Organotrialkoxysilane-mediated synthesis of Ni–Pd nanocatalysts at lower concentrations of noble metal: Catalysts for faster hydrogen evolution kinetics

Abstract

The fabrication of alkoxysilane-based nickel (Ni)–palladium (Pd) bimetallic nanoparticle catalysts with several compositions (Pd—0.001M and Ni—0.001–0.1M) was attempted for the first time; these materials were investigated for use as low-cost catalysts in the hydrogen evolution reaction (HER). Functional alkoxysilane [2-(3,4 epoxycyclohexyl)ethyltrimethoxysilane]-assisted conversion of Pd2+ to Pd0 was demonstrated. Palladium nanocrystallites with an average dimension 4.03 ± 1.29 nm were synthesized, which acted as seeds in the synthesis of Ni–Pd bimetallic nanoparticles. The effect of the nanoparticle catalysts on the HER in an alkaline environment was studied using linear sweep voltammetry and electrochemical impedance spectroscopy. A nanostructured thin film containing Ni3PdNPs produced a 100 mA cm−2 current density at an overpotential of −90 mV with a small Tafel slope of 25 mV dec−1 at a catalyst loading of 0.1 mg cm−2. The annealed Ni3PdNPs catalyst further enhanced the current density to ∼ 240 mA cm−2 at an overpotential of −56 mV.