I finished reading a science fiction book series, and it was based on mars, where they were developing carbon dioxide generators to realase the gas into the air to create a thicker and sutainable enviroment to go out onto the surface without a space suit. Is this/ could this be theoretically possible?

With planning and construction of semi-permanent moon bases and similar for Mars, infrastructure will have already been considered, including electrics. Have the engineers pondered this question too? And have they decided on a solution.