Experimental and first-principles theoretical studies on Ag-doped cuprous oxide as photocathode in photoelectrochemical splitting of water

• Published in: Journal of materials science 2014-01, Vol.49 (2), p.868-876
• Main Authors: Upadhyay, Sumant, Sharma, Dipika, Singh, Nirupama, Satsangi, Vibha R., Shrivastav, Rohit, Waghmare, Umesh V., Dass, Sahab
• Format: Article
• Language: English
• Subjects: Brillouin zones; CATHODES; Characterization and Evaluation of Materials; Chemistry and Materials Science; Classical Mechanics; Conduction bands; Copper oxide; Copper oxides; Crystallography and Scattering Methods; Cuprite; CUPROUS OXIDE; Density; Density functional theory; Dielectric films; DOPING; Electric properties; Electronic structure; Energy gap; First principles; Glass substrates; Indium; Indium tin oxides; Materials Science; MATHEMATICAL ANALYSIS; MICA; MICROSTRUCTURES; Nanostructure; OXIDES; Photocathodes; Photoelectric effect; Photoelectric emission; Polymer Sciences; Pyrolysis; Silver; Solar energy; Solid Mechanics; Spray pyrolysis; THIN FILMS; Valence band; Water splitting
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1007/s10853-013-7770-2

Nanostructured thin films of undoped and Ag-doped cuprous oxide were deposited on indium tin oxide-coated glass substrate using simple spray pyrolysis method for their use as photocathode in photoelectrochemical (PEC) cell for solar energy based water splitting. Combination of experiments and first-principles density functional theory based calculations was used to determine and understand the effect of Ag substitution on electronic structure and PEC performance. Thin films were characterized using XRD, FE-SEM, UV–Vis spectroscopy and PEC measurements. The results of DFT calculations show that the top of valence band and bottom of conduction band of undoped Cu 2 O lie at Г point of brillouin zone, respectively, suggesting that pure Cu 2 O is a direct band gap material. Minimal changes appear in the band gap and band gap energies in the Ag-doped Cu 2 O system, keeping it still a direct band gap material. A defect band appearance can be seen between −4 and −5 eV in the valence band consisting mainly of Ag 4d states and can be explained by a stronger interaction between the Ag 4d and O 2p, due to the larger Ag size. Ag-doped samples exhibit improved conductivity and fourfold increase in photocurrent density with respect to undoped samples.