Designing of Highly Efficient Oxygen Evolution Reaction Electrocatalysts Utilizing A Correlation Factor: Theory and Experiment

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 (Ovac) offers a promising strategy for enhancing the catalytic activity of materials. In this study, we effectively modulated the concentration of Ovac 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-Zr1.0 specimen demonstrated outstanding OER electrocatalytic performance, achieving an overpotential of 257 mV at 10 mA cm-2 and 299 mV at 100 mA cm-2, a small Tafel slope of 40.3 mV dec-1. At the same time, the HEO-Zr1.0||HEO-Zr1.0 cell demonstrates excellent performance in complete water splitting. These findings underscore the effectiveness of moderate Ovac concentrations in enhancing catalytic activity, as confirmed by both experimental data and density functional theory simulations. This approach of controlled Ovac introduction provides a viable path for optimizing HEO catalytic performance, offering valuable insights for advancing electrocatalytic applications.

Tailoring OER/ORR activity in TM1N4 catalysts through first-/second-shell nitrogen doping: a density functional theory investigation

Proposing an effective modification strategy to optimize catalyst reaction potentials is crucial for enhancing catalytic performance. In this study, we employed a combined approach by adjusting nitrogen dopants in the first- and second-shell environments to tailor the OER/ORR reaction potentials of Fe1N4, Co1N4, and Ni1N4 active centers. Using density functional theory simulations, we systematically compared the effects of first- and second-shell nitrogen dopants on the local atomic/electronic structures and catalytic activities. The results showed that first-shell nitrogen dopants had a dominant influence on the reaction potentials, while second-shell dopants provided fine-tuning adjustments. This combined regulation of nitrogen dopants in both shells significantly lowered the overpotentials for the OER and ORR, enhancing the overall catalytic performance. Specifically, N3-doped Fe1-pyrrole N4 and N2-doped Fe1-pyridine N4 active centers demonstrated the lowest overpotentials of 209 mV for the OER and 196 mV for the ORR, respectively. This strategy offers a promising pathway for designing more efficient catalysts.

Designing highly efficient oxygen evolution reaction electrocatalyst of high-entropy oxides FeCoNiZrOx: Theory and experiment

The correlations between the experimental methods and catalytic activities are urgent to be defined for the design of highly efficient catalysts. In this work, a new oxygen evolution reaction electrocatalyst of high-entropy oxide (HEO) FeCoNiZrOx was designed and analyzed by experimental and theoretical methods. On account of the shortened coordinate bond along with the increased annealing temperature, the atomic/electronic structures of active site were adjusted quantitatively with the aid of the pre-designed correlator of d electron density, which contributed to adjust the catalytic activity of HEO specimens. The prepared HEO specimen exhibited the low overpotentials of 245 mV at 10 mA cm-2 and 288 mV at 100 mA cm-2 with small Tafel slope of 35.66 mV dec-1, fast charge transfer rate, and stable electrocatalytic activity. This strategy would be adopted to improve the catalytic activity of HEO by adjusting the d electron density of transition metal ions with suitable preparation method.