2019 Volume 65 Issue 1 Pages 19-27
In order to achieve the spontaneous hydrogen (H2) evolution by using a photochemical reaction of fullerene (C60), voltammetric behaviors of C60 and its anion radical (C60•−) were investigated by means of voltammetry with an electron conductor separating oil-water (ECSOW) system. Nitrobenzene (NB) solutions and acidic aqueous solutions were used as the oil phase and the water (W) phase, respectively. In this work, two working electrodes with greatly different areas were used as the electron conductors, although two working electrodes with almost the same areas are usually used in voltammetry for the ECSOW system. As a result, we confirmed that the currents are controlled by the working electrode with a smaller area. Especially, when a microelectrode was used in the NB phase containing C60 or C60•−, s-shaped voltammograms with limiting currents were obtained and thereby the diffusion coefficients of C60 and C60•− were easily estimated to be 3.2×10−6 and 2.9×10−6 cm2 s−1, respectively. On the other hand, we could determine a criterion for the spontaneous H2 evolution from the voltammogram measured for the ECSOW system, considering that the potential of the voltammogram corresponds to the electromotive force of the voltaic cell consisting of the NB and W phases. Based on this criterion, we supposed conditions for the spontaneous H2 evolution and successfully achieved the spontaneous H2 evolution using a photovoltaic cell.
