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.
Development of state-of-the-art electrocatalysts with inexpensive and commercially available materials to facilitate sluggish cathodic oxygen reduction reaction (ORR) is a key issue in the ...development of fuel cells and other electrochemical energy devices. Although great progress has been achieved in this area of research and development, there are still some challenges in both their ORR activity and stability. The emergence of graphene (GN) provides an excellent alternative to electrode materials and great efforts have been made to utilize GN-based nanomaterials as promising electrode materials for ORR due to the high electrical conductivity, large specific surface area, profuse interlayer structure and abounding functional groups involved. It should be noted that rational design of these GN-based nanomaterials with well-defined morphology also plays an important role in their electrochemical performance for ORR. Considerable attempts were achieved to construct a variety of heteroatom doped GN nanomaterials or GN-based nanocomposites, aiming at fully using their excellent properties in their application in ORR. In this critical review, in line with the material design and engineering, some recent advancements in the development of GN-based electrocatalysts for ORR in electrochemical energy devices (fuel cells and batteries) are then highlighted, including heteroatom-doped GN nanomaterials, GN-based nonprecious hybrid nanocomposites (GN/metal oxides, GN/N-M, GN/carbon nitride, etc.) and GN/noble metal nanocomposites.
We report that considerable attention has been devoted to the integration of recognition elements with electronic elements to develop electrochemical sensors and biosensors.Various electrochemical ...devices, such as amperometric sensors, electrochemical impedance sensors, and electrochemical luminescence sensors as well as photoelectrochemical sensors, provide wide applications in the detection of chemical and biological targets in terms of electrochemical change of electrode interfaces. Here, this review focuses on recent advances in electrochemical sensors and biosensors based on nanomaterials and nanostructures during 2013 to 2014. The aim of this effort is to provide the reader with a clear and concise view of new advances in areas ranging from electrode engineering, strategies for electrochemical signal amplification, and novel electroanalytical techniques used in the miniaturization and integration of the sensors. Moreover, the authors have attempted to highlight areas of the latest and significant development of enhanced electrochemical nanosensors and nanobiosensors that inspire broader interests across various disciplines. Electrochemical sensors for small molecules, enzyme-based biosensors, genosensors, immunosensors, and cytosensors are reviewed herein (Figure 1). Such novel advances are important for the development of electrochemical sensors that open up new avenues and methods for future research. In conclusion, we recommend readers interested in the general principles of electrochemical sensors and electrochemical methods to refer to other excellent literature for a broad scope in this area.(3, 4) However, due to the explosion of publications in this active field, we do not claim that this Review includes all of the published works in the past two years and we apologize to the authors of excellent work, which is unintentionally left out.
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.
We demonstrated a facile and green approach to synthesize bifunctional fluorescent carbon nanodots via soy milk, which not only showed favorable photoluminescent properties, but also exhibited good ...electrocatalytic activity towards oxygen reduction reaction.
In this paper, we developed a green and facile approach to the synthesis of chemically converted graphene nanosheets (GNS) based on reducing sugars, such as glucose, fructose and sucrose using ...exfoliated graphite oxide (GO) as precursor. The obtained GNS is characterized with atomic force microscopy, UV−visible absorption spectroscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and so on. The merit of this method is that both the reducing agents themselves and the oxidized products are environmentally friendly. It should be noted that, besides the mild reduction capability to GO, the oxidized products of reducing sugars could also play an important role as a capping reagent in stabilizing as-prepared GNS simultaneously, which exhibited good stability in water. This approach can open up the new possibility for preparing GNS in large-scale production alternatively. Moreover, it is found that GNS-based materials could be of great value for applications in various fields, such as good electrocatalytic activity toward catecholamines (dopamine, epinephrine, and norepinephrine).
Inspired by the diverse drug compounds with various heteroatoms (such as N, S, and P) in the drug library, facile synthesis of a new kind of bright and color-tunable N-doped carbon dots (NCDs) has ...been reported by using a popular antibioticaminosalicylic acidas precursor. The N doping of CDs not only enable great improvement of photoluminescence (PL) efficiency and tunability of PL emission, but also enrich surface functional groups to broaden its application. The as-prepared NCDs possess tunable PL and show a quantum yield of 16.4%, which is the result of PL improvement effect of introduced nitrogen atoms among CDs. The cellular toxicity on H1299 cancer cells indicates that the NCDs have negligible cytotoxicity, excellent biocompatibility, and great resistance to photobleaching. Moreover, the drug-derived NCDs showed excellent sensitivity in detection of Fe3+ in living cells, which indicates the potential application in diagnosis and related biological study.
Single-atom electrocatalysts (SAEs) can realize the target of low-cost by maximum atomic efficiency. However, they usually suffer performance decay due to high energy states, especially in a harsh ...acidic water splitting environment. Here, we conceive and realize a double protecting strategy that ensures robust acidic water splitting on Ir SAEs by dispersing Ir atoms in/onto Fe nanoparticles and embedding IrFe nanoparticles into nitrogen-doped carbon nanotubes (Ir-SA@Fe@NCNT). When Ir-SA@Fe@NCNT acts as a bifunctional electrocatalyst at ultralow Ir loading of 1.14 μg cm–2, the required overpotentials to deliver 10 mA cm–2 are 250 and 26 mV for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in 0.5 M H2SO4 electrolyte corresponding to 1370- and 61-fold better mass activities than benchmark IrO2 and Pt/C at an overpotential of 270 mV, respectively, resulting in only 1.51 V to drive overall water splitting. Moreover, remarkable stability is also observed compared to Pt/C-IrO2.
The traditional luminol–H2O2 electrochemiluminescence (ECL) sensing platform suffers from self‐decomposition of H2O2 at room temperature, hampering its application for quantitative analysis. In this ...work, for the first time we employ iron single‐atom catalysts (Fe‐N‐C SACs) as an advanced co‐reactant accelerator to directly reduce the dissolved oxygen (O2) to reactive oxygen species (ROS). Owing to the unique electronic structure and catalytic activity of Fe‐N‐C SACs, large amounts of ROS are efficiently produced, which then react with the luminol anion radical and significantly amplify the luminol ECL emission. Under the optimum conditions, a Fe‐N‐C SACs–luminol ECL sensor for antioxidant capacity measurement was developed with a good linear range from 0.8 μm to 1.0 mm of Trolox.
Boosting luminescence: The traditional luminol–H2O2 electrochemiluminescence (ECL) sensing platform suffers from self‐decomposition of H2O2 at room temperature, hampering its application for quantitative analysis. Single‐atom iron boosts luminol ECL by in situ generating reactive oxygen species, achieving sensitive detection of antioxidants.
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