Preparation characterizatin and investigation of their electrocatalytic effects on hydrogen gas production

Highly efficient and stable three-dimensional (3D) Ni nanodome (Ni-NDs) arrays were fabricated as candidate cathode material for alkaline water splitting. The NDs were prepared by a combined method of soft lithography-nanosphere lithography, physical vapor deposition and electrochemical methods using polydimethylsiloxane as template. The surface structures of nanodomes were examined by scanning electron microscopy and atomic force microscopy. The water splitting activity of the 3D nanostructures were examined in 6 M KOH solution using polarization and electrochemical impedance spectroscopy techniques. Their surfaces were also electrochemically characterized using cyclic voltammetry technique. The electrochemical stability of the Ni-NDs electrode in the electrolysis conditions was tested by electrochemical impedance spectroscopy. The data obtained showed that well-structured and uniformly distributed Ni-NDs could be fabricated using this combined method. The ND arrays perform excellent hydrogen evolution activity with respect to Ni plate as a reference point since their nano-sized roughness results in larger real surface area. By comparing with Ni plate, lower hydrogen onset potential (85 mV) and charge transfer resistance (90.1%) as well as higher current density (90.4%) corresponding to the amount of evolved hydrogen were observed at the NDs. The Ni-NDs have high time-stability in the electrolysis conditions. It is believed that the Ni-ND arrays contribute to the design of novel electrocatalytic electrodes as candidate supporting materials.