摘要
We report a Ba-based high-entropy ferroelectric oxide, Ba(Ni, Nb, Zr, Sn, Ti)O3, with B-site disorder in the perovskite structure, exhibiting distinctive relaxor behavior and a strong piezoelectric response. This property makes it a promising candidate for hydrogen evolution reaction (HER). Notably, under mechanical vibration in the dark, HEF achieves a high hydrogen production rate of 1832 μmol·g−1·h−1, outperforming conventional perovskite ferroelectrics such as Ba(Ni0.5Nb0.5)O3 (BNN), Ba(Zr0.1Ti0.9)O3 (BZT), Ba(Sn0.2Ti0.8)O3 (BST), and BaTiO3 (BTO). Furthermore, when poled under an electric field of 6 kVcm−1 to HEF, the HER activity further increases to 2110 μmol g−1 h−1. Piezoresponse force microscopy (PFM) and theoretical calculations show that HEF has stronger piezoelectric properties than conventional ferroelectrics. This improvement comes from the formation of polar nanoregions (PNRs) in HEF, caused by high-entropy effects like sluggish diffusion, which result in randomly oriented B-site polarizations. The dynamic polarization behavior of PNRs under mechanical stimulation introduces a paradigm of highly active catalysis. In high-entropy ferroelectric (HEF) systems, these PNRs function as embedded nanoscopic reactors, autonomously generating strong internal piezoelectric fields without the need for external power input. The polarization–electric field (P–E) curve shows a slim hysteresis loop and higher recoverable energy density than other perovskite ferroelectrics, highlighting HEF’s unique properties and its superior HER performance compared to BaTiO3. This study presents a straightforward approach for synthesizing high-entropy ferroelectric oxides with enhanced piezoelectric response, active under dark conditions, and offering strong potential for industrial use, sustainable hydrogen production, and highly active electromechanical responsive catalytic systems.
[Display omitted]
•Hydrogen evolution enabled by polar nanoregions in high-entropy ferroelectric oxide catalysts.•PNRs serve as piezo-reactors, confirmed by FEM simulations and piezoresponse force microscopy.•High-resolution TEM and XRD reveal nanoscale compositional disorder and single-phase perovskite HEF structure.•Time-resolved photoluminescence and EPR confirm extended carrier lifetimes and enhanced radical generation.•Dark-operating catalyst achieves 2110 μmol·g−1·h−1 HER rate, surpassing conventional ferroelectric benchmarks.