Ultra-broadband piezoelectric energy harvesting via bistable multi-hardening and multi-softening

Nonlinear Dynamics - An electromechanical coupled distributed parameter model is derived for a broadband piezoelectric energy harvester with nonlinear magnetic interaction and...     

Nanostructures for Electrocatalytic CO2 Reduction

One of the most effective ways to cope with the problems of global warming and the energy shortage crisis is to develop renewable and clean energy sources. To achieve a carbon-neutral energy cycle, advanced carbon sequestration technologies are urgently needed, but because CO₂ is a thermodynamically stable molecule with the highest carbon valence state of +4, this process faces many challenges. In recent years, electrochemical CO₂ reduction has become a promising approach to fix and convert CO₂ into high-value-added fuels and chemical feedstock. However, the large-scale commercial use of electrochemical CO₂ reduction systems is hindered by poor electrocatalyst activity, large overpotential, low energy conversion efficiency, and product selectivity in reducing CO₂. Therefore, there is an urgent need to rationally design highly efficient, stable, and scalable electrocatalysts to alleviate these problems. This minireview also aims to classify heterogeneous nanostructured electrocatalysts for the CO₂ reduction reaction (CDRR).     

Dodecahedral Au/Pt Nanobowls as Robust Plasmonic Electrocatalysts for Methanol Oxidation under Visible-Light Illumination

Plasmonic nanostructures with large absorption areas under resonant excitation have been utilized extensively in photon-assisted applications. In this work, dodecahedral Au nanobowls were first prepared by an easy and template-free method only through the introduction of H₂PtCl₆ and I⁻ during the growth procedure. The Au nanobowls show electron-field enhancement due to the high curvature of the bowl edge, the open region, and dodecahedral morphology. Au/Pt nanobowls, which couple plasmonic Au and catalytic Pt, were then constructed as plasmonic electrocatalysts for methanol oxidation. The mass activity reached 497.6 mA mg⁻¹ under visible-light illumination, which is 1.9 times that measured in the dark. Simultaneously, the electrocatalytic stability is also greatly improved under light excitation. The enhanced properties of the plasmonic Au/Pt electrocatalysts are ascribed to the synergistic effect of the plasmon-enhanced photothermal and hot-carrier effects on the basis of experimental investigations. This work thus offers an effective methodology to construct efficient plasmonic electrocatalysts for fuel cells.     

Covalently Trapped Triarylamine-Based Supramolecular Polymers

C₃-Symmetric triarylamine trisamides (TATAs), decorated with three norbornene end groups, undergo supramolecular polymerization and further gelation by π–π stacking and hydrogen bonding of their TATA cores. By using subsequent ring-opening metathesis polymerization, these physical gels are permanently crosslinked into chemical gels. Detailed comparisons of the supramolecular stacks in solution, in the physical gel, and in the chemical gel states, are performed by optical spectroscopies, electronic spectroscopies, atomic force microscopy, electronic paramagnetic resonance spectroscopy, X-ray scattering, electronic transport measurements, and rheology. The results presented here clearly evidence that the core structure of the functional supramolecular polymers can be precisely retained during the covalent capture whereas the mechanical properties of the gels are concomitantly improved, with an increase of their storage modulus by two orders of magnitude.     

AuPt Bipyramid Nanoframes as Multifunctional Platforms for In Situ Monitoring of the Reduction of Nitrobenzene and Enhanced Electrocatalytic Methanol Oxidation

Multifunctional metal nanostructures with a hollow feature, especially for nanoframes, are highly attractive owing to their high surface-to-volume ratios. However, pre-grown metal nanocrystals are always involved during the preparation procedure, and a synthetic strategy without the use of a pre-grown template is still a challenge. In this article, a template-free strategy is reported for the preparation of novel AuPt alloy nanoframes through simply mixing HAuCl₄ and H₂PtCl₆ under mild conditions. The alloy nanostructures show a bipyramid-frame hollow architecture with the existence of only the ten ridges and absence of their side faces. This is the first report of bipyramid-like nanoframes and a template-free method under mild conditions. This configuration merges the plasmonic features of Au and highly active catalytic sites of Pt in a single nanostructure, making it an ideal multifunctional platform for catalyzing and monitoring the catalytic reaction in real time. The superior catalytic activity is demonstrated by using the reduction of nitrobenzene to the corresponding aminobenzene as a model reaction. More importantly, the AuPt nanoframes can track the reduction process on the basis of the SERS signals of the reactants, intermediates, and products, which helps to reveal the reaction mechanism. In addition, the AuPt nanoframes show much higher electrocatalytic properties toward the methanol oxidation reaction than commercial Pt/C electrocatalysts.     

如何解释红外谱图

红外光谱(IR)主要提供分子的官能团和化学键的丰富的结构信息。通常一个化学键会出现多个不同位置的吸收峰,而图中每个峰又可能是不同化学键的加合峰。因此在红外光谱分析中,并不要求也不可能准确地归属出图中所有的峰,通常只要求能较确切地识别出其中几个特征峰已足矣。     

Assembly-enhanced triplet-triplet annihilation upconversion in the aggregation formed by Schiff-base Pt(Ⅱ) complex grafting-permethyl-β-CD and 9,10-diphenylanthracence dimer

Water-soluble triplet sensitizer with permethyl-β-cyclodextrin(PMCD) grafting on a Schiff-base Pt(Ⅱ)complex(Pt-2),in which PMCD unit serves as a host for binding the acceptors and the Schiff-base Pt(Ⅱ)complex serves as a triplet sensitizer,was synthesized to investigate the effect of supramolecular complexation and assembly on the triplet-triplet annihilation upconversion emission in water.9,10-Diphenylanthracence(DPA) carboxylate(A-1) and its dimer(A-2) in which two DPA carboxylate were covalently linked with an alkyl chain were synthesized as triplet acceptors which also play a role of guest molecules for PMCD.A-1 and A-2 showed high affinity with PMCD,and A-2 can readily aggregate in water and form micron sized assemblies due to the hydrophobic effect and π-π stacking of anthracene core in A-2.The efficiency of TTA-UC was demonstrated to be enhanced by a synergistic effect of host-guest complexation of Pt-2 with A-2 and the self-aggregation of the acceptor A-2,which facilitated the energy transfer and energy fusion among donor and acceptor.