From the appearance of hot spots in the contour plots in Figure and, it is clear that the yield is maximized for a specific combination of ΔT and Δtc. For Tf = 680 ºC, the optimal temperature difference appears to be between 200 and 250 ºC, with a cooling rate of ~10 s (Figure ). Growth experiments outside this range exhibited a significant decrease in yield (𝐺 -./ decreased by an order of magnitude). Remarkably, this combination of ΔT and Δtc also resulted in high max. growth rates (Figure ) and lifetimes (Figure ). This achievement of high growth rates and lifetimes in non-isothermal growth overcomes a commonly observed limitation in the growth kinetics, namely the inverse relationship between CNT growth rate and catalyst lifetime.