Guolong Lu

Synthesis of a conjugated porous Co(II) porphyrinylene–ethynylene framework through alkyne metathesis and its catalytic activity study

The development of efficient catalysts for the oxygen reduction reaction (ORR) is crucial for a number of emerging technologies, to counter energy and environment crises. Herein, we report an alkyne metathesis polymerization protocol to synthesize a conjugated microporous metalloporphyrin-based framework containing interconnected ORR catalytic centers. A simple composite of the framework and carbon black shows excellent ORR electrocatalytic activity and specificity through a four-electron reduction mechanism under both acidic and alkaline conditions. The pyrolysis of the catalyst, which is commonly involved in the preparation of ORR catalytic systems, is not necessary. Compared to monomeric metalloporphyrins, the framework shows enhanced ORR catalytic activity, presumably due to the porous and conjugated nature of the framework structure, which allows better exposure of the catalytically active sites, and efficient electron/mass transport. More importantly, the composite electrocatalyst exhibits superior durability and methanol tolerance over commercial Pt/C and metalloporphyrin monomers. Given the highly structural tunability of conjugated microporous polymers, it is conceivable that such a non-pyrolytic approach could enable the systematic exploration of the structure–activity relationship of organic framework-based ORR catalysts and eventually lead to the development of cost-effective replacements for Pt/C.

Graphene-Supported Silver Nanoparticles for pH-Neutral Electrocatalytic Oxygen Reduction

In order to improve the electrocatalysis of oxygen reduction and reduce the captive cost of microbial fuel cell (MFC), graphene-supported catalyst of silver nanoparticles (Ag/RG) was prepared and its activity toward oxygen reduction reaction (ORR) in pH-neutral condition was examined. The Ag/RG catalyst was prepared by chemical reduction of aqueous silver ions to silver nanoparticles on the surface of reduced graphene (RG), which was obtained from graphene oxide (GO) precursor synthesized via classic Hummers method using graphite as starting material. The results demonstrated that aqueous co-reduction method could yield high-quality Ag/RG catalyst, in which Ag nanoparticles were dispersed on the graphene surface with average diameter of 13 nm as revealed by XRD and TEM examination. The XPS results suggested the presence of polar oxygen-containing functional groups on the graphene sheets could provide the nuclei to form Ag nano-structure. The CV results showed that Ag/RG was active of catalyzing ORR electrochemically in pH-neutral electrolyte. Since Ag costs much less than Pt, Ag/RG is expected to hold remarkable potential as a promising alternative to promote the commercialization of MFC for practical application.

Recent advances in the development of functionalized carbon nanotubes: a versatile vector for drug delivery

Carbon nanotubes (CNTs) possess unique physical and chemical properties and can serve as a platform for transporting a variety of bioactive molecules, such as drugs, proteins, and genes, given appropriate surface modifications. Here, we present an overview of the progress in applying CNTs as therapeutic agent carriers. Drugs can be attached to CNTs either through supramolecular chemistry to form noncovalent assembly or via covalent linkage to the functional groups preinstalled on CNTs. In addition to surface loading, packing of molecules inside the internal cavity of CNTs to protect less stable entities has also been achieved. Besides drugs, the high specific surface area of CNTs can also allow the installation of multiple molecules with different functions, e.g. target recognition and optical imaging, simultaneously to achieve synergistic effects. The drug release process tends to be gradual and sustained after being attached to CNTs, and could be tuned by various factors, such as pH, diameter of CNTs, and target recognition. The content throughout this review is mainly focused on the different protocols of loading drugs onto or into CNTs as well as how to control the drug release.

ZnO nanodisks decorated with Au nanorods for enhanced photocurrent generation and photocatalytic activity

A facile approach for the preparation of Au nanorod/ZnO nanodisks (AuNR/ZnONDKs) through in situ nucleation and growth of ZnO in AuNR colloidal solution was developed. This is the first report of AuNRs modified on the ZnO surface. Furthermore, the aspect ratios of AuNRs in nanohybrids of AuNR/ZnONDKs were also tuned to achieve tunable and broad LSPR bands for an optimized photocatalytic performance. All of the resultant AuNR/ZnONDK nanohybrids with exposed AuNRs exhibit much higher photocatalytic activity and photocurrent generation compared to commercial ZnO (C-ZnO). In particular, AuNR-707/ZnONDKs express a swift and steady photocurrent of 0.33 mA cm−2, which is 16.5 times higher than the photocurrent generated by C-ZnO. The facile approach presented here opens up a new avenue for the rational design and preparation of high-performance photocatalysts for the future applications in both environmental purification and photoelectric conversion.

Spiky nanohybrids of titanium dioxide/gold nanoparticles for enhanced photocatalytic degradation and anti-bacterial property

We present a facile two-step procedure for synthesizing spiky nanohybrids of titanium dioxide/gold (TiO2/Au) nanoparticles. In this process, spiky TiO2 is obtained using a hydrothermal method, followed by the introduction of plasmonic Au nanoparticles (AuNPs) via a photoreduction approach in which titanium fluoride and chloroauric acid tetrahydrate are used as raw materials. The photodegradation property of the resulting sample was evaluated according to the removal of Rhodamine B (RhB) and ciprofloxacin (CIP) via excitation with visible light. Additionally, the antimicrobial property of the spiky TiO2/Au nanoparticles was examined with respect to the suppression of the growth of Escherichia coli (E. coli). Compared with commercial TiO2, the spiky TiO2/Au nanoparticles exhibited a significantly enhanced photocatalytic efficiency in persistent organic pollutant degradation and bacteria inactivation under simulated environmental conditions. The photocatalysis mechanism primarily entails the combination of AuNPs with spiky TiO2 nanoparticles, which increases the optical path owing to the unique spiky structures of the latter. This results in an improved light-harvesting efficiency based on the localized surface plasmon resonance (LSPR) of AuNPs and the promotion of the charge-separation efficiency through electron-trap processes. These nanoparticles realize the objective of effectively addressing the inherent weaknesses of bare TiO2 and potentially facilitate new fitting approaches for applications in sewage treatment and marine antifouling paint.