Construction of structural defects to enhance the electrocatalytic performance of reduced graphene oxide (rGO)

Abstract

Carbon catalysts are becoming a pivotal alternative to noble metal catalysts. Constructing topological defects on a carbon skeleton is an effective way to increase the catalytic performance of carbon materials. Herein, topological defects were successfully examined by N-doping and subsequent removal of nitrogen elements on the carbon skeleton of graphene. After carrying out the elaborate investigations via XRD, XPS, and Raman analyses, it was observed that more N atomic defects transferred to topological defects (pentagon defects) on the carbon skeleton at 1100 °C. The synergies of active sites via topological defects and the large specific surface area of carbon led fabricated TDG-1100 to exhibit relatively excellent carbon catalytic performance. For instance, in 1 M KOH medium, the hydrogen evolution reaction (HER) overpotential of TDG-1100 was 332 mV, with a Tafel slope of 38 mV dec⁻¹. Meanwhile, the HER overpotential of TDG-1100 was 337 mV, with a Tafel slope of 98 mV dec⁻¹, in 0.5 M H₂SO₄ medium. Density functional theory calculations revealed the superior HER catalytic properties of the C atoms in the topological defects with low Gibbs free energy of hydrogen adsorption. These mutually corroborative results confirm that constructing topological defects in carbon materials is an effective way to achieve economical and high-performance metal-free catalytic materials in the future.