Chitosan-based hybrid nanocomposite on aluminium for hydrogen production from water

The activity of the hydrogen evolution reaction (HER) has been investigated on a polypyrrole-chitosan composite film decorated with a small amount of gold (Au) nano-particles coated on an aluminium electrode. The facile aluminium modified with such a hybrid nanocomposite and its performance was investigated for hydrogen evolution for the first time. A simple two-step approach was applied, including the first co-electrodeposition of polypyrrole and chitosan at a constant current electrolysis accompanied by the electrodeposition of Au nanoparticles via cyclic voltammetry. The chitosan (Chi), which is available in abundant quantities as a raw material, was incorporated into polypyrrole (PPy) chains, and it plays a key role in keeping metal nanoparticles highly dispersed and interconnected through the formation of a collaborative hybrid network. The low loading (approximate to 2 wt%) of Au on this composite film favoured the related reaction more with a high cathodic current density and reduced the Tafel slope (-152 mV dec(-1)) confirming that the reaction proceeded via the Volmer-Heyrovsky mechanism with a rate control step by the Volmer reaction (proton discharge step). In addition, the long-term durability over 8 h achieved this hybrid composite as a promising nano-electrocatalyst for HER.