if TiO2 absorbs too much sunlight in the photo catalyst process, It may prevent further decomposition .

any experiments done so far?

The question is not correct. Probably you want to know how the activity of TiO2 depends on light intensity. Do your own literature search 

Dear  Harrish Sajiv 

First of all you have to carry out UV-vis-DRS  analysis on  your TiO2 powder to determine the band absorption edge.

Secondary, you must to know the LUMO and HOmo énergies of the explored pollutant;

in order to see if it is about photocatalysis process or an other mechanisme

Regards

the way to think about the problem is to model how light is absorbed by homogeneous solutions and add a reflective factor to that to account for surface reflectivity of a heterogenous (particle) system. The simplest realations is

                         Light absorbed = light incident on particle -reflected light

As the fraction of incident light intensity absorbed by the catalyst particle gets closer to the incident light intensity, the less effect light intensity has on the rate of the photochemical reaction, so that at low intensities loss of the reactant may be close to first order, the rate of loss becomes independent of intensity when the fraction absorbed is very high.

In other words, while the photochemistry is not affected by intensity in any normal intensity range,  the rate of reaction no longer increases at high intensity

I agree with the explanation of Prof.Theodore Mill.The energy of the incident light is the deciding factor and not its intensity. and as rightly pointed out by him the rate of loss  becomes independent of intensity when the fraction absorbed is very high

I agreed with Prof Yurii that you need to understand the fundamental of TiO2 photocatalysis before proceed with the question.