reductants and/or oxidants) used, a small portion of the film could remain in its oxide state at the time the hydrocarbon is introduced into the reactor. A fraction of these catalyst particles nucleate and grow CNTs, while the rest undergo (to varying degrees) coarsening, sub-surface diffusion or encapsulation by carbon (overcoating), rendering them inactive for growth. In the case of nonisothermal growth, because of cooling, one can expect catalyst coarsening to be mitigated due to a reduction in atom and particle diffusion. This is corroborated by our observation of similar particle sizes in the non-isothermal annealing experiment compared to isothermal annealing at 750 ºC (Figure ). The same reasoning can be applied to our observation of poor growth when the temperature was increased rather than decreased. Non-isothermal heating likely led to greater coarsening and therefore resulted in a higher fraction of inactive catalyst particles, reducing the CNT yield.