Metal Leaching Research Articles

Droplet-Based EPR Spectroscopy for Real-Time Monitoring of Liquid-Phase Catalytic Reactions.

In situ monitoring is essential for catalytic process design, offering real-time insights into active structures and reactive intermediates. Electron paramagnetic resonance (EPR) spectroscopy excels at probing geometric and electronic properties of paramagnetic species during reactions. Yet, state-of-the-art liquid-phase EPR methods, like flat cells, require custom resonators, consume large amounts of reagents, and are unsuited for tracking initial kinetics or use with solid catalysts. To overcome these limitations, a droplet-based microfluidics platform is introduced for real-time EPR monitoring of liquid-phase catalytic reactions. By encapsulating solid and dissolved species within nanoliter droplets, this approach enables precise control over mass transport, reduces reagent consumption, and maintains uniform residence times irrespective of acquisition duration, permitting precise analysis of each spectral component under identical conditions. The platform's compatibility with standard resonators facilitates straightforward integration into any EPR spectrometer. Its versatility is demonstrated by monitoring dynamic ligand exchange processes, key for activating homogeneous catalysts, and tracking redox and radical kinetics in ascorbic acid oxidation by Cu(II) catalysts. Importantly, this method captures both supported and dissolved transition metal species, offering comprehensive insights into catalyst deactivation via metal leaching. This microfluidic approach sets a new standard for liquid-phase in situ EPR measurements, advancing studies of homogeneous and heterogeneous catalytic systems.

Study on the synergistic hydration mechanism of granulated blast furnace slag-carbide slag-based cementitious materials and the properties of full-solid waste backfill materials

The synergistic utilization of multiple solid waste is an effective means of achieving green filling and resource utilization of solid waste in mines. In this paper, the synergistic effects of solid waste granulated blast furnace slag (GS) and carbide slag (CS) as cementitious materials (GCCM) are investigated, along with their preliminary feasibility in combination with coal gangue (CG) and furnace bottom slag (FBS) for the preparation of backfill materials. The synergistic hydration mechanism, mechanical properties, working performance of GCCM and GBC were studied, and the environmental impact and cost-effectiveness of GBC were evaluated. The results indicate that when the molar ratio of n(CaO)/n(SiO2 + Al2O3) is 0.635 in GCCM, CS has a significant alkaline excitation effect on GS. In addition, the hydration products mainly composed of C-(A)-S-H gel, AFm and hydrotalcite. However, when the concentration of OH- is high in GCCM, Ca(OH)2 preferentially precipitates, leading to a reduction in the amount of main hydration product C-(A)-S-H gel. Moreover, GBC has better competitive strength performance than ordinary Portland cement (OPC). The optimal compressive strength of GBC at 28 days is 19.699 MPa, with a standard slump is 228 mm, fully meeting the strength and transportation requirements for mine filling. The heavy metal leaching rate at 28 days meets the requirements of GB 8978, demonstrating potential for carbon reduction and cost savings. The full-solid waste GBC developed in this study can replace cement as a backfill material, which is of significant importance for achieving green mining, the synergistic utilization of solid waste resources, reducing filling costs, and enhancing environmental benefits.

High-efficiency leaching of valuable metals from waste lithium-ion ternary batteries under mild conditions using green deep eutectic solvents

This work introduces a novel environmentally friendly and biodegradable deep eutectic solvent for High-leaching valuable metals from waste LIBs, which includes VC derived from fruits and DMSP derived from fish attractants.

Enhanced elevated-temperature performance of LiMn2O4 cathodes in lithium-ion batteries via a multifunctional electrolyte additive

LiMn2O4 is a promising cathode material for lithium-ion batteries (LIBs) due to its low cost, environmental friendliness, and high voltage operation. However, its electrochemical performance deteriorates at elevated temperatures, primarily by reason of the structural degradation during cycling and proliferation of adverse reactions at the electrode/electrolyte interface. One of the main reasons is that the hydrolysis and decomposition of the LiPF6 at high temperatures produces HF, which leads to corrosion at the electrode/electrolyte interface and accelerates manganese dissolution. In this work, we report a multifunctional silane-based electrolyte additive, trimethoxyphenylsilane (TMPS), to solve these problems. Theoretical calculations and experimental results both demonstrate that TMPS can eliminate HF, stabilize PF5, and inhibit LiPF6 hydrolysis, thereby mitigating transition metal leaching. Additionally, TMPS improves the stability between cathode and electrolyte by constructing a highly stable and homogeneous cathode-electrolyte interfacial. The LiMn2O4//Li cell using the electrolyte containing 1 wt% TMPS retains 95.5 % and 83.7 % of its capacity after 500 cycles at 25 °C and 60 °C, respectively. Moreover, 18650-type cylindrical cells with this electrolyte also exhibit enhanced electrochemical performance at elevated temperatures. It demonstrates that TMPS is a promising multifunctional additive for manganese-based cathodes in LIBs.

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.

In Situ Quantification of Transition Metal Cation Leaching from a Pt-Alloy Cathode Catalyst in a PEM Fuel Cell

The application of Pt-alloy cathode catalysts for proton exchange membrane fuel cells (PEMFCs) is hampered by the leaching of the alloyed transition metal into the ionomer phase of the membrane electrode assembly (MEA). To date, accelerated stress tests used to assess the degradation of Pt-alloy catalysts lack non-destructive, facile diagnostics to quantify transition metal leaching in an operating PEMFC. Here, we present a method based on electrochemical impedance spectroscopy that exploits the high sensitivity of the high frequency resistance (HFR) at low relative humidity (RH) to quantify transition metal cation contamination. A series of model MEAs with varying fractions of protons intentionally exchanged by Co2+ cations was fabricated. Based on these, we identified the HFR at 30% RH and zero current (i.e., at a homogenous Co2+ distribution in the ionomer phase) as a robust measure of Co2+ contamination. A calibration curve that correlates the HFR at 30% RH to the fraction of protons displaced by Co2+ in the model MEAs could be established, which then allowed quantitative tracking of the Co leached from a PtxCo/C cathode catalyst, both at the beginning-of-test (∼6%) and after 100,000 voltage cycles (∼30%). Capabilities and limitations of this method for Pt-alloy catalyst testing are discussed.

Comprehensive Assessment of Environmental Behavior of Mine Tailings for Sustainable Waste Management and Mitigation of Pollution Risks

The substantial volumes of tailings produced during ore beneficiation present significant challenges for sustainable management due to potential public health hazards, particularly from metal leaching. The risk associated with tailings varies greatly depending on their mineralogical composition and climatic conditions. If tailings are classified as a non-hazardous by-product, they may serve as secondary raw materials, offering a sustainable alternative to the reliance on non-renewable primary resources. In this study, the recycling feasibility of tailings from an active copper mine was assessed through mineralogical characterization, environmental tests (e.g., static, kinetic, and leaching tests), and geochemical modeling. This multi-faceted approach aimed to predict the geochemical behavior and reactivity of tailings under varying conditions. Results from the static tests indicated that the tailings were non-acid generating. Weathering cell tests revealed circumneutral pH conditions (6.5–7.8), low sulfide oxidation rates, and low instantaneous metal concentrations (<1 mg/L), except for copper (0.6–3.5 mg/L) and iron (0.4–1.4 mg/L). These conditions are attributed to the low abundance of sulfide minerals, such as pyrite, chalcopyrite, bornite, covellite (<0.1 wt.%), and chalcocite (0.2 wt.%), which are effectively encapsulated within gangue minerals. Additionally, the presence of neutralizing minerals, specifically dolomite (27.4 wt.%) and calcite (2.4 wt.%), further stabilizes pH and promotes metal sequestration in secondary mineral forms. The Toxicity Characteristic Leaching Procedure (TCLP) test confirmed low leachability, classifying the tailings as non-hazardous.

Achieving High Solid-Liquid Ratio through Competitive Coordination towards Efficient Recovery of Metals from Spent Batteries.

The recycling of critical metals from spent lithium-ion batteries represents a significant step towards meeting the enhancing resource requirements in the new energy industry. Nevertheless, achieving effective leaching of metals from the stable metal-oxygen (MO6) structure of spent ternary cathodes and separation of metal products simultaneously still remained a huge challenge towards industrial applications. Herein, a competitive coordination strategy was proposed to design a novel deep eutectic solvent (DESs), which improved both leaching and selective metal recycling capacity even at high solid-liquid ratio (1:10). The results demonstrated that the number of hydrogen bonds in designed ternary DESs was 16.5% higher compared to those in the binary DESs, resulting in efficient reaction kinetics to break the metals-oxygen bond. More importantly, the competing-ligand (p-toluenesulfonic acid) could preferentially enter into the first nanostructure sheath and reduce the proportion of solvated oxalic acid (OxA) from 28.36% to 17.76% within the nanostructure, which enable OxA molecules to enhance the coordination interaction with metal for precipitating NiC2O4·2H2O product (~ 95.7% purity) from spent cathodes. This work achieved impressive profitability ($16.05 per kg feedstock) and effectively reduction of GHG emissions during the recycling process, making it applicable to critical sustainability initiatives.

Fly ash from municipal solid waste incineration: types, composition, and leaching of heavy metals

The problems of heavy metals (HM) leaching from fly ash (FA) produced by municipal solid waste incineration during its burial or use are considered. The composition, chemical properties and mineralogy of FA are described, experiments on leaching from FA in waste incinerators and in buried FA are considered, the risk from HM release is assessed, and the results of calculation and modeling of HM leaching coefficients are presented.

Optimizing Stabilization of Contaminated Mining Sludge: A Machine Learning Approach to Predict Strength and Heavy Metal Leaching

Optimizing Stabilization of Contaminated Mining Sludge: A Machine Learning Approach to Predict Strength and Heavy Metal Leaching

Multifunctional Heterogeneous Cobalt Catalyst for the One-Pot Synthesis of Benzimidazoles by Reductive Coupling of Dinitroarenes with Aldehydes in Water.

The endeavor of sustainable chemistry has led to significant advancements in green methodologies aimed at minimizing environmental impact while maximizing efficiency. Herein, a straightforward synthesis of benzimidazoles by reductive coupling of o-dinitroarenes with aldehydes is reported for the first time in aqueous media while using a non-noble metal catalyst. This work demonstrates that the combination of nitrogen and phosphorous ligands in the synthesis of supported heteroatom-incorporated Co nanoparticles is crucial for obtaining the desired benzimidazoles. The process achieves >99 % conversion, >99 % chemoselectivity and stability for the reduction of dinitroarenes using water as the solvent and hydrogen as the reductant under mild reaction conditions. The robustness of the catalyst has been investigated using several advanced techniques such as HRTEM, HAADF-STEM, XEDS, EELS, and NAP-XPS. In fact, we have shown that the introduction of N and P dopants prevents metal leaching and the sintering of the cobalt nanoparticles. Finally, to explore the general catalytic performance, a wide range of substituted dinitroarenes and benzaldehydes were evaluated, yielding benzimidazoles with competitive and scalable results, including MBIB (94 % yield), which is a compound of pharmaceutical interest.

Impact of Microwave Pre-Curing on Pore Structure and Environmental Performance of Metakaolin- and Fly Ash-Based Geopolymers

Microwave technology in geopolymer synthesis offers a transformative, sustainable alternative to traditional methods, enhancing material properties and production efficiency. However, the effects of microwave-induced changes on pore structure and their relationship with mechanical strength and environmental performance, such as heavy metal leachability, are not fully understood. This study investigates the impact of microwave pre-curing on geopolymers, focusing on how microwave power and duration influence their pore structure and environmental performance. A total of 48 mixtures were prepared using sodium silicate and sodium hydroxide as alkali activators, with metakaolin and fly ash as raw materials. The modulus was adjusted to 1.5, and the liquid-to-solid ratio was set at 1.6 for metakaolin and 0.7 for fly ash. Microwave irradiation power settings of 100 W, 300 W, 440 W, 600 W, and 800 W were tested. The heating times ranged from 30 s to 90 s at intervals of 15 s. Our findings reveal that optimal microwave settings (100 watts for 45 s) can significantly enhance mechanical properties, with compressive strengths reaching 15.9 MPa for fly ash-based and 9.094 MPa for metakaolin-based geopolymers. However, excessive microwave energy leads to increased porosity, with adverse effects on structural integrity. Moreover, microwave pre-curing effectively reduces heavy metal leachability. Chromium (III) was used in leaching tests and it was demonstrated that ion concentrations as low as 0.097 mg/L enhance environmental safety. Advanced techniques like Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and X-ray CT were applied for the analysis of the atomic bonding, phases and pore structure of the studied geopolymers along with their ability to withstand compression (MPa). Chromium (III) was encapsulated and its leached concentration was measured by ICP-MS to evaluate the performance of the synthesized geopolymers. These results underscore the need for precise control over microwave irradiation parameters to maximize the benefits while mitigating negative impacts. This study provides valuable insights into the controlled use of microwave technology for geopolymer synthesis, recommending optimal irradiation conditions for improved performance and sustainability and advancing sustainable construction materials. The developed geopolymers show promise for applications in construction, waste stabilization, and heavy metal immobilization, contributing to more sustainable and environmentally friendly materials in these industries.

Stepwise extraction of zinc, indium and lead from secondary zinc oxide dusts experimental study

Secondary zinc oxide dust is rich in high-grade metals such as Zn, In, Pb, and Ga, and in the face of the depletion of ore resources at home and abroad, it is of great significance to seek an efficient process to realize the full resource recovery of valuable metals in secondary zinc oxide dust. In this study, on the basis of the thermodynamic analysis of the wet treatment process, three wet treatment methods, namely “low acid leaching”, “high acid leaching” and “chlorination leaching”, were used to explore the suitable parameters for stepwise extraction of Zn, In and Pb metals. The results showed that the three wet treatment methods could effectively extract the corresponding main elements, and the optimal leaching rates of Zn, In and Pb were 73, 90 and 94%, respectively. Thermodynamic analysis shows that under ideal conditions, the “cascade separation” of some or all metals can be theoretically achieved by using a suitable leaching solvent for zinc oxide dust. The concentration of sulfuric acid, the ratio of liquid solid volume to mass and temperature had great effects on the leaching rate of Zn and In, and the leaching rate of Zn and In also increased with the increase of the values of the three experimental parameters, which was positively correlated. The leaching rate of Pb will increase with the increase of sulfuric acid concentration, but when the pH of the solution system is < 2, Pb will form PbSO4 precipitate, which inhibits the leaching ability of Pb. In the chlorinated leaching system with “ammonium chloride + hydrochloric acid” as the leaching solvent, the excess Cl− and Pb2+ fully coordinated to promote the efficient leaching of Pb metal, and the initial pH value of the solution had a great influence on the Leaching Rate of Pb. The multi-stage combined wet treatment process is an effective solution to realize the full quantitative recovery of valuable elements in Secondary zinc oxide dust, In this paper, the suitable process conditions for stepwise extraction of Zn, In and Pb metals were obtained through wet treatment experiments, and the cascade separation of metals in zinc oxide dust was preliminarily realized, which provided an important idea for the efficient utilization of metallurgical dust and sludge solid wastes, and at the same time provided theoretical support for the industrial practice of recycling valuable elements in metallurgical dust.

Metals leached from aluminium foil into Clarias gariepinus muscles roasted at high temperatures: Potential contamination and controlling factors

Aluminium (Al) foil can leach metals into fish during roasting, potentially creating health implications, which informed this study. The roasted (using Al foil) and unroasted fish (control) samples (n = 48) were analysed for metals (Al, Co, Pb, Ni, Cr, Cd, and As) using ICP-AES. The following ranges were recorded for Al (5.51 - 6.35 mg/kg), Co (0.25 - 0.35 mg/kg), Pb (0.48 - 0.65 mg/kg), Ni (2.37 - 4.70 mg/kg), Cr (0.25 - 0.43 mg/kg), Cd (0.05 - 0.07 mg/kg), As (0.32 - 0.45 mg/kg). According to redundancy analysis, foil area had the most influence on metal leaching. The percentage weight loss of the foil after fish roasting indicates leaching of its metal contents into the fish. The EDI and THQ of As, and HI of metals indicate potential risk over time, as a result, roasting of fish with foil should be discontinued.

Impact of scrap dumpsite leachates on African land snails: insights into toxicity, biochemical responses, and reproductive implications

Abstract This research delved into the intricate physiological responses of African land snails exposed to leachates from metal scrap dumpsites in Ado Ekiti metropolis. Raw leachates were collected from different leachate wells at the two dumpsites, these were used to form concentrations (v/v; leachate: dechlorinated tap water) and offered as drinking water throughout the study. A total of 80 points of lay snails (Archachatina marginata) 160.25 ± 5.84g and 7–8 months were used as test organism to assess the effect of the leachate. The snails were randomly allotted into four treatments, with four replicates and five snails per replicate representing the different leachate sample concentrations i.e T1-0%, T2-33.3%, T3- 66.67% and T4-100%. Results obtained indicated that the sodium, calcium, potassium, chromium, manganese and magnesium values of the leachates were higher than safety limits. The final weight of snails in T3 was significantly (P&lt;0.05) higher than other treatment. The gonadosomatic index of snails in T1 was similar to T3 and T4 but significantly (p&lt;0.05) higher than those on T2. Snails exposed to metal leachates have lower antioxidant activities compared with those on T1. In conclusion, the exposure of snails to higher concentrations of the leachates indicates potential toxicity and a tendency for impairment in reproductive capacity.

Enhanced heavy metal immobilization in cementitious materials through CO2 mineralization: A kinetic analysis and physicochemical evolution

The leaching of heavy metals (HMs) from industrial solid waste during its treatment and utilization has garnered extensive attention within the scientific community. The incorporation of cementitious materials to both consume waste and immobilize HMs within the construction sector is a promising strategy. Traditional suppression techniques, employing additives, incur higher costs and may adversely affect the mechanical performance of cement. This research introduces a CO2 mineralization technology synergistically enhancing the immobilization of HMs, which inhibiting the leaching channels in cement-based materials and strengthening the chemical chelation of HMs, thereby suppressing their leaching. The results indicated that the cementitious materials, with a carbonation rate of 10 %-12 %, demonstrated enhanced physical adsorption and chemical chelation capabilities, achieving a 98 % reduction in Pb leaching and a decrease of over 50 % for Mn. Conversely, the post-mineralization reduction in free Ca2+ ions adversely affected the immobilization of soluble HMs like Cr(VI). Overall, this study aimed to enhance the efficacy of current methods for utilizing solid waste and sequestrating HMs whilst simultaneously pioneering innovative concepts for the mineralization application of cement-based materials.

Long-term soil remediation using layered double hydroxides: Field evidence for simultaneous immobilization of both cations and oxyanions

Layered double hydroxides (LDHs) have great potential for immobilizing potentially toxic elements in soil. Nevertheless, their practical effectiveness under field conditions remains largely unknown. In this study, we conducted a 2.5-year field trial using pristine Mg-Al LDHs, Ca-Al LDHs, and iron (Fe)-modified LDHs to simultaneously immobilize both oxyanions (including As and Sb) and cations (including Cd and Pb) in historically contaminated soil affected by mining activities since the 1950s. The immobilization performance of LDHs was examined using various batch tests, including water and DTPA extraction, and by measuring metal(loid) concentrations in Coriandrum sativum (coriander). We found that both pristine and Fe-modified LDHs showed promising initial immobilization performance 7 days after application, achieving significant reductions in DTPA-extractable concentrations of As, Sb, Cd, and Pb by 45.6%–68.3%, 55.4%–94.2%, 11.2%–50.9%, and 62.9%–64.9%, respectively, compared to the control soil without amendment. Notably, pristine LDHs showed diminished immobilization performance in the long term, while Fe-modified LDHs exhibited long-term stability over 2.5 years. A conditional probability-based model was used to depict long-term metal(loid) leaching characteristics in LDH-amended soils. Temporal changes in metal(loid) concentrations in the aboveground edible parts (namely, stems and leaves) of coriander corroborated well with DTPA extraction results. Coriander grown in Fe-modified LDH-amended soils had much lower metal(loid) concentrations compared to those grown in pristine LDH-amended soils. As a result, reductions of 35.1%–42.2% for As, 54.4%–66.2% for Sb, 8.5%–22.8% for Cd, and 56.0%–62.7% for Pb concentrations in coriander were still observed 2.5 years after soil amendment with Fe-modified LDHs. To the best of our knowledge, this is the first field-based evidence using LDHs to simultaneously stabilize both cations and oxyanions in soil. The findings support the potential of LDHs for long-term immobilization of metal(loid)s in soil.

A method and mechanism for extracting Cu, Co, and Zn from limonite tailings

The development of green methods to process and use iron tailings is crucial due to the accumulation of tailings, which poses significant environmental and human health risks. In this study, a scheme of extracting Cu, Co and Zn from limonite tailings by sulfuric roasting with ammonium sulfate and then water leaching was proposed. Most of the Fe is converted to jarosite and enriched in the leaching residue. Ferric iron is present in the leaching residue in the form of jarosite and can be reused as an adsorbent. The impact of various factors, including roasting temperature, time, ammonium sulfate dosage, leaching temperature, and liquid-to-solid ratio, on the metal leaching rate was investigated. The findings indicated that when the roasting temperature was set at 400°C, the roasting time was 120 minutes, the quantity of ammonium sulfate was 1.5 times the original amount, the leaching temperature was 70°C, and the liquid-to-solid ratio was 10:1, the leaching rate of Fe was as low as 34.20 %, and the leaching rates of Cu, Co, and Zn were 81.25 %, 91.35 %, and 89.35 %, respectively. A mechanistic analysis indicates that during the calcination process, the phase transitions of Fe are (NH₄)₃Fe(SO₄)₃, NH₄Fe(SO₄)₂, and Fe₂(SO₄)₃, and the phase transformations of Cu, Co, and Zn are in accordance with these changes. A higher leaching temperature makes it easier for iron to form jarosite, which reduces the leaching rate of iron. This study has a simple, efficient, and environmentally friendly method for extracting valuable metals from limonite tailings.

(Invited) Development of Biosensors Based on Graphene-Coated Porous Silica Spheres

During the onset of the COVID-19 pandemic, the public was reminded of how quickly routine diagnostic tests could overwhelm the health-care system when no other options are available. As mass adoption of the at-home rapid tests were developed and accepted thereby relieving the first responders to care for more critically ill patients, it sparked a resurgence of interest in affordable point-of-care (POC) diagnostics. Currently, besides a handful of common POC devices (e.g., glucose sensor, pregnancy tests and COVID test) there are not many commercially successful examples due to complex design, high production costs, and material stability for field deployment. In this study, we demonstrate that graphene coated porous silica spheres (G/PSS) can be a simple and affordable material for target sensing. Porous carbons particles are low-cost materials widely used as electrode materials in applications such as electric double layer capacitors, batteries, biofuel cells, and biosensors. In the above applications, the non-uniformity of the particles does not interfere with their performance. However, for target sensing, the reduction of noise is generally achieved by working with uniform material. In our case, we developed a method to synthesize uniformly coated graphene on uniformly sized porous silica. The triple pore structure and increased surface area enable, the diffusion of enzymes, mediators, and substrates for rapid enzyme electrode reactions - the mesopores provide a reaction field, the micropores trapping mediators, and the macropores providing substrate, mediator, and enzyme diffusion. Of particular interests to the audience are three key areas: 1) the development of porous silica spheres with controllable particle size and pore size, 2) the graphene chemistry to deposit graphene on to the particles as developed and 3) fine-tuned by our group for this application, and the fabrication technical to prepare electrodes using screen-printing. We succeeded in developing a sensor chip with G/PSS arranged on the surface with high efficiency by selecting a mediator that can smoothly transfer electrons to and from the carbon, which enables various sensing applications. Furthermore, to expand the portfolio of new and improved components that increase the field usability of POC diagnostic devices, we demonstrate that Prussian blue (PB) dispersed in G/PSS functions as an effective and affordable reference electrode as a promising alternative to industry standards. The solubility product of PB is approximately only 1/1031 of that of AgCl, rendering PB a water-insoluble electrode that is free from metal leaching in small devices. The support material, G/PSS, provides conductive mesopores that accommodate insulating PB clusters, ensuring effective contact between the PB clusters and electrolytes and stable potential. Furthermore, the monodisperse spherical shape of G/PSS is beneficial for the production of a reference electrode for POC devices through a low-cost, highly reproducible screen-printing process. This study successfully demonstrated the feasibility and stability of the prototype small biosensor, opening the door for future improvements in the device’s ability to perform similar sensing in complex media such as biological samples.

An Unwanted Guest in the Electrochemical Oxidation of High-Voltage Li-Ion Battery Electrolytes: The Life of a Superacidic Proton

Lithium-ion batteries (LIBs) are central to the urgent societal need to decarbonize both transportation and energy storage on the grid. Unfortunately, despite their attractive energy/power density and high coulombic efficiency, further improvement of this technology – especially their durability – is desperately needed. To support these efforts, our study focuses on fundamental understanding of the decomposition pathways for LIB electrolytes at the cathode-electrolyte interface (CEI), as the nature of these reactions directly controls the extent to which cell capacity and voltage decays in these systems. In this study, we employ electrochemical methods, coupled with product analysis using NMR spectroscopy and mass spectrometry, to determine the decomposition mechanisms for a model electrolyte (1.3 M LiClO4 in EC) and demonstrate the impact of these mechanisms on technologically relevant systems (1.0 M LiPF6 in EC/EMC). Remarkably, we discover the electrochemical formation of superacidic protons, which provides a unified origin for a myriad of side reactions in every individual component of the CEI. In particular, electrochemically generated protons chemically catalyze EC decomposition into CO2 and other short and long chain ethers. They also react with LiPF6 to form the weaker acid HF and are involved in a direct acid-base reaction with the cathode active material, causing the leaching of transition metals into the electrolyte. Collectively, the results of this study all point to the urgent need to either mitigate this proton formation or introduce benign harvesting additives via new electrolyte design strategies.___________________The submitted manuscript has been created by UChicago Argonne, LLC, Operator of Argonne National Laboratory (“Argonne”). Argonne, a U.S. Department of Energy Office of Science laboratory, is operated under Contract No. DE-AC02-06CH11357. The U.S. Government retains for itself, and others acting on its behalf, a paid-up nonexclusive, irrevocable worldwide license in said article to reproduce, prepare derivative works, distribute copies to the public, and perform publicly and display publicly, by or on behalf of the Government. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan. http://energy.gov/downloads/doe-public-access-plan