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Upgrading of polyethylene terephthalate (PET) waste into valuable oxygenated molecules is a fascinating process, yet it remains challenging. Herein, we developed a two‐step strategy involving methanolysis of PET to dimethyl terephthalate (DMT), followed by hydrogenation of DMT to produce the high‐valued chemical methyl p‐methyl benzoate (MMB) using a fixed‐bed reactor and a Cu/ZrO2 catalyst. Interestingly, we discovered the phase structure of ZrO2 significantly regulates the selectivity of products. Cu supported on monoclinic ZrO2 (5 %Cu/m‐ZrO2) exhibits an exceptional selectivity of 86 % for conversion of DMT to MMB, while Cu supported on tetragonal ZrO2 (5 %Cu/t‐ZrO2) predominantly produces p‐xylene (PX) with selectivity of 75 %. The superior selectivity of MMB over Cu/m‐ZrO2 can be attributed to the weaker acid sites present on m‐ZrO2 compared to t‐ZrO2. This weak acidity of m‐ZrO2 leads to a moderate adsorption capability of MMB, and facilitating its desorption. Furthermore, DFT calculations reveal Cu/m‐ZrO2 catalyst shows a higher effective energy barrier for cleavage of second C−O bond compared to Cu/t‐ZrO2 catalyst; this distinction ensures the high selectivity of MMB. This catalyst not only presents an approach for upgrading of PET waste into fine chemicals but also offers a strategy for controlling the primary product in a multistep hydrogenation reaction. [ABSTRACT FROM AUTHOR]

Two phosphates, Cs2Zn5(PO4)4 and Cs3La(PO4)2 have been successfully synthesized by employing the conventional solid‐state reaction method, and their structures were determined by single‐crystal X‐ray diffraction. Cs2Zn5(PO4)4 owns a three‐dimensional ∞3[Zn4P4O16] framework and Cs3La(PO4)2 features ∞2[La3P6O29] layers spreading in the bc plane. Infrared spectroscopy, UV/Vis‐NIR diffuse reflectance spectroscopy were performed. The thermal properties and electronic structures of two compounds were investigated. In addition, the Ce3+ doped Cs3La(PO4)2 phosphor was synthesized and its photoluminescence was analyzed. The results indicate that the Cs2Zn5(PO4)4:0.01Ce3+ phosphor can be excited by ultraviolet light to obtain blue luminescence. [ABSTRACT FROM AUTHOR]

Herein, a promising infrared nonlinear optical (IR NLO) material, Li2ZnGeS4, was successfully synthesized in the typical quaternary diamond-like semiconductor (DLS) system. This material exhibits excellent performances including a wide band gap (3.49 eV), a high laser-damage threshold (LDT, 8 × benchmark AgGaS2), and a good NLO effect (0.7 × AgGaS2) with phase-matching behavior. Furthermore, based on first principles calculations, the theoretical results are in agreement with the experimental results. [ABSTRACT FROM AUTHOR]

The introduction of d10-metal cations is of importance in the design of infrared nonlinear optical materials. The role of d10-metal cations on the band gap and the second-harmonic generation (SHG) effect as well as the structure–property relationship were investigated in the Li2MGeS4 (M = Cd, Hg) and AB2S4 (A = Cd, Hg; B = Al, Ga) systems by using the first-principles calculations. The results show that the decreased band gap is related to a higher valence band maximum (VBM) caused by the larger dp repulsion from the Hg-5d orbitals and a downshift in the conduction band minimum (CBM) due to the lower energy of the Hg-6s orbitals. In addition, the relatively enhanced SHG response can be attributed to the decreased charge-transfer energy and the enhanced hybridization between the S-3p orbitals and the Hg-5d orbitals. [ABSTRACT FROM AUTHOR]

Upgrading of polyethylene terephthalate (PET) waste into valuable oxygenated molecules is a fascinating process, yet it remains challenging. Herein, we developed a two-step strategy involving methanolysis of PET to dimethyl terephthalate (DMT), followed by hydrogenation of DMT to produce the high-valued chemical methyl p-methyl benzoate (MMB) using a fixed-bed reactor and a Cu/ZrO 2 catalyst. Interestingly, we discovered the phase structure of ZrO 2 significantly regulates the selectivity of products. Cu supported on monoclinic ZrO 2 (5 %Cu/m-ZrO 2 ) exhibits an exceptional selectivity of 86 % for conversion of DMT to MMB, while Cu supported on tetragonal ZrO 2 (5 %Cu/t-ZrO 2 ) predominantly produces p-xylene (PX) with selectivity of 75 %. The superior selectivity of MMB over Cu/m-ZrO 2 can be attributed to the weaker acid sites present on m-ZrO 2 compared to t-ZrO 2 . This weak acidity of m-ZrO 2 leads to a moderate adsorption capability of MMB, and facilitating its desorption. Furthermore, DFT calculations reveal Cu/m-ZrO 2 catalyst shows a higher effective energy barrier for cleavage of second C-O bond compared to Cu/t-ZrO 2 catalyst; this distinction ensures the high selectivity of MMB. This catalyst not only presents an approach for upgrading of PET waste into fine chemicals but also offers a strategy for controlling the primary product in a multistep hydrogenation reaction., (© 2024 Wiley-VCH GmbH.)

Herein, a promising infrared nonlinear optical (IR NLO) material, Li2ZnGeS4, was successfully synthesized in the typical quaternary diamond-like semiconductor (DLS) system. This material exhibits excellent performances including a wide band gap (3.49 eV), a high laser-damage threshold (LDT, 8 × benchmark AgGaS2), and a good NLO effect (0.7 × AgGaS2) with phase-matching behavior. Furthermore, based on first principles calculations, the theoretical results are in agreement with the experimental results.

The introduction of d10-metal cations is of importance in the design of infrared nonlinear optical materials. The role of d10-metal cations on the band gap and the second-harmonic generation (SHG) effect as well as the structure-property relationship were investigated in the Li2MGeS4 (M = Cd, Hg) and AB2S4 (A = Cd, Hg; B = Al, Ga) systems by using the first-principles calculations. The results show that the decreased band gap is related to a higher valence band maximum (VBM) caused by the larger dp repulsion from the Hg-5d orbitals and a downshift in the conduction band minimum (CBM) due to the lower energy of the Hg-6s orbitals. In addition, the relatively enhanced SHG response can be attributed to the decreased charge-transfer energy and the enhanced hybridization between the S-3p orbitals and the Hg-5d orbitals.

Two borate chlorides LaB 4 O 6 (OH) 2 Cl and CeB 4 O 6 (OH) 2 Cl have been synthesized and characterized. Both of them exhibit structure similar to that of notable KBe 2 BO 3 F 2 and feature two-dimensional [B 4 O 6 (OH) 2 ] ∞ layers constructed by [B 4 O 8 (OH)] 2 fundamental building blocks. Thermal analyses, infrared spectroscopy, UV-vis-NIR spectra, and second harmonic generation measurement were performed to investigate their physical properties. The results show that both of them have high decomposition temperatures and large second-harmonic generation responses (2.3 and 2.1 × KH 2 PO 4 , respectively), and LaB 4 O 6 (OH) 2 Cl possesses a deep-UV cutoff edge below 180 nm and large band gap. Moreover, the first-principle calculations were carried out to clarify the role of the electronic structure in determining the associated optical properties of LaB 4 O 6 (OH) 2 Cl. These results demonstrate that LaB 4 O 6 (OH) 2 Cl can be considered as a candidate for ultraviolet nonlinear optical material.