The redox potentials of M(H2O)mn+/M0(atom) couples are often far too negative to enable the formation of M0(atom) by most reducing agents.

The nature of H-atoms adsorbed on M 0 -nanoparticles is of major importance in many catalyzedr eduction processes.Using isotope labeling,wedetermined that hydrogen evolution from transient {(M 0 -NP)-H n } nÀ proceeds mainly via the Heyrovsky mechanism when nislarge (i.e., the hydrogens behave as hydrides) but mainly via the Tafel mechanism when niss mall (i.e., the hydrogens behave as atoms). Additionally, the relative contributions of the two mechanisms differ considerably for M = Au and Ag.T he results are analogous to those recently reported for the M 0 -NP-catalyzed de-halogenation processes.

Silica supported silver nanoparticles, SiO2‐Ag0‐NPs, catalyze the hydrolysis of BH4−. A comparison of the isotopic composition of the hydrogen formed in the hydrolysis of BD4− points out that the contribution of hydrides, the Heyrovsky mechanism, rather than that of hydrogen atoms, the Tafel mechanism, to the hydrogen evolution is considerably larger for the SiO2‐Ag0‐NPs catalyzed process than for the Ag0‐NPs catalyzed process. This indicates some electron transfer from the SiO2 to the silver that increases the negative charge on the Ag0‐NPs.

The nature of H-atoms adsorbed on M 0 -nanoparticles is of major importance in many catalyzedr eduction processes.Using isotope labeling,wedetermined that hydrogen evolution from transient {(M 0 -NP)-H n } nÀ proceeds mainly via the Heyrovsky mechanism when nislarge (i.e., the hydrogens behave as hydrides) but mainly via the Tafel mechanism when niss mall (i.e., the hydrogens behave as atoms). Additionally, the relative contributions of the two mechanisms differ considerably for M = Au and Ag.T he results are analogous to those recently reported for the M 0 -NP-catalyzed de-halogenation processes.

The mechanism of reduction of AuCl 4 − /AuCl 3 OH − by BH 4 − was analyzed by density functional theory (DFT). The results point out that Au atoms 0