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Metal oxide nanostructures with single-atomic heteroatom incorporation are of interest for many applications. However, a universal and scalable synthesis approach with high heteroatom concentrations represents a formidable challenge, primarily due to the pronounced structural disparities between Mhetero–O and Msub–O units. Here, focusing on TiO2 as the exemplified substrate, we present a diethylene glycol-assisted synthetic platform tailored for the controlled preparation of a library of M1-TiO2 nanostructures, encompassing 15 distinct unary M1-TiO2 nanostructures, along with two types of binary and ternary composites. Our approach capitalizes on the unique properties of diethylene glycol, affording precise kinetic control by passivating the hydrolytic activity of heteroatom and simultaneously achieving thermodynamic control by introducing short-range order structures to dissipate the free energy associated with heteroatom incorporation. The M1-TiO2 nanostructures, characterized by distinctive and abundant M–O–Ti units on the surface, exhibit high efficiency in photochromic photothermal catalysis toward recycling waste polyesters. This universal synthetic platform contributes to the preparation of materials with broad applicability and significance across catalysis, energy conversion, and biomedicine. This work showcases a versatile and scalable synthetic platform for photochromic single-atom catalysts, which effectively upcycle diverse waste polyesters into value-added monomers. [ABSTRACT FROM AUTHOR]

Incorporating high‐energy ultraviolet (UV) photons into photothermal catalytic processes may enable photothermal‐photochemical synergistic catalysis, which represents a transformative technology for waste plastic recycling. The major challenge is avoiding side reactions and by‐products caused by these energetic photons. Here, we break through the limitation of the existing photothermal conversion mechanism and propose a photochromic‐photothermal catalytic system based on polyol‐ligated TiO2 nanocrystals. Upon UV or sunlight irradiation, the chemically bonded polyols can rapidly capture holes generated by TiO2, enabling photogenerated electrons to reduce Ti4+ to Ti3+ and produce oxygen vacancies. The resulting abundant defect energy levels boost sunlight‐to‐heat conversion efficiency, and simultaneously the oxygen vacancies facilitate polyester glycolysis by activating the nucleophilic addition‐elimination process. As a result, compared to commercial TiO2 (P25), we achieve 6‐fold and 12.2‐fold performance enhancements under thermal and photothermal conditions, respectively, while maintaining high selectivity to high‐valued monomers. This paradigm‐shift strategy directs energetic UV photons for activating catalysts and avoids their interaction with reactants, opening the possibility of substantially elevating the efficiency of more solar‐driven catalysis. [ABSTRACT FROM AUTHOR]

Photothermal catalytic conversion of waste plastics into fuels and/or feedstocks using renewable solar energy can achieve solar‐to‐chemical conversion, resource sustainability, and environmental remediation simultaneously. However, the construction of photothermal catalysts with strong light absorption and high catalytic activity remains a great challenge. In this work, integrated cobalt single‐site catalysts (Co SSCs), coupled with strong photothermal conversion, high catalytic activity, and stability, are employed to catalyze the glycolysis of polyesters. The unique coordination‐unsaturated CoO5 single‐site can coordinate with the carbonyl groups in polyester, thus boosting the nucleophilic addition elimination processes. As a result, the space‐time yield of Co SSCs is an order of magnitude higher than that of general catalysts. In addition, the polyethylene terephthalate (PET) conversion and bis(2‐hydroxyethyl) terephthalate yield in photothermal catalysis are 5.4 and 6.6 times higher than those of thermal catalysis under the same conditions, which are contributed by the localized heating effect. Technical economic analysis shows that the recycling of 105 tons of waste PET by photothermal catalysis consumes 146.4 GW·h electrical energy and misses 7.44 × 104 tons of CO2 emission. Therefore, a high‐efficient photothermal catalytic plastic recycling system is of great significance for waste plastic valorization. [ABSTRACT FROM AUTHOR]