Previous MD simulations investigating the thermal decomposition of TCP on hydroxylated amorphous Fe 3 O 4 showed that the dominant reaction pathway involved Fe-C bonding. To investigate this further, we plotted the change in the number of carbon atoms bonded to iron atoms at different pressures and temperatures. The Fe-C bonds present in the Fe 3 C(010) surfaces before exposure to TCP are not included in the analysis. Figure shows the variation in the number of Fe-C bonds with time for the simulated TCP systems at 600 K between 1-5 GPa for α-Fe(110), Fe 3 C(010), and Fe 3 O 4 (100). The number of Fe-C bonds at a given time increases as Fe 3 O 4 (100) < Fe 3 C(010) < α-Fe(110), which is the same order observed for the rates of TCP decomposition for the three surfaces. We also see a clear trend of an increase in the number of Fe-C bonds, and therefore chemisorption of TCP, with an increase in pressure for all three surfaces. The increased bonding of the TCP carbon atoms on α-Fe(110) compared to Fe 3 C(010) and Fe 3 O 4 (100) can be visualised in the number density profiles shown in the ESI (Figure ). The carbon peaks from the TCP molecules show increased overlap with the iron peaks for α-Fe(110) than the other surfaces.