Pretreatment of stainless steel substrate surface for the growth of carbon nanotubes by PECVD

Multiwalled carbon nanotubes were grown from acetylene and hydrogen gas mixture directly on stainless steel plates by rf powered PECVD and then electric double layer capacitors were fabricated from them without any further treatment. It was found that suitable pretreatment of stainless steel substrates was required for the satisfactory growth of carbon nanotubes on them. In this study substrates were polished, etched in HF solution and then treated with hydrogen plasma before the growth of carbon nanotubes. SEM shows that the surface of the substrate became smooth after polishing. It was severely etched to reveal grains of stainless steel after dipping in HF solution. With hydrogen plasma treatment the grains become more rounded in shape and grew in size. When the grains size was tens of nanometers, carbon nanotubes were grown. Exposing substrates to the hydrogen plasma for 10 min or longer caused the grains to grow larger and the growth of carbon nanotubes became poorer. Carbon nanotubes grown in this study were mutiwalled and curly in shape. Capacitors made from the carbon nanotubes showed initial specific capacitance in the range of 80–100 F/g.