Xueqiu You 1 , James H. Pikul 2 , William P. King 2 , and James Jungho Pak 1 *
1 School of Electrical Engineering, Korea University, Seoul, Korea
2 Department of Mechanical Science and Engineering,
University of Illinois at Urbana – Champaign, Urbana, IL, USA
* Email: pak@korea.ac.kr
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Figure S1 shows a cross  section of a cleaved inverse opal ZnO enzymatic electrode.
The nanoscale interconnects in the inverse opal enzymatic electrode, as shown in Figure
S1(b) (higher magnification SEM image) has diameters in the range from several nanometers to ~100 nanometers after GOx deposition.
Figure S1 (a) SEM of a cross section of a cleaved ZnO inverse opal enzymatic electrode. (b) SEM (at higher magnification) of the nanoscale interconnects in the ZnO inverse opal enzymatic electrode.
Figure S2 (a) shows X-ray diffraction (XRD) measurement result of the inverse opal
ZnO on Au electrodes. The XRD measurement was performed by using Cu-Kα radiation (λ = 1.54178 Ǻ) in the range of 30–80° with 5 °/min scanning speed. All the diffraction peaks can be indexed to the hexagonal Wurtzite phase of ZnO with lattice
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constants of a = 0.325 nm and c = 0.520 nm, which match the standard XRD data file
(JCPDS 79-2205). No other crystalline form, such as Zn or other Zn compounds, was detected. The (002) peak was the dominant peak for the ZnO inverse opal on Au, whereas the dominant peaks for the ZnO powder were (100) and (101). The enhanced
(002) peak indicates the prevailing presence of ZnO crystals with a C-axis orientation normal to the Au surface during the electrochemical deposition.
The Energy dispersive
X  ray (EDX) spectroscopy shown in Figure S2 (b) confirms the chemical composition
(Zn:O=1:1.1) of the prepared ZnO inverse opal.
Figure S2 (a) An XRD spectrum of ZnO inverse opal on Au electrode.
(b) EDX of the ZnO inverse opal on Au electrode.
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