To quote from a recent U.S. Naval Research Laboratory publication, “Hydrogenated graphene (graphane) will remain a powerful influence in the field of materials science not only for its own sake, but also for the lessons that it will impart to newer and more advanced 2D materials.” [Whitener, KE, “Review Article: Hydrogenated graphene: A user’s guide.” J. Vac. Sci. Technol. A 36, 05G401 (2018)]
Highly hydrogenated graphene (graphane), like graphene oxide and fluorinated graphene, also exhibits photoluminescence properties as a result of electronically unconnected conjugated polycyclic regions are that are formed as adatoms populate the graphene lattice. These areas show a range of absorption profiles and strongly fluorescent emission properties . Because of its white light fluorescence, optoelectronic features, and imaging capabilities, highly hydrogenated graphene has been proposed for use in such applications as quantum dots .
Hydrogenation endows graphene with some interesting magnetic properties. The interaction between hydrogen atoms distorts the planar graphene lattice, leading to the enhancement of spin-orbit interaction and the formation of local magnetic moments, hence ferromagnetism. Hydrogenated graphene is thus a promising candidate for magnetic data storage, spintronic devices and solid-state masers [1,2].
Researchers at the US Naval Research Lab have made significant progress towards the development of practical graphene-based low-power spintronic devices. They have incorporated hydrogenated graphene into these devices where it “serves as the tunnel barrier for spin injection into the graphene carrier channel of a nonlocal spin valve. The tunnel barrier is necessary to overcome the conductivity mismatch problem, and using hydrogenated graphene, it is possible to achieve significant levels of spin polarization.” 
Fully hydrogenated graphite or graphene, also known as graphane (CH)n, has a theoretical hydrogen storage capacity of 7.7 wt% . It is stable in air up to 400oC before it thermally decomposes to liberate gaseous hydrogen, H2 . The hydrogen stored within the graphane possesses a maximum volumetric density on the order of 135 g H2 L−1, over three times greater than hydrogen gas pressurized to 10,000 PSI , and significantly higher than the US Department of Energy’s target of 50 g H2 L-1 . This combination of features makes graphane a particularly promising material for hydrogen storage. [1-7].
Graphene is a zero-bandgap conductor while hydrogenated graphene is a semiconductor with a wide band gap. Interestingly, hydrogenated graphene has a tunable band gap that ranges from 0 eV to 5.4 eV depending on the level of hydrogenation, making it a semiconductor  of interest for optical and electronic devices [2-6]. With a variable bandgap and the potential for a high degree of functionalization, hydrogenated graphene exhibits fluorescence that can be modified for potential applications in sensors and other devices .