Faradaically Resilient Triphase Wedge‐Shaped Nanowire Arrays for Robust Bioanalysis

ABSTRACT Gas‐containing triphase interfaces are attractive for oxygen‐mediated electrochemical systems, yet faradaic stress‐induced electrowetting remains unresolved in triphase biointerfaces. This work presents faradaically resilient wedge‐shaped copper nanowire arrays (W‐CuNWAs) that stabilize oxygen‐enriched triphase interfaces during sustained and repeated electrochemical operations. In contrast with conventional passive liquid‐repellent nanostructures, W‐CuNWAs employ co‐programmed structural–wettability anisotropy to reconcile wettable charge‐transfer regions with gas‐retaining regions within a single nanoarchitecture. Compared to cylindrical CuNWAs, W‐CuNWAs introduce shape‐encoded wetting barriers that increase capillary breakthrough pressure by 2.85‐fold and pin the contact line at the upper edge. Across 3 h of continuous bias, 500 potential cycles, repeated impedance perturbations, and cathodic electrodeposition of a high‐surface‐energy co‐catalyst, W‐CuNWAs retain stable wettability and electrochemical responses with only 0.88 kΩ mass‐transport‐resistance drift, whereas cylindrical counterparts undergo electrolyte infiltration and structural failure. The retained atmosphere‐connected gas phase enables Pt/W‐CuNWAs to achieve 1.65‐fold higher oxygen‐reduction current, 8.96‐fold lower oxygen mass‐transfer resistance, and 2.96‐fold faster current stabilization than cylindrical counterparts. Integration with an FeOOH/BiVO 4 photoanode enables near‐drift‐free, unbiased photoelectrochemical operation over 8.42 h of repeated cathodic cycling, and reliable detection of Alzheimer's neurofilament light chain in clinical plasma. This work establishes shape‐encoded faradaic electrowetting resistance as a design principle for operationally stable, oxygen‐mediated triphase nanoarchitectures in bioanalysis.