TY - JOUR
T1 - Alteration of the morphology and electrocatalytic activity of IrO2 nanowires upon reduction by hydrogen gas
AU - Ha, Yejin
AU - Jung, Hayoung
AU - Lee, Chongmok
AU - Kim, Myung Hwa
AU - Lee, Youngmi
N1 - Funding Information:
This work was financially supported by the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT and Future Planning ( 2014R1A2A2A05003769 for YL); and the Korean Government ( 2014R1A1A2059791 for MHK).
Publisher Copyright:
© 2015 Elsevier B.V. All rights reserved.
PY - 2015/9/1
Y1 - 2015/9/1
N2 - This paper reports the facile synthesis of highly single-crystalline IrO2 nanowires grown on an Au microwire (IrO2NW-Au) and its reduced form (Ir/IrO2NW-Au); and their electrocatalytic activity for oxygen reduction reaction, H2O2 reduction/oxidation, and dopamine (DA) oxidation. IrO2NW-Au, prepared by direct vapor transport process under atmospheric pressure, was reduced by H2 gas flowing at 200°C. This additional modification resulted in the significant morphological changes from the smooth nanowire structures of IrO2NW-Au to substantially porous structures of Ir/IrO2NW-Au with sustaining the external nanowire frameworks. The compositions were also changed from mostly IrO2 in IrO2NW-Au to the mixture of IrO2 and Ir(0) metal in Ir/IrO2NW-Au. Ir/IrO2NW-Au showed highly enhanced and facilitated electrochemical reaction kinetics compared to IrO2NW-Au for ORR and H2O2 reduction/oxidation. The ORR limiting-like current at Ir/IrO2NW-Au was measured to be ∼19-fold greater than that of IrO2NW-Au. In addition, the amperometric responses to varying H2O2 concentration confirmed that Ir/IrO2NW-Au exhibited ∼8-fold (for H2O2 oxidation) and ∼750-fold (for H2O2 reduction) higher sensitivity than IrO2NW-Au. The observed enhanced activity of Ir/IrO2NW-Au could be attributed to the enlarged active surface area as well as the inherent electroactivity of Ir/IrO2NW material induced by co-existence of Ir oxide and metal. In contrast, more stable and decent anodic current responding to DA oxidation was measured at IrO2NW-Au than Ir/IrO2NW-Au, indicating IrO2 rather than Ir(0) has higher catalytic activity for DA oxidation.
AB - This paper reports the facile synthesis of highly single-crystalline IrO2 nanowires grown on an Au microwire (IrO2NW-Au) and its reduced form (Ir/IrO2NW-Au); and their electrocatalytic activity for oxygen reduction reaction, H2O2 reduction/oxidation, and dopamine (DA) oxidation. IrO2NW-Au, prepared by direct vapor transport process under atmospheric pressure, was reduced by H2 gas flowing at 200°C. This additional modification resulted in the significant morphological changes from the smooth nanowire structures of IrO2NW-Au to substantially porous structures of Ir/IrO2NW-Au with sustaining the external nanowire frameworks. The compositions were also changed from mostly IrO2 in IrO2NW-Au to the mixture of IrO2 and Ir(0) metal in Ir/IrO2NW-Au. Ir/IrO2NW-Au showed highly enhanced and facilitated electrochemical reaction kinetics compared to IrO2NW-Au for ORR and H2O2 reduction/oxidation. The ORR limiting-like current at Ir/IrO2NW-Au was measured to be ∼19-fold greater than that of IrO2NW-Au. In addition, the amperometric responses to varying H2O2 concentration confirmed that Ir/IrO2NW-Au exhibited ∼8-fold (for H2O2 oxidation) and ∼750-fold (for H2O2 reduction) higher sensitivity than IrO2NW-Au. The observed enhanced activity of Ir/IrO2NW-Au could be attributed to the enlarged active surface area as well as the inherent electroactivity of Ir/IrO2NW material induced by co-existence of Ir oxide and metal. In contrast, more stable and decent anodic current responding to DA oxidation was measured at IrO2NW-Au than Ir/IrO2NW-Au, indicating IrO2 rather than Ir(0) has higher catalytic activity for DA oxidation.
KW - Electrocatalysis
KW - Hydrogen peroxide reduction/oxidation Dopamine oxidation
KW - Iridium dioxide
KW - Iridium metal
KW - Nanowire
KW - Oxygen reduction
UR - http://www.scopus.com/inward/record.url?scp=84928963609&partnerID=8YFLogxK
U2 - 10.1016/j.snb.2015.04.037
DO - 10.1016/j.snb.2015.04.037
M3 - Article
AN - SCOPUS:84928963609
SN - 0925-4005
VL - 216
SP - 159
EP - 164
JO - Sensors and Actuators, B: Chemical
JF - Sensors and Actuators, B: Chemical
ER -