The interesting electrochemical stability and reversibility of BT-DCAF made us move forward to evaluate BT-DCAF for electrocatalytic H2 evolution in presence of different acids. As a strong acid, trifluoroacetic acid (TFA, pKa = 0.23 in water) was incorporated into the solution of BT-DCAF and studied first (Figures and). Processes occurring at different time scales can be identified and monitored by varying the scan rate in a CV experiment. For the first reduction of BT-DCAF, a consistent shift from -1.42 V (vs Fc + /Fc) to -1.19 V (vs Fc + /Fc) was observed when TFA was added to the solution. This shift of 0.23 V is indicative of BT-DCAF being capable of binding protons upon reduction, forming a new chemical species. Integration of the signal corresponding to the first reduction process obtained at 1 V/s and 100 mV/s (Figures and) reveals that upon addition of TFA, the reduction of BT-DCAF goes from being a one-electron process (absence of TFA) to a two-electron process (presence of TFA). Considering the electronic properties of BT-DCAF and the electrochemical reactivity of other BT molecules, this new species is assigned to a doubly reduced double protonated species BTH2-DCAF. Additionally, the CV at the fastest scan rate evaluated (1 V/s) showed an oxidation process at -0.78 V (vs Fc + /Fc) during the anodic scan (Figure ), this peak is assigned to the one-electron oxidation of BTH2-DCAF to form the radical cation [BTH2-DCAF] •+ . Notably, the cyclic voltammogram obtained at the slowest scan rate (10 mV/s) showed a significant increase in current for a new redox event Ep = -1.60 V (vs Fc + /Fc), this signal revealed the electrocatalytic properties of BT-DCAF towards the H2 evolution reaction.