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

## TL;DR

This paper introduces a new selenium-doped cobalt-nickel composite catalyst that efficiently performs oxygen evolution reactions without using precious metals.

## Contribution

A one-step pyrolysis method was used to create a high-performance Se-doped Co/Ni bimetallic catalyst for oxygen evolution.

## Key findings

- The Se–CoNi@NCNTs catalyst achieved 10 mA cm−2 at 289 mV overpotential in alkaline conditions.
- It showed a Tafel slope of 66.94 mV dec−1 and excellent stability over 100 hours.
- In urea electrolyte, it delivered 10 mA cm−2 at only 98 mV overpotential.

## 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) via 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 in situ 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.

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.