Spontaneous Photoelectrolysis of HBr and HI

Abstract

Spontaneous and efficient photoelectrolysis of into hydrogen and bromine is reported for light of wavelengths to 950 nm in a p‐n photoelectrolysis cell composed of a photocathode with noble metal catalyst islands on the surface and an or an photoanode. Photoelectrolysis of with the same photoelectrodes yields hydrogen and iodine and simultaneously produces electrical power. The efficiency of the photoelectrolysis is calculated by two methods, one based on the stored free energy and the other based on electrical power saved. The efficiencies for photoelectrolysis by 632.8 nm light are 7.8%, if calculated by the first method, and 11.2%, if calculated by the second.