Catalyst: A catalyst is a substance that increases the rate of a chemical reaction without undergoing any permanent change itself.
Platinum Group Metals (PGMs): The platinum group metals consist of six chemically similar elements - platinum (Pt), palladium (Pd), rhodium (Rh), ruthenium (Ru), iridium (Ir), and osmium (Os). They exhibit similar properties, including their ability to act as catalysts.
Surface Area: In the context of catalysis, surface area refers to the total exposed area of a solid catalyst. A higher surface area allows more reactant molecules to come into contact with the catalyst, increasing the reaction rate.