The surface area of a catalyst plays a crucial role in the rate of a heterogeneous catalytic reaction. In a heterogeneous catalytic reaction, the reactants and the catalyst are in different phases, typically solid and gas or liquid. The catalyst provides a surface for the reactants to adsorb, interact, and form products, which then desorb from the catalyst surface. The overall rate of the reaction depends on the number of active sites available on the catalyst surface.An increase in the surface area of a catalyst leads to a higher number of active sites available for the reactants to interact. This results in an increased rate of reaction, as more reactant molecules can simultaneously adsorb, react, and desorb from the catalyst surface. Conversely, a decrease in the surface area of a catalyst will result in a lower reaction rate due to fewer active sites being available for the reactants.Experimental evidence supporting the relationship between catalyst surface area and reaction rate can be found in numerous studies. One such example is the catalytic decomposition of hydrogen peroxide H2O2 on various metal catalysts, such as platinum, gold, and silver. In these experiments, the rate of the reaction is measured by monitoring the evolution of oxygen gas O2 as a function of time.By comparing the reaction rates of catalysts with different surface areas, it has been observed that the rate of the reaction increases with the increase in the surface area of the catalyst. For instance, in a study by Haruta et al. 1993 , gold nanoparticles were used as catalysts for the decomposition of hydrogen peroxide. They found that the reaction rate increased with decreasing particle size and thus increasing surface area of the gold catalysts.Similarly, in a study by Zhang et al. 2008 , platinum nanoparticles with varying sizes were used as catalysts for the same reaction. They observed that smaller nanoparticles with higher surface areas exhibited higher catalytic activity compared to larger nanoparticles with lower surface areas.These experimental findings support the notion that the surface area of a catalyst plays a significant role in determining the rate of a heterogeneous catalytic reaction. The higher the surface area, the more active sites are available for reactants to interact, leading to an increased reaction rate.