The regulation mechanism of V-shaped 103 nano-twin grain boundary on OER performance of rutile RuO2

[Display omitted] •The V-shaped RuO2 103-TGB with roof structure produce the double dangling-O atoms.•The double dangling-O can regulate the adsorption energies of key intermediates.•The double dangling-O can provides excellent electrocatalytic activity sites. During the oxygen evolution reaction (OER), surface oxygen adsorption plays a crucial role in electrocatalysis. The stability of surface adsorption is closely related to the surface morphology of the catalyst. As one of the V-shaped nanotwins, 103 nano-twin grain boundary (103-TGB) has a special roof structure, which results in the presence of double dangling-O atoms at the junction of 103-TGB with (110) surface. In contrast to the ideal RuO2, the d-band center of Ru atoms located on the surface of 103-TGB is shifted to the Fermi level by 1.66 eV. Moreover, the key intermediates, namely *OH, *O, and *OOH, have suitable adsorption energies, providing a lower overpotential of OER (ηOER), via adsorbate evolving mechanism (AEM), of just 0.45 eV. Therefore, the OER via AEM is strongly focused on site 02 with double dangling-O atoms, revealing a synergistic effect due to the presence of both the 103-TGB defect and (110) surface.