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[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]

[Display omitted] • The porous carbon polyhedron is obtained from controlled carbonization of Ba-BDC. • PCP-based evaporator and device realize freshwater production and energy harvesting. • Evaporator shows the evaporation rate of 2.74 kg m-2h−1 with efficiency of 98.2 % • Device shows the open-circuit voltage of 210 mV with the good cycling stability. The integration of interfacial solar steam generation with water evaporation-driven electricity generation is regarded as one of the most hopeful strategies for addressing global energy and freshwater crises. However, constructing low-cost, multi-functional porous carbon materials-based devices for freshwater-electricity co-generation remains challenging. Herein, we report the preparation of porous carbon polyhedron (PCP) by the controllable carbonization of barium-based metal–organic frameworks produced by the two-step ball milling of waste polyester bottles, and subsequently fabricate PCP-based solar evaporators and energy harvesting devices, capable of freshwater production and electrical energy generation all day. The as-prepared PCP evaporator owns good hydrophilicity, sunlight absorption, excellent photothermal conversion capability as well as low evaporation enthalpy. Under 1 Sun irradiation, it exhibits the evaporation flux of 2.74 kg m-2h−1 as well as the conversion efficiency of 98.2 %. Importantly, the PCP evaporator-based energy generation device realizes the open-circuit voltage of 212 mV, along with the good cycling stability. The well-developed pore channels, large specific surface area, and abundant functional groups are proved to be key parameters for electricity generation. Furthermore, the density functional theory model result unravels that the as-formed potential field inhibits OH–, thus creating a potential difference between upper and lower terminals. This research outlines a "Win-Win" strategy aimed at achieving environmentally friendly, high-value repurposing of waste polyester. Additionally, it aims to develop sophisticated co-generation devices for producing both freshwater and electricity. [ABSTRACT FROM AUTHOR]

The coupling of solar-driven interfacial evaporation with hydrovoltaic technology is emerged as a hopeful approach to alleviate energy crisis and freshwater shortage. However, constructing low-cost evaporators with high-performance freshwater and electricity co-generation and unveiling the co-generation mechanism remain a grand challenge. Herein, we report the green transformation of waste poly(ε -caprolactone) into graphene through a salt-assisted carbonization strategy and build a flexible bi-functional graphene-based evaporator for freshwater and electricity co-generation. The graphene exhibits a typical wrinkled structure with curved edges and is composed of 7–8 discontinuous layers with rich oxygen-containing groups. The graphene-based evaporator exhibits excellent sunlight absorption (98%), photo-to-thermal conversion property, good water transport ability, low water evaporation enthalpy, and low thermal conductivity of 0.06 W m−1 K−1. The evaporator not only exhibits a notable water evaporation rate (2.92 kg m−2 h−1), but also achieves the maximum output voltage of 310 mV, surpassing many previously reported evaporators/generators. The result of molecular dynamics simulation proves the diffusion difference between H+ and OH− in water and graphene, which eventually leads to the voltage generation. Not only will this work help to improve the upcycling of waste plastics and achieve carbon neutrality, but it will also open an avenue for co-generation of freshwater and electricity. [Display omitted] • The salt-assisted carbonization strategy is used to produce graphene from waste PET. • Graphene-based evaporator owns good light absorption and solar-thermal conversion. • The evaporator realizes high-performance freshwater and electricity co-generation. • The evaporation rate is up to 2.92 kg m−2 h−1, with high solar-to-vapor efficiency. • The device shows a high open-circuit voltage of 310 mV with good cycling stability. [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]

Integrating interfacial solar steam generation with advanced oxidation process (AOP) is regarded as a promising strategy for addressing energy and environmental issues. However, developing dual-functional evaporators well-integrated with synergistic photothermal-AOP catalysis properties remains challenging. Herein, we synthesize cobalt-based metal-organic framework (Co-CAT) and prepare dual-functional Co-CAT evaporators. Co-CAT is endowed with "all-in-one" functions, i.e., high specific surface area, effective light absorption, and high catalytic activity. Co-CAT exhibits superior sunlight absorption and photo-to-thermal conversion property. The large specific surface area and abundant micropore of Co-CAT facilitate water permeation and evaporation enthalpy reduction. COMSOL Multiphysics and density functional theory calculation results prove that Co2+ sites in Co-CAT and heat localization promote peroxymonosulfate activation. Consequently, it not only exhibits a high-water evaporation rate of 2.2 kg m−2 h−1, outperforming the-state-of-art evaporators, but also presents the notable tetracycline degradation efficiency (91.1 %). This work proposes an ingenious way to deal with freshwater shortage and water pollution. [Display omitted] • Co-CAT with "all-in-one" functions is prepared by a facile hydrothermal method. • Co-CAT evaporator realizes wastewater purification and freshwater production. • Co-CAT owns good photothermal conversion ability and rises AOP catalysis efficiency. • Localized solar heat and rich open Co sites of Co-CAT promote the activation of PMS. • Evaporator shows an evaporation rate of 2.2 kg m−2 h−1 with TC removal of 91.1 %. [ABSTRACT FROM AUTHOR]

[Display omitted] • Semiconductive Co-MOF nanorod in large quantity is prepared from discarded PET. • Co-MOF/CNT evaporator realizes wastewater purification and freshwater production. • CNT owns good photothermal conversion ability and rises photocatalysis efficiency. • Localized solar heat and rich open Co site of Co-MOF promote the activation of PMS. • Evaporator shows an evaporation rate of 2.25 kg m−2h−1 with TC removal of 99.8 % Catalytic conversion of waste plastics into semiconductive metal–organic framework (MOF) kills two birds with one stone, since it not merely offers promising possibility to realize freshwater production and water decontamination through interfacial solar evaporation and photocatalysis, but also advances upcycling of waste plastics. Nevertheless, exploiting synergistic photothermal-photocatalysis materials from recycled plastics remains a challenge. Herein, we report a facile solvothermal method of waste poly(ethylene terephthalate) bottles for the massive production of Co-MOF nanorod and construct a dual-functional Co-MOF/carbon nanotube (CNT) solar evaporator integrated with advanced oxidation process for simultaneous wastewater purification and freshwater production. Firstly, we prove that the evaporator owns high sunlight absorption due to the presence of CNT, super-hydrophilicity, and low heat conductivity, which endow it with fine photothermal conversion capability and reduced vaporization enthalpy. Benefiting from the above advantages, Co-MOF/CNT evaporator displays a high evaporation rate of 2.25 kg m−2 h−1 under 1 kW m−2 illumination, when treating tetracycline (TC)-polluted water, along with good mechanical property, high flexibility, long-term stability, and high scalability. Secondly, based on the results of COMSOL and density functional theory calculation, the localized solar heat from CNT and rich open cobalt sites of Co-MOF nanorod are proved to play a synergistic effect in the activation of peroxymonosulfate to generate various oxidation reactive species. Thereby, the dual-functional evaporator achieves a superb TC degradation activity. Lastly, an outdoor device is designed for freshwater generation and catalytic decomposition of TC. The daily freshwater production amount is 4.5 kg m−2, and the TC degradation efficiency is 93.1%. This study not merely advances the upcycling waste plastics into useful products, but also offers a sustainable platform to wastewater purification via a waste-treating-waste strategy. [ABSTRACT FROM AUTHOR]