Which of Pluto's moons has scientists just discovered the gases hydrogen peroxide and carbon dioxide?

On Charon, Pluto's biggest moon, scientists discovered hydrogen peroxide and carbon dioxide. Charon was found in 1978 and is 1,214 kilometres wide, half the size of Pluto. It takes its name from the Greek mythological ferryman of dead souls. With masses more than a tenth of Pluto's, Charon and Pluto make up a twin dwarf planet system. Pluto and Charon are separated by 19,640 km. Both bodies are tidally locked, meaning they are always on the same side of one another. In 6.4 Earth days, Charon completes one round around Pluto.