Abstract: Methods of fabricating nano particulate Titanium dioxide photocatalysts onto a conducting substrate are disclosed. The methods include hydrothermal fabrications with heat treatment steps to increase the crystallinity and photoactivity of the titanium dioxide layers.

Abstract: Methods of fabricating nano particulate Titanium dioxide photocatalysts onto a conducting substrate are disclosed. The methods include hydrothermal fabrications with heat treatment steps to increase the crystallinity and photoactivity of the titanium dioxide layers.

Abstract: A method of determining chemical oxygen demand (COD) of a water sample, which is useful in an on-line configuration comprising the steps of a) applying a constant potential bias to a photoelectrochemical cell, having a photoactive working electrode, optionally a reference electrode and a counter electrode, and containing a supporting electrolyte solution; b) illuminating the working electrode with a light source and recording the background photocurrent produced at the working electrode from the supporting electrolyte solution; c) adding a water sample, to be analysed, to the photoelectrochemical cell; d) illuminating the working electrode with a light source and recording the hydro dynamic photocurrent produced under continuous flow of the water to be analysed; e) determining the chemical oxygen demand of the water sample using a number of different formulae. The applied potential is preferably from ?0.4 to +O.8V more preferably about +0.3V.

Abstract: A method of determining chemical oxygen demand (COD) of a water sample which is useful in a probe configuration includes the steps of a) applying a constant potential bias to a photoelectmchemical cell, having a photoactive working electrode optionally a reference electrode and a counter electrode, and containing a supporting electrolyte solution; b) illuminating the working electrode with a light source and recording the background photocurrent produced at the working electrode from the supporting electrolyte solution; c) adding a water sample, to be analysed, to the photoelectrochemical cell; d) illuminating the working electrode with a light source and recording the steady state photocurrent produced with the sample; e) determining the chemical oxygen demand of the water sample using the formula (I): where ? is the Nernst diffusion layer thickness, D is the diffusion coefficient, A is the electrode area, F the Faraday constant and iss the steady state photocurrent.

Abstract: A method of determining chemical oxygen demand in water samples containing chloride ions above 0.5 mM concentration in which the samples are diluted and a known quantity of an organic substance is added to the diluted sample which is the subjected to an assay by a photoelectrochemical method using a titanium dioxide nanoparticulate semiconductor electrode and measuring the photo current produced until a stable value is reached and then using the difference between the initial and stable photocurrents as a measure of the chemical oxygen demand. An alternative method involves determining chemical oxygen demand in water samples containing chloride ions by measuring the chlorine content and measuring chemical oxygen demand by a photoelectrochemical method using a titanium dioxide nanoparticulate semiconductor electrode and adjusting the chemical oxygen demand measurement using the chlorine measurement.