Preparation of Se-doped Co/Ni bimetallic composite carbon nanotubes and investigation of their oxidation properties.

Abstract

Developing highly efficient and stable selenium-doped transition metal bimetallic catalysts to replace precious metal electrocatalysts for the alkaline oxygen evolution reaction (OER) remains an ongoing challenge. This paper reported the synthesis of a highly efficient redox-active selenium-doped bimetallic composite catalyst (Se-CoNi@NCNTs) <i>via</i> a one-step pyrolysis method using cobalt-nickel and g-C₃N₄ as precursors. The Se-CoNi@NCNTs catalyst delivered a current density of 10 mA cm^-2 at a low overpotential of merely 289 mV. Furthermore, in a 1 M KOH solution, the Tafel slope for electron transfer kinetics was determined to be 66.94 mV dec^-1. It exhibited excellent stability during 100 h of alkaline overcurrent operation, with negligible electrocatalytic current density loss during 100 h of continuous electrolysis. Enhanced electrochemical performance was observed in 1 M KOH + 0.33 M urea electrolyte, requiring only a low overpotential of 98 mV to deliver a current density of 10 mA cm^-2. Utilizing <i>in situ</i> catalysis of g-C₃N₄ precursors with metallic nanoparticles to generate nitrogen-doped carbon nanotubes (NCNTs) endows the composite CoNiSe compound with high intrinsic activity and conductivity, enabling highly efficient water oxidation.