Recent years have witnessed a dramatic increase in the production of sustainable and renewable energy. However, the electrochemical performances of the various systems are limited, and there is an ...intensive search for highly efficient electrocatalysts by more rational control over the size, shape, composition, and structure. Of particular interest are the studies on single‐atom catalysts (SACs), which have sparked new interests in electrocatalysis because of their high catalytic activity, stability, selectivity, and 100 % atom utilization. In this Review, we introduce innovative syntheses and characterization techniques for SACs, with a focus on their electrochemical applications in the oxygen reduction/evolution reaction, hydrogen evolution reaction, and hydrocarbon conversion reactions for fuel cells (electrooxidation of methanol, ethanol, and formic acid). The electrocatalytic performance is further considered at an atomic level and the underlying mechanisms are discussed. The ultimate goal is the tailoring of single atoms for electrochemical applications.
When less is more: Single‐atom electrocatalysts are characterized by high catalytic activity, selectivity, and maximum metal utilization. They hold great promise in various electrochemical applications, such as the oxygen reduction reaction, the hydrogen evolution reaction, and hydrocarbon conversion reactions for fuel cells.
Abstract
Single-atom catalysts (SACs) are promising candidates to catalyze electrochemical CO
2
reduction (ECR) due to maximized atomic utilization. However, products are usually limited to CO ...instead of hydrocarbons or oxygenates due to unfavorable high energy barrier for further electron transfer on synthesized single atom catalytic sites. Here we report a novel partial-carbonization strategy to modify the electronic structures of center atoms on SACs for lowering the overall endothermic energy of key intermediates. A carbon-dots-based SAC margined with unique CuN
2
O
2
sites was synthesized for the first time. The introduction of oxygen ligands brings remarkably high Faradaic efficiency (78%) and selectivity (99% of ECR products) for electrochemical converting CO
2
to CH
4
with current density of 40 mA·cm
-2
in aqueous electrolytes, surpassing most reported SACs which stop at two-electron reduction. Theoretical calculations further revealed that the high selectivity and activity on CuN
2
O
2
active sites are due to the proper elevated CH
4
and H
2
energy barrier and fine-tuned electronic structure of Cu active sites.
Due to their unique structures and multifunctionalities, two-dimensional (2D) nanomaterials have aroused increasing interest in the construction of the novel biointerfaces for biosensing ...applications. Efforts in constructing novel biointerfaces led to exploit the more versatile and tunable graphene-like 2D nanomaterials (e.g. graphitic carbon nitride, boron nitride, transition metal dichalcogenides, and transition metal oxides) with various structural and compositional characteristics. This review highlights recent efforts in the design of graphene-like 2D nanomaterials and their derived biointerfaces and exploitation of their research on fluorescent sensors and a series of electrochemical sensors, including amperometric, electrochemiluminescence, photoelectrochemical and field-effect transistor sensors. Finally, we discuss some critical challenges and future perspectives in this field.
•Graphene-like 2D nanomaterials are promising in designing functional biointerfaces.•We review graphene-like 2D nanomaterial-based electrochemical sensors.•We review graphene-like 2D nanomaterial-based fluorescent sensors.•Rational design of novel graphene-like nanomaterial-based biointerfaces is summarized.
Interphases in Sodium‐Ion Batteries Song, Junhua; Xiao, Biwei; Lin, Yuehe ...
Advanced energy materials,
June 15, 2018, Letnik:
8, Številka:
17
Journal Article
Recenzirano
Sodium‐ion batteries (SIBs) as economical, high energy alternatives to lithium‐ion batteries (LIBs) have received significant attention for large‐scale energy storage in the last few years. While the ...efforts of developing SIBs have benefited from the knowledge learned in LIBs, thanks to the apparent proximity between Na‐ions and Li‐ions, the unique physical and chemical properties of Na‐ions also distinctly differ themselves from Li‐ions. It is expected that SIBs have drastically different electrode material structure, solvation–desolvation behavior, electrode–electrolyte interphase stabilities, ion transfer properties, and hence electrochemical performance of batteries. In this review, the authors comprehensively summarize the current understanding of the anode solid electrolyte interphase and cathode electrolyte interphase in SIBs, with an emphasis on how the tuning of the stability and ion transfer properties of interphases fundamentally determines the reversibility and efficiency of electrochemical reactions. Through these carefully screened references, the authors intend to reveal the intrinsic correlation between the properties/functionalities of the interphases and the electrochemical performance of batteries.
Anode solid electrolyte interphases (SEI) and cathode electrolyte interphases are essential to improving a battery's electrochemical performance, safety and tolerance against cell failure, and are indispensable components in sodium‐ion batteries (SIBs). This review starts from the SEI function and provides a comprehensive summary of the current scientific understanding about how SEI composition and structural properties are related to the interphasial functions in SIBs.
In this paper, we reported a ZnO quantum dots-based pH-responsive drug delivery platform for intracellular controlled release of drugs. Acid-decomposable, luminescent aminated ZnO quantum dots (QDs) ...were synthesized as nanocarriers with ultrasmall size (∼3 nm). The dicarboxyl-terminated poly(ethylene glycol) (PEG) had been introduced to NH2-ZnO QDs, which rendered it stable under physiological fluid. Moreover, a targeting ligand, hyaluronic acid (HA), was conjugated to ZnO QDs for specifically binding to the overexpressed glycoprotein CD44 by cancer cells. Doxorubicin (DOX) molecules were successfully loaded to PEG functionalized ZnO QDs via formation of metal-DOX complex and covalent interactions. The pH-sensitive ZnO QDs dissolved to Zn(2+) in acidic endosome/lysosome after uptake by cancer cells, which triggered dissociation of the metal-drug complex and a controlled DOX release. As result, a synergistic therapy was achieved due to incorporation of the antitumor effect of Zn(2+) and DOX.
Here we present a detailed protocol for in situ multiple fluorescence monitoring of adenosine-5'-triphosphate (ATP) and guanosine-5'-triphosphate (GTP) in MCF-7 breast cancer cells by using graphene ...oxide nanosheet (GO-nS) and DNA/RNA aptamers. FAM-labeled ATP aptamer and Cy5-modified GTP aptamer are used to construct the multiple aptamer/GO-nS sensing platform through 'π-π stacking' between aptamers and GO-nS. Binding of aptamers to GO-nS guarantees the fluorescence resonance energy transfer between fluorophores and GO-nS, resulting in 'fluorescence off'. When the aptamer/GO-nS are transported inside the cells via endocytosis, the conformation of the aptamers will change on interaction with cellular ATP and GTP. On the basis of the fluorescence 'off/on' switching, simultaneous sensing and imaging of ATP and GTP in vitro and in situ have been realized through fluorescence and confocal microscopy techniques. In this protocol, we describe the synthesis of GO and GO-nS, preparation of aptamer/GO-nS platform, in vitro detection of ATP and GTP, and how to use this platform to realize intracellular ATP and GTP imaging in cultured MCF-7 cells. The preparation of GO-nS is anticipated to take 7-14 d, and assays involving microscopy imaging and MCF-7 cells culturing can be performed in 2-3 d.
Graphene, a single layer 2-dimensional structure nanomaterial with unique physicochemical properties (e.g. high surface area, excellent electrical conductivity, strong mechanical strength, ...unparalleled thermal conductivity, remarkable biocompatibility and ease of functionalization), has received increasing attention in physical, chemical and biomedical fields. This article selectively reviews current advances of graphene based materials for biomedical applications. In particular, graphene based biosensors for small biomolecules (glucose, dopamine etc.), proteins and DNA detection have been summarized; graphene based bioimaging, drug delivery, and photothermal therapy applications have been described in detail. Future perspectives and possible challenges in this rapidly developing area are also discussed.
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