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Jiao J.,Institute of Hybrid Materials | Xia J.,Sun Yat Sen University | Qiu W.,Sun Yat Sen University | Tang J.,Institute of Hybrid Materials | And 4 more authors.
Electrochimica Acta | Year: 2014

The structure of biomimetic approach to converting sunlight was applied for design of composite materials. Here, hierarchical tree-like heterostructure Ag/ZnO (Ag wt%: 8.9%) arrays were fabricated by two-step electrodeposition, and it exhibited improved activity during photoelectrochemical water oxidation. The wurtzite-structured ZnO arrays prepared are the "trunk". Ag nanoclusters were selectively deposited on the top of arrays as the "leaf", which can strongly interact with visible light due to surface plasmon resonance. The inducted electromagnetic fields around Ag would efficiently propagate energy to composites by hot electrons injection. Based on morphology and crystal structure analysis, the linear sweep voltammagrams display that photocurrent increase to 0.17 mA/cm2 at 1.23 V RHE, and the photo-to-hydrogen generation is 0.23%. Additionally, the amperometric I-t curves collected without voltage displayed better photocurrent response under sunlight. The kinetics of PEC process at the electrode surface was investigated by electrochemical impedance spectroscopy (EIS). The mechanism was deduced based on the energy level of ZnO and Ag. The designed plasmonic crystal system exhibited that tree-like heterostructure is favorable for improving sunlight absorption and photoeletrochemical performance. © 2014 Elsevier Ltd.

Xu Q.,Institute of Hybrid Materials | Tang J.,Institute of Hybrid Materials | Wang Y.,Institute of Hybrid Materials | Liu J.,Institute of Hybrid Materials | And 5 more authors.
Journal of Colloid and Interface Science | Year: 2013

A general protocol to prepare photoluminescent polymeric aggregates with multiple morphological structures was proposed in this article. The amphiphilic diblock copolymer, polystyrene-block-poly (acrylic acid) (PS-b-PAA) which acted as the polymer ligand, was synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization. Eu3+ ions were selected as the cross-linkers to coordinate with the carboxyl groups along PAA segments of the diblock copolymer, resulting in cross-linked PAA networks as the core. At the same time, PS coronas still kept their solubility to the solvent phase, preventing the precipitation of the complex. The obtained aggregates dispersed well in dimethyl formamide (DMF) instead of precipitation occurred in complex systems between non-block copolymers and lanthanide ions. It is the first time that the aggregates with rich morphological structures, including ordinary micelles, rod-wrapped micelles, sun-shaped micelles, vesicles and large compound micelles (LCMs), were obtained by adjusting the molar ratio or the concentration of Eu3+ ions and diblock copolymer. Importantly, the aggregates have enhanced photoluminescent properties via the coordination between Eu3+ and diblock copolymer at their optimal ratio. The obtained aggregates are convenient for further processing, such as spin-coating and casting. This strategy can also be applied to other coordination systems between diblock copolymers and lanthanide ions. © 2013 Elsevier Inc.

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