Fabrication of composite Cu2O/Au inverse opals for enhanced detection of hydrogen peroxide: Synergy effect from structure and sensing mechanism

Abstract

Composite Cu2O/Au inverse opals are fabricated by pulse electrodeposition of Cu2O on the skeletons of Au inverse opals, and their H2O2 sensing performances are investigated in a phosphate buffered saline solution. In our composite structure, the Cu2O is responsible for H2O2 sensing, and the Au inverse opals not only contribute to H2O2 sensing but also serve as a current collector providing a large accessible area with interconnected pore channels for facile mass transport. The sensing mechanism of Cu2O and Au complement each other so their simultaneous exposure to H2O2 leads to a larger sensing response. The composite Cu2O/Au inverse opals display a wide linear detection range (5–11,000 µM) and low detection limit (5 µM), as well as a two-stage sensitivity of 304.8 and 60.8 μA/(mM·cm2). In addition, they reveal a relatively low sensing potential (−0.1 V) as compared to alternative nanostructured counterparts. The selectivity and durability of composite Cu2O/Au inverse opals are also validated. The composite Cu2O/Au inverse opals are readily detached from the ITO substrate, rendering a free-standing sample that could accommodate designs for both in-vivo and in-vitro testing.