Efficient “Click”‐Dendrimer‐Supported Synergistic Bimetallic Nanocatalysis for Hydrogen Evolution by Sodium Borohydride Hydrolysis

Hydrogen is efficiently generated upon click dendrimer-supported catalysis of NaBH4 hydrolysis by a series mono- and bimetallic nanoparticles (NPs) of the late transition metals. Among the monometallic NPs, PtNPs show the best performances, Co being the best first-raw transition metal. A remarkable synergy between Pt and Co in Pt/CoNP@dendrimer is also disclosed, compared with various other bimetallic NP catalysts, achieving a TOF of 303mol(H2)mol(catal.)(-1)min(-1) when the ratio of Pt to Co is 1:1. In the presence of NaOH, the catalytic activity is boosted for all monometallic NPs except PtNPs, but NaOH exerted a negative influence on the bimetallic NP catalysts. The kinetic studies with the catalyst Pt1Co1NP@dendrimer involve in particular a primary kinetic isotope effect k(D)/k(H)=3.41 obtained for the hydrolysis reaction with D2O, suggesting that O-H bond cleavage of water is involved in the rate-determining step, and an overall reaction mechanism is proposed.