Oxidation Method Research Articles

Enhancing the electrochemical performance of semicoke‐based hard carbon anode through oxidation‐crosslinking strategy for low‐cost sodium‐ion batteries

AbstractSemicoke, a coal pyrolysis product, is a cost‐effective and high‐yield precursor for hard carbon used as anode in sodium‐ion batteries (SIBs). However, as a thermoplastic precursor, semicoke inevitably graphitizes during high‐temperature carbonization, so it is not easy to form the hard carbon structure. Herein, we propose an oxidation‐crosslinking strategy to realize fusion‐to‐solid‐state pyrolysis of semicoke. The semicoke is first preoxidized using a modified alkali‐oxygen oxidation method to enrich its surface with carboxyl groups, which are localization points and the cross‐linking reactions occur with citric acid to build the semicoke precursor with homogeneous and abundant ‐C‐(O)–O‐ groups (up to 21 at% oxygen content). The ‐C‐(O)–O‐ groups effectively prevent the rearrangement of carbon microcrystals in semicoke during carbonization, resulting in the formation of an abundant pseudographite structure with larger carbon interlayer spacing and micropores. The optimized semicoke‐based hard carbon shows both a high initial Coulombic efficiency of 81% and a specific capacity of 307 mAh g−1, with low‐voltage plateau capacity increased to 2.5 times, compared to that of the unmodified semicoke carbon. By the combination of detailed discharge curves and in situ X‐ray diffraction analysis, the plateau capacity of semicoke‐based hard carbon is mainly derived from interlayer intercalation of Na+ ion. The proposed oxidation‐crosslinking strategy can contribute to the usage of low‐cost and high‐performance hard carbons in advanced SIBs.

Unlocking multi-mode sensing potential: Phosphorus-doped graphitic carbon nitride quantum dots for Ag+, ciprofloxacin, and riboflavin analysis in environment and food matrices

The simultaneous detection of multiple analytes through a single fluorescence sensor is highly attractive. In this study, phosphorus-doped graphitic carbon nitride quantum dots (P-CNQDs) were developed, achieving multi-mode sensing through three distinct response mechanisms. The preparation involved using melamine as the carbon and nitrogen source and ammonium dihydrogen phosphate as the phosphorus source. Uniform and narrowly distributed P-CNQDs were successfully synthesized through chemical oxidation and hydrothermal methods, with an average size of 2.4 nm. These unique P-CNQDs exhibited fluorescence quenching through photo-induced electron transfer (PET) in response to Ag+. Additionally, the formation of hydrogen bonds and coordination interactions between P-CNQDs-Ag+ and ciprofloxacin (CIP) led to a pronounced fluorescence response to CIP by the chelation enhanced fluorescence (CHEF) mechanism. Furthermore, leveraging the principle of fluorescence resonance energy transfer (FRET), P-CNQDs-CIP served as a ratio fluorescence sensor for riboflavin (RF), enabling ultra-sensitive detection of RF. The combination of PET, CHEF, and FRET response mechanisms successfully facilitated multi-mode sensing for Ag+, CIP, and RF. The detection ranges were 0.05–100 μM, 0.002–2 μM, and 0.05–60 μM, with corresponding lowest detection limits of 17.1 nM, 1.1 nM, and 29.2 nM, respectively. This versatile sensor has been effectively applied to real samples, including the detection of river water and vitamin B2 tablets.

Catalytic oxidation of toluene over ZIF-8 composited with Mn by different methods

ZIF-8 composites with Mn (Mn-ZIF-8 & Mn/ZIF-8) were prepared by two methods for the complete catalytic oxidation of toluene. The results revealed that catalytic activity increased with the increasing content of manganese, and the activities of the two series composites were different from each other. The Mn[Formula: see text]-ZIF-8 prepared by the methanol thermal method showed the best catalytic performance, which had the lowest T[Formula: see text] of toluene conversion, compared with the series of Mn/ZIF-8 catalysts. The resulting composites were characterized by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), scanning electron microscopy (SEM), thermogravimetric analysis (TG) and X-ray photoelectron spectroscopy (XPS). It was concluded that Mn, as the active species, might partly replace Zn in the frame of Mn-ZIF-8 for the catalytic oxidation of toluene at lower temperatures.

Reaction-controlled Pickering interfacial catalysis: A green route to produce crystalline adipic acid under solvent-free conditions

The pursuit of a greener adipic acid synthesis process, aiming to replace the highly polluting nitric acid oxidation method, has been a longstanding endeavor in both academic and industrial spheres. In this study, we present a reaction-controlled Pickering interfacial catalysis system, enabling the efficient oxidation of cyclohexene to adipic acid using 30 wt% hydrogen peroxide without the involvement of organic solvents. Following the reaction, the system spontaneously undergoes demulsification, facilitating easy recovery of catalyst particles via simple filtration, followed by product separation through cooling-induced crystallization. Employing high speed microscopic imaging for in-situ characterization of interfacial properties, we elucidate the influence of reaction conditions on interfacial properties and catalytic performance. The reaction-controlled Pickering interfacial catalysis system demonstrated herein offers a novel and industrially feasible strategy for developing green adipic acid synthesis route.

Green Molecular Reactor Boosting the Photocatalytic Aerobic Oxidation of Sulfides in Clean Solvent

AbstractThe synthesis of sulfoxides has long attracted considerable interest due to their pivotal role in organic synthesis, pharmaceutics and environmental protection. Oxidation of the corresponding sulfides is recognized as the most effective strategy. Traditional oxidation methods, however, fall short of the growing demands of green chemistry. Photocatalytic aerobic oxidation has thus garnered attention, employing the greenest and most sustainable oxidants—oxygen or air—and sunlight as the energy source. Nevertheless, these reactions are typically conducted in potentially pollutive organic solvents rather than in the greenest solvent, water. To facilitate this organic transformation in aqueous phase, molecular reactors that can encapsulate reactants within their confined pores and facilitate photocatalytic reactions have been developed recently. This Concept article summarizes the development of molecular reactors for the photocatalytic oxidation of sulfides and provides perspectives for the design and construction of effective photocatalytic molecular reactors.

Enhanced degradation of crystal violet using PANI-ZnO nanocomposites: Electro-oxidation and photocatalysis studies

This work compares the transformation capabilities of crystal violet (CV), a toxic cationic dye of the triphenylmethane family, by advanced oxidation processes, especially heterogeneous photocatalysis and electrochemical oxidation, on new nanocomposite materials with a composition of zinc oxide (ZnO) and polyaniline (PANI) by chemical polymerization in solution. Concerning the synthesis of PANI, we have exploited the radical oxidative polymerization method; this latter is functional and uncomplex, as it does not require expensive equipment, using ammonium persulfate as an oxidant with a part of monomer (Aniline) to remove pollutants present in the environment. After physicochemical analyses including FTIR, SEM, and electrochemical characterizations by cyclic voltammetry and conductimetry, the results show that the photocatalytic activity of PANI-ZnO 5 % resulted in a better yield (85 %) compared to PANI alone and other composites (PANI-ZnO 10 % and PANI-ZnO 20 %). However, the electro-oxidation discoloration rates on all PANI alone and PANI-ZnO composite electrodes (5 %, 10 %, and 20 %) reached almost 99 %. To deepen our understanding, computational DFT calculations were employed, complementing experimental findings, and together, they contribute to elucidating the intricate mechanisms underlying the enhanced performance of these nanocomposite materials in both photocatalysis and electrochemical oxidation processes.

Peroxymonosulfate activated by CoMn@CNT nanocomposite for moxifloxacin degradation

As a fourth quinolone drug, the efficient and rapid degradation of moxifloxacin (MOX) remain a rigorous problem. Peroxymonosulfate (PMS)-based oxidation method poses a promising application prospect for refractory antibiotic wastewater with an excellent degradation efficiency. Herein, the Co/Mn doped-carbon nanotube catalyst (CoMn@CNT) was successfully synthesized by a two-step pyrolysis method and applied to activate PMS for MOX degradation. The degradation efficiency of MOX could reach 89.7 % in 30 min with relatively low concentrations of PMS (100 mg/L) and CoMn@CNT (30 mg/L). The effects of catalyst dosage, PMS dosage, initial pH, reaction temperature, and co-existing ions for the degradation of MOX were investigated. The CoMn@CNT/PMS system possessed wide pH application range (3.0–11.0). Sulfate radical (SO4−) was verified as the dominant reactive species responsible for degradation of MOX by quenching experiment. Finally, the possible MOX degradation pathways were also proposed. Overall, this study could provide some inspirations of the CoMn@CNT/PMS as a new system which applied to wastewater treatment of antibiotics.

Evaluating the significance of rare earth and iron doping on structure-property of lead titanate

The samples (Pb0.8Ln0.2 Fe0.2 Ti0.8O3, (Ln= La, Nd, Sm, Gd)) were synthesized successfully by mixed oxide method. A significant reduction in tetragonality is observed with the modification of structure. The grain size from FESEM study was observed to be decreasing with increase in ionic radii of rare earth ions. Specifically, the dielectric constant is found to be maximum for the Sm-doped sample. Conductivity studies at varying temperature and frequencies reveal the NTCR behaviour of these samples. In Sm, Nd and Gd doped samples, tunnelling of small polarons is responsible for conduction process whereas for La doped sample, the conduction process is mediated through the combined effect of small polaron tunnelling and bipolaron hopping. The Sm-doped sample exhibits highest remanent polarization. All the results of this comprehensive study provide valuable insights into the effect of dopant ions on various properties of the studied materials, paving the way for device applications.

Role of magnesium ions in modifying oxide growth rate on Zircaloy under breakaway corrosion regimes

General corrosion of nuclear reactor in core material like Zircaloy-2 and breakaway corrosion in particular are of great importance in ensuring its smooth long term operation. Metal ions like Mg2+ added to the coolant, to mitigate corrosion of other structural materials like Carbon steel, can get incorporated in the corrosion product oxide on Zircaloy-2 and alter its corrosion behavior. Plasma Electrolytic Oxidation (PEO) method was employed to investigate the effect of Mg2+ ions during breakaway corrosion of Zircaloy-2. The main objective was to understand the morphology, protectiveness, semiconducting properties of the Mg modified oxide films on Zircaloy-2 surface. DC potentials 300, 400 and 500 V were used to accelerate corrosion kinetics and form oxide mimicking the breakaway corrosion regime. Borate buffer (pH 9.8) was used as the electrolyte, and Mg acetate was added as Mg source for probing the effect of Mg2+ ions. Oxide morphology depended largely on the formation potentials. The presence of magnesium resulted in thinner oxides with lower defect densities. GIXRD of the oxide showed stabilization of tetragonal phase in presence of Mg at 300 and 400 V. Oxide resistance and charge transfer resistances measured by EIS were observed to be higher due to Mg incorporation at these potentials. Mg addition facilitated formation of t-ZrO2. The electrochemical measurements suggested that the presence of Mg in ZrO2 could reduce the connected porosity in the oxide thereby stifling the diffusion paths. These factors lead to improved corrosion protectiveness of the oxide formed in the presence of Mg.

Improved lifetime of a pulsed electric field (PEF) system-using laser induced surface oxidation

In this research, we explore the possibility and effectiveness of using laser-induced surface oxidation methods to enhance the durability and effectiveness of PEF (Pulsed Electric Field) systems. Despite advantages over thermal pasteurisation, PEF faces challenges like electrode corrosion and biofouling, hindering its adoption. This research introduces laser-induced oxidation to mitigate metal ion release during PEF, directly targeting electrode alteration. Our examination adopts a comprehensive method, integrating Design of Experiments (DoE) parameter sets for PEF trials, morphological analysis, evaluation of metal ion release via Inductively Coupled Plasma Quadrupole Mass Spectrometry (ICP-QMS), waveform capture utilizing a Data Acquisition (DAQ) system, electrochemical assessment via impedance spectroscopy, and examination of oxide layer composition employing X-ray photoelectron spectroscopy. Pulse waveform characteristics shows the intricate relationship between PEF processing parameters with metal ion release, alongside XPS analysis providing insights into surface chemistry. Optimized results show a three-fold reduction in metal ion release post-PEF, with laser-treated samples outperforming untreated stainless steel due to selective surface chemistry alteration, notably an increased Cr/Fe ratio, reducing harmful elements. This study highlights laser-induced oxidation as a practical solution for enhancing PEF electrode performance and reducing metal ion release, addressing key challenges in PEF technology. It advances sustainable food processing, promising extended PEF system lifespan while maintaining efficiency and product quality.

Investigation of thermal properties and structural characterization of novel boron-containing Schiff base polymers

Three novel Schiff base polymers were synthesized by using the Schiff base monomer obtained using aldehyde containing boric acid and amines containing hydroxyl groups as the starting materials. The polymers were synthesized at the same temperature and using the same amount of oxidizing agent by the oxidative polycondensation method. The characterization of all polymers and monomers was achieved by using Fourier transform infrared spectroscopy (FT-IR), ultraviolet–visible spectroscopy (UV–vis), nuclear magnetic resonance spectroscopy (1H-NMR), liquid chromatography-mass spectrometry (LC–MS), gel permeation chromatography (GPC) and scanning electron microscopy (SEM). The thermal stability of these compounds was studied by employing thermogravimetric analysis (TGA), and thermodynamics parameters such as activation energy (Ea), enthalpy (∆H), entropy (∆S), and Gibbs free energy(∆G) for the decomposition process were calculated using the Flynn–Wall–Ozawa method.

Research on micro-arc oxidation method based on passivation layer on non-valve metal low-carbon steel surface

In this study, a method for preparing micro-arc oxidation (MAO) coatings on the surface of non-valve metal low-carbon steel based on a passivation layer is proposed. Microstructure and elemental composition of the surface and cross-section were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy-dispersive spectroscopy (EDS). Micro-scratch tests, tribological tests and electrochemical corrosion tests were conducted. Compared to MAO coatings, coatings obtained by pre-passivation treatment exhibit fewer surface micropores with smaller pore sizes, and both wear resistance and corrosion resistance are enhanced. In summary, the method for preparing MAO coatings based on the passivation layer on the surface of low-carbon steel provides feasible approach to improving the drawbacks of low-carbon steel.

First-principles study of electrochemical H2O2 production on Pd-B40 single-atom catalyst

Hydrogen peroxide (H2O2), a versatile green compound, is increasingly in demand. The electrochemical two-electron oxygen reduction reaction (2e− ORR) is a simple and environmentally friendly substitute method to the traditional anthraquinone oxidation method for H2O2 production. This study systematically investigates the 2e− ORR process on single transition metal atom-loaded boron fullerene (M − B40) using density functional theory calculations. In evaluating the stability of the catalysts, we found that Au, Pd, Pt, Rh, and Ir atoms adsorbed on hexagonal or heptagonal sites of B40 exhibit good stability. Among these, Pd-modified B40 heptagonal cavity (Pd-B40-heptagonal) demonstrates an ideal Gibbs free energy change for OOH* (4.49 eV) and efficiently catalyzes H2O2 production at a low overpotential (0.27 V). Electronic structure analysis reveals that electron transfer between Pd-B40-heptagonal and adsorbed O2 facilitates O2 activation. Additionally, the high 2e− ORR activity of Pd-B40-heptagonal is attributed to electron transfer from the Pd-d orbitals to the π* anti-bonding of p orbitals of OOH*, moderately activating the O-O bond. This study offers valuable understanding designing high-performance electrocatalysts for 2e− ORR.

Iron-cobalt loading carbon nitride bimetallic catalyst activates peroxymonosulfate for bisphenol A degradation

In order to reduce metal leaching loss and carbon emissions, an active Peroxymonosulfate (PMS) catalyst (Fe/Co–CN) was prepared using a one-step thermal polycondensation method for the efficient treatment of wastewater containing bisphenol A (BPA). Fe/Co–CN has a low metal leaching (＜1 mg/L) and has good catalytic degradation performance for BPA. The degradation efficiency was 90.7% in 5 min and ∼100% in 10 min, which is much higher than single metal-loaded Fe–CN (77.2%) and Co–CN (73.2%). Nonradical species dominated by 1O2 and high-valent species were the main reactive oxygen species that degraded BPA in the Fe/Co–CN/PMS system. By strictly controlling the energy consumption during the synthesis and application of Fe/Co–CN, lower carbon emissions have been achieved than most catalysts reported. This achievement is of great significance for applying advanced oxidation methods to treat organic micro-pollutants and provides reference for the calculation of PMS catalysts carbon emissions.

Mechanism of iron-activated ozone/persulfate coupled oxidation for petroleum-contaminated soil

Soil contamination by petroleum remains a critical environmental challenge. Single oxidation methods, while widely employed for remediation, often exhibit limitations in effectively degrading these contaminants. This hinders their broader application and necessitates the investigation of the complementary effects of commonly employed single oxidation method such as ozone (O3) and persulfate (PS) oxidation to explore their potential for enhanced degradation. In this study, the O3/PS coupling oxidation system activated by iron-loaded activated carbon (Fe@AC) was employed for the remediation of petroleum contaminated soil, and to evaluate the removal efficiency and underlying mechanism for petroleum contaminants. The results demonstrated a significant improvement in the apparent reaction rate constant of the O3/PS/Fe@AC system, recorded at 0.1253 h−1. This rate was approximately twice that of the PS/Fe@AC system (0.0572 h−1) and two orders of magnitude greater than the Fe2+/PS system (0.0014 day−1). Under the conditions of 6 % PS dosage, 0.6 % Fe@AC dosage, a soil-to-water ratio of 1:2, an O3 gas flow rate of 2.5 mg/L, and a pH of 5 at room temperature, the O3/PS/Fe@AC system removed 46.8 % of total petroleum hydrocarbon at an initial concentration of 5000–6000 mg/kg within 3 h. The reaction of the O3/PS/Fe@AC system involved multiple radicals, such as sulfate radicals (SO4•-), hydroxyl radicals (•OH), and superoxide radicals (O2•-), with the reactivity of SO4•- enhanced by O3. This study demonstrates an efficient method for remediating petroleum contaminated soil, providing a theoretical and technical foundation for the application of the O3/PS/Fe@AC system.

Effect of Functionalized Carbon Nanotubes and Graphene Oxide Nanoribbons on the Supercapacitive Behavior of Zr-Based Metal-Organic Frameworks in Acid Media

Metal-organic frameworks (MOFs) as a kind of crystalline porous materials have attracted much attention due to their high surface area and high electrochemical performance as electrode materials in supercapacitors 1. Recently, there has been a lot of interest in functionalized multiwalled carbon nanotubes (F-MWCNTs) based materials and especially graphene oxide nanoribbons (GONRs), which have unusual characteristics of ultrathin two-dimensional structures and, as promising materials for supercapacitors and other electrochemical energy storage devices. The F-MWCNTs and GONRs' high electrical conductivity, highly changeable surface area, strong chemical stability, excellent mechanical behavior, and capacity to modify attributes for the desired application are behind the reasons for choosing to make a composite of these materials with Zr-MOF 2.In this work, Zr-MOF was synthesized using the solvothermal method 3, MWCNTs were functionalized using acid washing (3 M H2SO4: 1 M HNO3), and GONRs were fabricated using the oxidative unzipping method 4. The Zr-MOF/F-MWCNTs and Zr-MOF/GONRs composites were prepared through physical mixing. The physical and chemical structures of the synthesized Zr-MOF, F-MWCNTs, and GONRs were evaluated using XRD, SEM, TEM, FT-IR, Raman spectroscopy, and XPS. The supercapactive behavior of the prepared composites was evaluated in comparison to their components (Zr-MOF, F-MWCNTs, and GONRs) in 1M H2SO4 utilizing various evaluation systems (three and two-electrode systems). Zr-MOFs showed a high specific capacitance (248 F/g at 1 A/g), making it a promising supercapacitor electrode material. That performance is dramatically improved by the addition of the nanocarbon materials (F-MWCNTs and GONRs). Zr-MOF-GONRs showed the highest specific capacitance (448 F/g at 1 A/g), with a large potential window (1.7 V) in the three-electrode system extended to (2V) in the two-electrode system, and good stability over 10,000 cycles at a high current density of 10 A/g. Reference: (1) Tan, Y.; Zhang, W.; Gao, Y.; Wu, J.; Tang, B. Facile Synthesis and Supercapacitive Properties of Zr-Metal Organic Frameworks (UiO-66). RSC Adv. 2015, 5 (23), 17601–17605. https://doi.org/10.1039/c4ra11896k.(2) Shrivastav, V.; Sundriyal, S.; Tiwari, U. K.; Kim, K. H.; Deep, A. Metal-Organic Framework Derived Zirconium Oxide/Carbon Composite as an Improved Supercapacitor Electrode. Energy 2021, 235, 121351. https://doi.org/10.1016/j.energy.2021.121351.(3) Abdelhamid, H. N. UiO-66 as a Catalyst for Hydrogen Production: Via the Hydrolysis of Sodium Borohydride. Dalton Trans. 2020, 49 (31), 10851–10857. https://doi.org/10.1039/d0dt01688h.(4) Kosynkin, D. V.; Higginbotham, A. L.; Sinitskii, A.; Lomeda, J. R.; Dimiev, A.; Price, B. K.; Tour, J. M. Longitudinal Unzipping of Carbon Nanotubes to Form Graphene Nanoribbons. Nature 2009, 458 (7240), 872–876. https://doi.org/10.1038/nature07872.

(Nanocarbons Division Poster Award, 3rd Place) Hybrid Supercapacitance and Stability of Fe-Based Metal-Organic Frameworks/Graphene Oxide Nanoribbons Composite Allover the pH Range

Adopting renewable energy sources is growing fast, and hence it should be accompanied by tremendous efforts to develop energy storage technologies that can mitigate the intermittent nature of these sources. Supercapacitors (SCs) are considered among the most promising technologies for that purpose due to their high durability, power density, and charging/discharging competency. SCs have two types according to their electrochemical charge storage mechanism: pseudocapacitance (PCs) or battery-like behavior and electrochemical double-layer capacitors (EDLCs). The development of next-generation supercapacitors requires a holistic approach that integrates both mechanisms. Because of their huge surface area, porous structure, and abundance of active redox sites, metal-organic frameworks (MOFs) have exceptional potential in energy storage devices. However, due to the MOFs’ low conductivity and stability, they are in need to be mixed with highly conductive and stable materials such as carbon-based ones.In this work, Fe-based MOFs were selected to be responsible for mainly the battery-like contribution to the overall supercapacitance due to the presence of the redox-active sites. Even though little attention has been given to the Fe-based MOFs they showed a promising performance in several solutions, with low stability.1,2 To enhance the Fe-MOFs stability and conductivity and add an EDLC component to the overall capacitance behavior graphene oxide nanoribbon (GONRs) was used. The GONRs' exceptional properties such as ultrathin two-dimensional structures, superior mechanical behavior, strong chemical stability, and high electrical conductivity make them promising materials for supercapacitor applications.In this study, Fe-MOFs were synthesized using a hydrothermal method,3 and GONRs were prepared using an oxidative unzipping method.4 A composite of Fe-MOFs/GONRs was prepared by physical mixing. The physical and chemical properties of the synthesized Fe-MOFs, GONRs, and Fe-MOFs/GONRs were characterized using XRD, SEM, TEM, FT-IR, Raman spectroscopy, and XPS. Since the electrolyte properties have a substantial impact on the supercapacitive behavior and stability of the electrode materials, the specific capacitance of the prepared composites was measured in 1M H2SO4, 1M KOH, 1M K2SO4, and 1M KCl utilizing different evaluation systems (three and two-electrode systems). The Fe-MOFs/GONRs composite showed a significant synergistic effect in comparison to its pure components. Further discussion will be given regarding the pH and ion size/type effect on the supercapacitive performance and stability.

(Invited) Selective Glucose Conversion into Gluconic Acid By Dye-Sensitized Photoelectrochemical Cell

Gluconic acid, one of the valuable products of oxidized glucose projected to soon hit a market value of US$1.9 billion is currently produced using relatively expensive electrochemical, environmentally unsafe chemical or thermal selective oxidation methods to meet market demand. Dye-sensitized photoelectrochemical cells (DSPECs) which has effectively been utilized for selective biomass conversion into other valuable products (alongside hydrogen evolution) is a cheaper, greener and safer alternative unexplored in this field. Herein, we explore this green technology for selective oxidation of glucose into gluconic acid in an aqueous system, employing metal-free organic dye (E)-3-(5-(4-(bis(2',4'-dibutoxy-[1,1'-biphenyl]-4-yl) amino) phenyl) thiophen-2-yl)-2-cyanoacrylic acid (D35) with organic catalyst (4-Acetamido-2,2,6,6-tetramethylpiperidine 1-oxyl) ACT at 0 V vs NHE. Photophysical details revealed the occurrence of intermolecular electron transfer between D35 and ACT under 1 sun illumination (100 mW/cm²). Enhanced generation of the strongly oxidizing reactive oxoammonium species, ACT+, by the photoanode drives the conversion of glucose into gluconic acid. The photoanode assembly employed exhibited remarkable stability, sustaining a continuous operation for 3 days and 88% selectivity for gluconic acid at pH 7. The aqueous phase stability, selectivity, neutral environment and ambient operation of the setup indicates it potential for biomass conversion and hydrogen production towards commercialization purposes.

(Invited) Density Functional Theory Study on Molecular Structures of Polyhydroxy Fullerenes

Polyhydroxy fullerenes (PHF), also known as fullerenols or fullerols, are water-soluble fullerenes that are being studied for several applications. PHF is usually synthesized by acid or alkali method and is assumed to have only hydroxyl groups. These approaches use uncontrolled oxidation method and it is possible to have unintended functionalization. In fact, few studies have proposed presence of hemi-ketal and carbonyl groups based on NMR, XPS and FTIR studies. However, a complete understanding of their molecular structures is still lacking. Theoretical quantum chemical calculations based on density functional theory (DFT) are commonly used to predict and corroborate vibrational spectrum of molecules. Interestingly, in silico studies thus far have considered fullerenes with only hydroxyl groups with a big mismatch in their calculated vibrational energies and experimental FTIR spectrum.In this study, we investigated the presence of carbonyl and hemi-ketal functional groups on hydroxylated fullerenes using DFT. We also evaluated the influence of counterions on oxygen-containing functional groups. All DFT calculations were carried out on Gaussian19 with hybrid B3LYP functional and 6-31G(d,p) basis set. By bridging the gap between theoretical calculations and experimental measurements, we offer an alternative interpretation for the characteristic peaks observed in the FTIR spectrum. Furthermore, our theoretical calculations suggest a dynamic nature inherent in these oxygen-containing functional groups residing on the carbon cage of the fullerene structure.

Exploring Anion Exchange Phase Transformations in 1D Solid Systems

Phase transformations through ion exchange reactions represent a relatively new strategy, offering a promising route for synthesizing complex and metastable morphologies and phases in nanoscaled solid ionic materials, which are challenging or even impossible to achieve through standard bottom-up approaches. Moreover, they provide a unique opportunity to investigate the mechanisms and new, yet unexplored phenomena accompanying the chemical modifications in the solid state. These mechanisms remain largely unknown and unexplored, thereby limiting the full potential of ion exchange reactions as one of the primary synthesis or modification strategies for complex ionic nanomaterials. In this study, copper oxide (CuO) nanowires were prepared via thermal oxidation method and used as a template material to explore oxide-sulfide anion exchange transformation mechanism. Following the synthesis, CuO nanowires underwent treatment with sulfur-containing gases in both thermal and non-thermal environments under various conditions to achieve a controllable exchange of oxygen anions with sulfur. The mechanisms underlying these transformations were unraveled with the use of electron microscopy. The copper oxide–sulfide system is particularly intriguing due to the promising properties of copper oxide and sulfide in gas sensing, solar cells, energy storage systems, and photocatalysis. The full or partial transformation between the two phases can therefore represent a route to manipulate and enhance the properties desired for each application.