High-Performance Photoelectrochemical Enzymatic Bioanalysis Based on a 3D Porous Cu x O@TiO 2 Film with a Solid-Liquid-Air Triphase Interface.

The accurate detection of H 2 O 2 is crucial in oxidase-based cathodic photoelectrochemical enzymatic bioanalysis but will be easily compromised in the conventional photoelectrode-electrolyte diphase system due to the fluctuation of oxygen levels and the similar reduction potential between oxygen and H 2 O 2 . Herein, a solid-liquid-air triphase bio-photocathode based on a superhydrophobic three-dimensional (3D) porous micro-nano-hierarchical structured Cu x O@TiO 2 film that was constructed by controlling the wettability of the electrode surface is reported. The triphase photoelectrochemical system ensures an oxygen-rich interface microenvironment with constant and sufficiently high oxygen concentration. Moreover, the 3D porous micro-nano-hierarchical structures possess abundant active catalytic sites and a multidimensional electron transport pathway. The synergistic effect of the improved oxygen supply and the photoelectrode architecture greatly stabilizes and enhances the kinetics of the enzymatic reaction and H 2 O 2 cathodic reaction, resulting in a 60-fold broader linear detection range and a higher accuracy compared with the conventional solid-liquid diphase system.