Three-dimensionally printed materials show great performance and reliable stability in the removal of refractory organic pollutants in Fenton-like reactions. In this work, hierarchically porous zero-valent copper (3DHP-ZVC) was designed and fabricated via 3D printing and applied as a catalyst for the degradation of tetracycline (TC) through heterogeneous Fenton-like processes. It was found that the 3DHP-ZVC/H₂O₂ system could decompose over 93.2% of TC within 60 min, which is much superior to the homogeneous Cu²⁺/H₂O₂ system under similar conditions. The leaching concentration of Cu²⁺ ions in the 3DHP-ZVC/H₂O₂ system is 2.14 times lower than that in the Cu powder/H₂O₂ system in a neutral environment, which could be ascribed to the unique hierarchically porous structure of 3DHP-ZVC. Furthermore, 3DHP-ZVC exhibited compelling stability in 20 consecutive cycles. The effects of co-existing inorganic anions, adaptability, and pH resistance on the degradation of TC were also investigated. A series of experiments and characterizations revealed that Cu⁰ and superoxide radicals as reducing agents could facilitate the cycling of Cu(II)/Cu(I), thus enhancing the generation of hydroxyl radicals to degrade TC. This study provides new insights into employing promising 3D printing technology to develop high-reactivity, stable, and recycling-friendly components for wastewater treatment.

Fe-based heterogeneous catalytic advanced oxidation processes show great potential for treating wastewater. However, catalyst instability often hinders their practical use, mainly due to the slow regeneration of Fe²⁺ sites. Herein, we developed a Fe₃S₄/WO₃ catalyst, where the electron-rich Wx and Sx sites promoted efficient electron transfer, enabling continuous regeneration of Fe²⁺ active sites on the catalyst surface. The Fe₃S₄/WO₃ catalyst exhibited outstanding degradation efficiency for tetracycline (TC) in the peroxymonosulfate (PMS) system, achieving a 92.5% removal efficiency, significantly higher than its individual components of Fe₃S₄ (52.8%), WO₃ (43.1%), and WS₂ (53.2%). Moreover, the Fe₃S₄/WO₃/PMS system demonstrated a broad operational pH range (3.0–9.0), excellent degradation efficiency for various emerging pollutants, minimal interference from background electrolytes and organic matter, and strong stability in real water treatment. Chemical scavenger tests and electron paramagnetic resonance (EPR) analysis confirmed that the oxidative degradation of TC was driven by multiple reactive species, including SO₄^•−, ^•OH, ^•O₂⁻, and ¹O₂. This study provides a novel strategy for regulating active sites in Fe-based catalysts to ensure sustained performance, offering a pathway for the rational design of next-generation Fenton-like catalysts for efficient and sustainable micropollutant removal from wastewater.

Polysulfide-ferricyanide redox flow batteries (PFRFBs) are gaining significant attention in long-duration energy storage for their abundant availability and environmental benignity. However, the sluggish kinetics of the polysulfide redox reactions have tremendously constrained their performances. To address this issue, we developed a NiMoS catalyst-modified carbon felt (NiMoS-CF) electrode, which significantly accelerates the electrochemical reaction rates and enhances the cycling stability of PFRFB. Our PFRFB system, integrated with the NiMoS-CF electrode, exhibited an energy efficiency of 70% and a voltage efficiency of 87%, with a remarkable doubling of its cycle life as opposed to the pristine carbon felt (CF) electrode at a current density of 40 mA cm⁻². Notably, during 2500 cycles of charge–discharge testing, we achieved an average coulombic efficiency exceeding 99%. These improvements in PFRFB performance can be attributed to the NiMoS-CF electrode’s large surface area, low resistance, and robust redox activity. This study offerings a novel approach for enhancing the electrochemical reaction kinetics and cycling stability in PFRFBs, laying a scientific foundation in the applications of practical PFRFBs for next-generation energy storage.