[userulluipeste]

That induced hydrogen, which you're looking for, can very well be the material particles in the solar wind. They don't reach much the Earth because are mostly charged protons and thus collide with Earth's magnetosphere. However, the lack of a strong magnetosphere on Venus means that, once that carbon dioxide layer gets reduced to lower levels and the reactive (free) oxygen can stay below a certain altitude, that shower of hydrogen should naturally become water. Therefore, the key to water on Venus is the reduction of carbon dioxide levels and production of free oxygen.

I've touched this idea before: https://news.ycombinator.com/item?id=26575155