Pt-cathode hydrogen evolution enabled by low-potential [Co(en)₃]-intercalated layered MnO₂ anodes on bamboo and CNT composite films

A layered manganese dioxide (MnO₂) film with [Co(en)₃] intercalated as the gallery ion was fabricated on a carbon-based composite coating obtained by co-kneading bamboo charcoal and carbon nanotubes, followed by electrodeposition. Linear sweep voltammetry of the resulting [Co(en)₃]@MnO₂ film displayed anodic current maxima at +0.08, +0.56, and +1.10 V <i>versus</i> Ag/AgCl. Potentiostatic electrolysis at +1.10 V generated gas at the platinum counter electrode (cathode) opposite the MnO₂ anode. Gas-chromatographic analysis identified the product as hydrogen, released at a rate of 0.14 mL h^-1 from a 1.0 cm² Pt substrate under the applied potential. No visible oxygen bubbles were detected at the [Co(en)₃]@MnO₂ anode, indicating that continuous hydrogen evolution at the cathode proceeds through the primary reduction of MnO₂ by the interlayer [Co(en)₃] ions together with a secondary reduction of [Co(en)₃] by water molecules.