Lilin Lu

A Family of High‐Efficiency Hydrogen‐Generation Catalysts Based on Ammonium Species

Development of highly active, low cost, ecologically friendly, and durable homogenous catalysts for hydrogen generation from hydrolysis of borohydride is one of the most desirable pathways for future hydrogen utilization. The unexpected catalytic activities of inorganic ammonium species and the corresponding mechanisms underpinning them are studied. The catalytic activities of the ammonium species are higher than or comparable to those of mostly investigated noble-metal/transition-metal catalysts (such as Pd, Pt, Ni, and Co) but are considerably cheaper, more environmentally friendly, and more readily available. Quantum chemical calculations indicate that the unique ammonium-induced reaction pathway involved with a barrierless elementary reaction at the reaction entrance and the formation of the highly active intermediate BH3 are responsible for the unexpected catalytic activities and the significantly accelerated hydrogen generation.

Synthesis of Ni/Au/Co trimetallic nanoparticles and their catalytic activity for hydrogen generation from alkaline sodium borohydride aqueous solution

A series of poly (N-vinyl-2-pyrrolidone) stabilized colloidal Ni/Au/Co trimetallic nanoparticles (TNPs) were synthesized by co-reduction of their corresponding metal precursors via dropwise addition of NaBH4. Ultraviolet-visible spectrophotometry (UV-Vis), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), powder X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HR-TEM) combined with energy dispersive spectrometry (EDS) were used to characterize the morphology, crystalline structure and electron distribution of the as-prepared TNPs. The effects of metal composition on the size distribution and hydrogen generation from catalytic hydrolysis of alkaline NaBH4 aqueous solutions were also investigated. The results indicated that the as-prepared alloy-structured Ni45Au45Co10 TNPs showed a maximum catalytic activity of 1170 mol-H2 per h per mol-M, which is several times higher than that of the as-prepared Au, Ni or Co monometallic nanoparticles (MNPs), or Au50Ni50, Au50Co50 or Ni50Co50 bimetallic nanoparticles (BNPs). The enhanced catalytic activity of the TNPs compared with the MNPs and BNPs could be attributed to the presence of electron charge transfer effects among Au, Ni and Co atoms, which is supported by the results of X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) calculation. The apparent activation energy of the as-prepared Au45Ni45Co10 TNPs in hydrolysis of NaBH4 aqueous solution was determined as 18.8 kJ mol−1.

Theoretical study of complexation of resveratrol with cyclodextrins and cucurbiturils: structure and antioxidative activity

Resveratrol is an outstanding natural antioxidant which is often found in a wide variety of plant species; its antioxidative activity has been recently reported as being influenced by complexation with macromolecules such as cyclodextrins (CDs). In this work, the complexation of resveratrol with CDs and cucurbiturils (CBs) has been studied by density functional theory calculations, the equilibrium geometries and the electronic structures of the complexes are investigated at the B3LYP/6-311G(d, p) level of theory, the antioxidative capabilities of the inclusion complexes have been elucidated based on H-atom transfer (HAT), sequential proton loss electron transfer (SPLET) and single electron transfer (SET) antioxidative mechanisms. The influence of inclusion complexation on the structure and antioxidative activity of resveratrol has been investigated. Our results show that resveratrol exhibits a non-planar geometry when it is included in CDs and CBs. Complexation of resveratrol with these two macromolecules results in negligible change in frontier orbital distribution, but distinct change in orbital energies. Different inclusion complexes and inclusion modes show different influences on 4′-OH bond dissociation enthalpy (4′-OH BDE), proton affinity (PA) and the electron transfer enthalpy (ETE) of the 4′-phenolate anion, and the ionization potential (IP) of resveratrol. Compared to cyclodextrins, cucurbiturils exhibit better performance in improving the antioxidative capacity of resveratrol.

Carbon Nanotube Reinforced Ceramic Composites: A Review

Carbon nanotubes (CNTs) have been extensively studied over the last two decades because of their excellent properties. In particular, they have been considered as promising reinforcements for development of novel ceramic composites (CCs). In this paper, current researches on CNT-reinforced CCs are briefly highlighted and reviewed. CNT-reinforced CCs possess remarkable electrical and thermal properties as well as superior mechanical properties compared to conventional CCs without using CNTs.

Fabrication of Porous Ceramics by Direct Foaming

Porous ceramics have been extensively studied during the last two decades because of their application potentials in various fields including thermal insulators, radome materials, gas or molten metal filters, catalytic supports and biomedical substitutes for bone. This paper gives a brief review on the recent developments of preparation of porous ceramics by direct foaming method, it shows that the direct foaming method is a more effective way for preparation of high performance porous ceramics with high porosity, high mechanical strength and an even pore size distribution compared with conventional methods.