Two-dimensional (2D) semiconductor heterojunctions are considered as an effective strategy to achieve fast separation of photoinduced carriers. Herein, a novel CoWO₄/g-C₃N₄ (CWO/CN) p—n junction was synthesized using an electrostatic self-assembly method. The constructed 2D/2D p—n heterostructure had a rich hetero-interface, increased charge density, and fast separation efficiency of photoinduced carriers. The in-situ Kelvin probe force microscopy confirmed that the separation pathway of photoinduced carriers through the interface obeyed an II-scheme charge transfer mechanism. Experimental results and density functional theory calculations indicated the differences of work function between CWO and CN induced the generation of built-in electric field, ensuring an efficient separation and transfer process of photoinduced carriers. Under the optimized conditions, the CWO/CN heterojunction displayed enhanced photocatalytic H₂ generation activity under full spectrum and visible lights irradiation, respectively. Our study provides a novel approach to design 2D/2D hetero-structured photocatalysts based on p—n type semiconductor for photocatalytic H₂ generation.

Bimetallic catalysts have significantly contributed to the chemical community, especially in environmental science. In this work, a CoAl₂O₄ spinel bimetal oxide was synthesized by a facile co-precipitation method and used for the degradation of organic pollutants through peroxymonosulfate (PMS) activation. Compared with Co₃O₄, the as-prepared CoAl₂O₄ possesses a higher specific surface area and a larger pore volume, which contributes to its becoming increasingly conducive to the degradation of organic pollutants. Under optimal conditions (calcination temperature: 500 °C, catalyst: 0.1 g/L, and PMS: 0.1 g/L), the as-prepared CoAl₂O₄ catalyst could degrade over 99% of rhodamine B (RhB) at a degradation rate of 0.048 min⁻¹, which is 2.18 times faster than Co₃O₄ (0.022 min⁻¹). The presence of Cl⁻ could enhance RhB degradation in the CoAl₂O₄/PMS system, while HCO₃⁻ and CO₃²⁻ inhibit RhB degradation. Furthermore, the considerable reusability and universality of CoAl₂O₄ were testified. Through quenching tests, ¹O₂ and SO₄•⁻ were identified as the primary reactive species in RhB degradation. The toxicity evaluation verified that the degraded solution exhibited lower biological toxicity than the initial RhB solution. This study provides new prospects in the design of cost-effective and stable cobalt-based catalysts and promotes the application of PMS-based advanced oxidation processes for refractory wastewater treatment.

High‐precision separation with increased water permeability is critical for efficient membrane‐based water treatment processes. To achieve high selectivity toward different targeted species while allowing rapid water transportation, the structure of the membrane polyamide selective layer requires delicate regulation. Herein, an effective approach to systematically expand the pore size of polyamide layers by incorporating ammonium ion‐modified carbon dots (CDs) into the polyamide network is developed. The ammonium ions with different alkyl chain lengths attached to the CDs create nanochannels of different sizes in the network to lower the energy barrier for water transportation while maintaining high selectivity to targeted species. When the alkyl chain length of the ammonium ions reaches eight carbon atoms (i.e., C₈ ions), the amphiphilic C₈‐CDs induce the formation of the ridged nanostructure on the membrane surface and hence the increased membrane filtration area. The resultant thin‐film nanocomposite (TFN) membrane, denoted as the TFN‐C₈‐CDs membrane, demonstrates a higher Na₂SO₄ rejection of 98.9% and NaCl/Na₂SO₄ selectivity of 83.1 than the pristine polyamide membrane, together with a tripled pure water permeability of 29.0 L m⁻² h⁻¹ bar⁻¹. Herein, a viable approach for ingeniously designing the nanochannels and surface nanostructure of polyamide membranes for more efficient filtration processes is provided.

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.