Photoelectrochemical hydrogen evolution

The (photo)electrochemical behavior of p-InSe single-crystal vdW surface was studied in 0.5 M H2SO4 and 1.0 M NaOH solutions, in relation to the effect of surface steps on the crystal [183]. The pH-potential diagram was constructed, in order to examine the thermodynamic stability of the InSe crystals (Fig. 5.12). The mechanism of photoelectrochemical hydrogen evolution in 0.5 M H2SO4 and the effect of Pt modification were discussed. A several hundred mV anodic shift of the photocurrent onset potential was observed by depositing Pt on the semiconductor electrode. 

Djellal L, Omeiri S, Bouguelia A, Traii M (2009) Photoelectrochemical hydrogen-evolution over p-type chalcopyrite CulnSe2. J AUoys Compd 476 584-589... 

Aspnes DE, Heller A (1983) Photoelectrochemical hydrogen evolution and water- photolyzing semiconductor suspensions Properties of platinum group metal catalyst emiconductor contacts in air and in hydrogen. J Phys Chem 87 4919-4929... 

Aspnes, D.E. and Heller, A. 1982. Photoelectrochemical Hydrogen Evolution and Water-Photolyzing Semiconductor Suspensions Properties of Platinum Group Metal Catalyst-Semiconductor Contacts in Air and in Hydrogen. J. Phy s. Chem., 87, 4919-1929. 

U. T. Mueller-Westerhoff and A. Nazzal, Ferrocenophanes as effective catalysts in the photoelectrochemical hydrogen evolution from acidic aqueous media, J. Am. Chem. Soc. 106, 5381, 1984. 

Study of photoelectrochemical hydrogen evolution at p-Inp , J. Electroanal. Chem. 397,45-52. 

A comparison of this method with photoelectrochemical impedance spectroscopy" as applied to photoelectrochemical hydrogen evolution at p-lnP has been reported [728]. Intensity modulated photocurrent spectroscopy has been compared with intensity-modulated photo voltage spectroscopy (IMVS) [729]. Intensity modulated photocurrent spectroscopy has been applied in a study of the silicon dissolution in aqueous solutions of NH4F [730] and n-GaAs electrodes [731] a general review is available [732]. Photocorrosion of CdS has been investigated with IMPS and photoelectrochemical impedance spectroscopy (PEIS) [733] a mechanism could be de-... 

Basu M, Zhang ZW, Chen CJ, Chen PT, Yang KC, Ma CG, Lin CC, Hu SF, Liu RS (2015) Heterostracture of Si and CoSc2 a promising photocathode based on a non-noble metal catalyst for photoelectrochemical hydrogen evolution. Angew Chem Int Ed 54 6211... 

Fig. 3.4a Schematic representation of a conventional three-electrode photoelectrochemical cell showing WE = working electrode, RE = reference electrode, CE = counter electrode. If the working electrode is an n-type semiconductor and the counter electrode is a metal, then oxygen evolution occurs at the WE and hydrogen evolution occurs at the CE.

Fretwell R, Douglas P (2002) Nanocrystalline Ti02-Pt photoelectrochemical cells-UV induced hydrogen evolution from aqueous solution of ethanol. Photochem Photobiol Sci 1 793-798... 

ZnS-CdS (bandgap = 2.3-2.4 eV) composite semiconductor photoelectrodes show a broad spectral response and n-type behavior, with saturation of the anodic photocurrent upon increasing anodic potential making the system suitable for use as a photoelectrochemical cell photoanode [72], Nanostructured ZnS-CdS thin film electrodes show that anodic photocurrent saturation can be attained with the application of a small, 0.1 V, bias [73], while hydrogen evolution is observed at the Pt cathode. The performance of the ZnS-CdS photoanodes appear strongly dependent upon the method of film preparation [72,73], with Zn rich films demonstrating superior photocurrent generation, and stability, in comparison to Cd rich films. 

Tafel s law applies also in current density ranges well below that of the limiting current at semiconductor/solution interfaces and to photoelectrochemical reactions. Its application to liquid-liquid interfacial electron transfer is also good [see Fig. 9.25(d)] (Schmickler 1995). In hydrogen evolution, it has been followed down to the picoam-pere region and up to 100 A cm-2. 

Carbon-carbon coupling of radicals observed in the photo-Kolbe reaction could also be observed with other surface generated radicals. Kisch and coworkers have shown, for example, that cyclic allylic ethers undergo alpha deprotonation under photoelectrochemical activation, producing radicals that can be oxygenated, Eq. (29). On colloidal zinc sulfide, hydrogen evolution accompanies the photocatalytic... 

Many photoelectrochemical reactions of interest involve multistep electron transfer reactions. Examples that have been studied are hydrogen evolution on InP [29] and Si [30], oxygen evolution on Ti02 [31] and photodecomposition of CdS [32]. These reactions involve the formation of charged surface bound intermediates, and the accumulation of surface charge modified the potential distribution across the interface. For example, the photodecomposition of n-CdS is believed to occur by the route... 

An example of recent achievement in this area is a flexible, thin film Cu(In,Ga)Se2 solar cell deposited on a titanium foil, which was combined with a TiC>2 photocatalyst layer and modified by a niobium-doped titanium oxide front electrode to function as a photoelectrochemical tandem cell/membrane for a direct light-driven hydrogen evolution from an aqueous solution [48], Under illumination with UV/vis light, the system produced up to 0.052 pLH2/scm2 (e.g. the hydrogen formation rate was approximately 7,250 pmol/h g relative to the amount of TiC>2 used). Several aspects of the operating principles of the photoelectrochemical devices, the materials requirements, main bottlenecks, and the various device concepts (in relation to H2... 

Neumann B, Bogdanoff P, Tributsch H. TiC>2-protected photoelectrochemical tandem Cu(In,Ga)Se2 thin film membrane for light-induced water splitting and hydrogen evolution. J Phys Chem C. 2009 113 20980-9. 

The quantum efficiency of photoelectrochemical reactions may vary from 2 to 4, effective dissolution valence from 2 to 4, and efficiency of hydrogen evolution from 1 to near zero depending on light intensity and potential. 

It is important to determine the conductivity and flat-band potential ( ft) of a photoelectrode before carrying out any photoelectrochemical experiments. These properties help to elucidate the band structure of a semiconductor which ultimately determines its ability to drive efficient water splitting. Photoanodes (n-type conductivity) drive the oxygen evolution reaction (OER) at the electrode-electrolyte interface, while photocathodes (p-type conductivity) drive the hydrogen evolution reaction (HER). The conductivity type is determined from the direction of the shift in the open circuit potential upon illumination. Illuminating the electrode surface will shift the Fermi level of the bulk (measured potential) towards more anodic potentials for a p-type material and towards more cathodic potentials for a n-type material. The conductivity type is also used to determine the potential ranges for three-electrode j-V measurements (see section Three-Electrode J-V and Photocurrent Onset ) and type of suitable electrolyte solutions (see section Cell Setup and Connections for Three- and Two-Electrode Configurations ) used for the electrochemical analyses. 

A theory of the photoelectrochemical kinetics of the hydrogen evolution reaction at the metal-solution interface was developed by Bockris, Khan, and Uosaki. This theory takes into account photoemission into the solution, the reflective properties of the electrode material, absorption of light by the electron, and the excitation probability from photon-electron interactions. 

Fig. 7.4 Schematic eneigy band diagram for an ideal photoelectrochemical cell with a singleabsorber semiconductor photoanode and a metal cathode for light assisted water splitting. The electrochemical potentials for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) are represented by —qE°, where represents the reduction potential for the corresponding redox couples...

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