The
search of new H2 evolution systems avoiding fossil
sources and their mechanisms is a priority in the 21st century society.
Hydrolysis of tetrahydroxydiboron (TDB), a current borylation source
in the literature, is used here for H2 evolution for the
first time. It is catalyzed by graphene quantum dot-stabilized nanoparticles
(NPs). With RhNP- or PtNP-catalyzed reactions, D2 formation
from D2O confirms that water is the only hydrogen source.
Kinetic isotopic effects yield k
H/k
D = 5.91 and 4.18, strongly suggesting double
water O–H bond cleavage on the NP surface in the rate-limiting
step. The most efficient catalysts are the RhNP and PtNP (total turnover
frequencies: 3658 and 4603 molH2
·molcat
–1·min–1, respectively).
The order of catalytic activity is as follows: PtNP > RhNP >
AuNP
> PdNP > IrNP > RuNP, and a catalytic mechanism of TDB hydrolysis
is proposed.