Insulating Polymer‐Hydrogel Nanocomposite Thin Film ‐ Based Catalytic Electrode for Efficient Oxygen Evolution Reaction

The counter‐intuitive choice of an insulating polymer for embedding electrocatalysts is shown to facilitate a simple and general strategy to fabricate catalytic electrodes for efficient oxygen evolution reaction (OER) during water splitting. The hydrogel characteristics and appreciable swelling of the polymer in aqueous medium are the key enabling factors; electrolyte absorbed in the polymer matrix is likely to be involved in the electrocatalytic process. Nanocomposite thin films of chitosan spin‐cast on common conducting substrates, with an optimal content of NiO and [Ni,Fe]O nanoplates generated through a facile and simple in situ protocol, are shown to effect OER with excellent overpotentials (down to 240 mV at 10 mA/cm2), low Tafel slope, high Faradaic efficiency, appreciable turn‐over frequency, and extended stability with high current density. Preliminary investigations with a range of catalyst‐polymer combinations illustrate the general applicability of the approach. The fabrication of robust electrodes using insulating polymer‐hydrogel nanocomposite thin films, spin‐coated on conducting substrates with in situ generated semiconductor nanoplates, is reported. Efficient oxygen evolution is demonstrated using these electrodes.