Influence of pulsed laser ablation temperature on structure, morphology and electrocatalytic properties of cobalt-based films deposited on carbon cloth

Abstract

Cobalt-based electrocatalytic films on electrochemically activated carbon cloth (EACC) were prepared by pulsed laser deposition (PLD) technique at different substrate temperatures. The composition, nanostructure and morphology of the films were thoroughly characterized and their electrocatalytic activities towards hydrogen and oxygen evolution in alkaline solutions were assessed. The electrochemical performances were correlated with material characteristics. The cobalt-based film morphology and structure changed significantly with increasing growth temperature, from nanocrystalline dense film, through uniform monocrystalline nanopillar structure, up to coarser irregular grains. Also, the film composition has clearly changed in the series of electrodes. The films prepared at lower temperatures were predominantly composed of CoCO3, while at higher temperatures their primary component was Co3O4. For prepared electrodes, the influence of material morphology on hydrogen evolution activity is shown to be pivotal, while no effect of material composition on performance is confirmed. Careful control over deposition parameters enabled formation of the film with optimal electrocatalytic performance towards both HER and OER, characterized with nanopillar morphology topped with pyramid-shape caps, providing high electrochemically active surface area for electrochemical reactions. The optimized electrode requires the overpotentials of 270 and 400 mV to deliver the current density of 10 mA cm−2 for HER and OER respectively.