The present study describes the development of a potentiometric sensor for microbial monitoring in water based on catalase activity. The sensor comprises a MnO2-modified electrode that responds linearly to hydrogen peroxide (H2O2) from 0.16 M to 3.26 M. The electrode potential drops when the H2O2 solution is spiked with catalase or catalase-producing microorganisms that decompose H2O2. The sensor is responsive to different bacteria and their catalase activities. The electrochemical sensor exhibits a lower limit of detection (LOD) for Escherichia coli at 11 CFU/ml, Citrobacter youngae at 12 CFU/ml, and Pseudomonas aeruginosa at 23 CFU/ml. The sensor shows high sensitivity at 3.49, 3.02, and 4.24 mV/cm2dec for E. coli, C. youngae, and P. aeruginosa, respectively. The abiotic sensing electrode can be used multiple times without changing the response potential (up to 100 readings) with a shelf-life of over six months. The response time is a few seconds, with a total test time of 5 min. Additionally, the sensor effectively tested actual samples (drinking and grey water), which makes it a quick and reliable sensing tool. Therefore, the study offers a promising water monitoring tool with high sensitivity, stability, good detection limit, and minimum interference from other water contaminants.

Electrocatalytic hydrogen evolution reaction (HER) is critical for green hydrogen generation and exhibits distinct pH-dependent kinetics that have been elusive to understand. A molecular-level understanding of the electrochemical interfaces is essential for developing more efficient electrochemical processes. Here we exploit an exclusively surface-specific electrical transport spectroscopy (ETS) approach to probe the Pt-surface water protonation status and experimentally determine the surface hydronium pKa [Formula: see text] 4.3. Quantum mechanics (QM) and reactive dynamics using a reactive force field (ReaxFF) molecular dynamics (RMD) calculations confirm the enrichment of hydroniums (H3O[Formula: see text]) near Pt surface and predict a surface hydronium pKa of 2.5 to 4.4, corroborating the experimental results. Importantly, the observed Pt-surface hydronium pKa correlates well with the pH-dependent HER kinetics, with the protonated surface state at lower pH favoring fast Tafel kinetics with a Tafel slope of 30 mV per decade and the deprotonated surface state at higher pH following Volmer-step limited kinetics with a much higher Tafel slope of 120 mV per decade, offering a robust and precise interpretation of the pH-dependent HER kinetics. These insights may help design improved electrocatalysts for renewable energy conversion.

The electrochemical potential difference (Δμ̅) is the driving force for the transfer of a charged species from one phase to another in a redox reaction. In Li-ion batteries (LIBs), Δμ̅ values for both electrons and Li-ions play an important role in the charge-transfer kinetics at the electrode/electrolyte interfaces. Because of the lack of suitable measurement techniques, little is known about how Δμ̅ affects the redox reactions occurring at the solid/liquid interfaces during LIB operation. Herein, we outline the relations between different potentials and show how ambient pressure photoelectron spectroscopy (APPES) can be used to follow changes in Δμ̅e over the solid/liquid interfaces operando by measuring the kinetic energy (KE) shifts of the electrolyte core levels. The KE shift versus applied voltage shows a linear dependence of ∼1 eV/V during charging of the electrical double layer and during solid electrolyte interphase formation. This agrees with the expected results for an ideally polarizable interface. During lithiation, the slope changes drastically. We propose a model to explain this based on charge transfer over the solid/liquid interface.

Herein, titanium (Ti3+) self-doped strontium titanate (SrTiO3), so-called blue SrTiO3, with a bandgap of 2.6 eV and favorable photocatalytic characteristics was fabricated through a facile and effective method. For electrochemical investigations, the electrophoretic deposition was applied to produce SrTiO3 thin films on (fluorine-doped tin oxide) FTO conductive substrates. The electrophoretic voltage of 20 V and a process duration of 10 min were optimized to reach transparent and uniform coatings on FTO. The blue SrTiO3 reveals lower resistance (charge transfer resistance of 6.38 Ω cm-2) and higher electron mobility (current density value of 0.25 mA cm-2) compared to a pure SrTiO3 electrode. These findings may provide new insights for developing high-performance visible light photocatalysts.

Lithium metal anode holds great promises for next-generation battery technologies but is notoriously difficult to work with. The key to solving this challenge is believed to lie in the ability of forming stable solid-electrolyte interphase (SEI) layers. To further address potential safety issues, it is critical to achieve this goal in nonflammable electrolytes. Building upon previous successes in forming stable SEI in conventional carbonate-based electrolytes, here we report that reversible Li stripping/plating could be realized in triethyl phosphate (TEP), a known flame retardant. The critical enabling factor of our approach was the introduction of oxygen, which upon electrochemical reduction induces the initial decomposition of TEP and produces Li3 PO4 and poly-phosphates. Importantly, the reaction was self-limiting, and the resulting material regulated Li plating by limiting dendrite formation. In effect, we obtained a functional SEI on Li metal in a nonflammable electrolyte. When tested in a symmetric Li∥Li cell, more than 300 cycles of stripping/plating were measured at a current density of 0.5 mA cm-2 . Prototypical Li-O2 and Li-ion batteries were also fabricated and tested to further support the effectiveness of this strategy. The mechanism by which the SEI forms was studied by density functional theory (DFT), and the predictions were corroborated by the successful detection of the intermediates and products.

Solid-gas interactions at electrode surfaces determine the efficiency of solid-oxide fuel cells and electrolyzers. Here, the correlation between surface-gas kinetics and the crystal orientation of perovskite electrodes is studied in the model system La0.8 Sr0.2 Co0.2 Fe0.8 O3 . The gas-exchange kinetics are characterized by synthesizing epitaxial half-cell geometries where three single-variant surfaces are produced [i.e., La0.8 Sr0.2 Co0.2 Fe0.8 O3 /La0.9 Sr0.1 Ga0.95 Mg0.05 O3-δ /SrRuO3 /SrTiO3 (001), (110), and (111)]. Electrochemical impedance spectroscopy and electrical conductivity relaxation measurements reveal a strong surface-orientation dependency of the gas-exchange kinetics, wherein (111)-oriented surfaces exhibit an activity >3-times higher as compared to (001)-oriented surfaces. Oxygen partial pressure ( p O 2 )-dependent electrochemical impedance spectroscopy studies reveal that while the three surfaces have different gas-exchange kinetics, the reaction mechanisms and rate-limiting steps are the same (i.e., charge-transfer to the diatomic oxygen species). First-principles calculations suggest that the formation energy of vacancies and adsorption at the various surfaces is different and influenced by the surface polarity. Finally, synchrotron-based, ambient-pressure X-ray spectroscopies reveal distinct electronic changes and surface chemistry among the different surface orientations. Taken together, thin-film epitaxy provides an efficient approach to control and understand the electrode reactivity ultimately demonstrating that the (111)-surface exhibits a high density of active surface sites which leads to higher activity.

This article introduces significant cognitive and usable values in the field of abrasive technology especially in the development of new methods of the electrochemical dressing of superhard grinding wheels with metal bonds. Cognitive values mainly concern the elaboration of the theoretical backgrounds of the electrochemical digestion of compounds of grinding wheel metal bond and gumming up products of the cutting surface of grinding wheel (CSGW). Cognitive values also deal with determining the mathematical relationships describing the influence of technological conditions of dressing on shaping of cutting abilities of superhard grinding wheels. On the other hand, the useful values refer to the industry implementation of the elaborated method and equipment for the electrochemical dressing of suparhard grinding wheels using alternating current (ECDGW-AC). The cost of the device for the realization of this process is low and can be applied in the production conditions. The novel achievements presented in the article are: the elaboration of a new method and equipment for electrochemical dressing of superhard grinding wheels (ECDGW-AC), the selection of electrolytes of low concentration of chemical compounds, tests concerning the digestion of grinding wheel metal bond compounds and gumming up products of CSGW using X-ray analysis, as well as the determination of chemical reactions taking place during elaborated new dressing process, the elaboration of mathematical relationships describing influence of technological conditions of this process on dressing speed and shaping of cutting abilities of superhard grinding wheels, and the performance of technological tests of dressing of superhard grinding wheels using ECDGW-AC method. The elaborated method can be used in ambient temperature and does not cause thermal damages of abrasive grains of cutting surface of grinding wheel and is useful not only for dressing super hard grinding wheels but also for correcting their geometrical deviations.

Superwetting interfaces arising from the cooperation of surface energy and multiscale micro/nanostructures are extensively studied in biological systems. Fundamental understandings gained from biological interfaces boost the control of wettability under different dimensionalities, such as 2D surfaces, 1D fibers and channels, and 3D architectures, thus permitting manipulation of the transport physics of liquids, gases, and ions, which profoundly impacts chemical reactions and material fabrication. In this context, the progress of new chemistry based on superwetting interfaces is highlighted, beginning with mass transport dynamics, including liquid, gas, and ion transport. In the following sections, the impacts of the superwettability-mediated transport dynamics on chemical reactions and material fabrication is discussed. Superwettability science has greatly enhanced the efficiency of chemical reactions, including photocatalytic, bioelectronic, electrochemical, and organic catalytic reactions, by realizing efficient mass transport. For material fabrication, superwetting interfaces are pivotal in the manipulation of the transport and microfluidic dynamics of liquids on solid surfaces, leading to the spatially regulated growth of low-dimensional single-crystalline arrays and high-quality polymer films. Finally, a perspective on future directions is presented.

Homogeneous catalysis of electrochemical reactions, related to contemporary energy challenges, often involves proton-coupled electron transfer sequences. The idea rapidly emerged that installing the proton donor (for reductions, or acceptor for oxidations) inside the catalyst molecule should be beneficial in terms of efficiency, as it would then be closer to the nerve center of the process (usually the metal in the case of transition metal complex catalysts). If this proton relay has indeed done the job, it has lost its proton at the end of each catalytic loop, and must therefore be reprotonated (for reductions, or deprotonated for oxidations) from acid (or base) from the solution before a new catalytic loop can start. The impression may thus be that there is a zero-sum game. The conditions under which this is not the case may entail, in contrast, a considerable boosting of catalysis. This will also allow explain why the proton is such a specifically appropriate agent for this task.

Sludge treatment and disposal have become critical environmental issues in China. Electro-dewatering (ED) is an attractive technology for enhancing dewaterability and improving the sustainability of waste activated sludge (WAS) handling. However, electrically assisted mechanical dewatering processes consume more energy and the extracellular polymeric substance (EPS) dissolution caused by electrochemical reactions can lead to clogging of the filter cloth. Carbon-based materials (CBMs) such as activated carbon and graphite have electrical conductivity and well-developed pore structures which can adsorb the biopolymers. Therefore, addition of CBMs is expected to improve WAS electro-dewatering performance for fuel treatment by enhancing sludge conductivity and filterability. In this study, we evaluated the effects of the three carbon materials (AC-0, AC-5, and graphite) on sludge electro-dewatering behavior and the flammability of sludge cakes. The results showed that CBMs promote the performance of WAS electro-dewatering, and the promoting effect of the carbon materials on the sludge electro-dewatering is proportional to the electrical conductivity of the carbon material, and carbon materials can increase the electrophoretic mobility of sludge flocs and the electro-osmotic effect. Moreover, CBMs can adsorb the dissolved EPS, thus alleviate the plugging and filtration resistance of the filter medium. The addition of CBMs also decreases the energy consumption for water removal during the electro-dewatering process and improves the calorific value and sustainable combustion time of the sludge cake. Our approach can facilitate the resource utilization of the dewatered sludge cake in electro-dewatering processes.