CdS-based photocatalyst for the Conversion of Formic acid to H₂

Abstract

Cadmium dithiocarbamate complexes of M(L)2 type were synthesized by reacting two different sodium salts of dithiocarbamate with Cd(NO3)2.4H2O (where L1= Sodium dibutylcarbamodithioate and L2= Sodium 4-chlorobenzyl(benzyl)carbamodithioate ). The synthesized complexes and ligands were characterized by NMR spectroscopy. The synthesized complexes were used as single source precursor for the synthesis of CdS nanoparticles by simple reflux method with ethylenediamine and octylamine as thermalizing solvent. The CdS nanoparticles were characterized by UV-Visible spectroscopy, XRD, FTIR, SEM and EDX and evaluated as a photocatalyst for decomposition of formic acid into hydrogen gas. The photocatalytic activity was remarkably enhanced by employing inexpensive co-catalysts e.g. NiCl2.6H2O, and CoCl2.6H2O in photocatalytic decomposition of formic acid. The hydrogen production of 16.4±2.2 mmolH2h-1g-1 and 25.1±4.2 mmolH2h-1g-1 was observed for Nickel and Cobalt as a co-catalyst respectively. Further improvement was observed in the activity due to synergetic effect by adding both co-catalyst (dual) simultaneously to the reaction mixture of CdS-SF/FA, resulting in 27.5±5.1 mmolH2h-1g-1 hydrogen production. H2 production was sustained for more than 12 hour with turnover numbers greater than 2×103 for CdS/Co-Ni and 1.5×103, 1×103 for CdS/Ni, and CdS/Co respectively. Keywords: Nanoparticles; cadmium sulfide; photocatalysis; inexpensive co-catalyst; Hydrogen production