Cu1+ in heterometallic Cu2+[Ni2+(CN)4] utilized as electrocatalytic mediator.
Anodized Ti electrode and Ni2+(CN)4 favors the formation of Cu1+.
Removal of TCE gas attained 100% up to 4 L min−1 gas flow rate.
Electro-generated Cu1+[Ni2+(CN)4]1− helps TCE gas convert to CO2.