TiO2 nanoparticles doped with different concentrations of Zr4+ ions were prepared by the sol–gel method and annealed at different temperatures. X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and high resolution transmission electron microscopy (HRTEM) techniques were used to investigate the existing states and doping mechanism of dopants as well as the phase transition of the Zr4+-doped TiO2 samples. It was revealed that the doping behavior of introduced Zr4+ ions was closely related to the doping concentration. The Zr4+ ions would replace the lattice Ti4+ ions directly in substitutional mode at a certain annealing temperature. Moreover, if the concentration of doped Zr4+ ions is high enough, excess Zr4+ ions would form ZrTiO4 on the surface of TiO2. In addition, the phase transition temperature from anatase to rutile increases significantly after doping Zr4+ ions, due to their larger electropositivity and radius than those of Ti4+ ions. Our results may afford a better understanding on the doping mechanism and aid in the preparation of Zr-doped TiO2 with high photoelectric performance.

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In order to enhance the efficiency and safety of production and management of modern agriculture in China, problems, such as the quality and safety of agricultural products and the pollution of the environment from agricultural activities, should be unraveled. Based on the new generation of information technology (IT), an integrated framework system platform incorporating the Internet of Things (IoT), cloud computing, data mining, and other technologies is investigated and a new proposal for its application in the field of modern agriculture is offered. The experimental framework and simulation design suggest that the basic functions of the monitoring system of the IoT for agriculture can be realized. In addition, the innovation derived from integrating different technologies plays an important role in reducing the cost of system development and ensuring its reliability as well as security. INDEX TERMS Management system, modern agriculture, big data, cloud computing, Internet of Things (IoT).

Density functional theory (DFT) calculation is carried out to access the band structure and density of states (DOS) based on the models of TiO2 nanoparticle, nanotube, and nanosheet, predicting the order of the photocatalytic activity for three different nanostructures. Sol–gel method and hydrothermal method are used to achieve desired morphologies: nanoparticles, nanotubes, and nanosheets (fragmentized nanotubes). The photocatalytic activity ranks in the order of nanosheets > nanotubes > nanoparticles, which is consistent with theoretical prediction. It was revealed that the enlargement of band gap is caused by the quantum confinement effect; the prolonged lifetime of photogenerated electrons and increased specific surface areas are dependent on the morphology of the nanostructure. All these factors contribute to the improvement of the photocatalytic activity for nanostructures. Our results can guide the design and selection of low-dimensional nanomaterials with desired morphology and improved photoelectric functional properties, which can be used in many fields, such as solar cells, photocatalysis, and photosynthesis.

Different approaches like doping and sensitization have been used to develop photocatalysts that can lead to high reactivity under visible-light illumination, which would allow efficient utilization of solar irradiation and even interior lighting. We demonstrated a conceptually different approach by changing reaction route via introducing the idea of conventional Pd catalysis used in cross-coupling reactions into photocatalysis. The –O–Pd–Cl surface species modified on Ni-doped TiO2 can play a role the same as that in chemical catalysis, resulting in remarkably enhanced photocatalytic activity under visible-light irradiation. For instance, Pd/Ni-TiO2 has much higher activity than N-TiO2 (about 3 ~ 9 times for all of the 4-XP systems) upon irradiation with wavelength of 420 nm. The catalytically active Pd(0) is achieved by reduction of photogenerated electrons from Ni-TiO2. Given high efficient, stable Pd catalysts or other suitable chemical catalysts, this concept may enable realization of the practical applications of photocatalysis.