Enhanced gas-sensing by diamond nanoneedle arrays formed by reactive ion etching

Vertically aligned diamond nanoneedles were fabricated on nanocrystalline diamond (NCD) films by reactive ion etching (RIE), in which diamond nanoparticles similar to 10 nm in diameter seeded on the nanodiamond film to serve as an etching mask. The sensing ability of the elaborated diamond nanoneedle arrays was measured at room temperature with NH3 and NO2 diluted in air. The results showed that the diamond nanoneedle arrays had a greatly enhanced chemical sensing ability compared with the unmodified nanodiamond films, mainly due to the increased surface area-to-volume ratio and nanotip effect of the diamond nanoneedles. In addition, the diamond nanoneedle arrays evidenced different gas sensing processes when exposed to reducing and oxidizing gases, in which the direction of electron transport plays an important role. (C) 2011 Elsevier B.V. All rights reserved.