Table 4. Summary of the Spectroscopic Features Observed for the MoS_x Film As Prepared and Under Pre-Catalytic (0.3 V) and Catalytic (−0.3 V) Conditions.

	Mo K-edge EXAFS		S K-edge XANES	Mo L-edge XANES
sample	number and nature of interaction	R, Å	sulfur oxidation state and binding mode	formal oxidation states of molybdenum
dry (as prepared)	1 Mo–O	1.74	μ-η2 S2–, μ-η3 S2–, μ-η2:η2 S22–	Mo(V) or Mo(IV)a
	3 Mo–S	2.44
	1 Mo–Mo	2.75
↓	shortening of Mo–S bond, increased number of Mo–Mo bonds		reduction	reduction
0.3 V (precatalytic)	6 Mo–S	2.40	μ-η2 S2–, μ-η3 S2–, μ-η2:η2 S22–	Mo(IV)
	1 Mo–Mo	2.74
↓	shortening of Mo–S bond, diminished Mo–Mo interactions		oxidation	reduction
–0.3 V (catalytic)	6 Mo–S	2.36	μ-η2 S2–, μ-η3 S2–, η2 S22–	Mo(IV), Mo(III)

^aIn MoS₃, the molybdenum ion is described as Mo(V) in the Hibble model and as Mo(IV) in the Weber model.