First of all I would not call HO and CO as a functional group. They are molecules and I supposed that they were not covalently binded. Secondly it is very difficult to understand something from your question except the fact that the all peaks were gone. The fact that H2O and CO2 are not presented in the spectra might be because your contamination dissapeared.

However you need to clarify what is PURE nanocomposite and what you by "you increasedd the concentration of composite? When during preparation of analysis?

Hi! it is very difficult to predict until you say what is the composite, still I would say if your pure compound is, say Graphene Oxide, then you will not find any peaks related to OH- or -CO groups, present in the pure compound. 

I have synthesized WO3 and Graphene nanocomposites. In Pure WO3 i have observed CO2 OH and H2O  peaks in FTIR. When i induce Graphene in WO3 the intensity of OH CO2 and H2O peaks are decreased. Further increase in the concentration of Graphene in WO3 cause total vanishing of these peaks. So i want to know why this happening what is the physics behind this? @ Anton Manakhov

"Further increase in the concentration of Graphene in WO3 cause total vanishing of these peaks"

I think it is the other way around. Increase the concentration of WO3 into graphene, the peaks are decreased, because there might strong interaction between WO3 and graphene, where the functional groups have taken part.

But still, I would say that graphene does not have strong peaks corresponding to H2O, OH and CO. These are strongly present in graphene oxide (GO), while making the composite, GO transform to rGO (reduced graphene oxide), hence, the peaks got decreased.

I suppose that you are not simply mixing Graphne with WO3, right? YOu are doing thermal treatment, I suppose? That would explain the desorption of H2O and CO2. But I might be wrong, cause I dont know the procedure of NC preparationj in your case.

I'm agree with Dr Malakhov the explanation could be on your reacting conditions (temperature, irradiation..) or even in your reacting mechanism. For example at room temperature reaction you can check the article of Qin et al, Graphene-wrapped WO3 nanoparticles with improved performances in electrical conductivity and gas sensing properties. J. Mater. Chem., 2011, 21, 17167-17174; where they claim the formation of O2 by water reduction on WO3, that could help to the desorption by displacement. But unfortunately their IR shows the opposite of your case. Just keep in main both; conditions or mechanism which let the desorption.