拉曼光谱在燃料电池领域的应用

随着社会经济的快速发展,环境污染与能源短缺逐渐成为人们必须面对的热点问题。为实现人类社会的可持续发展,开发环境友好新型清洁能源技术成为二十一世纪的迫切任务。其中,燃料电池被认为是最具发展潜力的新型清洁能源技术之一。拉曼光谱作为一种无损的指纹识别的分子光谱技术,适用于燃料电池材料的研究,尤其是表面增强拉曼光谱技术(SERS)和壳层隔绝表面增强拉曼光谱技术(SHINERS)的发展,为研究燃料电池中反应的痕量中间物种,理解燃料电池实际反应机理提供了一种非常好的原位光谱实验平台,有助于合理设计更高效的催化剂及电极材料。本文主要对拉曼光谱以及SERS和SHINERS在燃料电池领域从电池材料层面和电极表面分子反应层面的应用及其发展前景进行相关讨论。

Pollen morphology of Rhododendron subgen. Tsutsusi and its systematic implications

Eighty-four pollen samples were obtained for 80 taxa, of which, 13 species and one variety are from sect. Brachycalyx Sweet, 58 species and two varieties from sect. Tsutsusi Sweet, and six species from subgen. Pentanthera （G. Don） Pojarkova, respectively. Pollen morphology of all samples was observed using LM and SEM. Pollen grains are revealed to be spheroidal and tetrahedral with tricolporate apertures. Pollen sizes of subgen. Tsutsusi （Sweet） Pojarkova range from 37.67 μm to 61.06μm, and the exine sculptures are more or less compactly granulated. Pollen sizes are significantly different between sect. Brachycalyx and sect. Tsutsusi of subgen. Tsutsusi. Rhododendron tashiroi Maxim. of sect. Tsusiopsis Sleumer shows a close affinity to sect. Brachycalyx. Pollen size and exine are consistent with general morphology in differentiating species in sect. Tsutsusi. Rhododendron huadingense B. Y. Ding ＆ Y. Y. Fang, once placed as a member of sect. Brachycalyx, should be considered as a species in subgen. Pentanthera.

Electron transition manipulation under graphene-mediated plasmonic engineering nanostructure

Monolayer graphene has attracted enormous attention owing to its unique electronic and optical properties.However,achieving an effective approach without applying electrical bias for manipulating the charge transfer based on graphene is elusive to date.Herein,we realized the manipulation of excitons’transition from emitter to the graphene surface with plasmonic engineering nanostructures and firstly obtained large enhancements for photon emission on the graphene surface.The localized plasmons generated from the plasmonic nanostructures of shell-isolated nanoparticle coupling to ultra-flat Au substrate would dictate a consistent junction geometry while enhancing the optical field and dominating the electron transition pathways,which may cause obvious perturbations for molecular radiation behaviors.Additionally,the three-dimensional finite-difference time-domain and time-dependent density functional theory were also carried out to simulate the distributions of electromagnetic field and energy levels of hybrid nanostructure respectively and the results agreed well with the experimental data.Therefore,this work paves a novel approach for tunning graphene charge/energy transfer processes,which may hold great potential for applications in photonic devices based on graphene.

Plasmonic photocatalysis:Mechanism,applications and perspectives

The process of photocatalysis,regarded as a promising approach for tackling the energy crisis and environmental pollution issues,is crucial for turning solar light into chemical resources.However,the solar-chemical conversion efficiency of typical semiconductor catalysts is still too low,so it is vital to figure out how to boost photocatalytic performance of semiconductors.Under visible light illumination,the local surface plasmon resonance(LSPR)induced by coinage metal would enhance the local electric field and improve photocatalytic performance of semiconductors,especially in the visible range.Therefore,its attachment to semiconductors has been regarded as an efficient strategy to improve photocatalytic performance.This paper reviews the latest research progress of plasmonic photocatalysis from theory to application.Starting from the excitation and relaxation of plasmons,four main mechanisms of plasmon-enhanced semiconductor photocatalysis are introduced,including enhanced light absorption and scattering,local electromagnetic field enhancement,improved hot carriers(HCs)injection and enhanced thermal effect.Secondly,the current mainstream plasmonic photocatalysts,such as monometallic,bimetallic and non-noble metal-based plasmonic catalysts,are reviewed.Finally,the applications of plasmonic photocatalysts in H_(2) production,CO_(2) reduction,and antibacterial are further summarized.

Protecting Cell Walls from Binding Aluminum by Organic Acids Contributes to Aluminum Resistance

Aluminum-induced secretion of organic acids from the root apex has been demonstrated to be one major AI resistance mechanism in plants. However, whether the organic acid concentration is high enough to detoxify AI in the growth medium is frequently questioned. The genotypes of AI-resistant wheat, Cassia tora L. and buckwheat secrete malate, citrate and oxalate, respectively. In the present study we found that at a 35% inhibition of root elongation, the AI activities in the solution were 10, 20, and 50 μM with the corresponding malate, citrate, and oxalate exudation at the rates of 15, 20 and 21 nmol/cm2 per 12 h, respectively, for the above three plant species. When exogenous organic acids were added to ameliorate AI toxicity, twofold and eightfold higher oxalate and malate concentrations were required to produce the equal effect by citrate. After the root apical cell walls were isolated and preincubated in 1 mM malate, oxalate or citrate solution overnight, the total amount of AI adsorbed to the cell walls all decreased significantly to a similar level, implying that these organic acids own an equal ability to protect the cell walls from binding AI. These findings suggest that protection of cell walls from binding AI by organic acids may contribute significantly to AI resistance.

Plasmonic Core−Shell Materials:Synthesis,SpectroscopicCharacterization,and Photocatalytic Applications

CONSPECTUS:The ability to concentrate light at the nanoscale and produce extremely high local electromagnetic(EM)fields makes plasmonics a promising and rapidly developing research area.In the region with high EM field intensity(usually called the“hot spot”),various processes can be significantly enhanced,including spectroscopy,luminescence,catalysis,etc.However,only coinage metals(material limitation)with nanoscale roughness(morphological limitation)exhibit significant plasmonic effects under the visible light region,which greatly hinders wider and further applications of plasmonics.Constructing plasmonic core−shell materials by coating a second material onto the surface of a plasmonic metal core is a potential solution to these limitations.The plasmonic core can amplify the signals and/or accelerate the processes of the shell materials or other substrates of interest,making plasmonic research on nonplasmonic materials possible,thus expanding the applications of plasmonics.Besides,through controllable synthesis,the size and composition of both the core and the shell can be tuned simultaneously and precisely.This offers huge possibilities to study and tune plasmonic structure−performance effects at the(sub)nanometer level,which would otherwise not be feasible.

Investigating Why Sulfurization Can Greatly Improve Ethanol Selectivity for Carbon Dioxide Electroreduction

Carbon dioxide(CO_(2))electroreduction of products using renewable electricity sources is a promising avenue for chemical energy storage that is attracting increasing attention.Considerable effort has been focused on improving the activity and selectivity for CO_(2)electroreduction of C2+products,especially for ethanol.However,studies of this process’s underlying mechanism are still lacking.