Oxygen reduction reaction(ORR) occurs at the cathode of fuel cells and metal-air batteries,but usually suffers from sluggish kinetics.To solve this issue,efficient electrocatalysts are highly desired.Palladium(Pd)-bas...Oxygen reduction reaction(ORR) occurs at the cathode of fuel cells and metal-air batteries,but usually suffers from sluggish kinetics.To solve this issue,efficient electrocatalysts are highly desired.Palladium(Pd)-based nanomaterials,as the most promising substitute of platinum(Pt),exhibit superior activity and stability in ORR electrocatalysis.The delicate regulation of the structure and/or composition shows great potential in improving the electrocatalytic ORR performance of Pd-based nanomaterials.In this review,we retrospect the recent advance of Pdbased ORR electrocatalysts,and analyses the relationship between nanostructure and catalytic performance.We start with the ORR mechanism and indicators of ORR performance in both alkaline and acidic media,followed by the synthetic methods for Pd-based nanoparticles.Then,we emphasize the design strategies of efficient Pd-based ORR catalysts from the perspective of composition,crystal phase,morphology,and support effects.Last but not least,we conclude with possible opportunities and outlook on Pd-based nanomaterials toward ORR.展开更多
Graphene is an ideal 2D material system bridging electronic and photonic devices. It also breaks the fundamental speed and size limits by electronics and photonics, respectively. Graphene offers multiple functions of ...Graphene is an ideal 2D material system bridging electronic and photonic devices. It also breaks the fundamental speed and size limits by electronics and photonics, respectively. Graphene offers multiple functions of signal transmission, emission, modulation, and detection in a broad band, high speed, compact size, and low loss. Here, we have a brief view of graphene based functional devices at microwave, terahertz, and optical frequencies. Their fundamental physics and computational models were discussed as well.展开更多
Graphene, defined as a single atomic plane of graphite, is a semimetal with a small overlap between the valence and conduction bands. The stacking of graphene up to several atomic layers can lead to diverse physical p...Graphene, defined as a single atomic plane of graphite, is a semimetal with a small overlap between the valence and conduction bands. The stacking of graphene up to several atomic layers can lead to diverse physical properties, depending on the stacking method. Bi layer graphene is also a semimetal, adopting the AB-stacked (or Bernal-stacked) structure or the rare AA-stacked structure . Trilayer or few-layer graphene (FLG) can be semimetals or semiconductors, depending on whether they adopt Bernal (ABA) stacking or rhoinbohedral (ABC) stacking.展开更多
Motivated by the recent pioneering advances on nanoscale plasmonics and also nanophotonics tech- nology based on the surface plasmons （SPs）, in this work, we give a master equation model in the Lindblad form and inv...Motivated by the recent pioneering advances on nanoscale plasmonics and also nanophotonics tech- nology based on the surface plasmons （SPs）, in this work, we give a master equation model in the Lindblad form and investigate the quantum optical properties of single quantum dot （QD） emitter coupled to the SPs of a metallic nanowire. Our main results demonstrate the QD luminescence results of photon emission show three distinctive regimes depending on the distance between QD and metallic nanowire, which elucidates a crossover passing from being metallic dissipative for much smaller emitter-nanowire distances to surface plasmon （SP） emission for larger separations at the vicinity of plasmonic metallic nanowire. Besides, our results also indicate that, for both the resonant case and the detuning case, through measuring QD emitter luminescence spectra and second-order correlation functions, the information about the QD emitter coupling to the SPs of the dissipative metallic nanowire can be extracted. This theoretical study will serve as an introduction to un- derstanding the nanoplasmonic imaging spectroscopy and pave a new way to realize the quantum information devices.展开更多
In this work, we present a schematic configuration and device model for a graphene-nanoribbon （GNR）-array-based nanolaser, which consists of a three-variable rate equations that takes into account carrier capture an...In this work, we present a schematic configuration and device model for a graphene-nanoribbon （GNR）-array-based nanolaser, which consists of a three-variable rate equations that takes into account carrier capture and Pauli blocking in semiconductor GNR-array lasers to analyze the steady- state properties and dynamics in terms of the role of the capture rate and the gain coefficient in GNR array nanolasers. Furthermore, our GNR-array nanolaser device model can be determined as two distinct two-variable reductions of the rate equations in the limit of large capture rates, depending on their relative values. The first case leads to the rate equations for quantum well lasers, exhibiting relaxation oscillations dynamics. The second case corresponds to GNRs nearly saturated by the carriers and is characterized by the absence of relaxation oscillations. Our results here demonstrated that GNR-array as gain material embedded into a high finesse microcavity can serve as an ultralow lasing threshold nanolaser with promising applications ranging widely from optical fiber communi- cation with increasing data processing speed to digital optical recording and biology spectroscopy.展开更多
基金financially supported by the National Natural Science Foundation of China (No.52172058)。
文摘Oxygen reduction reaction(ORR) occurs at the cathode of fuel cells and metal-air batteries,but usually suffers from sluggish kinetics.To solve this issue,efficient electrocatalysts are highly desired.Palladium(Pd)-based nanomaterials,as the most promising substitute of platinum(Pt),exhibit superior activity and stability in ORR electrocatalysis.The delicate regulation of the structure and/or composition shows great potential in improving the electrocatalytic ORR performance of Pd-based nanomaterials.In this review,we retrospect the recent advance of Pdbased ORR electrocatalysts,and analyses the relationship between nanostructure and catalytic performance.We start with the ORR mechanism and indicators of ORR performance in both alkaline and acidic media,followed by the synthetic methods for Pd-based nanoparticles.Then,we emphasize the design strategies of efficient Pd-based ORR catalysts from the perspective of composition,crystal phase,morphology,and support effects.Last but not least,we conclude with possible opportunities and outlook on Pd-based nanomaterials toward ORR.
文摘Graphene is an ideal 2D material system bridging electronic and photonic devices. It also breaks the fundamental speed and size limits by electronics and photonics, respectively. Graphene offers multiple functions of signal transmission, emission, modulation, and detection in a broad band, high speed, compact size, and low loss. Here, we have a brief view of graphene based functional devices at microwave, terahertz, and optical frequencies. Their fundamental physics and computational models were discussed as well.
文摘Graphene, defined as a single atomic plane of graphite, is a semimetal with a small overlap between the valence and conduction bands. The stacking of graphene up to several atomic layers can lead to diverse physical properties, depending on the stacking method. Bi layer graphene is also a semimetal, adopting the AB-stacked (or Bernal-stacked) structure or the rare AA-stacked structure . Trilayer or few-layer graphene (FLG) can be semimetals or semiconductors, depending on whether they adopt Bernal (ABA) stacking or rhoinbohedral (ABC) stacking.
基金This work was financially supported by the National Natural Science Foundation of China under Grant No. 60721004, and the National Basic Research Program of China under Grant No. 2009CB010600.
文摘Motivated by the recent pioneering advances on nanoscale plasmonics and also nanophotonics tech- nology based on the surface plasmons （SPs）, in this work, we give a master equation model in the Lindblad form and investigate the quantum optical properties of single quantum dot （QD） emitter coupled to the SPs of a metallic nanowire. Our main results demonstrate the QD luminescence results of photon emission show three distinctive regimes depending on the distance between QD and metallic nanowire, which elucidates a crossover passing from being metallic dissipative for much smaller emitter-nanowire distances to surface plasmon （SP） emission for larger separations at the vicinity of plasmonic metallic nanowire. Besides, our results also indicate that, for both the resonant case and the detuning case, through measuring QD emitter luminescence spectra and second-order correlation functions, the information about the QD emitter coupling to the SPs of the dissipative metallic nanowire can be extracted. This theoretical study will serve as an introduction to un- derstanding the nanoplasmonic imaging spectroscopy and pave a new way to realize the quantum information devices.
文摘In this work, we present a schematic configuration and device model for a graphene-nanoribbon （GNR）-array-based nanolaser, which consists of a three-variable rate equations that takes into account carrier capture and Pauli blocking in semiconductor GNR-array lasers to analyze the steady- state properties and dynamics in terms of the role of the capture rate and the gain coefficient in GNR array nanolasers. Furthermore, our GNR-array nanolaser device model can be determined as two distinct two-variable reductions of the rate equations in the limit of large capture rates, depending on their relative values. The first case leads to the rate equations for quantum well lasers, exhibiting relaxation oscillations dynamics. The second case corresponds to GNRs nearly saturated by the carriers and is characterized by the absence of relaxation oscillations. Our results here demonstrated that GNR-array as gain material embedded into a high finesse microcavity can serve as an ultralow lasing threshold nanolaser with promising applications ranging widely from optical fiber communi- cation with increasing data processing speed to digital optical recording and biology spectroscopy.
