Decoration of Pd and Pt nanoparticles on a carbon nitride (C3N4) surface for nitro-compounds reduction and hydrogen evolution reaction

Abstract

Herein, we propose the synthesis of Pd and Pt monometallic nanoparticles on a carbon nitride (C₃N₄) surface for the reduction of nitro compounds as well as for electrocatalysis. For the synthesis of C₃N₄/Pd and C₃N₄/Pt, metal ions were initially adsorbed on the C₃N₄ surface and then subsequently reduced by NaBH₄. The as-synthesized heterostructures were authenticated by different characterization techniques: UV-vis, PXRD, XPS, TEM, FESEM, and EDS. Decorations of monometallic NPs on C₃N₄ not only improved the reduction efficiency of nitro-compounds but also enhanced the electrocatalytic activity in the hydrogen evolution reaction. C₃N₄/Pt proved to be an efficient electrocatalyst as it requires a potential of −0.339 V to attain a current density of 10 mA cm⁻²; whereas, C₃N₄/Pd requires −0.371 V to reach a current density of 10 mA cm⁻²vs. Ag/AgCl. Both C₃N₄/Pd and Pt heterostructures are better than bare C₃N₄, which needs −0.596 V to achieve a current density of 10 mA cm⁻²vs. Ag/AgCl. On the other hand, C₃N₄/Pd showed a better performance in nitro-compound reduction compared to C₃N₄/Pt and bare C₃N₄. The kinetic study reveals that the rate constant using a C₃N₄/Pd catalyst is 6.7 × 10⁻¹ min⁻¹ for p-nitroaniline reduction, which is 101 times higher compared to bare C₃N₄ and 4.7 times higher in comparison to C₃N₄/Pt.