Photodiodes promote electrochemical synthesis
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Antibody-functionalized MXene-based electrochemical biosensor for point-of-care detection of vitamin D deficiency
Clinical studies routinely show that individuals suffer from vitamin D deficiency, which can result in health complications that include cardiovascular disease, autoimmune disorders, neurodegenerative diseases, and different skeletal deformities. Given its integral role in homeostasis and connection to many pathologies, early diagnosis of vitamin D deficiency is crucial. However, monitoring vitamin D levels is challenging, particularly in remote regions, due to the cost, time, and complexity of existing methods. Here, we develop an electrochemical biosensor for vitamin D based on antibody-functionalized MXenes, offering clinically relevant sensitivity, specificity, and amenability for point-of-care testing. Ti3C2Tx MXene nanosheets are amine-functionalized by electrostatically-driven modification with polyethylenimine, whose functionalities are then used for covalent conjugation of anti-vitamin D antibodies via glutaraldehyde chemistry. This platform achieves a detection limit of 1 pg mL−1 with a dynamic range (0.1–500 ng mL−1) that covers clinically relevant deficiency, insufficiency, sufficiency, and toxicity.
Bipolar electrochemistry-driven wireless drug loading and energy harvesting in conductive hybrid hydrogels
Bipolar electrochemistry enables wireless and spatially controlled redox reactions on (semi)conductive objects immersed in an electrolyte. Here, we investigate advanced bipolar electrochemistry applications using flexible bipolar electrodes coated with hybrid films of conductive polymer poly(3,4-ethylenedioxythiophene) and alginate hydrogels. These coatings allow for the wireless creation of reversible redox and chemical gradients, providing targeted drug loading and energy harvesting opportunities. We use cyclic voltammetry, electrochemical impedance spectroscopy, Raman microscopy, and X-ray photoelectron spectroscopy to characterize distinct redox regions within the bipolar electrode. The wireless and selective loading of a model drug, fluorescein, into the hydrogel, demonstrated control over drug distribution, suggesting an alternative to conventional uniform doping techniques. Furthermore, cutting the gradient-encoded bipolar electrode and closing an external circuit between the halves, enables energy recovery through a concentration cell mechanism. Our findings illustrate the potential of bipolar electrochemistry in creating versatile platforms that bridge materials science, electrochemistry, and bioelectronics for innovative biomedical and energy applications.
Mechanisms of electrochemical hydrogenation of aromatic compound mixtures over a bimetallic PtRu catalyst
Efficient electrochemical hydrogenation (ECH) of organic compounds is essential for sustainability, promoting chemical feedstock circularity and synthetic fuel production. This study investigates the ECH of benzoic acid, phenol, guaiacol, and their mixtures, key components in upgradeable oils, using a carbon-supported PtRu catalyst under varying initial concentrations, temperatures, and current densities. Phenol achieved the highest conversion (83.17%) with a 60% Faradaic efficiency (FE). In mixtures, benzoic acid + phenol yielded the best performance (64.19% conversion, 74% FE), indicating a synergistic effect. Notably, BA consistently exhibited 100% selectivity for cyclohexane carboxylic acid (CCA) across all conditions. Density functional theory (DFT) calculations revealed that parallel adsorption of BA on the cathode (−1.12 eV) is more stable than perpendicular positioning (-0.58 eV), explaining the high selectivity for CCA. These findings provide a foundation for future developments in ECH of real pyrolysis oil.
A catalyst-coated diaphragm assembly to improve the performance and energy efficiency of alkaline water electrolysers
Alkaline water electrolysers are ideal for gigawatt-scale hydrogen production due to the usage of non-precious metal and low-cost raw materials. However, their performances are modest with the separated electrode and diaphragm structure which can date back to more than 100 years ago. Here we report a catalyst-coated diaphragm assembly to improve the performance of alkaline water electrolysers. The transport resistance of OH– ions is reduced and the electrochemical surface area of catalysts is enlarged by more than forty fold, representing more than 40% increase in hydrogen production rate or as much as 16% reduction in energy consumption. The electrolyser with our catalyst-coated diaphragm assembly delivers current densities as high as 1 A cm−2 at 1.8 V or 2 A cm−2 at 2 V and shows good stability after more than 1000 hours of operation. Therefore, the catalyst-coated diaphragm assembly route is promising for the development of high-performance and efficient alkaline water electrolysers.
Anion vacancies activate N2 to ammonia on Ba–Si orthosilicate oxynitride-hydride
Anion vacancies on metal oxide surfaces have been studied as either active sites or promoting sites in various chemical reactions involving oxidation/reduction processes. However, oxide materials rarely work effectively as catalysts in the absence of transition metal sites. Here we report a Ba–Si orthosilicate oxynitride–hydride as a transition-metal-free catalyst for efficient ammonia synthesis via an anion-vacancy–mediated mechanism. The facile desorption of H− and N3− anions plus the flexibility of the crystal structure can accommodate a high density of electrons at vacancy sites, where N2 can be captured and directly activated to ammonia through hydrogenation processes. The ammonia synthesis rates reach 40.1 mmol g−1 h−1 at 300 °C by loading ruthenium nanoparticles. Although not found to dissociate N2, Ru instead facilitates the formation of anion vacancies at the Ru–support interface. This demonstrates a new route for anion-vacancy–mediated heterogeneous catalysis.
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