Electrochemical synthesis of Au-Ni(OH)2-nanocomposite on glassy carbon electrode as highly active bifunctional electrocatalyst for oxygen evolution and oxygen reduction reactions

- A new electrochemical method is demonstrated for the preparation of Au-Ni(OH)2-NC on GCE.
- More active β-Ni(OH)2 phase is formed during electrodeposition of Au-Ni(OH)2-NC/GCE.
- The Au-Ni(OH)2-NC/GCE shows excellent bifunctional activity towards ORR and OER.
- High electrocatalytic activity rely on synergism between AuNPs and β-Ni(OH)2,

In this work, we demonstrated an electrochemical method to prepare Au-Ni(OH)2-nanocomposite on a glassy carbon substrate (Au-Ni(OH)2-NC/GCE). This modified nanocomposite showed high electrocatalytic activity towards oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) compared to similarly prepared Au free Ni(OH)2-NC/GCE. The above nanocomposite was prepared through two step processes; first gold‑nickel hexacyanoferrate nanocomposite film on GCE (Au-NiHCF-NC/GCE) was synthesized by single step electrochemical cycling approach. Later, the Au-NiHCF-NC/GCE was treated electrochemically in alkaline solution to produce Au-Ni(OH)2-NC/GCE. The as-formed Au-Ni(OH)2-NC/GCE was used as a bifunctional electrode to study the OER and ORR in alkaline solution. The resulting nanocomposite exhibits high electrocatalytic activity and fast electron transfer kinetics due to the synergic effect of the formation of more active β-Ni(OH)2 phase and Au nanoparticles (AuNPs) during the electrochemical cycling process.