Solvent molecules form surface redox mediators in situ and cocatalyze O reduction on Pd.

Solvent molecules influence the reactions of molecular hydrogen and oxygen on palladium nanoparticles. Organic solvents activate to form reactive surface intermediates that mediate oxygen reduction through pathways distinct from reactions in pure water. Kinetic measurements and ab initio quantum chemical calculations indicate that methanol and water cocatalyze oxygen reduction by facilitating proton-electron transfer reactions.

X-ray absorption spectroscopic and computational investigation of a possible S···S interaction in the [Cu3S2]3+ core.

The electronic structure of the [Cu(3)S(2)](3+) core of [(LCu)(3)(S)(2)](3+) (L = N,N,N',N'-tetramethyl-2R,3R-cyclohexanediamine) is investigated using a combination of Cu and S K-edge X-ray absorption spectroscopy and calculations at the density functional and multireference second-order perturbation levels of theory. The results show that the [Cu(3)S(2)](3+) core is best described as having all copper centers close to but more oxidized than Cu(2+), while the charge on the S(2) fragment is between that of a sulfide (S(2-)) and a subsulfide (S(2)(3-)) species. The [Cu(3)S(2)](3+) core thus is different from a previously described, analogous [Cu(3)O(2)](3+) core, which has a localized [(Cu(3+)Cu(2+)Cu(2+))(O(2-))(2)](3+) electronic structure.