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Electroreduction of CO2 into multi‐carbon (C2+) products (e.g. C2+ alcohols) offers a promising way for CO2 utilization. Use of strong alkaline electrolytes is favorable to producing C2+ products. However, CO2 can react with hydroxide to form carbonate/bicarbonate, which results in low carbon utilization efficiency and poor stability. Using acidic electrolyte is an efficient way to solve the problems, but it is a challenge to achieve high selectivity of C2+ products. Here we report that the amine modified copper nanoparticles exhibit high selectivity of C2+ products and carbon utilization at acidic condition. The Faradaic efficiency (FE) of C2+ products reach up to 81.8 % at acidic media (pH=2) with a total current density of 410 mA cm−2 over n‐butylamine modified Cu. Especially the FE of C2+ alcohols is 52.6 %, which is higher than those reported for CO2 electroreduction at acidic condition. In addition, the single‐pass carbon efficiency towards C2+ production reach up to 60 %. Detailed studies demonstrate that the amine molecule on the surface of Cu cannot only enhance the formation, adsorption and coverage of *CO, but also provide a hydrophobic environment, which result in the high selectivity of C2+ alcohols at acidic condition. [ABSTRACT FROM AUTHOR]

Electrochemical lactate biosensors based on lactate oxidase (LOx) are used for diagnostics, sports medicine, and the food industry. However, samples from these sectors may have acidic levels at which the biocatalytic activity of LOx may be diminished. In this work, the enhancement of the bio‐electrocatalytic activity of LOx at low pH by pKa modulation of its catalytic His265 was studied by rational engineering of lactate oxidase from Aerococcus viridans (AvLOx). Several candidates based on interactions with His265 were selected by in silico structural analysis. The designed variants were heterologously produced, and the S175A mutant showed considerable improvement over its wild‐type counterpart, showing 157 % of the enzymatic activity found in the wild‐type at pH 5. Bioelectrodes were assembled based on Prussian‐blue‐modified carbon paper mediator system. The electrocatalytic performance of the amperometric biosensors of S175A variant at pH 5 exhibited a linear range of 0.2–2 mM measured at 0 V vs SCE, a sensitivity of −17.52 μA/mM ⋅ cm2, representing 240 % of the sensitivity found in the wild‐type biosensor, and a limit of detection of 38 μM, lower than observed with the wild‐type enzyme. These results show that the mutant obtained offers a significant improvement in lactate biosensing at low pH. [ABSTRACT FROM AUTHOR]

Engineering noble metal‐based electrocatalysts (NMEs) with high activity is of vital importance to accelerate the hydrogen production from proton exchange membrane water electrolyzers (PEMWEs). However, the poor stability and high price of NMEs greatly restrict the practical application. In this review, a series of strategies are summarized to boost the activity and reduce the cost of NMEs under acidic condition from the perspective of composition and structure optimization. The composition regulation through doping of metals or nonmetals can effectively inspire alloy effect or cocktail effect of NMEs, which provides an essential guidance to reduce the cost and enhance the stability of NMEs. Meanwhile, the structure optimization also directly improves the intrinsic activity of NMEs, which is comprehensively elaborated based on size, defect, and geometric effects. In addition, to extend the industrial application of PEMWEs, critical scientific issues behind the formulating of electrocatalyst slurry and coating method–PEMWEs performance relationships are fully clarified. Finally, the challenges for survivability of active center, catalytic mechanism research, and construction of membrane electrode are concluded. This review offers comprehensive and targeted guidelines for the rational design of NMEs for PEMWEs application. [ABSTRACT FROM AUTHOR]

Aiming to design a catalyst for stable electrooxidation of water at low pH, the present work explores the properties and structural features of electrodeposited composite oxides based on Bi and Co, which were anticipated to provide stability and catalytical activity, respectively. Materials deposited as very thin (ca 50 nm) films on F‐doped SnO2 (FTO) substrate do not initially exhibit high activity in 0.1 M H2SO4, but are activated during operation through the electrooxidatively‐induced enrichment of the catalytic surface with Co and Sn oxides. The latter originate from the FTO support and are identified as an important component of the catalyst through control experiments with a Sn‐free substrate and with Sn2+ intentionally added at the electrodeposition stage. A distinctive feature of the Co−Bi−Sn‐based electrocatalyst is the slow but persistent improvement in the activity during operation in 0.1 M H2SO4 at both ambient and elevated (60 °C) temperatures, which contrasts with the continuously degrading behaviour of state‐of‐the‐art oxygen evolution catalysts at low pH. This is demonstrated by 9‐day‐long galvanostatic tests at 10 mA cm−2, during which the Co−Bi−Sn‐based thin film catalyst shows no degradation and sustains stable water oxidation at ca 1.9 V vs. reversible hydrogen electrode. The effects of tin leaching from the support detected herein might have implications to other acidic water oxidation catalysts supported on high‐surface area doped SnO2 materials. [ABSTRACT FROM AUTHOR]

Acidic oxygen reduction is vital for renewable energy devices such as fuel cells. However, many aspects of the catalytic process are still uncertain—especially the large difference in activity in acidic and alkaline media. Thus, the design and synthesis of model catalysts to determine the active centers and the inactivation mechanism are urgently needed. We report a pyrolysis‐free synthesis route to fabricate a catalyst (CPF‐Fe@NG) for oxygen reduction in acidic conditions. By introducing a deprotonation process, we extended the oxygen reduction reaction (ORR) activity from alkaline to acidic conditions. CPF‐Fe@NG demonstrated outstanding performance with a half‐wave potential of 853 mV (vs. RHE) and good stability after 10000 cycles in 1 M HClO4. The pyrolysis‐free route could also be used to assemble fuel cells, with a maximum power density of 126 mW cm−2. Our findings offer new insights into the ORR process to optimize catalysts for both mechanistic studies and practical applications. [ABSTRACT FROM AUTHOR]

Efficient, earth‐abundant, and acid‐stable catalysts for the oxygen evolution reaction (OER) are missing pieces for the production of hydrogen via water electrolysis. Here, we report how the limitations on the stability of 3d‐metal materials can be overcome by the spectroscopic identification of stable potential windows in which the OER can be catalyzed efficiently while simultaneously suppressing deactivation pathways. We demonstrate the benefits of this approach using gamma manganese oxide (γ‐MnO2), which shows no signs of deactivation even after 8000 h of electrolysis at a pH of 2. This stability is vastly superior to existing acid‐stable 3d‐metal OER catalysts, but cannot be realized if there is a deviation as small as 50‐mV from the stable potential window. A stable voltage efficiency of over 70 % in a polymer–electrolyte membrane (PEM) electrolyzer further verifies the availability of this approach and showcases how materials previously perceived to be unstable may have potential application for water electrolysis in an acidic environment. Window of opportunity: Spectroscopic measurements allowed the identification of a stable potential window in which γ‐MnO2 is able to catalyze the oxygen evolution reaction under acidic conditions for more than 8000 hours. This shows how the limitations on the stability of 3d‐metal materials acting as electrocatalysts can be overcome. [ABSTRACT FROM AUTHOR]

This article, published in ChemElectroChem, discusses the development of bioengineered lactate oxidase mutants for use in biosensors that detect lactate in sweat. The mutants were designed to have improved catalytic activity and electrochemical response at low pH. Through in silico analysis, the researchers found that the S175A variant exhibited 240% higher sensitivity than the wild-type biosensor at pH 5. This research has potential applications in the field of biosensing and could contribute to advancements in healthcare and sports performance monitoring. [Extracted from the article]

The development of antibiotic resistance among hospital pathogens has provided a great need for new antimicrobial agents. Zinc oxide nanoparticles (ZnO NPs) in combination with various antibiotics can act as a reducing agent for antibiotic resistance. The aim of this study was to investigate the influence and the mechanism of ZnO NPs on the antimicrobial activity of ciprofloxacin (CP) and ceftazidime (CAZ) against Enterococcus faecalis (E. faecalis) and Acinetobacter baumannii (A. baumannii) bacteria in acidic conditions (pH 5.5). ZnO NPs were synthesised using the solvothermal method and characterised. The MIC90 value of ZnO NPs against A. baumannii was 0.25 mg ml−1 and its highest growth‐inhibitory activity was observed at 0.125 mg ml−1 for E. faecalis. The Fourier transform infrared spectroscopy spectra of ZnO NPs treated with antibiotics showed the interaction between ZnO NPs and each of the two antibiotics. ZnO NPs at a sub‐inhibitory concentration had no effect on the antibacterial activity of CP and CAZ against E. faecalis and CP against A. baumannii. The action mechanism of ZnO NPs for enhancing the antibacterial efficacy of CAZ against A. baumannii was evaluated. ZnO NPs caused to increase in the antibacterial activity of CAZ against A. baumannii, possibly through the release of Zn2+ and increasing of membrane permeability. [ABSTRACT FROM AUTHOR]

This work reports the dissolution of bioactive glasses in acidic solutions. The focus was on lactic acid, thus mimicking the conditions that may develop locally during in vivo degradation of polylactic acid/bioactive glass composites. First, the dissolution of glasses 45S5, S53P4, and S68 was studied in 1.2 m lactic acid. The leaching of ions from 45S5 in lactic acid solution was further compared with the reactions in hydrochloric acid solution. Finally, Tris-buffered solutions in which the pH was adjusted to 7.4 using hydrochloric or lactic acid were used to study the effect of the acidic components on the dissolution of 45S5. The dissolution extent followed the initial acid concentrations: greater in lactic acid and lower in hydrochloric acid of the same initial pH. Rapid, preferential dissolution of Na, Ca, and P took place in lactic acid solution, thus suggesting that locally high concentrations of degradation products of lactic acid may enhance the dissolution of bioactive glass in Polylactic acid composites. When solution pH exceeded 4, calcium phosphate started to form on the glass surface. [ABSTRACT FROM AUTHOR]

The use of polarography to accurately determine stability constants of complexes formed under very acidic conditions (below pH 2) is demonstrated. The diffusion junction potentials, which must be accounted for below pH 2, were evaluated by applying protocols developed where Tl(I) is used as an internal reference. The Cu(II)-picolinic acid (2-pyridinecarboxylic acid) system studied was chosen since the CuL+ species only exists in solution below pH 2 under the conditions used and literature data exists to confirm the accuracy of procedure. Additionally, the reduction of Cu(II) was quasi-reversible and procedures to determine the reversible half-wave potentials were investigated. Average log β values of 7.75±0.09 for CuL+ and 14.8±0.1 for CuL2 were obtained, which compared well to literature data. [ABSTRACT FROM AUTHOR]

Enzymatic hydrolysis of soybean protein isolate by the extracellular proteases from Actinomucor elegans and Rhizopus oligosporus at p H 3.0, 3.5, 5.0, 5.5 and 6.0 was investigated. The activity of the A. elegans protease is lower than that of R. oligosporus, but both proteases exhibit considerable degradation of soybean protein at p H 5.5 and 6.0. The water-soluble protein content and the degree of hydrolysis of the hydrolysates are increased significantly, and bitterness values are very low. Sodium dodecyl sulphate polyacrylamide gel electrophoresis ( SDS-PAGE) reveals that these proteases have different cutting sites on peptide polymers. At p H 5.5, there is a lower content of total free amino acids (39.20 mg per 100 m L; 62.68% hydrophobic amino acids) in the R. oligosporus protease hydrolysate. In conclusion, treatment with R. oligosporus protease at p H 5.5 achieves efficient degradation of soybean protein, suggesting a promising industrial process for making bitterless protein hydrolysates. [ABSTRACT FROM AUTHOR]

Abiotic and biotic oxidation of hydrogen sulfide related to concrete corrosion was studied in corrosion products originating from a sewer manhole. The concrete corrosion products were suspended in an acidic solution, mimicking the conditions in the pore water of corroded concrete. The removal of hydrogen sulfide and dissolved oxygen was measured in parallel in the suspension, upon which the suspension was sterilized and the measurement repeated. The results revealed the biotic oxidation to be fast compared with the abiotic oxidation. The stoichiometry of the hydrogen sulfide oxidation was evaluated using the ratio between oxygen and hydrogen sulfide uptake. The ratio for the biotic oxidation pointed in the direction of elemental sulfur being formed as an intermediate in the oxidation of hydrogen sulfide to sulfuric acid. The experimental results were applied to suggest a hypothesis and a mathematical model describing the hydrogen sulfide oxidation pathway in a matrix of corroded concrete. [ABSTRACT FROM AUTHOR]