Synthesis and characterization of poly(N-vinyl-2-pyrrolidone)-stabilized water-soluble nickel(0) nanoclusters as catalyst for hydrogen generation from the hydrolysis of sodium borohydride

Water-soluble PVP-stabilized nickel(0) nanclusters in particle size of 3.6 +/- 1.6 nm were synthesized by using a modified version Of alcohol reduction method and characterized by TEM, XPS and FT-IR. PVP polymer is coordinated to the nanoclusters surface through some of the carbonyl groups as concluded from a comparative FT-IR spectral study. The PVP-stabilized nickel(0) nanoclusters are very stable in solution and yet highly active catalyst providing 8700 turnovers of hydrogen gas generation from the hydrolysis of sodium borohydride over 27 h before deactivation, They can be isolated as stable solid material, which are redispersible in water and show still the same catalytic activity after redispersion. A kinetic Study shows that the catalytic hydrolysis of sodium borohydride is first order with respect to nickel concentration and zero order with respect to substrate concentration. The activation energy of the hydrolysis of sodium borohydride catalyzed by PVP-stabilized nickel(0) nanoclusters was determined to be E-lambda = 48 +/- 2 kJ mol(-1). (c) 2008 Elsevier B.V. All rights reserved.