Platinum Nanocrystal Assisted by Low‐Content Iridium for High‐Performance Flexible Electrode: Applications on Neural Interface, Water Oxidation, and Anti‐Microbial Contamination

Abstract Despite high charge capacity, iridium oxide (IrO x ) coating is susceptible to delamination under prolonged stimulation, restricting its long‐term application. Here, a flower‐shaped platinum (Pt) nanocrystal with intensive high‐surface area is developed as an intermediate layer for accumulating IrO x (<3 wt% Ir) with enhanced adhesion, showing a multiplier effect. The impedance of IrO x /Pt flower coated microelectrode at 1 kHz is down to ≈2 kΩ (reduction of 94.23%). The corresponding cathodic charge storage capacity (CSC c ) and charge injection capacity (CIC) are increased up to 202.75 ± 2.18 and 6.53 ± 0.16 mC cm –2 , respectively. IrO x layer adheres tightly to Pt nanocrystals, demonstrating robust chronic stability under continuous electrostimulation for 1 × 10 8 cycles. Besides, the as‐prepared coatings show good biosafety, and exhibit promising electrocatalytic activity toward oxygen evolution reaction (OER) in 0.5 m sulfuric acid (H 2 SO 4 ), requiring a low overpotential of ≈150 mV to reach 10 mA cm –2 . IrO x helps in reducing the Tafel slope of Pt flower from 162.9 to 41.1 mV dec –1 drastically, also with excellent durability after chronoamperometry test. Excellent antibacterial properties toward Escherichia coli are also observed. This coating strategy provides a functionalized flexible electrode for neural interface, water oxidation, and anti‐microbial contamination, which will moreover extend to numerous applications.