Abstract: Single-atom catalysts (SACs) anchored on mineral-amorphous functionalized supports, with their unique active sites and excellent stability, are promising materials for overall water splitting bifunctional electrocatalysts. In this paper, diatomaceous earth-amorphous cobalt oxide functionalized carrier anchored Ru single-atom electrocatalysts (Ru@A-CoO/DEs) are designed by combining the high atom utilization efficiency of SACs, the abundance of defective sites in mineral-amorphous functionalized carriers, the superior hydrophilicity, and the structural stability of the complementary features. Its lamellar structure possesses a larger specific surface area, and considering the abundance of active sites in the amorphous defective state, it induces a synergistic effect with the Ru atoms, which can effectively drive the oxygen evolution reaction (225.8 mV@10 mA cm^-2) and the hydrogen evolution reaction (64.3 mV@10 mA cm^-2) in alkaline solution. Furthermore, a low voltage of only 1.49 V is required to provide a current density of 10 mA cm^-2 in water electrolysis, which provides superior catalytic activity and stability. Theoretical analysis reveals that the d-band center of Co in the Ru@A-CoO/DEs single-atom catalyst is close to the Fermi energy level, and there exists an obvious polarization effect of Ru-4d, which in turn improves the carrier mobility and induces the structural stabilization of the functionalized carriers, and this synergistic effect between the orbitals jointly promotes the overall water splitting performance. It is also shown that the reaction free energy overcome by the reaction decisive step is smaller in the hydrogen and oxygen evolution free energy. As it exhibits efficient catalytic activity, it provides a feasible reference for the stable and efficient preparation of single-atom catalysts from functionalized carriers and the development of water electrolysis technology.

Key words: Amorphous material, Single-atom catalysts, d-band center, Functionalized carriers, Overall water splitting