Enhancing electrocatalytic performance in the oxygen evolution reaction of zirconium-based amorphous high-entropy oxides via controlled introduction of oxygen vacancies: experimental insights and DFT simulations.

The controlled introduction of oxygen vacancies (O) offers a promising strategy for enhancing the catalytic activity of materials. In this study, we effectively modulated the concentration of O in the zirconium-based amorphous high-entropy oxides (HEOs) by optimizing the Zr cation content. This adjustment facilitated precise tuning of the d-band center and chemical activity of Zr active sites, leading to substantial improvements in electrocatalytic performance for the oxygen evolution reaction (OER). Among the prepared zirconium-based materials, the HEO-Zr specimen demonstrated outstanding OER electrocatalytic performance, achieving an overpotential of 257 mV at 10 mA cm and 299 mV at 100 mA cm, a small Tafel slope of 40.3 mV dec. At the same time, the HEO-Zr||HEO-Zr cell demonstrates excellent performance in complete water splitting. These findings underscore the effectiveness of moderate O concentrations in enhancing catalytic activity, as confirmed by both experimental data and density functional theory simulations. This approach of controlled O introduction provides a viable path for optimizing HEO catalytic performance, offering valuable insights for advancing electrocatalytic applications.