Dual Plasmon Resonances and Tunable Electric Field in Structure-Adjustable Au Nanoflowers for Improved SERS and Photocatalysis

Flower-like metallic nanocrystals have shown great potential in the fields of nanophononics and energy conversion owing to their unique optical properties and particular structures. Herein, colloid Au nanoflowers with different numbers of petals were prepared by a steerable template process. The structure-adjustable Au nanoflowers possessed double plasmon resonances, tunable electric fields, and greatly enhanced SERS and photocatalytic activity. In the extinction spectra, Au nanoflowers had a strong electric dipole resonance located around 530 to 550 nm. Meanwhile, a longitudinal plasmon resonance (730~760 nm) was obtained when the number of petals of Au nanoflowers increased to two or more. Numerical simulations verified that the strong electric fields of Au nanoflowers were located at the interface between the Au nanosphere and Au nanopetals, caused by the strong plasmon coupling. They could be further tuned by adding more Au nanopetals. Meanwhile, much stronger electric fields of Au nanoflowers with two or more petals were identified under longitudinal plasmon excitation. With these characteristics, Au nanoflowers showed excellent SERS and photocatalytic performances, which were highly dependent on the number of petals. Four-petal Au nanoflowers possessed the highest SERS activity on detecting Rhodamine B (excited both at 532 and 785 nm) and the strongest photocatalytic activity toward photodegrading methylene blue under visible light irradiation, caused by the strong multi-interfacial plasmon coupling and longitudinal plasmon resonance.

Self-template formation of porous Co3O4 hollow nanoprisms for non-enzymatic glucose sensing in human serum

Co3O4 hollow nanoprisms based non-enzymatic glucose sensor were prepared by a self-template process, exhibiting wide linear range, good selectivity and stability, which can directly monitoring blood glucose without any dilution pretreatment.

An advanced structural characterization of templated meso-macroporous carbon monoliths by small- and wide-angle scattering techniques

This study is dedicated to link the nanoscaled pore space of carbons, prepared by hard-templating of meso-macroporous SiO2 monoliths, to the corresponding nanoscaled polyaromatic microstructure. Two different carbon precursors were used, which generally exhibit markedly different carbonization properties, i.e. a graphitizable pitch and a non-graphitizable resin. The micro- and mesoporosity of these monolithic carbons was studied by the sorption behaviour of a relatively large organic molecule (para-xylene) in comparison to typical gas adsorbates (Ar). In addition, to obtain a detailed view on the nanopore space small-angle neutron scattering (SANS) combined with in-situ physisorption was applied, using deuterated p-xylene (DPX) as a contrast-matching agent in the neutron scattering process. The impact of the carbon precursor on the structural order on an atomic scale in terms of the size and the disorder of the carbon microstructure, on the nanopore structure and on the template process is analysed by special evaluation approaches for SANS and wide-angle X-ray scattering (WAXS). The WAXS analysis shows that the pitch-based monolithic exhibits a more ordered microstructure consisting of larger graphene stacks and similar graphene layer sizes compared to the monolithic resin. Another major finding is the discrepancy in the accessible micro/mesoporosity between Ar and deuterated p-xylene, which was found for the two different carbon precursors (pitch, resin), which can be regarded as representatives in regard to carbon precursors in general. These differences essentially indicate that physisorption using probe gases such as Ar or N2 can provide misleading parameters if to be used to appraise the accessibility of the nanoscaled pore space.

Salt-templated synthesis of defect-rich MoN nanosheets for boosted hydrogen evolution reaction

The ultra-stable highly efficient HER over a wide pH range on defect-rich MoN nanosheets synthesized using a modified salt-template process.