Fermi level pinning or semiconductor electrodes in aqueous and non aqueous electrolytes: influence of the modification of the electrode surface

Abstract

Fermi level pinning or semiconductor electrodes in aqueous and non aqueous electrolytes:influence of the modification of the electrode surface Modification of several semiconductors material surfaces with H4SiW12040.~zH70 have been carried out to produce an increase in the open circuit photopotential at the semiconductor/electrolyte interface (V,,) without changing the flat-band potential. The augmentation of V, , is shown to be attributed to a decrease of the minority carriers recombination at the semiconductor/electrolyte interface along with the suppression of Fermi level pinning. The enhancement of V, and the electrocatalytic activity of the hydrogen evolution reaction in acidic medium of the derivatized electrodes is attributed to the Fermi level unpinning.Key words: photoelectrodes, photoelectrocatalysis, pinning, modification improvement.0 . SAVADOGO. Can. J. Chem. 67, 382 (1989).La modification des surfaces de matkriaux semiconducteurs avec H4SiW 12040.nHz0 conduit a une augmentation de la tension en circuit ouvert des cellules photoClectrochimiques (V,,) et a une diminution de la surtension des cellules photoClectrocatalytiques pour la rtaction de dCgagement d'hydrogene en milieu acide. Les potentiels de bandes plates des materiaux ne sont pas influencCs par cette modification. Ces rCsultats sont attribuis a une diminution du taux de recombinaison des porteurs minoritaires due a la suppression de l'ancrage du niveau de Fermi des materiaux.

Characterizations of Antimony Tri‐Sulfide Chemically Deposited with Silicotungstic Acid

“…The activation of electrode surfaces by heteropolyacids (HPAs), e.g., H4SiW12040 or H3PW1204o has been well established and largely used in the electrocatalysis of the hydrogen evolution reaction at modified semiconductor or metal electrode surfaces (12,13). The significant improvement of the hydrogen evolution reaction kinetics has also been observed on electrodeposited nickel with various HPAs whereas the electrode fabricated without HPAs do not show any improvement (14,15).…”

Chemically deposited n-CdSe thin film photo-electrochemical cells: effects of Zn2+-modification

“…Surface modification of semiconductors has been shown to be an interesting technique for the improvement of the surface properties, thereby enhancing the efficiency and stability of photoelectrochemical (PEC) solar cell. While the initial investigations were carried out on GaAs and [nP [1][2][3][4][5][6], the studies were later extended to the II-VI, CdSe and CdTe [7][8][9][10][11][12][13][14][15][16][17] which are of technological interest for thin film solar cell and other opto-electronic devices. An increase of Voc and a significant decrease in Jo of CdSe electrodes has been observed after dipping in a solution of ZnCI z [11][12][13][14][15][16][17] or in an aqueous solution of KzCrO4 [18,19].…”