Reaction kinetics: describe question

A student investigates the decomposition of hydrogen peroxide, $\ce{H2O2}$, which slowly decomposes to water and oxygen at room temperature. Adding a small amount of solid manganese(IV) oxide, $\ce{MnO2}$, causes rapid effervescence.

Describe how the heterogeneous catalyst $\ce{MnO2}$ increases the rate of this reaction. In your answer, explain the change in mechanism, use the Boltzmann distribution to account for the increase in rate, and describe how the reaction pathway diagram would differ in the presence of the catalyst.