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The activation and hydrogenation of CO 2 at the Cu/TiO 2 interfaces that are formed by depositing subnanometer Cu n (n = 1−8) clusters on TiO 2 (110) surfaces have been systematically investigated using density functional theory calculations. The most stable structures with a bent CO 2δ− configuration at the Cu n /TiO 2 interfaces are determined, which indicate that the binding strength of CO 2 on the Cu n /TiO 2 (110) surface can be tuned by controlling the size of the deposited Cu cluster. It is interesting that the copper cluster with a specific size of Cu 4 exhibits a distinct preference for CO 2 activation, and the strongest binding interaction between CO 2 and Cu 4 / TiO 2 (110) is mainly ascribed to the formation of the strong Cu−C and Ti−O adsorption bonds. The reaction mechanisms of CO 2 conversion to CH 3 OH at the Cu 4 /TiO 2 (110) interface via the formate and the reverse water gas shift (RWGS) + CO-hydrogenation pathways are further investigated by microkinetic simulations. The production of CH 3 OH over Cu 4 /TiO 2 is mainly via the RWGS pathway to yield CO followed by the formation of H 3 CO* as the most stable intermediate, while the formate pathway is not efficient enough because of the higher apparent activation energy of CH 3 OH generation and the overly strong binding of HCOO* species at the interface. Compared with other Cu n /TiO 2 interfaces, the TiO 2 (110) surface-supported size-selected Cu 4 cluster exhibits the highest CO 2 hydrogenation activity. The findings obtained in the present work provide useful insight to design Cu/oxide interfaces with high activity toward methanol synthesis from CO 2 hydrogenation by precisely controlling the size of copper clusters.

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The harmless treatments of medical waste have significantly drawn people's attention owing to their risks to health-care staff, the public, and the environment. The traditional thermal technology for processing medical waste may cause indispensable secondary pollution such as dioxin, furan, and heavy metals, and infectious materials that may remain in the solid residual. Thermal plasma technologies offer advantages of effectively treating medical waste due to its high temperature and energy density, lower pollutant emissions, rapid start-up and shutdown , and smaller size of the installation. These benefits play roles in the treatment of medical waste on-site or off-site, especially when somewhere encounters an abnormally sharp increase in medical waste. This paper mainly introduces the typical thermal plasma processes of medical waste and its central component, plasma furnace. Meanwhile, how process parameters influence the formed gaseous and solid products, the performances of mass and volume reduction, pathogen destruction, and energy recovery, are discussed in detail. Finally, the mechanism of the thermal plasma process is also analyzed.

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First-principles computations were performed to investigate the performance of KTiOPO 4 (KTP) as a cathode material for potassium-ion batteries (PIBs), including the stability and electronic properties of depotassiated structures and mechanisms of K deintercalation and diffusion. As depotassiation proceeds, oxygen hole polarons are produced, and there are not peroxides or superoxides formed after deep depotassiation. The anionic oxygen redox in KTP provides a voltage vs K/K + over 4 V by the PBE+U method and over 5 V with the more reliable HSE06 hybrid functional. When all K in KTP is removed, the calculated volume compression is only 1.528%. The AIMD simulations at 300 K for TiOPO 4 verify its thermal stability. The PBE+U calculations predict a low ion diffusion barrier of 0.29 eV in bulk KTP, indicating a good charge−discharge rate for KTP as a cathode for PIBs. All of the calculated results indicate that KTP can be a promising cathode material for PIBs.

Density functional theory calculations have been performed to investigate the linear and second-order nonlinear optical (NLO) properties of titanium-based MIL-125 metal−organic frameworks in crystalline form, in which the 1,4-benzenedicarboxylate (BDC) linkers are modified by introducing different functional groups or by extending the BDC ligand to contain two (MIL-126) and three (MIL-127) benzene rings. Our results reveal that the functionalization of the BDC linker tends to increase the dielectric constants and the magnitude of birefringence of MIL-125, especially for the aminated derivatives. Correspondingly, the incorporation of a substituent group will improve the phase matching performance of MIL-125. As for the second-harmonic generation (SHG) susceptibility, the SHG activity of the pristine MIL-125 is comparable to KDP, which can be attributed mostly to the contributions of TiO 5 (OH) octahedra. It is noted that after introducing the substituent group into the BDC linker, the organic part will have a remarkable influence on the SHG intensity. However, the specific effect on the NLO response is dependent on the type of functional group incorporated into the BDC ligand, and only the inclusion of the amine group that is strongly electron-donating can obviously enhance the SHG activity of MIL-125. In addition, MIL-126 and MIL-127 with longer aromatic linking units are not suitable to act as NLO materials due to their poor phase matching abilities, but they are promising candidates for the low dielectric constant materials. The present study can provide theoretical insights to design new secondorder NLO materials based on MIL-125.

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