Three-Dimensional TiO₂@Cu₂O@Nickel Foam Electrodes: Design, Characterization, and Validation of O₂-Independent Photocathodic Enzymatic Bioanalysis

Abstract

This work reports the innovative design and application of a three-dimensional (3D) TiO 2 @Cu 2 O@nickel foam electrode synergized with enzyme catalysis toward the proof-of-concept study for oxygen-independent photocathodic enzymatic detection. Specifically, a 3D-nanostructured photoelectrode has great potential in the semiconductor-based photoelectrochemical (PEC) biological analysis. On the other hand, using various photocathodes, cathodic PEC bioanalysis, especially the photocathodic enzymatic detection, represents an attractive frontier in the field. Different from state-of-the-art photocathodic enzymatic studies that are oxygen-dependent, herein, we present the ingenious design, characterization, and implementation of 3D TiO 2 @ Cu 2 O@nickel foam photocathodes for the first oxygen-independent example. In such a configuration, the Cu 2 O acted as the visible-light absorber, while the TiO 2 shell would simultaneously function as a protective layer for Cu 2 O and as a desirable substrate for the immobilization of enzyme biomolecules. Especially, because of the proper band positions, the as-designed photocathode exhibited unique O 2 -independent PEC property. Exemplified by glucose oxidases, the as-developed sensor exhibited positive response to glucose with good performance. Because various oxidases could be integrated with the system, this protocol could serve as a universal O 2 -independent platform for many other targets. This work is also anticipated to catalyze more studies in the advanced 3D photoelectrodes toward innovative enzymatic applications.

Enhanced Hydrogen Production from Ethanol Photoreforming by Site-Specific Deposition of Au on Cu2O/TiO2 p-n Junction

“…The Au@TiO 2 electrode shows a higher photocurrent than Au@Cu 2 O/TiO 2 . The interface of Au and TiO 2 is more favorable to charge separation than that of Au and Cu 2 O due to the lower conduction band potential of TiO 2 than that of Cu 2 O [42]. In addition, the existence of Ti 3+ defects associated with adjacent oxygen vacancies intensifies the interaction of Au and TiO 2 [25].…”

High-Performance Photocathodic Bioanalysis Based on Core–Shell Structured Cu 2 O@TiO 2 Nanowire Arrays with Air–Liquid–Solid Joint Interfaces

“…In Supporting Information Figure S4a, peaks at 529.6 and 530.2 eV can be ascribed to the O 2− state in TiO 2 and Cu 2 O, respectively, while the peak at 531.5 eV can be attributed to the OH − in Cu(OH) 2 . 40 In Supporting Information Figure S4b, peaks at 458.5 and 464.4 eV can be attributed to Ti 2p 3/2 and Ti 2p 1/2 , respectively. 41 This confirms the presence of TiO 2 .…”

A new strategy: fermi level control to realize 3D pyramidal NiCo-LDH/ReS2/n-PSi as a high-performance photoanode for the oxygen evolution reaction

“…33 Except for PSi, other 3D anti-reflection structures such as WS 2 /Si NWs, Cu 2 O-Ti 3 C 2 T X nanorods and TiO 2 @-Cu 2 O@nickel-foam as photocathodes with high PEC performances can also illustrate the superiority of the 3D light trapping effect. 16,34,35 By Fermi level control and light absorption enhancement, here we report a novel NiCo-LDH/ReS 2 /n-PSi photoanode with a 3D anti-reflection structure for the OER. The p-ReS 2 NSs were grown on the n-type PSi substrate to form a p-n junction, which means a different band alignment from the p-type Si substrate because of the Fermi level matching.…”