This is an interesting paper- and very relevant.
The surface treatment at high temperatures, such as 650°C,
increases the percentage of hydrogen storage in a sample of
• The comparison of the data of treated specimens vs. control
samples of untreated samples displays that treating the
surface of the diamond powder with an electronegative
element such as fluoride activates the surface of the material
allowing for the more loose bonds to be made between the
hydrogen molecules and the surface of the diamond powder.
It could be that the process of increased hydrogen storage and the formation of ultra dense hydrogen are different processes.
In the first case, the hydrogen could reside only on the surface of the carbon as a carbohydrate. In the second case, the hydrogen stays chemically pure but penetrates into the diamond where it is compressed by the diamond lattice thereby generating the ultra dense hydrogen form.