“…In this case, the catalyst morphology was based on Ni particles dispersed in the DLC matrix as also reported in previous studies [19][20][21], being the surface area of the resultant catalyst film a difficult measurable parameter. Although the resolution of these SEM images did not allow appreciating nickel particle sizes below 100 nm, the presence of these dispersed particles, even after the catalytic activity measurements at 320 ºC, denotes the enhanced thermal stability and wear resistance of metal-DLC composites commonly shown in literature [30,31]. Hence, the stabilization of the Ni particles by the DLC matrix under the studied reaction conditions is in good agreement with the high structure stability reported in literature for other metal-DLC composites [17,[32][33][34], annealed even at 800 ºC [34].…”