Electrochemical Adsorption Research Articles

Quantification of electrochemically accessible iridium oxide surface area with mercury underpotential deposition.

Research drives development of sustainable electrocatalytic technologies, but efforts are hindered by inconsistent reporting of advances in catalytic performance. Iridium-based oxide catalysts are widely studied for electrocatalytic technologies, particularly for the oxygen evolution reaction (OER) for proton exchange membrane water electrolysis, but insufficient techniques for quantifying electrochemically accessible iridium active sites impede accurate assessment of intrinsic activity improvements. We develop mercury underpotential deposition and stripping as a reversible electrochemical adsorption process to robustly quantify iridium sites and consistently normalize OER performance of benchmark IrOx electrodes to a single intrinsic activity curve, where other commonly used normalization methods cannot. Through rigorous deconvolution of mercury redox and reproportionation reactions, we extract net monolayer deposition and stripping of mercury on iridium sites throughout testing using a rotating ring disk electrode. This technique is a transformative method to standardize OER performance across a wide range of iridium-based materials and quantify electrochemical iridium active sites.

Redox active metallene anchored amino-functionalized cellulose composite for electrochemical capture and conversion of chromium

Considering the ubiquity and high toxicity of Cr(VI) species for destroying a sustainable environment, developing energy-efficient method for capturing and detoxifying chromium [Cr(VI) → Cr(III)] is imperative. Herein, ferrocene (Fc) was combined with carboxymethyl cellulose (CMC) and polyethyleneimine (PEI) for Cr(VI) remediation. Fc species possessed reversible redox behavior and low ionization potential, yet it faced challenges with conductivity and stability. Results revealed that, PEI facilitated the binding of Fc within the CMC through electrostatic interactions or coordination bonds, ensuring the good dispersion and stability of Fc. When applied in the electrochemical adsorption of Cr(VI), the combination created a synergistic effect. The presence of Fc and PEI boosted the electrochemical performance by providing faster electronic and ionic transportation, higher specific capacitance coupled with improved electrode-electrolyte interactions, leading to a higher Cr(VI) adsorption capacity over CMC/PEI/Fc (280.5 mg/g) compared to those over CMC and CMC/PEI. The interactions between the Cr(VI) and electrode included the electrosorption, electrostatic interaction of protonated PEI and oxidized Fc species. When the electric field was reversed, the Cr(VI) was electrostatic repulsed and electrocatalytic reduced to Cr(III) with a reduction rate of 85.4 %. This work promoted the development of effective electrosorption materials suitable for complete Cr(VI) removal and detoxification.

Triggering Ion Diffusion and Electron Transport Dual Pathways for High Efficiency Electrochemical Li+ Extraction.

Efficient electrochemical Li+ adsorption holds significant promise for lithium extraction, while the mismatched rate between Li+ diffusion and electron transport within the electrode material impedes the electrochemical activity and restricts the adsorption efficiency. To address this challenge, herein, we rationally design and integrate the ion and electron dual-conducting poly(vinyl alcohol)-polyaniline (PVA-PANI) copolymer (CP) within the H1.6Mn1.6O4 (HMO) electrode matrix to facilitate Li+ diffusion and electron transport. The Li+ diffusion coefficient (DLi+) increased from 3.03 × 10-10 to 5.92 × 10-10 cm2/s, while the charge transfer resistance (Rct) decreased from 53.73 to 29.57 ohm. Consequently, the HMO@CP electrode exhibits superior adsorption kinetics and a state-of-the-art high adsorption capacity of up to 49.48 mg/g. Comprehensive mechanistic studies reveal that the negatively charged hydroxyl groups (-OH) in PVA accelerate Li+ diffusion and that the conjugated structure and redox-active quinoid sites in PANI offer denser electron distribution and promote electron transport. This synergistic effect in CP significantly enhanced Li+ diffusion and electron transport, leading to electrochemical activity and adsorption efficiency. Our work highlights the critical role of simultaneously regulating the ion diffusion and electron transport dual pathways for optimizing Li+ adsorption performance and inspires development of the next generation electrochemical adsorption electrodes.

3D printer fabrication of boron doped Cu-MWCNT/PLA electrodes: Investigation of its efficiency in electrocatalytic hydrogen production

In this study, three-dimensional (3D) electrodes based on MWCNT-Cu/PLA with high electrocatalytic efficiency, large surface area and different amounts of nano‑boron doped MWCNT-Cu/PLA were fabricated using Fused Granular Fabrication (FGF) method with a 3D printer. When FE-SEM images are examined, MWCNT fibers and copper particles are seen more clearly on the surface due to the formation of more dense conductive networks between the conductive carbon fibers trapped in the PLA structure due to the increasing amount of boron. When XRD results are examined, it is observed that the characteristic peaks belonging to the face-centered cubic structure of Cu are dominant and the crystal size increases as MWCNT addition and boron doping increase. When Raman spectra were analyzed to investigate the internal structural changes of MWCNTs, three characteristic bands corresponding to the D band (defect), G band (graphite band) and G' band (D overtone) of MWCNTs were determined and it was observed that the ID/IG ratio decreased with increasing boron doping compared to MWCNT-Cu/PLA electrode. The B1s spectrum of the 3D 0.8B@MWCNT-Cu/PLA electrode confirmed the presence of boron with the peak corresponding to B@C bonds at 191.2 eV. The obtained 3D electrocatalysts were used as cathodes in an electrolysis cell in aqueous solution containing 1 M KOH and their catalytic efficiency in hydrogen evolution reaction (HER) was tested. In order to increase the activity of the 3D electrodes, unlike the literature, they were activated by electrochemical activation process without using organic solvent and HER measurements of the activated electrodes were performed. Before activation, the charge transfer resistance (Rct) value of the Cu/PLA electrode, which was 6219.00 Ω cm−2, decreased to 681.90 Ω cm−2 after 5 % MWCNT doping. It is seen that with boron doping, a greater decrease in Rct value is realized, reaching values of 66.50–74.56 Ω cm−2. The cathodic Tafel slopes show that the Volmer reaction is the rate-determining step for HER and the rate-determining step is the electrochemical adsorption of hydrogen on the metal surface. In addition, energy efficiency tests of the 3D electrodes in HER were also performed and electrochemically active surface areas were determined. Thus, this study has taken an important step toward using 3D electrocatalysts, which are produced with more cost and more flexible designs, unlike previous production techniques, for hydrogen energy production.

Unravelling the Effect of Crystal Facet of Derived-Copper Catalysts on the Electroreduction of Carbon Dioxide under Unified Mass Transport Condition.

Altering the physical structure and chemical property of copper, i.e., particle size, surface morphology, composition or crystal facet, has been demonstrated to be effective in steering the selectivity of products in electrochemical reduction of carbon dioxide. However, these modifications generally result in the change of active surface area, leading to differences in the geometric current density and local pH, which are also demonstrated to be the key factors for observed selectivity change. In this work, we deconvolute the effect of mass transport and local pH from the effect of crystal facet by investigating five copper-based catalysts with identical roughness factors for electrochemical reduction of carbon dioxide in an H-cell. Interestingly, CuO-derived catalyst stands out as the best catalyst for C-C coupling. At -1.07 V vs. RHE, the faradaic efficiency of C2+ product reaches 44.3%, with a partial current density of -10.8 mA cm-2. Electrochemical adsorption of *OH reveals that the C2+ product selectivity of derived-copper catalysts correlates positively with the ratio of Cu(100)/Cu(110) of five catalysts. Additionally, in situ Raman spectroscopy reveals that the percentage of low-frequency band linear CO (LFB-CO), which is attributed to the adsorbed *CO on Cu(100) facet, increases with the C-C coupling efficiency.

Unravelling the Effect of Crystal Facet of Derived‐Copper Catalysts on the Electroreduction of Carbon Dioxide under Unified Mass Transport Condition

Altering the physical structure and chemical property of copper, i.e., particle size, surface morphology, composition or crystal facet, has been demonstrated to be effective in steering the selectivity of products in electrochemical reduction of carbon dioxide. However, these modifications generally result in the change of active surface area, leading to differences in the geometric current density and local pH, which are also demonstrated to be the key factors for observed selectivity change. In this work, we deconvolute the effect of mass transport and local pH from the effect of crystal facet by investigating five copper‐based catalysts with identical roughness factors for electrochemical reduction of carbon dioxide in an H‐cell. Interestingly, CuO‐derived catalyst stands out as the best catalyst for C‐C coupling. At ‐1.07 V vs. RHE, the faradaic efficiency of C2+ product reaches 44.3%, with a partial current density of ‐10.8 mA cm‐2. Electrochemical adsorption of *OH reveals that the C2+ product selectivity of derived‐copper catalysts correlates positively with the ratio of Cu(100)/Cu(110) of five catalysts. Additionally, in situ Raman spectroscopy reveals that the percentage of low‐frequency band linear CO (LFB‐CO), which is attributed to the adsorbed *CO on Cu(100) facet, increases with the C‐C coupling efficiency.

Preparation of Microelectrolysis Filler Using Coal Slag for the Removal of Hazardous Substances in Contaminated Water.

Presently, the utilization of gasification slag in the context of wastewater treatment is constrained. Furthermore, the presence of dye wastewater and wastewater containing hazardous metals represents a significant threat to human health. Accordingly, the present study prepared a microelectrolytic filler (MF) from gasification slag via a high-temperature roasting method and evaluated its degradation performance in water containing organic matter and harmful metal ions. The impact of varying preparation conditions, including initial solution pH and MF dose, on the degradation process was examined. The removal of methyl blue was found to be 92.21% at an initial pH of 2, a reaction time of 300 min and a dosage of 40 g L-1. The removal of Cu(II), Cd(II), and Pb(II) metal ions was 97.32, 96.58, and 99.38%, respectively, at an initial pH of 4, a reaction time of 180 min, and a dosage of 10 g L-1. Following five cycles, the MF process demonstrated continued efficacy in the removal of dyes and heavy metals from the wastewater. A mechanistic analysis revealed that the water treatment process is not a single adsorption process. Instead, it was found that organic macromolecules undergo chain-breaking reactions, while heavy metal ions undergo redox reactions. The wastewater treatment process comprises a number of distinct strategies, including electrochemical reactions, adsorption, flocculation, and precipitation. These findings illustrate the potential of a gasification slag green recycling approach to treat waste with waste, in alignment with the principles of sustainable development.

Enhanced construction of 3D carbon skeleton through molten salt coupling activation effect for high efficiency capacitive deionization of lead (II) ions removal in wastewater

Efficiently eliminating of highly toxic ultra-dilute lead ions (Pb2+) from wastewater is a challenging task. Capacitive deionization (CDI) technology, based on the electrochemical capacitance mechanism, has emerged as a pivotal approach to address this challenge. In this work, a KNO3-mediated molten salt-coupled activation strategy was proposed to prepare nitrogen-doped hierarchical porous biomass carbon electrode material (3DCF-650-0.2) with a three-dimensional carbon skeleton, which was integrated into a symmetrical CDI device for Pb2+ removal. The 3DCF-650-0.2 electrode exhibited a high specific capacitance of 330.3 F g-1 at a current density of 1 A g-1, with a capacity retention rate of 98.45% after 10,000 cycles at 10 A g-1. Furthermore, the electrochemical adsorption capacity of the CDI device for Pb2+ reached 72.86 mg g-1 (1.2 V, 50 mg L-1), and the CDI device retained a high adsorption capacity of 91.14% after twenty adsorption/desorption cycles. These excellent adsorption properties are attributed to the in-situ activation and gas foaming of KNO3, which favors the production of reasonable pore structure (electric double-layer capacitance) and an appropriate pyrrolic nitrogen doping amount (selective adsorption) in the carbon materials. This work provides insight into the mechanism of the molten salt-coupled activation strategy, offering new ideas for the targeted design of high-performance CDI biomass carbon materials.

Anode process on gold in KF–AlF<sub>3</sub>–Al<sub>2</sub>O<sub>3</sub> melt

In the conditions of resource saving and carbon footprint reduction, the development of oxygen–releasing anodes for technologies of production of important metals and alloys by electrolysis of molten salts seems to be an urgent task. To determine the degree of “inertness” of a particular anode material, data on the kinetics and mechanism of the anode process on a material not subject to oxidation are required. In this connection, the anodic process on gold in the KF–AlF3–Al2O3 melt for electrolytic aluminum production was investigated by cyclic and square–wave voltammetry methods. The influence of temperature (715 and 775 оC) of the melt, the content of Al2O3 in it (from 0.1 to saturation), as well as the polarization rate (0.05–1 V/s) on the kinetics and some features of the mechanism of the investigated process was determined. An assumption is made that oxygen release on gold without dissolution of the substrate takes place in the region of overvoltages from 0 to 0.8 V. It is shown that the process includes the stages of electrochemical adsorption and desorption of the intermediate product, the first of which is limited by the diffusion of electroactive anions to the anode.

Toxic-Free Environment: Forever Chemicals Removal from Water and Wastewater

Per- and polyfluoroalkyl substances (PFAS), commonly known as "forever chemicals," are persistent synthetic compounds that have been widely utilized since the mid-20th century across various industries. Due to their environmental persistence and potential health risks, PFAS has become a significant concern, particularly in relation to water and wastewater contamination. This paper investigates the complex challenges associated with PFAS, focusing on existing regulatory frameworks, treatment strategies, and innovative clean technologies that aim to reduce or eliminate these harmful substances. The study emphasizes the importance of advanced treatment methods such as electrochemical degradation, nanofiltration, adsorption, and biodegradation, each offering varying degrees of success. Despite advancements in treatment technologies, prevention remains the most effective strategy to minimize PFAS pollution. The paper calls for collaborative efforts from regulatory bodies, industries, and communities to implement more sustainable practices, ensuring a toxic-free environment and aligning with circular economy principles. Continuous research and international cooperation are crucial for developing effective long-term solutions to address PFAS contamination and safeguard both public health and the environment.

Modulation of metal centers of MOF in-situ grown on lignin-derived carbon to enhance adsorption capacity and electrochemical sensing performance for bisphenol A

Metal-organic framework materials have unique advantages in providing active sites and shortening electron/proton transfer distances. Here, an efficient electrochemical sensing material LPC-700@NiCo-MOF has been obtained by in-situ growth of bimetallic NiCo-MOF on lignin-derived porous quasi-carbon nanosheets (LPC-700). Due to the electronic synergistic effect of bimetallic centers of NiCo-MOF, it has better electrochemical sensing performance for bisphenol A (BPA) than the monometallic MOF. The density of states and adsorption energies of monometallic and bimetallic MOF on BPA have been investigated by DFT theory, which further demonstrated that the bimetallic NiCo-MOF has better electrochemical performance and adsorption effect on BPA. The high-performance portable sensor based on LPC-700@NiCo-MOF has been able to quickly, sensitively and accurately detect BPA in water samples and food packaging. This strategy of metal-modulated MOF grown in-situ on conducting carbon-based materials to enhance electrochemical activity provides a method for application in electrochemical fields.

Integrated electrochemical-adsorption for simultaneous removal of pharmaceuticals from water: Process optimization and synergistic insights

Water contamination with pharmaceuticals has become an evident environmental challenge. Treatment processes such as electrochemical oxidation (EO) and adsorption have limitations in the simultaneous removal of pharmaceuticals from water. Therefore, this study examined the potential of coupled process (EO followed by adsorption) in binary pharmaceuticals (acetaminophen (ACM) + ciprofloxacin (CIP)) removal from water, with an emphasis on coupled process optimization. Consequently, optimized coupled process conditions including current density (22 mA/cm2), pH (5.5), EO time (40 min), adsorbent dose (0.1 g/L) and adsorption time (60 min) were obtained. Under optimal conditions, removal efficiencies of 94.6% (ACM)+92% (CIP), 94.07% (ACM)+91.15% (CIP), and > 99.8% (ACM + CIP) were recorded for 20 mg/L (ACM + CIP) removal in EO, adsorption and EO + adsorption, respectively. Further, the coupled process was employed in multiple pharmaceuticals (20 mg/L of ACM + CIP + ATN (atenolol) + AMX (amoxicillin)) removal from water and removal of > 97.56% (ACM + CIP + ATN + AMX) was achieved. Removal efficiencies of ACM (83.35%) + CIP (73.1%) + ATN (68.52%) + AMX (63.05%) and ACM (80.37%) + CIP (66.5%) + ATN (73.07%) + AMX (60.5%) were obtained in EO and adsorption, respectively. The noted lower removal efficiencies in EO and adsorption are associated with the diverse nature of the pharmaceuticals, limited adsorbent active sites, and the shared utilization of reactive oxygen species (ROS) among the pharmaceuticals in EO. The total organic carbon (TOC) removal of 40.24%, and 99% and chemical oxygen demand (COD) removal of 72.45%, and 99.6% were obtained under optimal conditions of EO, and coupled process, respectively. These findings indicate that the pharmaceuticals are only partially mineralized in EO and the subsequent adsorption effectively eliminated the remaining target pharmaceuticals, and degradation by-products from water. Additionally, integrating EO with adsorption reduced the electrical energy consumption of the EO process from 31.6 kWh/m³ to 6 kWh/m³ under optimal conditions. Overall, coupling EO with adsorption offers the utmost advantages when removing multiple pharmaceuticals from complex water matrices.

Built-in Electric Field in 1D/2D Heterostructure Boosts Zinc Air Battery Performance.

The realization of a rechargeable zinc-air battery (ZAB) is hindered by the low intrinsic oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) activities. In this work, an abundant built-in electric field is noticed in a 1D/2D CoO/CoS2 heterostructure, triggering electron transfer from CoO to CoS2 associated with a downshifted d band center of the Co atom mitigating the strong electrochemical adsorption of *OH species on active sites; thereby, boosted OER and ORR performance are achieved. Namely, the OER specific activity of CoO/CoS2 is enhanced by 3.8- and 2.2-fold compared to the counterpart of CoO and CoS2, respectively. Furthermore, the kinetic current density of CoO/CoS2, a fingerprint of intrinsic ORR activity, is promoted by 46 and 6.6 times relative to CoO and CoS2. The rechargeable ZAB performance attains 215.6 mW cm-2, 1.6-times better than Pt/C-IrO2. Moreover, the superior performance remained for 600 h. Besides, the battery performance of the all-solid-state ZAB reaches 83.8 mW cm-2, revealing its promising application in wearable device.

Exploring the thermodynamics and dynamics of lithium ions inserted into Li1-xMn2O4 electrode at different temperatures

Efficient lithium extraction via electrochemical adsorption holds great promise for resource utilization and energy storage. However, the mechanism of how temperature influences the electrochemical adsorption process, particularly the thermodynamics and dynamics in the liquid, liquid–solid interface, and solid remains unclear. To address this challenge, we explored the impact of temperature (273.15 to 328.15 K) using Li1-xMn2O4 as an adsorbent. For the liquid phase, the conductivity increased from 0.89 to 0.95 S/m following lnΛ = -0.11(1000/T) + 0.27 in thermodynamics; the solution viscosity decreased from 1.71 × 10-3 to 5.15 × 10-4 Pa·s conforming lnη = 1.96(1000/T) − 13.54 in dynamics. For the liquid–solid interface, the charge transfer resistance (Rct) decreased from 42.03 to 25.17 ohm obeying ln(1/Rct) = -0.82(1000/T) − 0.69 in thermodynamics; the exchange current (i0) showed a positive correlation with temperature in fitting Logi0 = -0.50(1000/T) − 1.40 in dynamics. For the solid phase, the increase in reduction peak voltage (ERP) and the decrease in Gibbs free energy (G), entropy (S), and enthalpy (H) all indicate that the increase of temperature promotes lithium ions to inserted into Li1-xMn2O4 in thermodynamics; the increased diffusion coefficient (DLi+(S)) and higher reduction peak current (IRP) suggest that higher temperature strengthens lithium ions diffusion and insertion in dynamics. In the temperature range, the adsorption capacity gradually increased from 1.15 to 7.37 mg/g, the initial current enhanced from −3.40 × 10-4 to −1.85 × 10-3 A, the terminal current raised from −1.59 × 10-4 to −7.40 × 10-4 A, and the current efficiency improved from 31.28 % to 66.11 % in the temperature range. This work provides a deeper understanding of the impact of temperature on the electrochemical lithium adsorption process from thermodynamics and dynamics. This work also offers crucial guidance for the upgrading of electrochemical lithium adsorption technology and can be applied to other fields such as energy storage, catalysis, and synthesis, providing a valuable reference for optimizing reaction parameter design in thermodynamics and dynamics.

Enhanced removal of lead ions from wastewaters by electrochemical adsorption using nitrogen-doped Ti3C2Tx MXene

As a two-dimensional material containing transition metal carbides and nitrides, MXene is often used in capacitive deionization for its excellent hydrophilic and pseudocapacitive properties. Nitrogen doping is widely used to improve the adsorption properties of certain materials. However, the effect of nitrogen doping on the electrochemical adsorption properties of MXene remains unclear. In this work, nitrogen-doped Ti3C2Tx MXene was synthesized using a simple hydrothermal method to achieve highly selective and efficient removal of Pb(II) at a constant cell voltage. The concentration of Pb(II) decreased from 4.95 to 0.02 mg L−1 in a 100 mg L−1 NaCl supporting electrolyte after electrosorption. The removal efficiency of Pb(II) reached 99.5%, whereas it was only 15.2% for Na+. The introduction of nitrogen functional groups increased the electrical conductivity and layer spacing of MXene, thereby improving the pseudocapacitive adsorption performance in the presence of Pb(II). The complexation function of the Ti-OH group on nitrogen-doped Ti3C2Tx surface increased and contributed to the selective adsorption of Pb(II). The removal efficiency of Pb(II) increased with increasing solution pH and cell voltage, reaching the maximum value at pH 5.0 and 1.5 V, respectively. The effect of supporting electrolyte type on the removal of Pb(II) was negligible. In addition, the removal efficiency for mixed heavy metal ion solutions, including Cu(II), Ni(II), and Pb(II), exceeded 79.0%. It exhibited the highest removal efficiency for Pb(II) at 97.9%. After five cycles of electrochemical adsorption–desorption, the nitrogen-doped Ti3C2Tx maintained a stable Pb(II) removal efficiency of 97.0%. This work provides a promising material for the electrochemical removal of low-concentration heavy metal ions from wastewaters.

Recent advances in MXene nanomaterials: Fundamentals to applications in environment sector

AbstractMXenes are a new type of 2D transition metal carbon/nitride or carbonitride, which are composed of Mn+1AXn phase material (MAX phase) through single‐layer or thin‐layer nanosheets obtained by exfoliation. Owning to unique two‐dimensional layered structure, large specific surface area, excellent electrical conductivity and mechanical stability, the MXenes have quickly become a research hotspot due to their magnetic and other properties, and have been widely used in many fields such as electrochemical sensors, energy storage, catalysis, and adsorption. This article summarizes and introduces preparation methods of two‐dimensional materials MXenes, and focus on reviewing their application research progress in the electrochemical sensors and environmental field in recent years, including detection of biomarkers and environmental pollutants, adsorption of heavy metals, adsorption of radiation metals, adsorption of organic matter, selective adsorption of carbon dioxide, membrane separation, sensors, electrocatalysis, photocatalysis, electromagnetic absorption and shielding, etc. A summary and review were conducted, and finally the existing problems and future development at this stage were analyzed.

Selective adsorption of divalent and trivalent cations in porous electrodes.

The capacitive deionization technology uses the electrochemical adsorption of ions in porous electrodes to desalinate seawater or brackish water. Recently, capacitive deionization has gained significant attention as a technology for selective adsorption of ionic species from multicomponent aqueous electrolytes. To investigate the mechanism of selective adsorption at the molecular level, we performed molecular dynamics simulations of aqueous electrolytes and porous electrodes with different divalent or trivalent ions, electrode pore sizes, and applied voltages. We calculated the free energy barriers preventing ions from entering the pores of the electrode and the structure of the water molecules near the ions and the electrode surface under various conditions. Our results suggest that, when the pore and ion sizes are comparable, the steric and electrostatic interactions between the hydrated ions and electrode pores are comparable in magnitude. Moreover, the relative importance of the two interactions can be reversed by slight changes in the external conditions, such as the ion size, valence of the ions, electrode pore size, and applied voltage. Thus, by finely tuning the electrode pore size and the applied voltage, it may be possible to selectively adsorb a particular ionic species from a multicomponent electrolyte through capacitive deionization using a porous electrode.

Strengthened ozone adsorption through positive electric field-induced charge migration on various TiO2 crystal surfaces: A mechanistic and theoretical study

This study investigates the enhancement of ozone adsorption on diverse TiO2 crystal interfaces through an innovative electrochemical modulation approach. The research focuses on the effects of applied electric field strength and reaction sites on ozone interfacial adsorption energies for Ti/Anatase TiO2 (0 0 1) and Ti/Rutile TiO2 (1 1 0) interfaces. The findings reveal that positive electric fields significantly enhance ozone adsorption on both interfaces, with adsorption energies increasing by up to 18% for Ti/Anatase TiO2 (0 0 1) and 15% for Ti/Rutile TiO2 (1 1 0). Notably, double water molecule sites (≡(H2O)2) play a crucial role in this enhancement process. The study demonstrates that the applied electric field alters the charge distribution at the TiO2 catalytic interface, thereby increasing interfacial charge density and promoting charge migration to ozone. Furthermore, this process leads to enhanced overlap and hybridization between ≡(H2O)2 sites and the s and p orbitals of ozone molecules, resulting in the formation of chemical bonds with lower Fermi levels. These comprehensive results demonstrate the broad applicability of the electrochemical interfacial ozone adsorption enhancement method across different crystal types and surfaces. Consequently, this study provides essential data to support the advancement of greener and more energy-efficient heterogeneous catalytic ozonation processes, potentially contributing to significant improvements in ozone-based water treatment technologies.

Unlocking the Impact of “Cell Position” on Solid‐State Hydrogen Storage: Investigations on an Activated Carbon Electrode Integrated in a Modified Reversible Polymer Electrolyte Membrane Fuel Cell

The presented maiden experimental study introduces a novel cell position concept for a modified reversible polymer electrolyte membrane fuel cell with an integrated hydrogen storage (H‐storage) electrode. The primary focus of the current study is to enhance the H‐storage capacity of a carbon‐based self‐standing electrode by testing it in vertical, horizontally upward, and horizontally downward positions to meet U.S. Department of Energy objectives. The results show that the developed cell achieves the highest electrochemical hydrogen adsorption (H‐adsorption) of 1.3 weight percent (wt%) in the horizontal downward position during charging, surpassing the vertical position by 36.1% and outperforming the horizontal upward position by 25.3%. The reversible rates of stored hydrogen are measured as 0.587 wt% in the vertical position, 0.781 wt% in the horizontal upward position, and 0.998 wt% in the horizontal downward position. The cell manages to deliver a peak output of 2.2 V and a maximum current of 0.5 mA during the initial discharging phase. The insights gained from this study on cell positioning are poised to inspire future research efforts aimed at enhancing hydrogen storage capacity and its reversibility.

Engineering ion diffusion and electron transfer dual pathways within porous spherical H1.6Mn1.6O4 for highly efficient Li+ separation

Efficient and selective electrochemical lithium adsorption from liquid resources is crucial for sustainable lithium extraction and purification. However, the sluggish Li+ diffusion kinetics often lag behind electron transfer rates, hindering the overall adsorption efficiency in capacity and kinetics. This work addresses this challenge by introducing a tunable porous spherical architecture in H1.6Mn1.6O4 adsorbent particles. The Li+ diffusion coefficient (DLi+) enhanced from 1.32 × 10-12 cm2/s to 3.61 × 10-12 cm2/s, the solution resistance (Rs) decreased from 28.88 ohm to 25.30 ohm, the charge transfer resistance (Rct) decreased from 31.04 ohm to 30.40 ohm, and the desolvation activation energy (Ea) reduced from 10.81 kJ/mol to 9.81 kJ/mol. Consequently, the optimized porous spherical H1.6Mn1.6O4 demonstrates superior adsorption capacity and adsorption kinetics, exceeding 24.23 mg/g at 180 min, which is 1.26 times that of the dense spherical counterpart (19.28 mg/g). The simulation calculations of Li+ diffusion highlight the pivotal role of the porous structure in accelerating internal Li+ diffusion, thereby significantly contributing to the enhanced overall adsorption efficiency of H1.6Mn1.6O4. This work emphasizes the significance of synergistically optimizing ion diffusion channels and electron transfer paths for enhancing electrochemical processes and provides a path for constructing similar pore structures in various ion–electron-related applications.