Yes, all the plants release oxygen in the daytime while the process of photosynthesis is done. But photosynthesis can only be done in the presence of sunlight i.e. daytime.
Carbon Dioxide is released throughout the day by the process of respiration but in the daytime it is compensated by the absorption of more carbon dioxide than released for photosynthesis. Again, since photosynthesis can only be done in the presence of sunlight i.e. daytime, in the night there is no way to absorb CO2 and hence it is released