Selective activation of C-H bonds in light alkanes under mild conditions is challenging but holds the promise of efficient upgrading of abundant hydrocarbons. In this work, we report the conversion of propane to propylene with ∼95% selectivity on Cu(I)-ZSM-5 with O at room temperature and pressure. The intraporous Cu(I) species was oxidized to Cu(II) during the reaction but could be regenerated with H at 220 °C.
View Article and Find Full Text PDFInterfacial pH is critical to electrocatalytic reactions involving proton-coupled electron transfer (PCET) processes, and maintaining an optimal interfacial pH at the electrochemical interface is required to achieve high activity. However, the interfacial pH varies inevitably during the electrochemical reaction owing to slow proton transfer at the interfacial layer, even in buffer solutions. It is therefore necessary to find an effective and general way to promote proton transfer for regulating the interfacial pH.
View Article and Find Full Text PDFDeveloping efficient catalytic systems for the hydrogen oxidation and evolution reactions (HOR/HER) is essential in the world's transition to renewable energy. There is a growing recognition that the HOR/HER activity depends on properties of the electrochemical interface, rather than just the composition and structure of the catalyst. Herein, we demonstrate that specifically adsorbed organic additives (theophylline derivatives) could enhance the intrinsic HOR/HER activity in base on polycrystalline Pt by up to a factor of 3 via introducing weakly hydrogen-bonded water, as confirmed by in situ surface enhanced infrared and Raman spectroscopies.
View Article and Find Full Text PDFBreast cancer appears to be one of the leading causes of cancer-related morbidity and mortality for women worldwide. The accurate and rapid diagnosis of breast cancer is hence critical for the treatment and prognosis of patients. With the vibrational fingerprint information and high detection sensitivity, surface-enhanced Raman spectroscopy (SERS) has been extensively applied in biomedicine.
View Article and Find Full Text PDFA single-crystal graphene film grown on a Cu(111) foil by chemical vapor deposition (CVD) has ribbon-like fold structures. These graphene folds are highly oriented and essentially parallel to each other. Cu surface steps underneath the graphene are along the <110> and <211> directions, leading to the formation of the arrays of folds.
View Article and Find Full Text PDFPrussian blue analogues are promising cathode material candidates for aqueous rechargeable metal-ion batteries. Although great efforts have been made on developing materials, there are still rare reports on optimizing cell performance from mechanistic understanding and studies. Here we unveil the alkali-metal-ion intercalation mechanism in Berlin green with a home-built spectroelectrochemical cell for X-ray Diffraction (XRD) and Raman spectroscopies, which allows us to obtain the correlated local structure, crystal structure, redox activity, and potential profiles during the charging and discharging processes.
View Article and Find Full Text PDFMetallic nanostructures exhibit superior catalytic performance for diverse chemical reactions and the in-depth understanding of reaction mechanisms requires versatile characterization methods. Plasmon-enhanced Raman spectroscopy (PERS), including surface-enhanced Raman spectroscopy (SERS), shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS), and tip-enhanced Raman spectroscopy (TERS), appears as a powerful technique to characterize the Raman fingerprint information of surface species with high chemical sensitivity and spatial resolution. To expand the range of catalytic reactions studied by PERS, catalytically active metals are integrated with plasmonic metals to produce bifunctional metallic nanostructures.
View Article and Find Full Text PDFDynamics are fundamental to all aspects of chemistry and play a central role in the mechanism and product distribution of a chemical reaction. All dynamic processes are influenced by the local environment, so it is of fundamental and practical value to understand the structure of the environment and the dynamics with nanoscale resolution. Most techniques for measuring dynamic processes have microscopic spatial resolution and can only measure the average behavior of a large ensemble of sites within their sampling volumes.
View Article and Find Full Text PDFActive oxygen species (AOS) play key roles in many important catalytic reactions relevant to clean energy and environment. However, it remains challenging to characterize the active sites for producing AOS and to image the surface properties of AOS, especially on multicomponent metallic catalyst surfaces. Herein, we utilize tip-enhanced Raman spectroscopy (TERS) to probe the local generation and diffusion of OH radicals on a Pd/Au(111) bimetallic catalyst surface.
View Article and Find Full Text PDFIschemic stroke (IS) caused by cerebral arterial embolism remains the leading cause of disability and death worldwide. Cerebral ischemia / reperfusion (CI / R) injury is one of the common complications of ischemic stroke. Growth arrest specific transcript 5 (GAS5) has been found to be abnormally expressed in various tumors.
View Article and Find Full Text PDFImpurities produced during the synthesis process of a material pose detrimental impacts upon the intrinsic properties and device performances of the as-obtained product. This effect is especially pronounced in graphene, where surface contamination has long been a critical, unresolved issue, given graphene's two-dimensionality. Here we report the origins of surface contamination of graphene, which is primarily rooted in chemical vapour deposition production at elevated temperatures, rather than during transfer and storage.
View Article and Find Full Text PDFIn the field of surface plasmon-mediated photocatalysis, the coupling reactions of p-aminothiophenol (PATP) and p-nitrothiophenol (PNTP) to produce p, p'-dimercaptoazobenzene (DMAB) are the most widely investigated systems. However, a clear understanding of the structure-function relationship is still required. Here, we used tip-enhanced Raman spectroscopy (TERS) to study the coupling reactions of PATP and PNTP on well-defined Ag(111) and Au(111) surfaces using 632.
View Article and Find Full Text PDFSensors (Basel)
November 2018
We investigated tip-enhanced Raman spectra excited by high-order fiber vector beams. Theoretical analysis shows that the high-order fiber vector beams have stronger longitudinal electric field components than linearly polarized light under tight focusing conditions. By introducing the high-order fiber vector beams and the linearly polarized beam from a fiber vector beam generator based on an electrically-controlled acoustically-induced fiber grating into a top-illumination tip-enhanced Raman spectroscopy (TERS) setup, the tip-enhanced Raman signal produced by the high-order fiber vector beams was 1.
View Article and Find Full Text PDFResolving atomic site-specific electronic properties and correlated substrate-molecule interactions is challenging in real space. Now, mapping of sub-10 nm sized Pt nanoislands on a Au(111) surface was achieved by tip-enhanced Raman spectroscopy, using the distinct Raman fingerprints of adsorbed 4-chlorophenyl isocyanide molecules. A spatial resolution better than 2.
View Article and Find Full Text PDFTip-enhanced Raman spectroscopy can provide molecular fingerprint information with ultrahigh spatial resolution, but the tip will be easily contaminated, thus leading to artifacts. It also remains a great challenge to establish tip-enhanced fluorescence because of the quenching resulting from the proximity of the metal tip. Herein, we report shell-isolated tip-enhanced Raman and fluorescence spectroscopies by employing ultrathin shell-isolated tips fabricated by atomic layer deposition.
View Article and Find Full Text PDFSurface and interfaces play key roles in heterogeneous catalysis, electrochemistry and photo(electro)chemistry. Tip-enhanced Raman spectroscopy (TERS) combines plasmon-enhanced Raman spectroscopy with scanning probe microscopy to simultaneously provide a chemical fingerprint and morphological information for the sample at the nanometer spatial resolution. It is an ideal tool for achieving an in-depth understanding of the surface and interfacial processes, so that the relationship between structure and chemical performance can be established.
View Article and Find Full Text PDFAn atomic- and molecular-level understanding of heterogeneous catalysis is required to characterize the nature of active sites and improve the rational design of catalysts. Achieving this level of characterization requires techniques that can correlate catalytic performances to specific surface structures, so as to avoid averaging effects. Tip-enhanced Raman spectroscopy combines scanning probe microscopy with plasmon-enhanced Raman scattering and provides simultaneous topographical and chemical information at the nano/atomic scale from ambient to ultrahigh-vacuum and electrochemical environments.
View Article and Find Full Text PDFJ Biomater Sci Polym Ed
December 2016
The accumulation of uremic toxins in blood might induce chronic renal failure (CRF). The incidence of CRF was as high as 10%. The traditional therapy for CRF was hemodialysis, which was more effective to remove small molecules, such as urea and creatinine.
View Article and Find Full Text PDFBurn wound dressings have played significant roles in daily clinical practice. An "ideal" burn wound dressing is non-adhesion, absorbency and antimicrobial activity. However, such a dressing is currently not available.
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