Mesoporous Carbon Thin Films with Large Mesopores as Model Material for Electrochemical Applications

The synthesis of mesoporous carbon thin films is proposed on titanium plates with well‐ordered 70 nm mesopores via soft templating of resol resins with poly(ethylene oxide)‐ block ‐poly(hexyl acrylate) copolymers. Surprisingly, regular carbonization in pure argon suffers from a metal substrate corrosion not yet observed in literature. This corrosion phenomenon is investigated by secondary ion mass spectrometry, electron microscopy, and X‐ray diffraction, and it is identified that the introduction of carbon monoxide into the carbonization atmosphere as successful approach to suppress substrate corrosion without changing microstructure, composition, or pore structure of the non‐graphitic carbon. The model electrodes, which consist of a 200–300 nm thick mesoporous carbon layer, the titanium substrate, and a 200 nm thick titanium carbide interphase, are tested for their suitability as electrocatalyst support: The electric transport through and along the thin film is investigated by impedance and Hall measurements and contrasted to similarly mesoporous IrO 2 thin films. Accessibility of the pore system and electrochemical stability under acidic water‐splitting conditions are studied by SIMS and cyclovoltammetry, respectively. The mesoporous carbon thin films reveal a conductivity similar to IrO 2 , high stability, and (tunable) accessibility, rendering them a promising model system for several applications like electrocatalysis and sodium‐ion batteries.