The escalation of anthropogenic activities contributes to the accumulation of chemicals in life-supporting ecosystems and water reserves, while nearly 80% of the global population faces a high risk of water insecurity. Therefore, advanced nanomaterials for environmental remediation and ecosystem preservation are essential. However, their adoption has been slow, mainly due to the need for water treatment strategies that comply with sustainability criteria. This work showcases the efficient removal of emerging pharmaceutical pollutants from water using functionalized graphenes and the direct upcycling of the used sorbents into electrodes for energy storage, without the need for any intermediate treatment. Remarkably, the performance of the repurposed sorbents as supercapacitor electrodes exceeds that of the parent functionalized graphenes by up to 100% in a full cell device. This enhanced performance and cycling stability are attributed to improved charge transport and redox activity induced by the strong adsorption of the pollutants, as supported by theoretical calculations. The findings open avenues for reclaiming the value of spent sorbents, mitigating the environmental and economic burden of their disposal or regeneration, while fostering sustainable resource management, and energy storage.
- Klíčová slova
- Decontamination, Energy storage, Estrogens, Pharmaceuticals, Repurposing, Supercapacitors, Upcycling,
- Publikační typ
- časopisecké články MeSH
The development of single-atom catalysts (SACs) with site-specific and tunable catalytic functionalities remains a highly desirable yet challenging goal in catalysis. In this study, we report a SAC featuring anisotropic coordination cavities synthesized via a one-step polymerization of 2,6-diaminopyridine and cyanuric chloride. These cavities provide a robust framework for anchoring isolated Pd single atoms with exceptional stability. The unique broken symmetry of the catalyst's local structure enables precise control over reaction pathways, allowing reactivity to be switched between distinct catalytic outcomes. Specifically, under tailored reaction conditions, the catalyst can either halt at the borylation step or proceed seamlessly to Suzuki coupling in a self-cascade process. Mechanistic studies unveil the pivotal role of Pd single atoms in driving key steps, including oxidative addition, base exchange, and reductive elimination. Furthermore, green metrics demonstrate the process's sustainability, with minimized waste generation and reduced reliance on hazardous reagents in the self-cascade transformation. This work establishes an innovative benchmark in the field of single-atom catalysis: by enabling complex, multistep transformations via strategic activation of multiple functional groups, this catalyst exemplifies the potential of self-cascade processes to revolutionize synthetic chemistry via catalysis engineering.
- Publikační typ
- časopisecké články MeSH
Hydrogenation reactions are fundamental in the fine chemical, pharmaceutical, and petrochemical industries, however heavily relying on H2 gas at high temperatures and pressures, incurring large energy and carbon costs. Photocatalytic transfer hydrogenation, using water as a proton source, offers a greener alternative, but existing photocatalysts often suffer from modest yields, limited selectivity, and narrow substrate scope. Additionally, they often require co-activation, such as Mg-activated water or non-sustainable hydrogen feeds. Here, a photocatalyst is introduced that offers high yields and selectivities across a broad spectrum of organic compounds. The developed photocatalyst is a multivalence palladium superstructure with ultrasmall Pd0 nanoparticles enveloped by isolated Pd2+/Pd4+ atoms within a carbon-nitride matrix. Mechanistic studies reveal that the redox-flexible Pd single atoms, with triethylamine as an electronic modulator, attract photogenerated holes for water oxidation, while Pd0 nanoparticles facilitate hydrogen transfer to the unsaturated bonds of the organic molecules. The cooperative and dynamic behavior of Pd centers during catalysis, involving transitions among Pd+2, Pd+3, and Pd+4 states, is validated using operando electron paramagnetic resonance spectroscopy. This multivalent palladium catalyst represents a conceptual advance in photocatalytic transfer hydrogenation with water as a hydrogen source, holding promise for sustainable hydrogenation processes in the chemical industry.
- Klíčová slova
- carbon nitride, hydride transfer, palladium, photocatalysis, selective hydrogenation,
- Publikační typ
- časopisecké články MeSH
Climate change and the depletion of fossil fuels increase the demand for sustainable energy. Biodiesel synthesized using heterogeneous acid catalysts is a promising clean-energy carrier that supports a circular carbon economy. Herein, the efficient synthesis of biodiesel is reported using a reusable solid acid graphene catalyst functionalized with a natural aminosulfonic acid. Experimental and theoretical studies reveal the key role of functionalities that simultaneously contain amino and sulfonate groups, which impart superior acidity. Excellent activity and selectivity for oleic acid conversion to oleic acid methyl esters (a sustainable biofuel) are obtained, offering a strategy for achieving improved catalytic performance compared to earlier or benchmark catalysts in the field. Notably, the catalyst also effectively converts common vegetable oils into biodiesel via transesterification and facilitates carbohydrate dehydration to value-added chemicals, demonstrating broad applicability. Two additional variants of aminosulfonic acid-functionalized graphene show similar activity, confirming the crucial role of these functionalities in achieving high acidity and catalytic performance. The development of such potent, recyclable catalysts is crucial because acid catalysis is highly versatile, underpinning many biological and synthetic transformations.
- Klíčová slova
- biodiesel, esterification, graphene catalysts, heterogeneous acid catalysts, solid acid catalysis, transesterification,
- Publikační typ
- časopisecké články MeSH
The selection of appropriate electrolytes plays a crucial role in improving the electrochemical performance of the supercapacitor electrode. The electrolyte helps to select an appropriate potential window of the device, which is directly related to its energy density. Also, the selection of an appropriate electrode material targets the specific capacitance. Therefore, in this work, we targeted an electrode material based on a ZIF-8@ZIF-67 (Z867) core-nanoshell structure and tested its performance in redox active electrolyte (RAE), i.e., 0.2 M K3[Fe(CN)6] in 1 M Na2SO4. The synergy between the core-nanoshell electrode having ZIF-8 as a core and ZIF-67 as a nanoshell along with RAE further complements the redox active sites, resulting in the improved charge transport. Therefore, when the Z867 core-nanoshell electrode is tested in a three-electrode system, it outperforms pristine ZIF-8 and ZIF-67 electrode materials. The working electrode modified with the Z867 core-nanoshell showed a maximum specific capacitance of 496.4 F g-1 at 4.5 A g-1 current density with the RAE, which is much higher than that of the aqueous electrolyte. A Z867-modified working electrode was assembled as the positive and negative electrode in a symmetrical cell configuration to create a redox supercapacitor device for practical application. The constructed device displayed maximal energy and power densities of 49.6 W h kg-1 and 3.2 kW kg-1 respectively, along with a capacitance retention of 92% after 10 000 charge-discharge cycles. Hence, these studies confirm that using RAE can improve the electrochemical performance of electrodes to a greater extent than that of aqueous electrolyte-based supercapacitors.
- Publikační typ
- časopisecké články MeSH
The outbreak of antibiotic-resistant bacteria, or "superbugs", poses a global public health hazard due to their resilience against the most effective last-line antibiotics. Identifying potent antibacterial agents capable of evading bacterial resistance mechanisms represents the ultimate defense strategy. This study shows that -the otherwise essential micronutrient- manganese turns into a broad-spectrum potent antibiotic when coordinated with a carboxylated nitrogen-doped graphene. This antibiotic material (termed NGA-Mn) not only inhibits the growth of a wide spectrum of multidrug-resistant bacteria but also heals wounds infected by bacteria in vivo and, most importantly, effectively evades bacterial resistance development. NGA-Mn exhibits up to 25-fold higher cytocompatibility to human cells than its minimum bacterial inhibitory concentration, demonstrating its potential as a next-generation antibacterial agent. Experimental findings suggest that NGA-Mn acts on the outer side of the bacterial cell membrane via a multimolecular collective binding, blocking vital functions in both Gram-positive and Gram-negative bacteria. The results underscore the potential of single-atom engineering toward potent antibiotics, offering simultaneously a long-sought solution for evading drug resistance development while being cytocompatible to human cells.
- Klíčová slova
- antibiotic, cytocompatibility, manganese, multi‐drug resistance, single‐atom,
- MeSH
- antibakteriální látky * farmakologie chemie MeSH
- bakteriální léková rezistence * účinky léků MeSH
- dusík chemie MeSH
- grafit chemie farmakologie MeSH
- lidé MeSH
- mangan chemie MeSH
- mikrobiální testy citlivosti * MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- antibakteriální látky * MeSH
- dusík MeSH
- grafit MeSH
- mangan MeSH
Anthropogenic activities related to population growth, economic development, technological advances, and changes in lifestyle and climate patterns result in a continuous increase in energy consumption. At the same time, the rare metal elements frequently deployed as catalysts in energy related processes are not only costly in view of their low natural abundance, but their availability is often further limited due to geopolitical reasons. Thus, electrochemical energy storage and conversion with earth-abundant metals, mainly in the form of single-atom catalysts (SACs), are highly relevant and timely technologies. In this review the application of earth-abundant SACs in electrochemical energy storage and electrocatalytic conversion of chemicals to fuels or products with high energy content is discussed. The oxygen reduction reaction is also appraised, which is primarily harnessed in fuel cell technologies and metal-air batteries. The coordination, active sites, and mechanistic aspects of transition metal SACs are analyzed for two-electron and four-electron reaction pathways. Further, the electrochemical water splitting with SACs toward green hydrogen fuel is discussed in terms of not only hydrogen evolution reaction but also oxygen evolution reaction. Similarly, the production of ammonia as a clean fuel via electrocatalytic nitrogen reduction reaction is portrayed, highlighting the potential of earth-abundant single metal species.
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
Water molecules confined in nanoscale spaces of 2D graphene layers have fascinated researchers worldwide for the past several years, especially in the context of energy storage applications. The water molecules exchanged along with ions during the electrochemical process can aid in wetting and stabilizing the layered materials resulting in an anomalous enhancement in the performance of supercapacitor electrodes. Engineering of 2D carbon electrode materials with various functionalities (oxygen (─O), fluorine (─F), nitrile (─C≡N), carboxylic (─COOH), carbonyl (─C═O), nitrogen (─N)) can alter the ion/water organization in graphene derivatives, and eventually their inherent ion storage ability. Thus, in the current study, a comparative set of functionalized graphene derivatives-fluorine-doped cyanographene (G-F-CN), cyanographene (G-CN), graphene acid (G-COOH), oxidized graphene acid (G-COOH (O)) and nitrogen superdoped graphene (G-N) is systematically evaluated toward charge storage in various aqueous-based electrolyte systems. Differences in functionalization on graphene derivatives influence the electrochemical properties, and the real-time mass exchange during the electrochemical process is monitored by electrochemical quartz crystal microbalance (EQCM). Electrogravimetric assessment revealed that oxidized 2D acid derivatives (G-COOH (O)) are shown to exhibit high ion storage performance along with maximum water transfer during the electrochemical process. The complex understanding of the processes gained during supercapacitor electrode charging in aqueous electrolytes paves the way toward the rational utilization of graphene derivatives in forefront energy storage applications.
- Klíčová slova
- EQCM, Graphene derivatives, confined water molecules, covalent functionalization, energy storage,
- Publikační typ
- časopisecké články MeSH
Green hydrogen from water splitting has emerged as a critical energy vector with the potential to spearhead the global transition to a fossil fuel-independent society. The field of catalysis has been revolutionized by single-atom catalysts (SACs), which exhibit unique and intricate interactions between atomically dispersed metal atoms and their supports. Recently, bimetallic SACs (bimSACs) have garnered significant attention for leveraging the synergistic functions of two metal ions coordinated on appropriately designed supports. BimSACs offer an avenue for rich metal-metal and metal-support cooperativity, potentially addressing current limitations of SACs in effectively furnishing transformations which involve synchronous proton-electron exchanges, substrate activation with reversible redox cycles, simultaneous multi-electron transfer, regulation of spin states, tuning of electronic properties, and cyclic transition states with low activation energies. This review aims to encapsulate the growing advancements in bimSACs, with an emphasis on their pivotal role in hydrogen generation via water splitting. We subsequently delve into advanced experimental methodologies for the elaborate characterization of SACs, elucidate their electronic properties, and discuss their local coordination environment. Overall, we present comprehensive discussion on the deployment of bimSACs in both hydrogen evolution reaction and oxygen evolution reaction, the two half-reactions of the water electrolysis process.
- Klíčová slova
- Hydrogen evolution, Oxygen evolution, Single-atom catalysts, Single-atom dimers, Water splitting,
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
Glass waveguides are the fundamental component of advanced photonic circuits and play a pivotal role in diverse applications, including quantum information processing, light generation, imaging, data storage, and sensing platforms. Up to date, the fabrication of glass waveguides relies mainly on demanding chemical processes or on the employment of expensive ultrafast laser equipment. In this work, we demonstrate an advanced, simple, low-temperature, postmelting encapsulation procedure for the development of glass waveguides. Specifically, silver iodide phosphate glass microwires (MWs) are drawn from splat-quenched glasses. These MWs are then incorporated in a controlled manner within transparent silver phosphate glass matrices. The judicious selection of glass compositions ensures that the refractive index of the host phosphate glass is lower than that of the embedded MWs. This facilitates the propagation of light inside the encapsulated higher refractive index MWs, leading to the facile development of waveguides. Importantly, we substantially enhance the light transmission within the MWs by leveraging the plasmon resonance effects due to the presence of silver nanoparticles spontaneously generated owing to the silver iodide phosphate glass composition. Employing this innovative approach, we have successfully engineered waveguide devices incorporating either one or two MWs. Remarkably, the dual MW devices are capable of transmitting light of different colors and in multipath direction, rendering the developed waveguides outstanding candidates for extending the functionalities of diverse photonic and optoelectronic circuits, as well as in intelligent signaling applications in smart glass technologies.
- Publikační typ
- časopisecké články MeSH
