Single cobalt atoms anchored on in-situ-formed carbon layers within restricted microenvironment: an efficient catalyst for oxygen evolution reaction

Cobalt-based materials are attractive non-noble metal catalysts for electrocatalytic oxygen evolution reaction (OER) due to their good performance. Cobalt active sites with high dispersion degree, especially single cobalt atoms, has been demonstrated with superior catalytic activity, while their preparation by using conventional methods is complicated. Here we present a convenient, solid grinding-heat treatment (SG-HT) method, for the preparation of cobalt single-atom catalysts (SACs) by using the special restricted microenvironment between silica wall and template in template-occupied SBA-15 (TOS). The precursor Co(NO₃)₂ can enter the restricted microenvironment by solid grinding, and in subsequent heat treatment, cobalt single atoms are generated and anchored on in-situ-formed carbon layers from template, yielding a new SAC denoted as Co₁@C-TOS. Computational and experimental results show that cobalt atoms exist in the form of Co[sbnd]C₄ structure. The synergistic interaction between the in-situ-formed carbon layers with mesoporous structure and the highly dispersed metal sites facilitates the diffusion of reactants and improves the catalytic activity. The Co₁@C-TOS catalyst exhibits excellent activity in alkaline electrocatalytic OER with an overpotential of only 260 mV at 10 mA·cm⁻², which is much superior to the reference catalysts Co@TFS prepared without restricted microenvironment (420 mV) and Co@C-TOS without in-situ-formed carbon layers (404 mV), commercial noble metal catalysts including IrO₂ (330 mV) and Pt/C (340 mV), as well as various reported Co-based SACs.