Charge-Tuned CO Activation over a χ-Fe₅C₂ Fischer–Tropsch Catalyst

We performed DFT calculations to understand CO activation over a χ-Fe5C2 Fischer–Tropsch catalyst. The χ-Fe5C2 catalyst exhibits unique CO activation behaviors, and the BEP relation is nearly valid for this system. The physical basis of this relation mainly originates from the site-dependent charge of the involved surface Fe atoms for the CO activation. This descriptor is also applicable to describe the CO activation on the χ-Fe5C2 catalyst with more complex surface properties involving K promoter, nonstoichiometric termination, and/or carbon vacancy. The insights revealed here might guide the rational catalyst design via surface electronic modification.