Synthetic, single crystal, n‐type semiconducting has been characterized as a photoanode in aqueous and nonaqueous electrolyte media. The was synthesized from the elements by bromine and chlorine transport to yield plates up to in dimension. Interface characterization includes (i) cyclic voltammetry in the presence of a large number of fast, one‐electron redox couples in solutions; (ii) steady‐state photocurrent‐voltage properties in aqueous and nonaqueous solutions of ; (iii) tests of durability; (iv) wavelength dependence of photocurrent and photovoltage; and (v) high resolution (∼5 μm) laser mapping of the surface to reveal surface inhomogeneity with respect to output photovoltage. Highlights of the results are: (i) n‐type is durable in aqueous electrolytes containing high concentrations of to yield efficient visible light‐assisted oxidation of ; e.g., has up to 6.9% and up to 12% efficiency at a 632.8 nm input power of 16 mW/cm2; (ii) in aqueous, but not nonaqueous, solutions I− adsorbs such that the onset of photocurrent is shifted several hundred millivolts as for other metal dichalcogenide photoanodes; the shift is sufficient that visible light can be used to sustain the conversion of to and with no other energy input; (iii) cyclic voltammetry in for a number of redox couples shows that a photovoltage of up to ∼0.7V is possible; photovoltage varies from 0.0 to ∼0.7V for redox couples having from ∼0.0V vs. SCE to ∼+0.8V while the photovoltage is fixed at ∼0.7V for more positive than ∼+0.8V vs. SCE; (iv) efficiency for halogen generation in aqueous solutions generally exceeds efficiency in solutions; and (v) the diffusion length of holes parallel to the surface is ∼200 μm which explains the dramatic influence of the steps on the recombination of carriers on layered compounds.