1986 Volume 59 Issue 2 Pages 599-605
The electrochemical behaviors of van der Waals face of p-InSe single crystal electrodes in 0.5M H2SO4 and 1M NaOH (1M=1 mol dm−3) with and without illumination have been thoroughly investigated. In 0.5M H2SO4, relatively large cathodic dark current was observed and the onset potentials for the current in dark and under illumination were ca. −0.8 V (vs. Ag/AgCl) and ca. −0.5 V, respectively, at as-prepared electrode. The current seemed to be mainly due to hydrogen evolution reaction. The dark current decreased significantly and the photo-current increased by removing surface steps. These results and impedance analyses show that the surface steps create surface states which act as recombination centers and mediators for charge transfer. Both the dark- and photocurrent onset potentials in 1M NaOH were more negative than those in 0.5M H2SO4 by ca. 0.5 V. The dark current was quite large and the photocurrent was small in 1M NaOH even after removing surface steps. By depositing Pt on p-InSe, the photocurrent onset potential shifted towards positive by several hundred mV. The reaction mechanism of photoelectrochemical hydrogen evolution was discussed by considering the above results.
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