Yes, pitcher plants give off oxygen. Pitcher plants are green because they have green chlorophyll molecules that help make oxygen from sunlight.

Here's an interesting article about research using pitcher plants to study plants and lakes and water; the pitcher plant has a tiny 'lake' of water inside its pitcher that's easier to study than a whole lake:

Thank you for your question. I didn't know about the research on pitcher plants, and I think it's exciting.

The pitcher plant is carnivorous, so it does get some of its energy from prey. But because it is still a plant, it also gets energy from photosynthesis. So the pitcher plant produces oxygen as a product of photosynthesis.

Yes, pitcher plants (and other meat-eating plants) get their energy from the sun like any plant, and to do that they give off oxygen as waste.

Pitcher plants eat insects not for the energy contained in the insects' bodies, but for certain elements: nitrogen, phosphorous, and sulfur. Most plants get these elements from the soil, but pitcher plants live in soils where these elements are rare, so they need to get them from in a different way. A pitcher plant living in rich soil wouldn't even need to eat insects, since again, they get their energy from the sun.

All plants give off oxygen! To produce their energy, plants perform the process of photosynthesis to convert sunlight into sugar. Part of this process involves the production of oxygen, which the plant releases to the environment. Even though pitcher plants trap and digest bugs, photosynthesis is their source of energy. Instead of a source of energy, the insects are a source of nutrients that might not be present in the soil.