Tafel slope analysis (Figure ) provides additional mechanistic insights by revealing distinct rate-determining steps (RDS) for ethane and ethylene. Specifically, the Tafel slopes for ethane (92.3 mV/dec) and ethylene (108.8 mV/dec) on the CTC-65 catalyst indicate efficient charge transfer kinetics but distinct RDS for each C2 product. The lower Tafel slope for ethane suggests that the RDS is the protonation of CO dimers, which aligns with a hydrogenation pathway. This is facilitated by Cl ions that stabilise CO intermediates, enhancing the local CO concentration and promoting hydrogenation to ethane. Conversely, the higher Tafel slope for ethylene suggests that C-C coupling is the RDS, involving CO dimerization followed by dehydrogenation. This aligns with the role of Sn species, which enhance CO binding strength and promote C-C coupling through electronic modifications of the Cu surface. These