Interfacial Electron Potential Well Facilitates the Design of Cobalt Phosphide Heterojunctions for Hydrogen Evolution.

The interfacial electron modulation of electrocatalysts is an effective way to realize efficient hydrogen production, which is of great importance for future renewable energy systems. However, systematic theory-guided design of catalysts in heterojunction coupling is lacking. In this work, a multi-level theoretical calculation is performed to screen optimal candidates to form a heterojunction with CoP (101) surface for electrocatalytic hydrogen production. To overcome the weak adsorption of H+ on CoP (101), rational design of electrons potential well at the heterojunction interface can effectively enhance the hydrogen adsorption. All p-type cobalt-based phosphides are considered potential candidates at the beginning. After screening for conductivity, stability, interface matching screening, and ΔGH* evaluation, the CoP/Co2 P-H system is identified to be able to display optimal hydrogen production performance. To verify the theoretical design, CoP, CoP/Co2 P-H, and CoP/Co2 P-O are synthesized and the electrochemical analysis is carried out. The hydrogen evolution reaction (HER) performance is consistent with the prediction. This work utilizes the electron potential well effect and multi-level screening calculations to design highly efficient heterojunction catalysts, which can provide useful theoretical guidance for the rational design of heterojunction-type catalysts.

Constructing Dual Cocatalysts of Ni2P-NiS-Decorated TiO2 for Boosting Photocatalytic H2 Evolution.

The loading of cocatalysts is an effective approach to optimize the separation of carriers during photocatalytic processes. Among them, cocatalysts often work independently during the photocatalytic production of H2. However, an investigation of the synergistic effect of dual cocatalysts is beneficial for further promoting photocatalytic H2 production activity. In this work, dual cocatalyst Ni2P-NiS-modified TiO2 nanosheets were fabricated through a solvent evaporation method. The investigation indicates that Ni2P-NiS can widen the light absorption range and reduce the contact angle between TiO2 and water from 26.71 to 8.27°, which facilitates the adsorption of water molecules. Besides, the introduction of Ni2P-NiS can decrease the overpotential of H2 evolution and induce more electrochemically active surface area. The photocatalytic tests show that the H2 production rate of 15% Ni2P-NiS/TiO2 can reach up to 4891.6 µmol·g-1·h-1, which is 30.2, 4.4, and 1.3 times than pure TiO2 (161.8 µmol·g-1·h-1), 15% Ni2P/TiO2 (1112.1 µmol·g-1·h-1), and 15% NiS/TiO2 (3678.1 µmol·g-1·h-1), respectively. The enhancement mechanism of photocatalytic H2 production is attributed to the Schottky barrier effect between Ni2P-NiS nanoparticles and TiO2 nanosheets, which can enormously promote the interface charge separation and transfer, and enhance the kinetics of H2 production. This work provides a potential strategy for enhancement H2 production using appropriate dual cocatalyst-decorated semiconductor materials.

Hole Storage Interfacial Regulation of Sb2Se3 Photocathode with Significantly Enhanced Photoelectrochemical Performance.

Although interfacial engineering materials for antimony selenide (Sb2Se3) photocathodes have been intensively studied, most of the previous research has focused on the development of photogenerated electron transfer promoters. In this work, Sb2Se3 photocathodes are innovatively modified by using ferrihydrite (Fh), which has been widely used as a hole storage layer in photoanodes. After modifying Fh, the photocurrent density of the Sb2Se3 photocathode was increased from -0.27 to -1.6 mA cm-2 at 0 VRHE with the onset potential positive shift about 150 mV, and an impressive injection efficiency of 83.84% was achieved. The major contribution of Fh to the photoelectrochemical (PEC) performance enhancement was demonstrated by various characterization studies. The results show that the enhancement performance of PEC is largely attributed to the capture of back-migrating holes by Fh, the reduction of interfacial charge transfer resistance, and the significant increase in electrochemical active surface area (ECSA). This work presents new insights into the application of hole storage layers in Sb2Se3-based photocathodes.

Recent Advances of Modified Ni (Co, Fe)-Based LDH 2D Materials for Water Splitting.

Water splitting technology is an efficient approach to produce hydrogen (H2) as an energy carrier, which can address the problems of environmental deterioration and energy shortage well, as well as establishment of a clean and sustainable hydrogen economy powered by renewable energy sources due to the green reaction of H2 with O2. The efficiency of H2 production by water splitting technology is intimately related with the reactions on the electrode. Nowadays, the efficient electrocatalysts in water splitting reactions are the precious metal-based materials, i.e., Pt/C, RuO2, and IrO2. Ni (Co, Fe)-based layered double hydroxides (LDH) two-dimensional (2D) materials are the typical non-precious metal-based materials in water splitting with their advantages including low cost, excellent electrocatalytic performance, and simple preparation methods. They exhibit great potential for the substitution of precious metal-based materials. This review summarizes the recent progress of Ni (Co, Fe)-based LDH 2D materials for water splitting, and mainly focuses on discussing and analyzing the different strategies for modifying LDH materials towards high electrocatalytic performance. We also discuss recent achievements, including their electronic structure, electrocatalytic performance, catalytic center, preparation process, and catalytic mechanism. Furthermore, the characterization progress in revealing the electronic structure and catalytic mechanism of LDH is highlighted in this review. Finally, we put forward some future perspectives relating to design and explore advanced LDH catalysts in water splitting.

Efficient photoelectrochemical water-splitting over carbon membrane linked Au and TiO2 nanotube arrays film based on multiple carriers transport paths.

Herein, a carbon membrane and Au nanoparticles were combined to improve the efficiency of photoelectrocatalytic water splitting over a TiO2 nanotube arrays film (TiO2 NTAF). Two different ternary nanostructures were constructed by hydrothermal and photochemical deposition processes. One was carbon membrane bridged Au nanoparticles and TiO2 nanotube arrays (Au/C/TiO2 NTAF), while the other was Au nanoparticles sandwiched between carbon membrane and TiO2 nanotube arrays (C/Au/TiO2 NTAF). The two structures exhibited enhanced visible light harvesting ability, but they showed distinctly different photoelectric properties. The unique microstructure of C/Au/TiO2 NTAF resulted in a much higher reduction of the electron cloud density of Au nanoparticles as carrier recombination centers, which were responsible for its poor photoelectrochemical performance. However, a champion photocurrent of Au/C/TiO2 NTAF was observed (0.984 mA cm-2), indicating superior ability of the photoelectrocatalytic water splitting. The great enhancement was attributed to multiple carriers transport paths, which can efficiently utilize the sensitization of the carbon membrane and the surface plasmon resonance effect of the Au nanoparticles.

Aqueous synthesis of L-cysteine and mercaptopropionic acid co-capped ZnS quantum dots with dual emissions.

In this paper, L-cysteine (L-cys) and mercaptopropionic acid (MPA) co-capped ZnS quantum dots (QDs) with dual emissions have been successfully synthesized by a one-pot aqueous-phase synthesis method. The intensities of the dual emissions could be controlled by regulating the molar ratio of L-cys to MPA, and the fluorescence color also turned from blue to yellow accordingly. The relationship between the ligands and fluorescence was investigated and the results indicated that L-cys could cause two emissions and MPA improved the emission intensity. In addition, the L-cys-MPA co-capped ZnS QDs showed high photostability under UV irradiation. Therefore, the L-cys-MPA co-capped ZnS QDs, which show the dual emissions and tunable emission intensities, have great potentials for use in ratiometric fluorescence sensors and multicolor bioimaging.

A Facile Strategy to Prepare Zr4+-Modified Bi2WO6 with Enhanced Visible-Light Photocatalytic Activities.

A series of Zr4+-modified Bi2WO6 photocatalysts were synthesized using a hydrothermal method employing Bi(NO3)3·5H2O, Na2WO4·2H2O and Zr(NO3)4 as precursors. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), UV-vis absorption spectroscopy (UV-vis) and photoluminescence spectroscopy (PL). The investigations indicated that the flower-like Bi2WO6 3D structures were constructed from a large number of 2D layers of interconnected nanoplates. The energy gaps of Zr4+-modified Bi2WO6 decreased compared with that of pure Bi2WO6. In addition, fluorescence quenching was observed because the recombination of charge carriers was effectively suppressed by Zr4+. The photocatalytic properties of samples were evaluated by the degradation of Rhodamine B (RhB) solution under visible-light irradiation. The results indicate that the 1.0 mol% Zr4+-modified Bi2WO6 possesses obviously enhanced photocatalytic activity, showing the great potential for wastewater purification. In addition, a tentative photocatalytic mechanism is proposed to understand the experimental results over the Zr4+-modified Bi2WO6 photocatalysts.

Fabrication and Enhanced Photoactivities of Plasmonic Ag/TiO2 Nano-Flower Films.

Titania nano-flower films were in this study decorated with silver nanoparticles (Ag/TiO2 NFFs) and fabricated through a facile hydrothermal route, followed by a microwave-assisted reduction process. The investigations indicated that the Ag nanoparticles were deposited evenly on the anatase TiO2 film, forming a heterogeneous structure. The prepared composites exhibited excellent visible light harvesting ability due to the light-scattering TiO2 nanostructures and localized surface plasmon resonance (LSPR) of Ag NPs. In addition, a lower recombination probability for the photoexcited charge carriers was observed. These experimental results demonstrated that the Ag/TiO2 NFFs possessed obviously enhanced photocatalytic activities for methyl orange (MO) degradation in comparison with pure TiO2 NFFs, and the corresponding degradation rate was 3.5 times as much as that of pure TiO2 NFFs. This enhancement arose from the positive synergetic effect between the charge separation behavior and LSPR effect from the Ag nanoparticles. The results from the present study demonstrate that the visible light capturing ability for the TiO2-based semiconductors can be achieved through rational design of their nanostructures or through the LSPR effect originating from the plasmonic nanoparticles. This work also offers a facile approach for developing film photocatalysts with high efficiency.

Effective improvement in optical properties of colloidal CdTe@ZnS quantum dots synthesized from aqueous solution.

Efficient synthesis of high-quality quantum dots (QDs) with excellent optical properties by aqueous synthesis is still of great significance for extended optical applications. Herein we highlight the advantages in optical properties of colloidal CdTe@ZnS QDs prepared by a facile and highly effective aqueous synthesis method. These achievements were realized by delicate manipulation of the conditions involved in nucleation and the growth process. Transmission electron microscopy (TEM) images indicated the QDs were uniform size and well dispersible. The emission peaks of the as-prepared QDs could shift from 496 to 698 nm with narrow full width at half maximum (FWHM), and the corresponding fluorescent color changed from green to red. Moreover, the emission could even reach to the near-infrared (NIR) region (706-796 nm) by extending the reaction time. The highest photoluminescence (PL) quantum yield (QY) of the QDs could reach to 60%, and the average of FWHM was about 55 nm. To address the problem of wide size-distribution in PL QY decrease and FWHM broadening, the colloids of QDs prepared at long reaction time (above 3 h) were centrifuged (12 000 r min(-1)). In addition, the assessment of QD cytotoxicity indicated the CdTe@ZnS QDs were much less cytotoxic and showed good biocompatibility. Compared with organic synthesis, our aqueous synthesis of QDs could be carried out efficiently on a large scale and showed good batch-to-batch reproducibility. The as-prepared CdTe@ZnS QDs exhibited excellent optical properties and hold a good potential to be applied in optoelectronic and biological applications.

Fabrication of plasmonic Au/TiO2 nanofiber films with enhanced photocatalytic activities.

TiO2 nanofiber films (TiO2 NFF) with visible light scattering ability were prepared using a hydrothermal method. Au nanoparticles (Au NPs) were then deposited on the surface of TiO2 film using a microwave-assisted chemical reduction process. An overlapped light-trapping phenomenon was observed in Au/TiO2 NFF due to the light-scattering nanostructures of TiO2 film and the localized surface plasmon resonance (LSPR) of Au NPs. The MB degradation over the composite films is much faster than that of pure TiO2 film. The enhanced photocatalytic activity is primarily attributed to the charge transfer property and the overlapped light-trapping nanostructures of Au/TiO2.

Incorporation of lanthanide (Eu(3+)) ions in ZnS semiconductor quantum dots with a trapped-dopant model and their photoluminescence spectroscopy study.

Doping quantum dots (QDs) with lanthanide (Ln) ions is promising to modify the optical properties of QDs, but incorporating Ln(3+) ions into QD hosts remains a challenge. In this work, we adopt the trapped-dopant model for fabricating Eu-doped ZnS QDs via direct wet chemical synthesis. Sharp Eu dopant photoluminescence (PL) was observed in the PL spectra of the as-prepared Eu-doped ZnS QDs and the bands at ~590, ~618 and ~695 nm were assigned to transitions from (5)D0 to (7)F1, (7)F2 and (7)F4, respectively. Quenching of the ZnS bandgap PL and enhancement of the Eu dopant PL were observed with increasing Eu(3+) doping concentration, and also, the excitation spectra for Eu emission (618 nm) were similar to the typical excitonic features of the ZnS host. These spectroscopic results, as well as the XRD and EDS data, demonstrated that Eu(3+) ions were incorporated in the ZnS host rather than just on the surface, and the Eu dopant PL was derived from energy transfer from the QD host to Eu(3+) rather than direct excitation of Eu(3+). By surface passivation, the sharp Eu emission was well-separated from the ZnS bandgap emission, which led to a good signal-to-noise ratio for more sensitive detection.

Plasmonic Ag deposited TiO2 nano-sheet film for enhanced photocatalytic hydrogen production by water splitting.

TiO2 nano-sheet film (TiO2 NSF) was prepared by a hydrothermal method. Ag nanoparticles (NPs) were then deposited on the surface of TiO2 NSF (Ag/TiO2 NSF) under microwave-assisted chemical reduction. The prepared samples were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), UV-visible (UV-vis) absorption spectroscopy, x-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectroscopy, and Raman scattering spectroscopy. The results revealed that the Ag NPs were well dispersed on the anatase/rutile mixed-phase TiO2 nano-sheet surface with a metallic state. The visible light absorption and Raman scattering of TiO2 were enhanced by Ag NPs based on its surface plasmon resonance effect. Besides, Ag NPs could also effectively restrain the recombination of photogenerated electrons and holes. Photocatalytic water splitting was conducted on the films to obtain hydrogen, and the experimental results indicated that plasmonic Ag NPs could greatly enhance the photocatalytic activity of TiO2 due to the synergistic effect between electron transfer and surface plasmon resonance enhanced absorption. The hydrogen yield obtained from the optimal sample reached 8.1 µmol cm(-2) and the corresponding energy efficiency was about 0.47%, which was 8.5 times higher than that of pure TiO2 film. Additionally, the formation mechanism of TiO2 nano-sheet film is preliminarily discussed.

Transition from Eu3+ to Eu2+ in SiO2 matrix prepared by sol-gel.

Activated silica matrix fluorescent materials doped with Al3+ and Eu2+ are prepared by sol-gel method. The effects of different atmospheres and annealing temperatures on luminescent properties are characterized by analysis techniques including X-ray diffraction, infrared spectroscopy and fluorescence spectra. When being excited at 281 nm wavelength, the fluorescent materials show a strong broad blue emission band, with the emission center at 430 nm and the FWHM of 56 nm. The results indicate that the blue emission is derived from 4f6 5d to 4f7 transition of the Eu2+ ions. Al3+ ion plays a key role in the process of deoxidization from Eu3+ to Eu2+. Al3+ and B3+ can enhance the blue-emission intensity. Also it is found that the highest luminescent intensity of the samples occurs in the sample Eu-03 annealed at 1150 degrees C in N2 atmosphere.

[Preparation of Tb3+, Yb3+ doped Y2O3 luminescent powders and near-infrared quantum cutting research].

Y2O3:Tb3+ and Y2O3:Tb3+, Yb3+ samples were prepared by co-precipitation method. The morphology, microstructure and fluorescence spectra at room temperature of samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and fluorescence spectrometer, The optimal process conditions of Y2O3:Tb3+ under different doping concentrations, annealing temperature, and pH value of the solution were obtained: Tb3+ concentration is 1.5%, annealing temperature is 1400 degrees C, an alkaline solution environment, and samples under 300 nm light excitation have the largest green light emission at 543 nm. The corresponding relation of Tb3+ ion level structure and transition properties and experimental spectra were analyzed in detail, and we explained the influence mechanism of process conditions and the fluorescence quenching process mainly effects luminous intensity of samples. The energy transfer from sensitizing ions Tb3+ to active ion Yb3+ was confirmed, it made the sample have considerable emitting light in the near-infrared region; the authors described the process of cooperation conversion luminescence between the two ions from the level transition angle, and also analyzed the system of fluorescence quenching process. Test results showed that the near infrared quantum cutting can effectively improve the luminous efficiency of doped ions, and will have broad application prospects in the silicon solar cells and other fields.

Double S-scheme Cu2-xSe/twinned-Cd0.5Zn0.5S homo-heterojunctions with surface plasmon effects for efficient photocatalytic H2 evolution.

The enhancement of charge separation and utilization efficiency in both the bulk phase and interface of semiconductor photocatalysts, as well as the expansion of light absorption range, are crucial research topics in the field of photocatalysis. To address this issue, twinned Cd0.5Zn0.5S (T-CZS) homojunctions consisting of wurtzite Cd0.5Zn0.5S (WZ-CZS) and zinc blende Cd0.5Zn0.5S (ZB-CZS) were synthesized via a hydrothermal method to facilitate the bulk-phase charge separation. Meanwhile, Cu2-xSe with localized surface plasmon resonance effect (LSPR) generated by Cu vacancies was also obtained through a hydrothermal process. Due to their opposite electronegativity, a solvent evaporation strategy was employed to combine Cu2-xSe and T-CZS by intermolecular electrostatic. After optimization, the photocatalytic hydrogen (H2) evolution rate of 5 wt% Cu2-xSe/T-CZS reached an impressive value of 60 mmol∙h-1∙g-1, which was 4.6 and 66.6 times higher than that of pure Cu2-xSe and T-CZS, respectively. Furthermore, this composites demonstrated a remarkable rate of 0.46 mmol∙h-1∙g-1 under near-infrared (NIR) wavelength (>800 nm). The enhanced performance observed in Cu2-xSe/T-CZS can be attributed to its unique and efficient double S-scheme charge transfer mechanism which effectively suppresses rapid recombination of electron-hole pairs both within the bulk phase and at the surface interfaces; this conclusion is supported by Density Functional Theory (DFT) calculations as well as electron paramagnetic resonance spectroscopy analysis. Moreover, incorporation of Cu2-xSe enables effective utilization ultraviolet visible-near infrared (UV-Vis-NIR) light by the composites while facilitating injection "hot electrons" into T-CZS for promoting photocatalytic reactions. This study provides a potential strategy for achieving efficient solar energy conversion through synergistic integration of non-stoichiometric plasmonic materials with photocatalysts with twinned-twinned structures.

Efficient photocatalytic degradation of antibiotics by binary heterojunction complex boron subphthalocyanine bromide/bismuth oxychloride.

The development of stable and efficient heterojunction photocatalysts for wastewater environmental purification exhibits a significant challenge. Herien, a promising binary heterojunction complex comprising boron subphthalocyanine bromide/bismuth oxychloride (SubPc-Br/BiOCl) was successfully synthesized using the hydrothermal method, which involved the self-assembled of SubPc-Br on the surface of BiOCl via intermolecular π-π stacking interactions to compose an electron-transporting layer. The photocatalytic efficiency of SubPc-Br/BiOCl for the degradation of tetracycline and the minocycline exhibited a substantial improvement of 29.14% and 53.72%, respectively, compared to the original BiOCl. Experimental characterization and theoretical calculations elucidated that the enhanced photocatalytic performance of the SubPc-Br/BiOCl composite photocatalysts stemmed from the S-scheme electron transport mechanism at the interface between BiOCl and SubPc-Br supramolecules, which broadened the visible light absorption range, increased the carrier molecular efficiency, and accelerated the carriers. Furthermore, molecular dynamic (MD) simulations provided insights into the action trajectories of the two semiconductors, revealing that the presence of SubPc-Br enhances the water and organic pollutant adsorption capabilities of the BiOCl surface within the supramolecular array system. In conclusion, the synthesis and analysis of the binary heterojunction complex SubPc-Br/BiOCl yield valuable insights into the efficient photocatalytic degradation of antibiotics, holding great promise for diverse environmental applications.

A direct Z-scheme NiCo2O4/ZnIn2S4 heterojunction for highly efficient visible-light-driven H2 evolution.

Exploiting efficient and stable photocatalysts is the primary goal of photocatalytic water splitting for H2 production. In this work, a sea urchin-like bimetallic NiCo2O4-decorated ZnIn2S4 heterojunction was fabricated via a solvent evaporation method. Investigation shows that the introduction NiCo2O4 can expand the UV-vis absorption range, enhance the absorption intensity, promote the charge separation, decrease the charge transfer resistance, induce more active sites, and decrease the H2 evolution overpotential of the composite. Besides, the charge transfer between NiCo2O4 and ZnIn2S4 follows a Z-scheme route based on the ˙OH radical capture experiments; this can preserve the strong oxidation-reduction reaction ability of photogenerated electrons and holes, leading to a faster H2 evolution rate, which reaches 17.28 mmol g-1 h-1 over the 4.8%-NiCo2O4/ZnIn2S4 composite under 300 W Xe lamp irradiation in 20 vol% triethanolamine (TEOA) solution and is 3.0 times higher than that of ZnIn2S4. In addition, NiCo2O4/ZnIn2S4 also has excellent stability during 5 consecutive cycles. This work provides an effective method for constructing a highly effective Z-scheme heterojunction system for photocatalytic H2 production.

Photocatalytic Cascade Reaction Driven by Directed Charge Transfer over VS -Zn0.5 Cd0.5 S/GO for Controllable Benzyl Oxidation.

Photocatalysis is an important technique for synthetic transformations. However, little attention has been paid to light-driven synergistic redox reactions for directed synthesis. Herein, the authors report tunable oxidation of benzyl to phenylcarbinol with the modest yield (47%) in 5 h via singlet oxygen (1 O2 ) and proton-coupled electron transfer (PCET) over the photocatalyst Zn0.5 Cd0.5 S (ZCS)/graphene oxide (GO) under exceptionally mild conditions. Theoretical calculations indicate that the presence of S vacancies on the surface of ZCS/GO photocatalyst is crucial for the adsorption and activation of O2 , successively generating the superoxide radical (• O2 - ) and 1 O2 , attributing to the regulation of local electron density on the surface of ZCS/GO and photogenerated holes (h+ ). Meanwhile, accelerated transfer of photogenerated electrons (e- ) to GO caused by the π-π stacking effect is conducive to the subsequent aldehyde hydrogenation to benzyl alcohol rather than non-selective oxidation of aldehyde to carboxylic acid. Anisotropic charge transport driven by the built-in electric field can further promote the separation of e- and h+ for multistep reactions. Promisingly, one-pot photocatalytic conversion of p-xylene to 4-methylbenzyl alcohol is beneficial for reducing the harmful effects of aromatics on human health. Furthermore, this study provides novel insights into the design of photocatalysts for cascade reactions.

Preparation of 3D network Na2Ti2O4(OH)2 nanotube film and study on formation mechanism of nanotubes and light absorption properties.

The 3D network Na2Ti2O4(OH)2 nanotube film was prepared by combining interface chemical reaction with hydrothermal reaction. It can be readily indexed based on an orthorhombic system Na2Ti2O4(OH)2 (JCPDS, 47-0124), corresponding with (200), (110), (600), and (020). The nanotubes are commonly multiwalled with a diameter about 40 nm, and a length more than 2000 nm. The interlamellar space of the nanotubes is about 0.9 nm, and these nanotubes loaded with silver exhibit a strong UV-Vis-NIR absorption from 200 nm to 1000 nm, with a resonance-absorption peak at 490 nm. In addition, the formation mechanism of 3D network Na2Ti2O4(OH)2 nanotube film was investigated, the formation mechanism can be expressed as follows: Ti --> TiCl3 --> TiO2(anatase) --> Na2Ti2O4(OH)2(nanotube).

[Upconversion properties of sodium and aluminum fluorides coated BaF2 material].

Sodium and aluminum fluorides coated BaF2 was synthesized by hydrothermal method. It was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and fluorescence spectrophotometer, respectively. The analysis results indicated that sodium and aluminum fluorides existed in the form of sodium fluoride and sodium fluoroaluminate, which combined with BaF2 surface via chemical bonds, and exhibited coated structure. Fluorescence spectroscopy testing showed that there were two wide upconversion emission peaks with maxima at 304 and 324 nm under the excitation at 583 and 863 nm, respectively. Its phosphorescence life time was greater than 18.4 ms, and the emission intensity exhibited a rising process from the beginning and a decaying process after 15 ms. The luminescence mechanism was proposed according to the energy conversion process of the upconversion emission, the results showed that the upconversion emission belonged to the quantum confinement effect-interface light emission center radiative recombination.