Surface-controlled Reaction Research Articles

3D-printed redox-active polymer electrode with high-mass loading for ultra-low temperature proton pseudocapacitor

The stable operation of supercapacitors at extremely low temperatures is crucial for applications in harsh environments. Unfortunately, conventional inorganic electrodes suffer from sluggish diffusion kinetics and poor cycling stability for proton pseudocapacitors. Here, a redox-active polymer poly(1,5-diaminonaphthalene) is developed and synthesized as an ultrafast, high-mass loading, and durable pseudocapacitive anode. The charge storage of poly(1,5-diaminonaphthalene) depends on the reversible coordination reaction of the C=N group with H+, which enables fast kinetics associated with surface-controlled reactions. The 3D-printed organic electrode delivers a remarkable areal capacitance (8.43 F cm–2 at 30.78 mg cm−2) and thickness-independent rate performance. Furthermore, the 3D-printed proton pseudocapacitor exhibits great low-temperature tolerance and delivers a high energy density of 0.44 mWh cm−2 at −60 °C, as well as operates well even at −80 °C. This work signifies that combining organic material design with 3D hierarchical network electrode construction can provide a promising solution for low-temperature-resistant supercapacitors.

Predicting hydrogen production from co-gasification of biomass and plastics using tree based machine learning algorithms

Hydrogen production from co-gasification of biomass and plastics are predicted using Machine Learning Algorithms, e.g., Decision tree and Ensemble methods. Independent variables are particle sizes of biomass and plastics, feedstock ratio and temperatures. The dependent variable is Hydrogen production. Model and prediction performances were evaluated/validated using model parameters. The relative importance scores for independent variables are RSS particle size > HDPE particle size > Temperature > Percent plastics. Size dependence of Hydrogen production indicated a surface-controlled reaction. Temperatures between 500 °C and 900 °C have less impact on H2 production compared to the size. Predictions were carried out using Train-test split, Cross-validation, and GridsearchCV model on the data unseen. Gradient Boosting performed the best.

Diffusion controlled electrochemical analysis of MoS2 and MOF derived metal oxide–carbon hybrids for high performance supercapacitors

In the context of emerging electric devices, the demand for advanced energy storage materials has intensified. These materials must encompass both surface and diffusion-driven charge storage mechanisms. While diffusion-driven reactions offer high capacitance by utilizing the bulk of the material, their effectiveness diminishes at higher discharge rates. Conversely, surface-controlled reactions provide rapid charge/discharge rates and high power density. To strike a balance between these attributes, we devised a tri-composite material, TiO2/Carbon/MoS2 (T10/MoS2). This innovative design features a highly porous carbon core for efficient diffusion and redox-active MoS2 nanosheets on the surface. Leveraging these characteristics, the T10/MoS2 composite exhibited impressive specific capacitance (436 F/g at 5 mV/s), with a significant contribution from the diffusion-controlled process (82%). Furthermore, our symmetrical device achieved a notable energy density of ~ 50 Wh/kg at a power density of 1.3 kW/kg. This concept holds promise for extending the approach to other Metal–Organic Framework (MOF) structures, enabling enhanced diffusion-controlled processes in energy storage applications.

The reaction kinetics and Sn isotope fractionation of Sn(IV) chloride hydrolysis

Hydrolysis of Sn is a pivotal step during the precipitation of cassiterite, the primary Sn-bearing mineral and thermodynamically stable Sn-oxide on Earth's surface. In this contribution, we investigated the reaction kinetics of Sn(IV) chloride hydrolysis by systematic experiments at temperatures of 6.4 °C to 28.6 °C. Experimental results show that the hydrolysis reactions of Sn(IV) chloride follow a first-order kinetics model, with rate constants (0.12 h−1 to 5.5 h−1) strongly controlled by temperature. Based on the obtained reaction constants at different temperatures and the Arrhenius equation, the activation energy of the Sn(IV) chloride hydrolysis reaction is calculated to be 26.05 ± 2.25 kcal/mol, indicating a surface-controlled reaction mechanism. Additionally, the Sn(IV) chloride hydrolysis rate increases with the ionic strength. No significant Sn isotope fractionation between aqueous Sn(IV) and the solid hydrolysis product was observed during the Sn(IV) hydrolysis experiments in this study. The activation energy data and Sn isotope behavior associated with Sn(IV) chloride hydrolysis may be used to better understand the behavior of Sn during various mineralization and weathering processes.

Pyrolysis of Automotive Shredder Residue (ASR): Thermogravimetry, In-Situ Synchrotron IR and Gas-Phase IR of Polymeric Components.

This article reports the characterisation of pyrolysis of automotive shredder residue using in situ synchrotron IR, gas-phase IR, and thermal analyses to explore if the automotive shredder residue can be converted into value-added products. When heating to ~600 °C at different heating rates, thermal analyses suggested one- to two-stage pyrolysis. Transformations in the first stage, at lower temperatures, were attributed to the degradation of carbonyl, hydroxyl, or carboxyl functional stabilisers (aldehyde and ether impurities, additives, and stabilisers in the ASR). The second stage transformations, at higher temperatures, were attributed to the thermal degradation of the polymer char. Simultaneous thermal analyses and gas-phase IR spectroscopy confirmed the evolution of the gases (alkanes (CH4), CO2, and moisture). The synchrotron IR data have demonstrated that a high heating rate (such as 150 °C/min) results in an incomplete conversion of ASRs unless sufficient time is provided. The thermogravimetry data fit the linearised multistage kinetic model at different heating rates. The activation energy of reactions varied between 24.98 and 124.94 kJ/mol, indicating a surface-controlled reaction exhibiting high activation energy during the initial stages and a diffusion and mass transfer control showing lower activation energy at the final stages. The corresponding frequency factors were in the range of 3.34 × 1013-5.68 × 101 mg-1/min for different pyrolysis stages. The evolution of the functional groups decreased with an increase in the heating rate.

A surface-controlled process renders high-power Li-ion storage in Mn3O4/RGO composites for both lithium-ion capacitors and batteries

Mn3O4/reduced graphene oxide composites were synthesized with a high capacity ratio via a surface-controlled reaction, making them ideal for fast energy storage in both lithium-ion batteries and lithium-ion capacitors.

Single Calcite Particle Dissolution Kinetics: Revealing the Influence of Mass Transport.

Calcite dissolution kinetics at the single particle scale are determined. It is demonstrated that at high undersaturation and in the absence of inhibitors the particulate mineral dissolution rate is controlled by a saturated calcite surface in local equilibrium with dissolved Ca2+ and CO3 2- coupled with rate determining diffusive transport of the ions away from the surface. Previous work is revisited and inconsistencies arising from the assumption of a surface-controlled reaction are highlighted. The data have implications for ocean modeling of climate change.

Rapid debromination of tetrabromobisphenol A by Cu/Fe bimetallic nanoparticles in water, its mechanisms, and genotoxicity after treatments

Tetrabromobisphenol A (TBBPA), a widely used brominated flame retardants, has been detected in various environmental matrices and is known to cause various adverse effects on human bodies. This study examined the feasibility and effectiveness of remediating TBBPA using Cu/Fe bimetallic nanoparticles (Cu/Fe BNPs) at various environmental and operational conditions. In general, TBBPA removal rate and debromination efficiency increased with higher Cu doping, higher Cu/Fe BNPs loading, higher temperature, and lower pH. At optimal conditions, TBBPA was completed removed at a rate constant > 0.2 min−1 where over 90% TBBPA was transformed to BPA within 30 min. The activation energy was found to be 35.6 kJ/mol, indicating that TBBPA was predominantly removed via surface-controlled reactions. Under pH 3–7 and ≥ 25 °C, debromination was the dominant removal mechanism compared to adsorption. The complete debromination pathway and the time-evolution of intermediates byproducts at different pHs were also presented. Cu/Fe BNPs can be reused for more than 6 times with performance constancy. Genotoxic tests showed that the treated solution did not find a significant hazardous potential. The byproducts can be further degraded by additional H2O2 through Fenton reaction. These results demonstrated the efficacy of Cu/Fe BNPs for treating TBBPA and its potential for degrading other halogenated organic compounds.

Ge nanoparticles uniformly immobilized on 3D interconnected porous graphene frameworks as anodes for high-performance lithium-ion batteries

Germanium (Ge), an alloy-type anode material for lithium-ion batteries (LIBs), possesses many advantages such as high theoretical capacity and decent electrical conductivity. Nevertheless, its application is restricted by tremendous volume variation and tardy reaction kinetic during discharge/charge process. In this paper, the Ge/3DPG composites with Ge nanoparticles uniformly dispersed in 3D interconnected porous graphene (3DPG) skeleton are successfully prepared using a template-assisted in-situ reduction method. The unique 3D interconnected porous graphene can not only enhance the electronic conductivity and reaction kinetics of the materials, but also provide sufficient buffer space to effectively mitigate the volume expansion during cycling and strengthen the structural integrity. Moreover, the small-sized Ge nanoparticles in close conjunction with the 3D graphene can boost the surface-controlled reaction of the electrode, which contributes to a fast charge–discharge rate capability. The Ge/3DPG composite with optimized Ge/graphene mass ratio delivers high reversible specific capacity (1102 mAh g−1 after 100 cycles at 0.2 C), outstanding rate capability (494 mAh g−1 at 5 C), and admirable cycling stability (85.3% of capacity retention after 250 cycles at 0.5 C). This work provides a significant inspiration for the design and fabrication of advanced Ge-based anode materials for next-generation high-performance LIBs.

Additive manufacturing and two-step redox cycling of ordered porous ceria structures for solar-driven thermochemical fuel production

This study focuses on thermochemical H2O and CO2-splitting processes using non-stoichiometric metal oxides and concentrated solar energy to produce solar fuels. The redox process involves two distinct reactions: (i) a thermal reduction at high temperature of the oxide with creation of oxygen vacancies in its crystallographic structure, resulting in released O2; (ii) a re-oxidation of the metal oxide by H2O and/or CO2, yielding H2 and/or CO. Hierarchically-ordered porous ceria materials offer high potential for solar-driven thermochemical fuel production based on two-step redox cycles for H2O and CO2-splitting. The emergence of additive manufacturing processes allows to develop architected reactive materials with 3D-ordered geometry and hierarchical structure (porosity gradient), able to enhance the volumetric solar absorptivity and provide homogeneous heating of the oxygen carrier. The investigation of additive-manufactured ordered porous ceria monoliths made from 3D-printed polymer scaffolds was performed in a solar reactor.In comparison with reticulated ceria foams, an improvement of the oxygen yields was achieved with 3D-ordered porous structures. A low total pressure during the reduction step (inducing low pO2) favored the reduction extent and associated fuel yields. The fuel production rate during the exothermal oxidation step was enhanced by decreasing the temperature and by increasing the CO2 partial pressure. In addition, since the oxidation step is a surface-controlled reaction, a natural pore former (woody biomass) was used to create µm-size pores within the struts of ceria scaffolds. This enhanced the oxidation kinetics with a maximal CO production rate of 4.9 mL/min/g and fuel yield up to 333 µmol/g (with a reduction step at 1400 °C under ~0.10 bar of total pressure). Thus, using a 3D-ordered open-cell geometry with addition of micro-scale porosity in the struts enhanced the thermochemical performance.

Fe-Cu Alloy-Based Flexible Electrodes from Ethaline Ionic Liquid

The effective implementation of energy storage systems within flexible structures has recently become of particular interest. Here, the fabrication of inexpensive flexible electrodes via a number of straightforward methods formed the motivation for this research. Thin film-based Fe-Cu alloys were cathodically electrodeposited on a graphite substrate. As ionic liquids consist purely of ions (not solvent), they have recently been used in some electrochemical applications. In this study, therefore, Fe-Cu alloy coatings were prepared from an ethaline ionic liquid containing iron and copper salts. The electrochemical behaviour of Fe-Cu alloy films was determined by scanning between − 1.0 V and − 0.3 V in 1 M KOH at various scan rates ranging from 5 mV s−1 to 200 mV s−1. These films were characterised in terms of their structural and morphological properties by means of Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and x-ray diffraction (XRD). Formation of iron and copper alloy was differentiated depending on applied potential. The supercapacitive ability of Fe-Cu-coated film observed in 1 M KOH electrolyte demonstrated a specific capacitance of 304 F g−1 at a scan rate of 5 mV s-1. The reaction between the alloy and the electrolyte was mainly controlled by a surface-controlled reaction. An asymmetric supercapacitor was constructed with an Fe-Cu-coated graphite negative electrode and a non-woven graphite positive electrode. Four asymmetric supercapacitors were connected in series and used to light up a blue light-emitting diode. This study shows that ethaline ionic liquid is a promising medium for the preparation of alloy-based electrodes in energy storage applications.

Green synthesis of iron nanoparticles using Artocarpus heterophyllus peel extract and their application as a heterogeneous Fenton-like catalyst for the degradation of Fuchsin Basic dye

Synthesis of nanoparticles by utilizing some of the green chemistry principles offers a viable and sustainable approach for nanotechnology. Iron nanoparticles (Fe NPs) were synthesised using Artocarpus heterophyllus (Jackfruit) peel extract. The peel, with its high antioxidant content, serves as a potential source of valuable biomolecules which act as the bio-reductants, capping and stabilizing agents for green synthesis of nanoparticles. The method, apart from using non toxic reactant materials and being cost effective, utilizes waste usefully and in the process reduces waste accumulation. The iron nanoparticles synthesised using jackfruit peel extract (Fe NPs-JF) were characterized by Fourier transform infrared spectroscopy (FTIR), Transmission electron microscopy (TEM), X-Ray diffraction (XRD), Scanning electron microscopy (SEM) equipped with energy dispersive X-ray (EDX) techniques. The nanoparticles so synthesised comprised of zero-valent iron nanoparticles (nZVI) along with iron oxides and oxyhydroxide, with an average size of 33 ​nm. Further, the efficacy of synthesised nanoparticles as Fenton-like catalyst has been demonstrated in the degradation of pollutant dyes like Fuchsin Basic. The experiment showed that these iron nanoparticles exhibited excellent catalytic activity with a high removal efficiency of 87.5% in initial 20 ​min at 318 ​K. In addition, removal of Fuchsin Basic dye fitted well to be a pseudo-first order model. On the basis of the activation energy for the oxidative degradation of the dye calculated using Arrhenius equation, it could be inferred that dye degradation followed a surface-controlled reaction wherein the rate-limiting step constituted a surface-chemical reaction instead of diffusion.

A mechanistic model of direct forsterite carbonation

Mineral carbonation is a promising method to sequester large amounts of carbon dioxide and to produce value-added substitutes for the cement, paper, and plastic industries. In understanding carbonation reaction mechanisms in batch operation, dynamic models play a crucial role, and they allow to evaluate the effects of important process quantities such as temperature, pressure, particle size of solid phases and additives on reaction kinetics. We develop a mechanistic, dynamic forsterite carbonation model that accounts for gas, liquid, and multiple solid phases. In this model, gas-liquid and dissociation equilibria and surface-controlled reactions between solids and liquid phase are based on nonideal thermodynamics. We account for particle size distribution of raw material and product phases by formulating population balances considering nucleation and growth of particles. We model gas and liquid phases each as a homogeneous phase and we use isopotential conditions to describe equilibrium. The resulting high index system of differential and algebraic equations (DAE) is reformulated to obtain a DAE of differential index 1. Model predictions qualitatively match experimental data taken from literature and thus, we can quantify influences of key process conditions by simulation.

Oxygen-functionalized soft carbon nanofibers as high-performance cathode of K-ion hybrid capacitor

Abstract Facing the calling for the new generation of large-scale energy storage systems that are sustainably low cost based on earth-abundant and renewable elements, the K-ion hybrid capacitor (KIHC) constructed with both carbonaceous cathode and anode will be one of the best choices. By using oxygen-functionalized engineering, we first obtained oxygen-containing soft carbon nanofibers (ONC) cathodes which delivered a high reversible capacity of 130 mA h g−1 over 200 cycles at a current density of 50 mA g−1 within a high voltage window. Even at 5.0 A g−1, a practical capacity of 68 mA h g−1 maintained. The surface-controlled reaction domination instead of diffusion-controlled reaction domination was proposed to harvest high capacitance performance. This storage model effectively overcomes the sluggish properties of storing large-sized K-ions by a diffusion-controlled reaction in conventional cathodes in K-ion batteries (KIBs). The rational design of oxygen functionalization towards approaching more and stable active sites was highlighted. Moreover, a renewable and low-cost full KIHC was configurated by carbonaceous cathode and anode derived from a single carbon source.

A small-strain niobium nitride anode with ordered mesopores for ultra-stable potassium-ion batteries

Niobium nitride is first reported as an ultra-stable anode for KIBs. The superior electrochemical performance is attributed to large host for accommodating K ions with small-strain, and a high portion of the surface-controlled reaction.

Effect of Acidic Conditions on Surface Properties and Metal Binding Capacity of Clay Minerals

Clays are one of the most abundant minerals on the Earth’s surface, and they play a significant role in global trace element cycling because of their ability to adsorb and incorporate a range of metal cations. However, to what extent clay surface reactivities are affected by changes in pH of the surrounding environment remains poorly understood. To address this uncertainty, we investigated three common clay minerals (kaolinite, illite, and montmorillonite) and compared their surface properties and metal binding capacity prior to and after acidic treatment (pH ranges from 0 to 7). We report that (1) the morphologies and crystal structures of the three studied clay minerals do not differ markedly after exposure to an acidic solution, (2) all three clays display increases in surface area after the pH 0 acidic treatment, and (3) cadmium adsorption to all three clays decreased after the pH 0 acidic treatment. Our results suggest that the variation in metal adsorption capacity is related to acidic modification of clay surface properties. Importantly, this work shows the relevance of acidic environments on surface-controlled reactions of trace metals to clay minerals.

Amoxicillin degradation using green synthesized iron oxide nanoparticles: Kinetics and mechanism analysis

Beta-lactam antibiotic amoxicillin (AMX) removal in aqueous solution using green synthesized iron oxide nanoparticles (gINPs) from Carob pod (Ceratonia siliqua) was studied. The characterization analyses of the gINPs were performed by TEM, SEM, EDX, XRD, BET, FESEM and Raman spectroscopy. The nanoparticles were found as oxide forms with the spherical shape at an average of 7 ± 5 nm dimensions with 7.67 m2/g surface area. The experimental analysis revealed that the amoxicillin removal efficiency depends on the initial pH, AMX concentration, temperature, and gINPs dose. High removal efficiency (99%) was obtained at a molar ratio of 1:50 AMX/gINPs in 200 min at pH 2. The removal of amoxicillin was investigated by the kinetic studies for the adsorption and degradation mechanisms. The kinetic analysis showed that the adsorption is a physical process with an activation energy of 30 kJ.mol−1. The removal process was determined as the pseudo-first-order following a chemically surface-controlled reaction due to the high activation energy of 87 kJ.mol−1. The occurrence of AMX degradation products was detected by UV–vis and HPLC/MS analyses. The potential degradation pathway of AMX using gINPs was determined as physical adsorption onto the iron corrosion products, and then reduction on the surface of gINPs.

Graphene/oligoaniline based supercapacitors: Towards conducting polymer materials with high rate charge storage

Carbon-based supercapacitors exhibit great rate capability, power density and cycle life, but suffer from relatively low energy density. Polyaniline provides high specific capacitance, but lacks cycling stability. By combining carbon-based materials with tetraaniline, an oligomer of polyaniline, a hybrid composite is formed that demonstrates improved supercapacitor performance relative to either material alone. In this study, the reduced graphene oxide-oligoaniline composites have been synthesized by a one-step hydrothermal process without the need for adding any oxidizing or reducing agents. FTIR, Raman spectroscopy, XPS, and MALDI-TOF mass spectroscopy indicate the successful reduction of GO to rGO and the formation of aniline oligomers. Unlike most polyaniline nanostructures for which charge storage kinetics are limited by slow diffusion-controlled reactions, the majority of oligoaniline in this composite is exposed to the electrolyte and stores charge through fast surface-controlled reactions. The unique microstructure of the rGO-oligoaniline composites facilitates transport of ions and electrons, leading to greater utilization of the active materials, high specific capacitance of 640 F/g at 0.2 mA/cm2 (corresponding to 707 C/g specific capacity), great rate capability and good cycle stability (91% retention after 2000 cycles).

A novel oxygen vacancy introduced microstructural reconstruction of SnO2-graphene nanocomposite: Demonstration of enhanced electrochemical performance for sodium storage

This paper reported an oxygen vacancy contained SnO2-graphene nanocomposite (OVs-SnO2-Gr), which was prepared by annealing SnO2-graphene nanocomposite in 3 vol% H2/Ar atmospheres. It demonstrated with a high reversible capacity of around 510 mAh g−1 after 300 cycles at a current density of 40 mA g−1, and an impressive reversible rate performance of 391 mAh g−1 can be obtained even at a high current density of 1200 mA g−1 when applied as anode for sodium storage. Evidenced by a new phase of Na2SnO3 during sodium storage reactions, it is found that sodium can insert into crystal lattice of oxygen vacancy contained SnO2. Moreover, sodium insertion could arouse a novel structural reconstruction and introduce amorphous phase SnO2, which promotes the surface-controlled reaction process and Na+ diffusion rates, and enables a good rate performance. Additionally, the H2/Ar annealing process increases overall conductivity of electrodes, which further reduces the barrier of Na+ diffusion. It is believe that the as-prepared OVs-SnO2-Gr is a promising anodes for Na-ion batteries with outstanding electrochemical performance.

PREPARATION METHOD OF NZVI-PVDF HYBRID FILMS WITH CATION-EXCHANGE FUNCTION FOR REDUCTIVE TRANSFORMATION OF CR(VI)

Poly (vinylidene fluoride) (PVDF) microporous film was successfully synthesized and functionalized by poly acrylic acid (PAA) for immobilization of nanoscale zero-valent iron (NZVI). PAA was innovatively introduced onto PVDF film via in situ polymerization of acrylic acid (AA) and followed by ion exchange procedure. The as-prepared PAA/PVDF-NZVI hybrids (PPN) were characterized in terms of morphology (SEM) and surface functional groups (FTIR). FTIR spectra confirms the functionalization of PVDF film by coating of PAA within its micropores. And SEM images suggested that NZVI were well immobilized onto the surface of the support. Over the reaction course, the resultant PPN hybrids demonstrated high reactivity, excellent stability and reusability for Cr(VI) removal. Results showed that lower pH and initial concentration facilitated the removal of Cr(VI) by PPN. Compared with bare NZVI, PAA/PVDF film-immobilized NZVI resulted in a lower activation energy for Cr(VI) removal, indicating that Cr(VI) reduction process with PPN is a surfacecontrolled chemical reaction. Moreover, a two-parameter pseudo-first-order model was provided and well-described the reaction kinetics of Cr(VI) over PPN under various conditions.