Figure4

Figure 4. FTS reaction pathways on $$ \chi $$-Fe$$ _5 $$C$$ _2 $$(510) surface, including (A) dissociation of H$$ _2 $$ and CO on A-P5 site; (B) *CH-*C coupling and following steps towards long-chain (C$$ _{2+} $$) hydrocarbon products; (C) *CH-*H coupling steps towards CH$$ _4 $$ product; and (D) *CH-*CH coupling steps towards CH$$ _2 $$CH$$ _2 $$ product. In these plots, red line denotes that the PES calculations are done merely by FT$$ ^2 $$DP, blue line denotes that the calculated data are acquired by single-point DFT calculation after FT$$ ^2 $$DP optimization, purple line denotes that the PES calculations are purely performed by DFT calculation, and C$$ _v $$ stands for carbon vacancy on A-P5 site. All the top views are for DFT-optimized structures. Orange: Fe atoms; Grey: C atoms; White: H atoms; Red: O atoms. FTS: Fischer-Tropsch synthesis; PES: potential energy surface; FT$$ ^2 $$DP: fine-tuned Fischer-Tropsch deep potential; DFT: density-functional theory.