Three-Dimensional Needle Branch-like PANI/CoNiP Hybrid Electrocatalysts for Hydrogen Evolution Reaction in Acid Media

Abstract

In this work, a kind of three-dimensional (3D) needle branch-like array nanostructured PANI/CoNiP hybrid electrode self-supported on nickle foam (NF) is explored. This 3D needle branch-like array nanostructured PANI/CoNiP–NF electrode can not only expose more activity sites but also effectively capture protons from hydrated ions to form protonated amino groups due to abundant lone pair electrons in the nitrogen of PANI. The as-synthesized nanostructured PANI/CoNiP–NF electrocatalyst exhibits outstanding catalytic activity, achieving 10 mA cm–2 current density at a lower overpotential of 61 mV. Density functional theory calculation shows that the Gibbs free energy of hydrogen adsorption (ΔGH*) of PANI/CoNiP is lower than that of CoNiP, further proving theoretically that polyaniline (PANI) can accelerate the hydrogen evolution reaction kinetic process and improve the catalytic activity, which is consistent with the experimental results. Especially, the Ni site of PANI/CoNiP has the lowest Gibbs free energy of hydrogen adsorption (ΔGH*) of −0.059 eV, close to 0, providing a basis for designing and preparing materials, that is, to expose the crystal planes with more Ni active sites as much as possible, thus improving the catalytic performance of the PANI/CoNiP materials.