Here are two gases that are more dense than carbon dioxide at standard temperature and pressure (STP):

* Sulfur hexafluoride (SF6): This gas is about 5 times denser than air and over 6 times denser than carbon dioxide. It's often used in electrical applications due to its excellent insulating properties.

* Xenon (Xe): This noble gas is about 4.5 times denser than air and roughly 5 times denser than carbon dioxide. It's used in some lighting applications and medical imaging.

Important Note: Density of gases can vary depending on temperature and pressure.