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Converting poly(ethylene terephthalate) (PET) into metal–organic frameworks (MOFs) has emerged as a promising innovation for upcycling of waste plastics. However, previous solvothermal methods suffer from toxic solvent consumption, long reaction time, high pressure, and high temperature. Herein, a mechanochemical milling strategy was reported to transform waste PET into a series of MOFs with high yields. This strategy had the merits of solvent‐free conditions, ambient reaction temperature, short running time, and easy scale‐up for large‐scale production of MOFs. The as‐prepared MOFs exhibited definite crystal structure and porous morphology composed of agglomerated nanoparticles. It was proven that, under mechanochemical milling, PET was firstly decomposed into 1,4‐benzenedicarboxylate, which acted as linkers to coordinate with metal ions for forming fragments, followed by the gradual arrangement of fragments into MOFs. This work not only promotes high value‐added conversion of waste polyesters but also offers a new opportunity to produce MOFs in a green and scalable manner. [ABSTRACT FROM AUTHOR]

Upcycling waste plastics into advanced semiconductor photocatalysts provides a new strategy to reasonably and economically solve the huge amount of waste plastics, which remains challenging. Herein, a carbon nitride‐based donor–acceptor (D–A) conjugated copolymer by copolymerization of dicyandiamide and terephthalic acid from discarded polyethylene terephthalate (PET) using Zn(OH)2 as catalyst and template at 360–440 °C is synthesized. The morphology and structure of the conjugated copolymer are well regulated by the calcination temperature. The resultant conjugated copolymer exhibits merits of high light absorption and low electron–hole recombination probability. Consequently, it works excellently in the persulfate‐based advanced oxidation process for visible light‐driven photocatalytic degradation of tetracycline. The kinetic constant (3.4 × 10−2 min−1) is 40.5 and 2.3 times that of the conjugated copolymer system and persulfate system, respectively. Furthermore, the reactive species (including •OH, SO4•−, •O2−, 1O2, and h+) and degradation intermediates of tetracycline are analyzed to expound its degradation process. This work not only pioneers design guidelines on upcycling of waste plastics in a sustainable manner, but also provides a facile strategy to synthesize carbon nitride‐based D–A conjugated copolymers for the efficient activation of persulfate‐based advanced oxidation process in wastewater treatment. [ABSTRACT FROM AUTHOR]

Upcycling waste plastics (e.g., polyethylene (PE)) into value‐added carbon products is regarded as a promising approach to address the increasingly serious waste plastic pollution and simultaneously achieve carbon neutrality. However, developing new carbonization technology routes to promote the oxidation of PE at low temperature and construct the stable cross‐linking network remains challenging. Here, a facile carbon‐grown‐on‐carbon strategy is proposed using carbon black (CB) to convert waste PE into core/shell carbon nanoparticles (CN) in high yields at low temperature. The yield of CN remarkably increases when the heating temperature decreases or the dosage of CB increases. The obtained CN displays turbostratic structure and closely aggregated granular morphology with a size of ≈80 nm. It is found that, prior to the oxidation and carbonization of PE, CB forms a 3D network architecture in the PE matrix. More importantly, CB not only catalyzes the partial oxidation of PE to form PE macromolecular radicals and introduce oxygen‐containing groups at low temperature in the early stage, but also favors for the construction of a stable cross‐linking network in the latter stage. This work offers a facile sustainable strategy for chemical upcycling of PE into value‐added carbon products without post‐treatments or usage of metallic catalysts. [ABSTRACT FROM AUTHOR]

Interfacial solar-driven vapor generation is considered to be a promising technology to produce freshwater from non-potable water. However, when the source water contains organic pollutants, the solar-driven water evaporation process might worsen the pollution of the source water. Herein, we construct a bifunctional interfacial solar-driven evaporator by facilely dip-coating MOF-derived N/Co-doped carbon on cotton cloth, which can simultaneously realize freshwater production by solar-driven evaporation and the degradation of organic pollutants. The derived carbon hybrid is composed of wrinkled bamboo-like N-doped carbon tubes and embedded Co nanoparticles, which not only contribute to efficient sunlight absorption and photothermal conversion but also provide abundant catalytic sites for visible light-driven peroxymonosulfate (PMS) activation to produce diverse reactive oxygen species (ROS). In another aspect, the cotton cloth consisting of interlaced cellulosic fibers offers hydrophilic channels for fast water transport and decreases the water evaporation enthalpy to accelerate evaporation. As a result, the bifunctional evaporator presents a notably high evaporation rate of 2.2 kg m−2 h−1 under 1 kW m−2 illumination, securing one of the best values among solar evaporators. More importantly, it displays excellent performance in PMS activation under visible light irradiation to produce plenty of ROS for the catalytic degradation of various toxic organic pollutants in source water (e.g., its Congo red degradation efficiency was 96.6% within 90 min). The bifunctional solar evaporator provides an ingenious way to handle the issues of global freshwater scarcity and water contamination via the marriage of interfacial solar-driven evaporation technology and advanced oxidation processes. [ABSTRACT FROM AUTHOR]

[Display omitted] • Cube-like Mn-MOF is synthesized from discarded poly(ethylene terephthalate) bottles. • MnO/C nanoparticle is easily tailored from cube to sphere, octahedron or polyhedron. • Evaporator owns good water transport, light absorption and solar-thermal conversion. • Evaporator shows the evaporation rate of 2.38 kg m−2 h−1 with efficiency of 98.4 %. • Evaporator recovers low-grade heat from evaporation for thermoelectric generation. The integration of freshwater and electricity cogeneration through photothermal effect is regarded as a new and promising strategy for high-efficiency solar energy utilization. However, the central issue is the design of low-cost, flexible photothermal materials to efficiently utilize solar energy. Herein, flexible MnO/C nanoparticle-based solar evaporators are constructed to realize simultaneously interfacial solar evaporation and thermoelectricity generation. The MnO/C nanoparticle is facilely fabricated by pyrolysis of Mn-MOF, which is synthesized from discarded poly(ethylene terephthalate) bottles in one-pot solvothermal method. By altering pyrolysis temperature of Mn-MOF from 400 °C to 700 °C, the morphology of MnO/C nanoparticle is readily tailored from cube to sphere, octahedron and polyhedron. Owing to the fast water transport, strong sunlight absorptivity, high solar-to-heat conversion efficiency, and low evaporation enthalpy, the hybrid solar evaporator presents the high evaporation rate of 2.38 kg m−2 h−1 and solar-to-vapor conversion efficiency of 98.4% under 1 Sun irradiation, surpassing many advanced photothermal materials. More importantly, integrated with a thermoelectric module, the bifunctional solar evaporator recovers low-grade heat from water evaporation to perform thermoelectric conversion, achieving the maximum output voltage of 330 mV under 3 Sun irradiation. This work highlights the potential of flexible and durable solar evaporators for freshwater and power cogeneration, not merely contributing to achieving carbon neutrality and upcycling of waste plastics, but also opening opportunities for giant electricity supply from sustainable solar energy. [ABSTRACT FROM AUTHOR]