Huajun Qiu

Publications (2)9.96 Total impact

• Article: Fabrication of stratified nanoporous gold for enhanced biosensing.

  Huajun Qiu, Feixue Zou
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  ABSTRACT: By a dealloying/annealing/redealloying strategy, nanoporous gold (NPG) with hierarchical microstructure is fabricated for electrochemical biosensing application. The first dealloying and annealing would produce NPG/AuAg alloy composite with a large-pore NPG layer and the second dealloying would further etch the AuAg alloy part in the composite, generating a small-pore NPG layer. By using the large-pore (≈ 100 nm) layer as the glucose oxidase (GOx) container, and the small-pore (≈ 12 nm) layer as a signal producer, this novel hierarchical NPG is demonstrated to be a good support for enzyme immobilization and fabricating enzyme-based biosensors. The immobilized GOx retains ≈ 92% of the initial activity after 7 repeated use. The GOx-loaded stratified NPG biosensor can detect glucose more sensitively with a wider linear range (up to 22 mM) than normal NPG with a uniform pore size of 30-40 nm (linear range: up to 17 mM).
  Biosensors & bioelectronics 03/2012; 35(1):349-54. · 5.43 Impact Factor
• Article: Nanoporous PtCo surface alloy architecture with enhanced properties for methanol electrooxidation.

  Huajun Qiu, Feixue Zou
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  ABSTRACT: By selectively dealloying a PtCoAl ternary alloy, a novel nanoporous PtCo (np-PtCo) alloy with a three-dimensional bicontinuous pore-ligament structure is successfully fabricated. X-ray diffraction and electron microscopic characterizations demonstrate the single-crystal nature of the alloy ligament with a ligament size down to ~3 nm. After a mild electrochemical dealloying process, a nanoporous near-surface alloy structure with a Pt-rich surface and a PtCo alloy core is obtained. Electrochemical measurements show that the np-PtCo surface alloy has greatly enhanced catalytic activity and durability toward methanol electrooxidation compared with a state-of-the-art Pt/C catalyst. The peak current density of methanol electrooxidation on a np-PtCo surface alloy is more than 5 times of that on Pt/C. More importantly, continuous potential cycling from 0.6 to 0.9 V (vs RHE) in a 0.5 M H(2)SO(4) aqueous solution demonstrates that a np-PtCo surface alloy has excellent structure stability, with more than 90% of the initial electrochemical active surface area (EASA) retained after 5000 potential cycles. Under the same conditions, the EASA of Pt/C drops to ~70%. With evident advantages of facile preparation as well as enhanced electrocatalytic activity and durability, a np-PtCo surface alloy nanomaterial holds great potential as an anode catalyst in direct methanol fuel cells.
  ACS Applied Materials & Interfaces 02/2012; 4(3):1404-10. · 4.53 Impact Factor