Photoelectrolytic generation

Early examples in the 1980s were aimed at the design of composite systems for photoelectrolytic generation of H2. Thus, Nafion and Si02 were used as supports for coprecipitated ZnS and CdS for photoassisted HER from aqueous sulfide media [407]. Subsequent work has addressed the mechanistic role of the support in the photoassisted HER [408]. Vectorial electron transfer was demonstrated in bipolar Ti02-Pt or CdSe-CoS photoelectrode panels arranged in series arrays for the photodecomposition of water to H2 and O2 [409, 410]. 

Fig. 10-28. Polarization curves for cell reactions of photoelectrolytic decomposition of water at a photoezcited n-type anode and at a metal cathode solid curve M = cathodic polarization curve of hydrogen evolution at metal cathode solid curve n-SC = anodic polarization curve of oxygen evolution at photoezcited n-type anode (Fermi level versus current curve) dashed curve p-SC = quasi-Fermi level of interfadal holes as a ftmction of anodic reaction current at photoezcited n-type anode (anodic polarization curve r re-sented by interfacial hole level) = electrode potential of two operating electrodes in a photoelectrolytic cell p. sc = inverse overvoltage of generation and transport ofphotoezcited holes in an n-type anode.

Figure 13. Schematic of the photoelectrolytic cell designed for the generation of hydrogen using a light source (UV or visible). The anode is carbon-doped titania nanotubular arrays prepared by the sonoelectrochemical anodization technique and the cathode is platinum nanoparticles S3mthesized on undoped titania nanotubular arrays. (Redrawn from Misra et al. [220] with permission from publisher, American Chemical Society. License Number 2627061508363).

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