Fig. 3. (a) CVs of the Re(i) complex (0.5 mM) in a DMF–TEOA mixed solution (5 : 1 v/v) containing Et₄NBF₄ (0.1 M) under 100% (blue), 10% (purple), and 1% (maroon) CO₂ atmospheres and under an Ar atmosphere (red). The sweep rate was 200 mV s^–1. A glassy carbon electrode (diameter: 3 mm), an Ag/AgNO₃ (10 mM) electrode and a Pt wire were used as working, reference, and counter electrodes, respectively. (b) Relationship between the catalytic current at –1.95 V and the square root of the dissolved CO₂ concentration.