Self-supported cobalt–nickel bimetallic telluride as an advanced catalyst for the oxygen evolution reaction

Abstract

Compared with a monometallic catalyst, nanostructured bimetallic catalysts present an enhanced electrocatalytic performance due to the synergistic effect of two metal elements. To improve the OER performance of metal tellurides, we propose to synthesize a cobalt–nickel bimetallic telluride electrocatalyst (Ni-doped CoTe₂) by a one-step hydrothermal method with the addition of transition metal Ni sources in this work. The influence of the addition amount of NiCl₂·6H₂O and the reaction temperature on the crystal structure, morphology, chemical composition, and electrocatalytic performance is studied systematically. The results show that the optimized sample Co@0.2gNiCoTe₂-240 exhibited a low overpotential of 280 mV to attain an anodic current density of 10 mA cm⁻², and the Tafel slope was as low as 34 mV dec⁻¹. The improved activity and stability could be attributed to the Ni-doped CoTe₂ structure that has an increased electrochemical surface area, the formation of the high valence state of Co and/or Ni species, rapid charge transfer ability, and faster catalytic kinetics during the OER process. This work not only provides a highly active and durable 3D catalyst for the OER under alkaline conditions, but also provides a new approach for the development of bimetallic tellurides for energy conversion application.