Facile Deposition of Metal Films on a Diamond Protected Silicon Window for In Situ ATR-IR Spectroelectrochemistry across a Wide pH Range

Facile fabrication of thin metal films on protected silicon internal reflection elements (IREs) is essential for electrochemical attenuated total reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) in various pH electrolytes to cater for broad application scenarios. In this technical note, we report a facile and low-cost chemical deposition tactic to fabricate robust Au, Pt, and Pd films on resistive boron-doped diamond-coated silicon wafer (BDD/Si) IREs, enabling electrochemical ATR-SEIRAS measurements with extended low-frequency detection in harsh acidic and alkaline solutions. This is achieved by initial seeding of metallic nuclei through the ultrafine nanochannels of the BDD protective layer, followed by further growth into a conductive metal film. Compared to those prepared by physical deposition, the as-deposited metal films on BDD/Si IRE exhibit excellent stability against multiple potential cycling and hydroxide attack as well as a higher IR absorption for surface CO species. Based on this tactic, in situ ATR-SEIRAS study of CO adsorption on Au, Pt, and Pd electrodes in solutions of pH1 and pH14 is comparatively probed, together with that of the interfacial hydrogen-bond broken H₂O.