Solar Chemical (artificial photosynthesis)
Sometimes direct-to-hydrogen processes are referred to as artificial photosynthesis, but there are other types as well such that aim to use carbon dioxide and water along with the sunlight in order to produce synthetic fuels or other useful energy such as methanol or methane.
Since the photosynthetic process removes CO2 from the atmosphere, a highly efficient system in wide commercial application could produce energy at the same time as it could help reduce atmospheric CO2 and potentially bring it back down to below 350 parts per million.
Photodimerization and Photoisomerization are two other processes that are being investigated as methods of storing solar energy in useable forms.