy for Zn ions, realizing fast Zn ion decoupling motion mode. Consequently, the VSSE gives impressive Zn ion conductance of (2.28 ± 0.07) ×10−3 S cm−1 at room temperature 10–1000 times higher than reported solid polymer electrolytes. Simultaneously, the restricted molecular activity of bound water allows for excellent storage/cycle life of the Zn metal anode, which is confirmed by remarkably improved storage life (720 h), shelving‐recovery lifespan (850–1200 h), and cycling life (1400–2050 h). This study offers fresh perspectives on multifunctional electrolyte design strategies based on soft‐matter science.

Hydrothermally Stable Zeolite-Encapsulated Metal Catalyst Promoted by Framework Sn Species

Hydrothermally Stable Zeolite-Encapsulated Metal Catalyst Promoted by Framework Sn Species

Deciphering Oxidation-Dominated Abnormal Rheology to Design Performance-Stable Liquid-Metal-Based Nanofluids for Transmission Applications.

With global decarbonization urgency for sustainability, enhancing the service stability of liquid metals (LMs) and reducing their oxidation-induced failures are crucial. The oxidation of LMs can adversely affect the fluidity required for hydraulic transmission, thermal management, and other transport scenarios. Given the importance, we have fabricated an LM-based SiC/graphene-Mo nanofluid (LMNF) and compared the rheological behavior to pure LM under an oxidative atmospheric environment. Using an omni-spectrum rotary rheometer and a water bath ultrasonic technique, we quantified a more stable rheological performance in our LMNFs and elucidated how it linked to LMNFs' phase interactions and oxidation. Their temperature-viscosity characteristics are less susceptible to dealloying-accompanied severe oxidation because the nanophase-enabled strong interfacial bonding by SiC, graphene, and Mo gives LMNFs a more viscoelastic solid nature. With these observations, a performance-predicting model, validated through real hydraulic transmission demonstrations, is developed to decipher the relationship among oxidation-influenced rheological performance like viscosity, temperature, and nanophase and guide LMNF design. This model provides a robust framework to fabricate LMNFs for long-term applications with a stable performance.

Insights into closed-wet ultrasonic carbonation of MSWI fly ash: Carbon sequestration, heavy metals stabilization, and PCDD/Fs migration and degradation.

This study proposed a novel closed-wet accelerated carbonation method based on ultrasonic chemistry for treating municipal solid waste incineration fly ash (MSWI FA), assessing various reaction parameters (time, temperature, CO2 pressure, ultrasonic power, and alkaline additives) on the detoxification and synergistic carbon fixation. The mechanisms of carbon sequestration, heavy metal migration-stabilization, and PCDD/Fs migration-degradation were elucidated. Key findings include the reaction kinetic of MSWI FA ultrasonic carbonation aligning with the surface coverage model (R2>0.999), achieving a carbonation efficiency of 29.4% within 30min. Optimal conditions-room temperature, 1-2MPa CO2 pressure, and 500W ultrasonic power-enhanced carbon sequestration and heavy metal stabilization. The formation of fine calcium carbonate resulted in the co-precipitation of heavy metals, such as Ba, Pb, and Zn, avoiding liquid phase heavy metal pollution and reducing their leaching concentrations in solid samples well below the HJ 1134-2020 standard. The particle size reduction rate was 69.9% (18.6μm) for non-ultrasonic carbonated FA compared to 89.2% (6.7μm) for ultrasonic carbonated FA (UFA). NaOH and ammonia addition effectively decreased calcium concentration in the carbonation reaction solution (<200mg/L) and calcium sulfate content in UFA. The ultrasonic carbonation process prevented PCDD/Fs from migrating into the reaction solution and achieved 35.0% PCDD/Fs degradation. This comprehensive evaluation supports the viability of ultrasonic carbonation for treating MSWI FA.

Rigid Additives Enabling Inorganic‐Rich Interphase via Steric Effects and Van der Waals Force for Stable Lithium Metal Batteries

Rigid Additives Enabling Inorganic‐Rich Interphase via Steric Effects and Van der Waals Force for Stable Lithium Metal Batteries

Challenges and Strategies for Zinc Metal Anode

Aqueous zinc‐ion batteries (AZIBs) are received intensive attention for their inherent safety, economic feasibility, competitive electrochemical performance, and environmental friendliness. However, the rampant side reactions such as dendrite growth, hydrogen evolution, corrosion, and passivation of zinc metal anode seriously hinder the stability of AZIBs. This concept is aim to enhancing the practical viability of AZIBs, with a particular focus on the stability of zinc metal anodes. Here, we summeriazed the strategies for achieving high reversibility zinc metal anode, and points out the shortcomings that still exist in current research. Then the crucial role of regulation electric double layer (EDL) layer, zinc ion transfer number and electrolyte design is summerized in detail. Finally, we consider that the design of zinc anode should focus more on practicality and commercialization, and provide a perspective for the future development direction of zinc anode. We hope to provide an inspiration for the design of stable zinc metal anodes in AZIBs from this concept.

Freeze–Thaw Dynamics in Postindustrial Soil: Implications for Metal Stability and Soil Enzymatic Activity During Phytostabilization

ABSTRACTPhytostabilization, a key strategy in addressing heavy metal contamination, faces challenges in regions with frequent temperature fluctuations. The challenges arise from the impact of temperature variations on microbial activity, plant metabolism, and metal bioavailability. Acknowledging the sensitivity of soil dynamics, amendments, and ecological interactions to temperature variations underscores the importance of considering these factors for effective phytostabilization strategies in dynamic environmental conditions. The aim of this study is to explore the effect of phytostabilization assisted with diatomite, halloysite, and biochar with and without freeze–thaw conditions on metal stability (as distribution patterns), and microbial activity (as dehydrogenase activity, DHA). The experiment comprised two variants. In the first, conducted without FTC, Lolium perenne seeds were sown in pots filled with soil from a contaminated area, both with and without amendments (3%), lasting for 52 days. The second variant replicated the process with 16 freeze–thaw cycles (FTC) and extended the duration to 116 days. Results revealed that FTC alters the distribution of heavy metals in soil compared to conditions without the FTC cycle. Diatomite reduces Cu mobility but may potentially increase Cd mobility. Halloysite enhances Cu exchangeability, restricts Cd mobility, and increases Pb retention in a stable form. Biochar exhibits mixed effects on Cu and Cd mobility, showcasing the influence of FTC on these soil amendments. As a vital microbial indicator, soil DHA responds dynamically to varying temperatures. The applied amendments seem to mitigate the adverse effects of FTC cycles by supporting DHA. Notably, halloysite exhibits a more favorable influence without FTC, while biochar and diatomite showcase enhanced stimulatory effects post‐FTC. It emphasises the need for a nuanced understanding of temperature–microbe interactions and the role of amendments in enhancing the sustainability of phytostabilization in metal‐contaminated environments.

Metal‐Bridging Cyclic Bilatriene Analogue Affords Stable π‐Radicaloid Dyes with Near‐Infrared II Absorption

Stable neutral metal radicaloid complexes have been synthesized from a modified tetrapyrrolic pigment, bilatriene, with iridium(I) and rhodium(I) cyclooctadiene (COD) synthons. The bilatriene skeleton contains α‐linked conjugated pyrrole units, whereas an N‐confused analogue used in this work possesses β‐linked pyrrole moieties at the terminal, demonstrating a unique metal binding capability. Unprecedentedly, the metal‐COD cations are accommodated at the outer nitrogen sites, which induced the formation of open‐shell metal‐radicaloid species. The resulting compounds are highly stable under ambient conditions and demonstrated facile redox conversion to afford the corresponding cation and anion species. Furthermore, the radicaloid complexes showed a distinct second near‐infrared absorption (NIR‐II) capability extending up to 1500 nm along with high photostability. These features emphasized that the complexes can be potential NIR‐II light‐responsible photothermal and photoacoustic imaging contrast agents based on the metal‐radicaloid dye platform.

Metal-Bridging Cyclic Bilatriene Analogue Affords Stable π-Radicaloid Dyes with Near-Infrared II Absorption.

Stable neutral metal radicaloid complexes have been synthesized from a modified tetrapyrrolic pigment, bilatriene, with iridium(I) and rhodium(I) cyclooctadiene (COD) synthons. The bilatriene skeleton contains α-linked conjugated pyrrole units, whereas an N-confused analogue used in this work possesses β-linked pyrrole moieties at the terminal, demonstrating a unique metal binding capability. Unprecedentedly, the metal-COD cations are accommodated at the outer nitrogen sites, which induced the formation of open-shell metal-radicaloid species. The resulting compounds are highly stable under ambient conditions and demonstrated facile redox conversion to afford the corresponding cation and anion species. Furthermore, the radicaloid complexes showed a distinct second near-infrared absorption (NIR-II) capability extending up to 1500 nm along with high photostability. These features emphasized that the complexes can be potential NIR-II light-responsible photothermal and photoacoustic imaging contrast agents based on the metal-radicaloid dye platform.

A Hydrolytically Stable Metal−Organic Framework for Simultaneous Desulfurization and Dehydration of Wet Flue Gas

Metal−organic frameworks (MOFs) have great prospects as adsorbents for industrial gas purification, but often suffer from issues of water stability and competitive water adsorption. Herein, we present a hydrolytically stable MOF that could selectively capture and recover trace SO2 from flue gas, and exhibits remarkable recyclability in the breakthrough experiments under wet flue‐gas conditions, due to its excellent resistance to the corrosion of SO2 and the water‐derived capillary forces. More strikingly, its SO2 capture efficiency is barely influenced by the increasing humidity, even if the pore filling with water is reached. Mechanistic studies demonstrate that the delicate pore structure with diverse pore dimensions and chemistry leads to different adsorption kinetics and thermodynamics as well as segregated adsorption domains of SO2 and H2O. Significantly, this non‐competitive adsorption mechanism enables simultaneous desulfurization and dehydration by a single adsorbent, opening an avenue toward cost‐effective and simplified processing flowcharts for flue gas purification.

Coulombic Condensation of Liquefied Gas Electrolytes for Li Metal Batteries at Ambient Pressure

The concept of employing highly concentrated electrolytes has been widely incorporated into electrolyte design, due to their enhanced Li‐metal passivation and oxidative stability compared to their diluted counterparts. However, issues such as high viscosity and sub‐optimal wettability, compromise their suitability for commercialization. In this study, we present a highly concentrated dimethyl ether‐based electrolyte that appears as a liquid phase at ambient conditions via Li+ ‐ solvents ion‐dipole interactions (Coulombic condensation). Unlike conventional high salt concentration ether‐based electrolytes, it demonstrates enhanced transport properties and fluidity. The anion‐rich solvation structure also contributes to the formation of a LiF‐rich salt‐derived solid electrolyte interphase, facilitating stable Li metal cycling for over 1000 cycles at 0.5 mA cm‐2, 1 mAh cm‐2 condition. When combined with a sulfurized polyacrylonitrile (SPAN) electrode, the electrolyte effectively reduces the polysulfide shuttling effect and ensures stable performance across a range of charging currents, up to 6 mA cm‐2. This research underscores a promising strategy for developing an anion‐rich, high concentration ether electrolyte with decreased viscosity, which supports a Li metal anode with exceptional temperature durability and rapid charging capabilities.

Coulombic Condensation of Liquefied Gas Electrolytes for Li Metal Batteries at Ambient Pressure.

The concept of employing highly concentrated electrolytes has been widely incorporated into electrolyte design, due to their enhanced Li-metal passivation and oxidative stability compared to their diluted counterparts. However, issues such as high viscosity and sub-optimal wettability, compromise their suitability for commercialization. In this study, we present a highly concentrated dimethyl ether-based electrolyte that appears as a liquid phase at ambient conditions via Li+ - solvents ion-dipole interactions (Coulombic condensation). Unlike conventional high salt concentration ether-based electrolytes, it demonstrates enhanced transport properties and fluidity. The anion-rich solvation structure also contributes to the formation of a LiF-rich salt-derived solid electrolyte interphase, facilitating stable Li metal cycling for over 1000 cycles at 0.5 mA cm-2, 1 mAh cm-2 condition. When combined with a sulfurized polyacrylonitrile (SPAN) electrode, the electrolyte effectively reduces the polysulfide shuttling effect and ensures stable performance across a range of charging currents, up to 6 mA cm-2. This research underscores a promising strategy for developing an anion-rich, high concentration ether electrolyte with decreased viscosity, which supports a Li metal anode with exceptional temperature durability and rapid charging capabilities.

Promoting Alcohols Electrooxidation Coupled with Hydrogen Production via Asymmetric Pulse Potential Strategy.

Electrocatalytic organic oxidation coupled with hydrogen (H2) production emerges as a profitable solution to simultaneously reduce overall energy consumption of H2 production and synthetic high-value chemicals. Noble metal catalysts are highly efficient electrocatalysts in oxidation reactions, but they deactivate easily weakening the benefit in actual production. Herein, we report a universal asymmetric pulse potential strategy to achieve long-term stable operation of noble metals for various alcohol oxidation reactions and noble metal catalysts. For example, by pulsed potentials between 0.8 V and 0 V vs. RHE, palladium (Pd)-catalyzed glycerol (GLY) electrooxidation can continuously proceed for more than 2800 h with glyceric acid (GLA) selectivity of >70 %. Whereas, Pd electrocatalyst becomes nearly deactivated within 6 h of reaction under conventional potentiostatic strategy. Experimental and theoretical calculation results reveal that the generated electrophilic OH* from H2O/OH- oxidation on Pd (denoted as Pd-OH*) acts as main active species for GLY oxidation. However, Pd-OH* is prone to be oxidized to PdOx resulting in performance decay. When a short reduction potential (e.g., 0 V vs. RHE for 5 s) is powered, PdOx can be reversibly reduced to restore the current. Moreover, we tested the feasibility of this strategy in a flow electrolyzer, verifying the practical application potential.

Weakly Solvating Cyclic Ether-Based Deep Eutectic Electrolytes for Stable High-Temperature Lithium Metal Batteries.

Deep eutectic electrolytes (DEE) have emerged as an innovative approach to address the instability and safety issues of lithium metal batteries at elevated temperatures. However, in practice, there is often an undesirable incompatibility between the eutectic mixture and electrodes, and also an insufficient reduction stability of DEE due to the increased Li+ concentration. Herein, we designed a new DEE by utilizing weakly solvating tetrahydropyran (THP) solvent. Due to the high reduction resistance of THP and concentrated lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), this DEE demonstrates enhanced compatibility with Li metal anode and high temperature tolerance with LiMn2O4 cathode. The Li||LiMn2O4 cell (1.6 mAh cm-2) shows a high capacity retention of 96.02 % after 600 cycles at room temperature. More importantly, this Li||LiMn2O4 cell achieves a remarkable high-temperature performance with a high capacity retention of 91.72 % after 120 cycles and low self-discharge after storage for 240 hours at a high temperature of 55 °C, which is critical for LiMn2O4 cathode. Overall, this electrolyte design provides an alternative pathway for the development of DEEs for high-temperature and high-voltage lithium metal batteries, which can also be expanded to other batteries.

Synergistic Effects of Unmodified Tea Leaves and Tea Biochar Application on Remediation of Cr-Contaminated Soil

Hexavalent chromium (Cr(VI)) contamination in soil presents significant risks due to its high toxicity to both the environment and human health. Renewable, low-cost natural materials offer promising solutions for Cr(VI) reduction and soil remediation. However, the effects of unmodified tea leaves and tea-derived biochar on chromium-contaminated soils remain inadequately understood. In this study, tea tree pruning waste was converted into biochar at various temperatures, and the impacts of both unmodified tea leaves and tea biochar on soil Cr(VI) content, chromium fractionation, and soil biochemical properties were assessed using a soil incubation experiment. The results showed that the combined treatment of tea and tea biochar produced at 500 °C reduced Cr(VI) content by up to 49.30% compared to the control. Chromium fractionation analysis revealed a significant increase in the residual chromium fraction, accounting for 32.97% of total chromium, substantially reducing its bioavailability and mobility. Soil properties were markedly improved, with notable increases in pH (14.89%), cation exchange capacity (CEC; up to 100.24%), and organic matter content (up to 167.12%) under the combined treatments. Correlation analysis confirmed that Cr(VI) content reductions were positively correlated with increases in pH, nutrient retention, and enzyme activities, highlighting their role in chromium stabilization. This study underscores the synergistic potential of unmodified tea leaves and tea biochar as an innovative, eco-friendly strategy for Cr(VI) remediation, enhancing both soil quality and heavy metal stabilization.

Stabilizing behaviors of Pseudomonas putida and Pseudomonas alcaligenes bacteria on heavy metal ions in electrolytic manganese residue

Electrolytic manganese residue (EMR) contains a significant amount of Mn ions as well as Zn, Cu and Cd ions, which have negative environmental impacts due to their toxicity. This study aims to investigate the effects of Pseudomonas putida (P. putida) and Pseudomonas alcaligenes (P. alcaligenes) on the stabilization of heavy metal ions in both simulated solutions and the EMR. The results demonstrated that the synergy of P. putida and P. alcaligenes was more effective than either P. putida or P. alcaligenes alone in stabilizing Mn ions. However, the presence of higher concentration of Zn, Cu and Cd ions in the simulated solution weakened the stabilization effect of Mn ions. Fortunately, when P. putida and P. alcaligenes were synergized together, they exhibited a stronger performance in stabilizing heavy metal ions present in the EMR compared to the bacteria employed alone. After 12 days of fermentation in the EMR slurry, almost all Mn ions were eliminated through the formation of deposits, while the concentrations of Zn, Cu and Cd ions decreased to 0.28 mg/L, 0.2 mg/L and 0.1 mg/L respectively after 10 days fermentation. Under the synergy of P. putida and P. alcaligenes, soluble components such as MnSO4·H2O, (NH4)2Mn(SO4)2·6 H2O and Zn, Cu and Cd compounds from the EMR were transformed into insoluble compounds including (MnCO3, Mn3(PO4)2·3 H2O, Mn2Zn(PO4)2·4 H2O, MnFe2(PO4)2(OH)2·8 H2O), Cu5Zn(PO4)2(OH)6·H2O and Cd(OH)2) for the stabilization of heavy metals ions in the EMR. This study proposes an eco-friendly and low-cost method for rendering EMR harmless through pretreatment.