(5.95 Å and 12.30 Å, respectively). The different crystal structures of the two phases result in differences in their electronic band structure as well. The d-orbitals of 2H-MoS2 are split into three bands: dz2, dx2-y2,xy, and dxz,yz. Of these, only the dz2 is filled; this combined with the splitting results in a semiconducting material with a bandgap of 1.9eV. 1T-MoS2, on the other hand, has partially filled d-orbitals which give it a metallic character. Because the structure consists of in-plane covalent bonds and inter-layer van der Waals interactions, the electronic properties of monolayer TMDs are highly anisotropic. For example, the conductivity of MoS2 in the direction parallel to the planar layer (0.1–1 ohm-1cm-1) is ~2200 times larger than the conductivity perpendicular to the layers. There are also differences between the properties of a monolayer compared to the bulk material: the Hall mobility at room temperature is drastically lower for monolayer 2H MoS2 (0.1–10 cm2V-1s-1) than for bulk MoS2 (100–500 cm2V-1s-1). This difference arises primarily due to charge traps between the monolayer and the substrate it is deposited on. MoS2 has important applications in (electro)catalysis. As with other two-dimensional materials, properties can be highly geometry-dependent; the surface of MoS2 is catalytically inactive, but the edges can act as active sites for catalyzing reactions. For this reason, device engineering and fabrication may involve considerations for maximizing catalytic surface area, for example by using small nanoparticles rather than large sheets or depositing the sheets vertically rather than horizontally. Catalytic efficiency also depends strongly on the phase: the aforementioned electronic properties of 2H MoS2 make it a poor candidate for catalysis applications, but these issues can be circumvented through a transition to the metallic (1T) phase. The 1T phase has more suitable properties, with a current density of 10 mA/cm2, an overpotential of –187 mV relative to RHE, and a Tafel slope of 43 mV/decade (compared to 94 mV/decade for the 2H phase). Graphane While graphene has a hexagonal honeycomb lattice structure with alternating double-bonds emerging from its sp2-bonded carbons, graphane, still maintaining the hexagonal structure, is the fully hydrogenated version of graphene with every sp3-hybrized carbon bonded to a hydrogen (chemical formula of (CH)n). Furthermore, while graphene is planar due to its double-bonded nature, graphane is rugged, with the hexagons adopting different out-of-plane structural conformers like the chair or boat, to allow for the ideal 109.5° angles which reduce ring strain, in a