In this work, protonated poly(heptazine imide) (H-PHI) was obtained by adding acid to the suspension of potassium PHI (K-PHI) in ethanol. It was established that the obtained H-PHI demonstrates very high photocatalytic activity in the reaction of hydrogen formation from ethanol in the presence of Pt nanoparticles under visible light irradiation in comparison with K-PHI. This enhancement can be attributed to improved efficiency of photogenerated charge transfer to the photocatalyst's surface, where redox processes occur.
View Article and Find Full Text PDFVisible-light responsive, stable, and abundant absorbers are required for the rapid integration of green, clean, and renewable technologies in a circular economy. Photoactive solid-solid heterojunctions enable multiple charge pathways, inhibiting recombination through efficient charge transfer across the interface. This study spotlights the physico-chemical synergy between titanium dioxide (TiO) anatase and carbon nitride (CN) to form a hybrid material.
View Article and Find Full Text PDFNanoporous carbons with tailorable nanoscale texture and long-range ordered structure are promising candidates for energy, environmental and catalytic applications, while the current synthetic methods do not allow elaborate control of local structure. Here we report a salt-assisted strategy to obtain crystalline nanocarbon from direct carbonization of metal-organic frameworks (MOFs). The crystalline product maintains a highly ordered two-dimensional (2D) stacking mode and substantially differs from the traditional weakly ordered patterns of nanoporous carbons upon high-temperature pyrolysis.
View Article and Find Full Text PDFDeveloping high-performance carbonaceous anode materials for sodium-ion batteries (SIBs) is still a grand quest for a more sustainable future of energy storage. Introducing sulfur within a carbon framework is one of the most promising attempts toward the development of highly efficient anode materials. Herein, a microporous sulfur-rich carbon anode obtained from a liquid sulfur-containing oligomer is introduced.
View Article and Find Full Text PDFTriazine-based graphitic carbon nitride is a semiconductor material constituted of cross-linked triazine units, which differs from widely reported heptazine-based carbon nitrides. Its triazine-based structure gives rise to significantly different physical chemical properties from the latter. However, it is still a great challenge to experimentally synthesize this material.
View Article and Find Full Text PDFSingle-atom catalysis is a field of paramount importance in contemporary science due to its exceptional ability to combine the domains of homogeneous and heterogeneous catalysis. Iron and manganese metalloenzymes are known to be effective in C─H oxidation reactions in nature, inspiring scientists to mimic their active sites in artificial catalytic systems. Herein, a simple and versatile cation exchange method is successfully employed to stabilize low-cost iron and manganese single-atoms in poly(heptazine imides) (PHI).
View Article and Find Full Text PDFDuring liquid-phase electron microscopy (LP-EM) observations, the application of different irradiation dose rates may considerably alter the chemistry of the studied solution and influence processes, in particular growth pathways. While many processes have been studied using LP-EM in the last decade, the extent of the influence of the electron beam is not always understood and comparisons with corresponding bulk experiments are lacking. Here, we employ the radiolytic oxidation of Ce in aqueous solution as a model reaction for the LP-EM study of the formation of CeO particles.
View Article and Find Full Text PDFRenewable-electricity-powered carbon dioxide (CO) reduction (eCOR) to high-value fuels like methane (CH) holds the potential to close the carbon cycle at meaningful scales. However, this kinetically staggered 8-electron multistep reduction suffers from inadequate catalytic efficiency and current density. Atomic Cu-structures can boost eCOR-to-CH selectivity due to enhanced intermediate binding energies (BEs) resulting from favorably shifted d-band centers.
View Article and Find Full Text PDFCarbonaceous materials are promising sodium-ion battery anodes. Improving their performance requires a detailed understanding of the ion transport in these materials, some important aspects of which are still under debate. In this work, nitrogen-doped porous hollow carbon spheres (N-PHCSs) are employed as a model system for operando analysis of sodium storage behavior in a commercial liquid electrolyte at the nanoscale.
View Article and Find Full Text PDFIn addition to causing trillion-dollar economic losses every year, counterfeiting threatens human health, social equity and national security. Current materials for anti-counterfeiting labelling typically contain toxic inorganic quantum dots and the techniques to produce unclonable patterns require tedious fabrication or complex readout methods. Here we present a nanoprinting-assisted flash synthesis approach that generates fluorescent nanofilms with physical unclonable function micropatterns in milliseconds.
View Article and Find Full Text PDFIron species are omnipresent in fertile soils and contribute to biological and geological redox processes. Here, we show by advanced electron microscopy techniques that an important, but previously not considered iron species, single atom Fe stabilized on clay mineral surfaces, is contained in soils when humic substances are present. As the concentration of neutral iron atoms is highest under frost logged soil conditions, their formation can be attributed to the action of a then reductive microbiome.
View Article and Find Full Text PDFMaterials dictate carbon neutral industrial chemical processes. Visible-light photoelectrocatalysts from abundant resources will play a key role in exploiting solar irradiation. Anionic doping via pre-organization of precursors and further co-polymerization creates tuneable semiconductors.
View Article and Find Full Text PDFSustainable, high-performance carbonaceous anode materials are highly required to bring sodium-ion batteries to a more competitive level. Here, we exploit our expertise to control the deposition of a nm-sized conformal coating of carbon nitride with tunable thickness to improve the electrochemical performance of anode material derived from sodium lignosulfonate. In this way, we significantly enhanced the electrochemical performances of the electrode, such as the first cycle efficiency, rate-capability, and specific capacity.
View Article and Find Full Text PDFSingle-atom catalysts have become a popular choice in various catalysis applications, as they take advantages of both homogeneous catalysis (e.g., high efficiency) and heterogeneous catalysis (e.
View Article and Find Full Text PDFMembrane-based water treatment processes offer possibility to alleviate the water scarcity dilemma in energy-efficient and sustainable ways, this has been exemplified in filtration membranes assembled from two-dimensional (2D) materials for water desalination purposes. Most representatives however tend to swell or disintegrate in a hydrated state, making precise ionic or molecular sieving a tough challenge. Here we report that the chemically robust 2D carbon nitride can be activated using aluminum polycations as pillars to modulate the interlayer spacing of the conjugated framework, the noncovalent interaction concomitantly affords a well-interlinked lamellar structure, to be carefully distinguished from random stacking patterns in conventional carbon nitride membranes.
View Article and Find Full Text PDF-pinacol coupling of -benzyl-1-phenylmethanimine using Zn dust affords a mixture of , or ,-diastereomers in a 1:1 ratio. The ,-diastereomer is solid with an m.p.
View Article and Find Full Text PDFPhotocatalysis provides a sustainable pathway to produce the consumer chemical HO from atmospheric O via an oxygen reduction reaction (ORR). Such an alternative is attractive to replace the cumbersome traditional anthraquinone method for HO synthesis on a large scale. Carbon nitrides have shown very interesting results as heterogeneous photocatalysts in ORR because their covalent two-dimensional (2D) structure is believed to increase selectivity toward the two-electron process.
View Article and Find Full Text PDFAdvanced oxidation processes (AOP) are a common tool to remove organic compounds from the water cycle. The process is mostly relied on free radicals (i.e.
View Article and Find Full Text PDFCarbon suboxide (C O ) is a unique molecule able to polymerize spontaneously into highly conjugated light-absorbing structures at temperatures as low as 0 °C. Despite obvious advantages, little is known about the nature and the functional properties of this carbonaceous material. In this work, the aim is to bring "red carbon," a forgotten polymeric semiconductor, back to the community's attention.
View Article and Find Full Text PDFHere we report a photocatalytic system based on crystalline carbon nitrides (PHI) and highly dispersed transition metals (Fe, Co and Cu) for controlled methane photooxidation to methanol under mild conditions. The Cu-PHI catalyst showed a remarkable methanol production (2900 μmol g) in 4 hours, with a turnover number of 51 moles of oxygenated liquid product per mole of Cu. To date, this result is the highest value for methane oxidation under mild conditions (1 bar, 25 °C).
View Article and Find Full Text PDFLaser-induced forward transfer (LIFT) has the potential to be an alternative approach to atomic force microscopy based scanning probe lithography techniques, which have limitations in high-speed and large-scale patterning. However, traditional donor slides limit the resolution and chemical flexibility of LIFT. Here, a hematite nanolayer absorber for donor slides to achieve high-resolution transfers down to sub-femtoliters is proposed.
View Article and Find Full Text PDFThe role of intermediate phases in CeO mesocrystal formation from aqueous Ce solutions subjected to γ-radiation was studied. Radiolytically formed hydroxyl radicals convert soluble Ce into less soluble Ce . Transmission electron microscopy (TEM) and X-ray diffraction studies of samples from different stages of the process allowed the identification of several stages in CeO mesocrystal evolution following the oxidation to Ce : (1) formation of hydrated Ce hydroxides, serving as intermediates in the liquid-to-solid phase transformation; (2) CeO primary particle growth inside the intermediate phase; (3) alignment of the primary particles into "pre-mesocrystals" and subsequently to mesocrystals, guided by confinement of the amorphous intermediate phase and accompanied by the formation of "mineral bridges".
View Article and Find Full Text PDFMaterial platforms based on interaction between organic and inorganic phases offer enormous potential to develop materials that can recreate the structural and functional properties of biological systems. However, the capability of organic-mediated mineralizing strategies to guide mineralization with spatial control remains a major limitation. Here, we report on the integration of a protein-based mineralizing matrix with surface topographies to grow spatially guided mineralized structures.
View Article and Find Full Text PDFTernary materials made up only from the lightweight elements boron, carbon, and nitrogen are very attractive due to their tunable properties that can be obtained by changing the relative elemental composition. However, most of the times, the synthesis requires to use up to three different precursor and very high temperatures for the synthesis. Moreover, the low reciprocal solubility of boron nitride and graphene often leads to BN-C composite materials due to phase segregation.
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