LAUSR

It is crucial to improve charge storage capacity (CSC) and charge transport efficiency with low impedance for electrochemical capacitors. Here, a well‐controlled three‐dimensional (3D) nanocrystal platinum (Pt) is electrodeposited as the intermediate layer on microelectrode (200 µm in diameter) to provide extensive large surface area, followed by introducing iridium oxide (IrOx) nanoparticles with excellent adhesion on the rough layer to fabricate high‐performance IrOx/Pt composite coatings. The uniform flower‐shaped coating presents a significantly low impedance ≈2.01 kΩ at 1 kHz (reduction of 94.52%). It has a cathodic CSC (CSCc) up to ≈200.64 mC cm−2, about 2, 17.51, and 56.18 times higher than that of nanocrystal Pt, IrOx, and flat Pt respectively. Robust chronic stability is observed with CSCc at ≈171.97 mC cm−2 after electrical stimulation for 12 d (>1 × 108 cycles). It also demonstrates record‐high charge injection capacity ≈6.37 mC cm−2 with excellent biocompatibility. Such coating is widely applicable for batch production on multichannel microelectrode arrays or substrates with different sizes. Moreover, it promotes excellent sensitivity to glucose detection up to ≈130 µA cm−2 mm−1, with a linear range of 1–30 × 10−3 m and a detection limit of 1.08 × 10−6 m. The promising coating will pave a new way for various electrochemical applications.