THEORETICAL INVESTIGATION OF OPTIMAL MIXING-RATIO FOR PBO2 AND TIO2 TO PRODUCE A LOW-BAND-GAP NON-CORROSIVE PHOTOELECTRODE

Abstract

A detailed characterisation of band gaps and the corresponding orbital profiles are offered for beta-PbO2, TiO2, and their 3:1, 1:1 and 1:3 mixtures using charge self consistent LCAO band structure (CSCBS) calculations with Bloch sums of STOs as the basis. The results indicate that an optimally non-corrosive reduced band gap electrode for photoelectrochemical solar cells may be produced from a 3:1 mixture of pure beta-PbO2 and TiO2 (both rutile). The position of band edges is used to construct decomposition potentials and predict photocorrosion behaviour for pure beta-PbO2, TiO2 and their (3:1), (1:1) and (1:3) mixtures. A detailed characterisation of the valence and conduction bands for all these compounds is also undertaken to offer a systematic guideline in the selection of compounds for fabrication of efficient photoelectrodes and the optimal ratio in which these should be mixed. The underlying mechanism is elaborated in detail to assist in this task.