Triboelectrification, a process that transforms mechanical energy into electrical energy through friction, holds promise for eco-friendly wastewater treatment. This study delves into the enhancement of tribocatalytic dye degradation using SrTiO₃, a material notable for its non-piezoelectric and centrosymmetric properties. The synthesis of uni- and bi-doped SrTiO₃ particles, achieved through a solid-state reaction at 1000 °C, results in a high-purity cubic perovskite structure. Doping with rhodium (Rh) and carbon (C) causes crystal lattice contraction, internal stress, and significant oxygen vacancies. These changes notably improve tribocatalytic efficiency under solar irradiation, with Rh-doped SrTiO₃ demonstrating an impressive degradation rate of approximately 88% for Rhodamine B (RhB), along with reaction rate constants near 0.9 h⁻¹ at 554 nm and a noticeable blueshift. This study highlights that defects introduced by doping are integral to this process, boosting catalytic activity through energy state modification and enhancing surface redox radical production. Additionally, these defects are instrumental in generating a flexoelectric field, which markedly influences the separation of electron–hole pairs under solar irradiation. Our findings illuminate the complex interplay between material composition, defect states, and environmental conditions, paving the way for advanced strategies in environmental remediation through optimized tribocatalytic activity.

The electrocaloric effect (ECE), known for its environmentally friendly characteristics, holds significant promise for advancing next-generation solid-state refrigeration technologies. Achieving a large ECE along with a wide working temperature range near room temperature remains a key developmental goal. In this study, we successfully obtained a substantial ECE of 1.78 K and an extensive working temperature range of 103 K (ΔT > 1.52 K) near room temperature in CaZrO₃-modified BaTiO₃ lead-free ferroelectric ceramics. Furthermore, this achievement was verified using direct methods. The piezoresponse force microscopy (PFM) results suggest that the broad temperature range is attributed to the formation of ferroelectric microdomains and polar nanoregions (PNRs). Furthermore, X-ray photoelectron spectroscopy (XPS) and ultraviolet‒visible (UV‒Vis) spectroscopy reveal a decrease in the oxygen vacancy concentration and an increase in the bandgap for higher CaZrO₃ doping levels. These changes synergistically enhance the maximum applied electric field, helping to achieve a high-performance ECE near room temperature. This research presents a straightforward and effective approach for achieving high-performance ECEs in BaTiO₃ lead-free ceramics, offering promising prospects for application in next-generation solid-state refrigeration technologies.

The BiFeO₃/g-C₃N₄ heterostructure, which is fabricated via a simple mixing-calcining method, benefits the significant enhancement of the pyrocatalytic performance. With the growth of g-C₃N₄ content in the heterostructure pyrocatalysts from 0 to 25%, the decomposition ratio of Rhodamine B (RhB) dye after 18 cold-hot temperature fluctuation (25-65 ℃) cycles increases at first and then decreases, reaching a maximum value of ~94.2% at 10% while that of the pure BiFeO₃ is ~67.7%. The enhanced dye decomposition may be due to the generation of the internal electric field which strengthens the separation of the positive and negative carriers and further accelerates their migrations. The intermediate products in the pyrocatalytic reaction also have been detected and confirmed, which proves the key role of the pyroelectric effect in realizing the dye decomposition using BiFeO₃/g-C₃N₄ heterostructure catalyst. The pyroelectric BiFeO₃/g-C₃N₄ heterostructure shows the potential application in pyrocatalytically degrading dye wastewater.