Niobic acid as a support for microheterogeneous nanocatalysis of sodium borohydride hydrolysis under mild conditions

Abstract

This study explores the stabilization by niobic acid, of Pt, Ni, Pd, and Au nanoparticles (NPs) for the efficient microheterogeneous catalysis of NaBH₄ hydrolysis for hydrogen production. Niobic acid is the most widely studied Nb₂O₅ polymorph, and it is employed here for the first time for this key reaction relevant to green energy. Structural insights from XRD, Raman, and FTIR spectroscopies, combined with hydrogen production data, reveal the role of niobic acid's Brønsted acidity in its catalytic activity. The supported NPs showed significantly higher efficiency than the non-supported counterparts regarding turnover frequency, average hydrogen production rate, and cost. Among the tested NPs, PtNPs and NiNPs demonstrate the most favorable results. The data imply mechanism changes during the reaction, and the kinetic isotope assay indicates a primary isotope effect. Reusability assays demonstrate consistent yields over five cycles for PtNPs, although catalytic efficiency decreases, likely due to the formation of reaction byproducts.