Electrochemical nitrogen reduction reaction (NRR) over nonprecious‐metal and single‐atom catalysts has received increasing attention as a sustainable strategy to synthesize ammonia. However, the ...atomic‐scale regulation of such active sites for NRR catalysis remains challenging because of the large distance between them, which significantly weakens their cooperation. Herein, the utilization of regular surface cavities with unique microenvironment on graphitic carbon nitride as “subnano reactors” to precisely confine multiple Fe and Cu atoms for NRR electrocatalysis is reported. The synergy of Fe and Cu atoms in such confined subnano space provides significantly enhanced NRR performance, with nearly doubles ammonia yield and 54%‐increased Faradic efficiency up to 34%, comparing with the single‐metal counterparts. First principle simulation reveals this synergistic effect originates from the unique Fe–Cu coordination, which effectively modifies the N2 absorption, improves electron transfer, and offers extra redox couples for NRR. This work thus provides new strategies of manipulating catalysts active centers at the sub‐nanometer scale.
The utilization of regular surface cavities with a unique microenvironment on graphitic carbon nitride as “subnano reactors” can precisely confine multiple Fe and Cu atoms for nitrogen reduction reaction (NRR) electrocatalysis. The synergy of the Fe and Cu atoms in such confined subnano space provides significantly enhanced NRR performance, in terms of much increased ammonia yield and faradic efficiency.
Precisely regulating the electronic structures of metal active species is highly desirable for electrocatalysis. However, carbon with inert surface provide weak metal–support interaction, which is ...insufficient to modulate the electronic structures of metal nanoparticles. Herein, we propose a new method to control the electrocatalytic behavior of supported metal nanoparticles by dispersing single metal atoms on an O‐doped graphene. Ideal atomic metal species are firstly computationally screened. We then verify this concept by deposition of Ru nanoparticles onto an O‐doped graphene decorated with single metal atoms (e.g., Fe, Co, and Ni) for hydrogen evolution reaction (HER). Consistent with theoretical predictions, such hybrid catalysts show outstanding HER performance, much superior to other reported electrocatalysts such as the state‐of‐the‐art Pt/C. This work offers a new strategy for modulating the activity and stability of metal nanoparticles for electrocatalysis processes.
Carbon‐based substrates with an inert surface provide weak metal–support interactions that are insufficient to effectively modulate the electronic structures of the loaded metal nanoparticles. Here we show that atomic metal species on the carbon substrate can remotely communicate with the supported metal nanoparticles, inducing synergistic electronic coupling with the nanoparticles and enabling the control of their electrocatalytic activity.
Magnetic nanocomposites with well‐defined mesoporous structures, shapes, and tailored properties are of immense scientific and technological interest. This review article is devoted to the progress ...in the synthesis and applications of magnetic mesoporous materials. The first part briefly reviews various general methods developed for producing magnetic nanoparticles (NPs). The second presents and categorizes the synthesis of magnetic nanocomposites with mesoporous structures. These nanocomposites are broadly categorized into four types: monodisperse magnetic nanocrystals embedded in mesoporous nanospheres, microspheres encapsulating magnetic cores into perpendicularly aligned mesoporous shells, ordered mesoporous materials loaded with magnetic NPs inside the porous channels or cages, and rattle‐type magnetic nanocomposites. The third section reviews the potential applications of the magnetic nanocomposites with mesoporous structures in the areas of heath care, catalysis, and environmental separation. The final section offers a summary and future perspectives on the state‐of‐the art in this area.
Magnetic nanocompsites with mesoporous structures, defined shapes, and tailored properties are of immense scientific and technological interest. This review highlights recent advances in the synthesis and applications of the nanocomposites of magnetic nanoparticles and mesoporous materials with different morphology and structures. In addition, some perspectives on the future developments and directions of the synthesis, device fabrication, and application of such magnetic particle and mesoporous material nanocomposites are provided.
The electrochemical nitrogen reduction reaction (NRR) is a promising energy‐efficient and low‐emission alternative to the traditional Haber–Bosch process. Usually, the competing hydrogen evolution ...reaction (HER) and the reaction barrier of ambient electrochemical NRR are significant challenges, making a simultaneous high NH3 formation rate and high Faradic efficiency (FE) difficult. To give effective NRR electrocatalysis and suppressed HER, the surface atomic structure of W18O49, which has exposed active W sites and weak binding for H2, is doped with Fe. A high NH3 formation rate of 24.7 μg h−1 mgcat−1 and a high FE of 20.0 % are achieved at an overpotential of only −0.15 V versus the reversible hydrogen electrode. Ab initio calculations reveal an intercalation‐type doping of Fe atoms in the tunnels of the W18O49 crystal structure, which increases the oxygen vacancies and exposes more W active sites, optimizes the nitrogen adsorption energy, and facilitates the electrocatalytic NRR.
More vacancies: Both high NH3 formation rate (24.7 μg h−1 mgcat−1) and Faradic efficiency (20.0 %) are achieved on Fe‐doped W18O49 nanowires@carbon fiber papers at −0.15 V (vs. reversible hydrogen electrode). Fe atoms not only efficiently increase the number of oxygen vacancies of W18O49, but optimize the nitrogen adsorption energy, and facilitate the electrocatalytic nitrogen reduction reaction (NRR).
A good egg: A general and facile template strategy is presented for the fabrication of yolk–shell structures (see picture) with various types of movable cores, such as gold, SiO2, and magnetic Fe3O4. ...The vesicle template, formed of a fluorocarbon surfactant, is built up around the core.
Sphere we go: Monodisperse resorcinol formaldehyde (RF) resin polymer spheres with finely tunable particle size ranging from 200 to 1000 nm (see pictures) are prepared by an extension of the Stöber ...method. Pyrolysis of the RF spheres at 600 °C under N2 atmosphere yields uniform carbon spheres with a volume shrinkage of 19 %.
Mesoporous silica nanoparticles (MSNs) provide a non-invasive and biocompatible delivery platform for a broad range of applications in therapeutics, pharmaceuticals and diagnosis. The creation of ...smart, stimuli-responsive systems that respond to subtle changes in the local cellular environment are likely to yield long term solutions to many of the current drug/gene/DNA/RNA delivery problems. In addition, MSNs have proven to be promising supports for enzyme immobilisation, enabling the enzymes to retain their activity, affording them greater potential for wide applications in biocatalysis and energy. This review provides a comprehensive summary of the advances made in the last decade and a future outlook on possible applications of MSNs as nanocontainers for storage and delivery of biomolecules. We discuss some of the important factors affecting the adsorption and release of biomolecules in MSNs and review of the cytotoxicity aspects of such nanomaterials. The review also highlights some promising work on enzyme immobilisation using mesoporous silica nanoparticles.
A simple and versatile in situ fabrication of MAPbX3 nanocrystal‐embedded polymer composite films is developed by controlling the crystallization process from precursor solutions. The composite films ...exhibit enhanced photoluminescence properties, improved stability, and excellent piezoelectric and mechanical properties. Applications of these composite films as color converters in liquid‐crystal‐display backlights are demonstrated, showing bright potential in display technology.
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•Development of MOF-derived electrodes for electrochemical sensors of neurotransmitters is reviewed.•MOFs act complementarily or synergistically with various materials.•Particular ...attention is paid to the structure-performance relationship.•The current challenges and perspectives in this area are discussed.
Neurotransmitters (NTs) control many behavioral and physiological functions in central and peripheral nervous system, and their detection is of great importance to disease diagnosis and environmental monitoring. Electrochemical sensors have been popular and convenient methods for detection of NTs that are electroactive or can be coupled with electroactive reactions. Metal–organic frameworks (MOFs), constructed by organic ligands connecting metal-based nodes, are promising candidates for electrochemical sensors due to their large surface areas, hybrid structures, tailorable functional sites, and variable catalytic activity. This article gives an overview of the general aspects of MOFs for electrochemical assays of NTs and focused on the state-of-art of the sensors based on MOFs and the composites of MOFs with various materials (mainly carbon-based materials, organic polymers and metal or metal oxide nanoparticle). The use of MOF-derived materials as electrode modifiers is also included.
Liu et al explores titanium dioxide (TiO2) crystals with tailored facets. They focus on the synthesis of TiO2 crystals with different facets, unusual properties of TiO2 crystals with different ...predominant facets, modification of the electronic structure and interfacial properties of faceted TiO2, and applications in the environment and energy.