Porous materials impregnated with metal nanoparticles are extremely useful in catalysis, an industry that had a global turnover in 2010 of over three trillion dollars. Understanding the structure of these materials and how the chemistry of the catalytic processes is affected by it is of paramount importance in the development of new catalysts. Neutron diffraction is one of the few techniques are able to probe the structural aspects of these materials since the "magic" happens in the interior of nanopores.This proposal aims to quantify the inner surface chemistry of these materials by using "in place" isotopic substitution to modify the surface. To do this we will use water and heavy water, or H2 and D2 gas. Understanding how the addition of these compounds affects the scattering from the inner surface will help in developing our knowledge of the underlying chemical processes.