Non-Metal Sulfur Doping of Indium Hydroxide Nanocube for Selectively Photocatalytic Reduction of CO2 to CH4: A "One Stone Three Birds" Strategy.

Photocatalytic CO2 reduction is considered as a promising strategy for CO2 utilization and producing renewable energy, however, it remains challenge in the improvement of photocatalytic performance for wide-band-gap photocatalyst with controllable product selectivity. Herein, the sulfur-doped In(OH)3 (In(OH)xSy-z) nanocubes are developed for selective photocatalytic reduction of CO2 to CH4 under simulated light irradiation. The CH4 yield of the optimal In(OH)xSy-1.0 can be enhanced up to 39 times and the CH4 selectivity can be regulated as high as 80.75% compared to that of pristine In(OH)3. The substitution of sulfur atoms for hydroxyl groups in In(OH)3 enhances the visible light absorption capability, and further improves the hydrophilicity behavior, which promotes the H2O dissociation into protons (H*) and accelerates the dynamic proton-feeding CO2 hydrogenation. In situ DRIFTs and DFT calculation confirm that the non-metal sulfur sites significantly weaken the over-potential of the H2O oxidation and prevent the formation of ·OH radicals, enabling the stabilization of *CHO intermediates and thus facilitating CH4 production. This work highlights the promotion effect of the non-metal doping engineering on wide-band-gap photocatalysts for tailoring the product selectivity in photocatalytic CO2 reduction.

Visible-near-Infrared Light-Driven Photocatalytic Characteristics of Er3+/Yb3+-Codoped BiOBr Upconverting Microparticles for Tetracycline Degradation.

To settle the unsatisfying efficiency and insufficient light harvesting ability of photocatalysts, we report on the development of Er3+/Yb3+-codoped BiOBr (BiOBr:Er3+/xYb3+) microparticles that were synthesized by a rational high-temperature solid-state reaction method. The prepared microcrystals exhibit high visible upconversion (UC) emissions with maximum intensities at x = 0.01 when excited by a 980 nm laser. Remarkably, the corresponding UC emission process is attributed to a two-photon absorption route. Furthermore, the photocatalytic activities of as-synthesized compounds were further evaluated through analyzing the visible-near-infrared light-triggered tetracycline degradation. Compared with BiOBr:Er3+ microparticles, BiOBr:Er3+/xYb3+ microparticles present superior photocatalytic properties and the optimal status is achieved when x = 0.05, in which h+, ·O2-, and ·OH active species contribute to the photocatalytic mechanism. Additionally, the designed microparticles exhibit better photocatalytic abilities than previously reported photocatalysts (i.e., TiO2, SnO2) upon full-spectrum light irradiation. These results reveal that Yb3+ codoping is able to not only enhance the UC emission properties of BiOBr:Er3+ microparticles but also reinforce their photocatalytic activities. Our findings may put forward a facile strategy to regulate the photodegradation capacity of photcatalysts.

Excellent upconversion luminescence and temperature sensing performance of CdMoO4:Er3+,Yb3+ phosphors.

In this paper, Er3+/Yb3+ co-doped CdMoO4 phosphors were prepared by a traditional high temperature solid state reaction method. Based on the 3D network structure of the CdMoO4 host and the efficient Er3+/Yb3+ upconversion luminescence combinations, excellent green emission properties were observed when the prepared sample is irradiated with a laser at about 980 nm. For optical temperature sensors based on the fluorescence intensity ratio (FIR), the prepared phosphors have excellent sensitivity to temperature in the range of 293 to 473 K. With increasing environmental temperatures, the absolute sensitivity of the CdMoO4:0.02Er3+,0.08Yb3+ sample reached a maximum at about 473 K (Sa = 1.388% K-1). The calculated relative sensitivity of the optical temperature sensor was Sr = 1.631% K-1 at 293 K. This is due to the sensitive thermally coupled energy levels (TCLs) of the Er3+ ions (2H11/2 and 4S3/2) in the CdMoO4 structure. Therefore, it is shown that the prepared CdMoO4:0.02Er3+,0.08Yb3+ phosphor has excellent applications in non-contact optical temperature measurement.

An Open-Framework Structured Material: [Ni(en)2]3[Fe(CN)6]2 as a Cathode Material for Aqueous Sodium- and Potassium-Ion Batteries.

Open-framework structured materials such as Prussian blue analogues and sodium superionic conductor (NASICON) materials have been regarded as promising electrode candidates for aqueous batteries. These materials exhibit outstanding long cycle stability and high rate capacity retention, due to their high ion diffusive rate in the crystal and the stable structure maintenance in the electrochemical reaction process. Herein, an open-framework structured material [Ni(en)2]3[Fe(CN)6]2 (NienHCF) is prepared and first used as a cathode material for aqueous sodium- and potassium-ion batteries. The resultant material exhibits a high output potential and outstanding cycle performance (93.4% after 500 cycles at 1 A g-1) in K-ion batteries. Meanwhile, the electrochemical reaction mechanism is investigated. After coupling with the activated carbon anode, the K-ion full cell has 91.5% capacity retention at 5 A g-1 and retains 77.2% after 1000 cycles at 0.5 A g-1, exhibiting the potential as an electrode material for rechargeable aqueous K-ion and Na-ion batteries.

Bifunctional application of La3BWO9:Bi3+,Sm3+ phosphors with strong orange-red emission and sensitive temperature sensing properties.

Through a solid-phase reaction technique, Sm3+ and Bi3+ co-doped La3BWO9 phosphors with high emission intensity and sensitive temperature sensing properties have been successfully synthesized. Based on XRD Rietveld refinement, the optimized crystal structure was used as the original model to calculate the band structure and partial density of states (PDOS) by density functional theory (DFT) calculations. The luminescence characteristics of Sm3+ and Bi3+ co-doped La3BWO9 phosphors were measured and analyzed. In addition, the optimal doping concentrations of Sm3+ and Bi3+ were investigated. The luminescence properties of Sm3+ doped phosphors were optimized by introducing Bi3+ ions. Efficient energy transfer from Bi3+ to Sm3+ ions was observed in La3BWO9:Sm3+, Bi3+ phosphors. An optical temperature sensor with high sensitivity was designed based on the different thermal quenching properties of Sm3+ and Bi3+ ions. In the temperature range of 293-498 K, the optimum absolute sensitivity (Sa) and maximum relative sensitivity (Sr) were 2.88 %K-1 and 1.32 %K-1, respectively. These results indicated that the prepared La3BWO9:Bi3+, Sm3+ phosphors have wide application prospects as solid state lighting materials and optical temperature sensors.

Bismuth atom tailoring of indium oxide surface frustrated Lewis pairs boosts heterogeneous CO2 photocatalytic hydrogenation.

The surface frustrated Lewis pairs (SFLPs) on defect-laden metal oxides provide catalytic sites to activate H2 and CO2 molecules and enable efficient gas-phase CO2 photocatalysis. Lattice engineering of metal oxides provides a useful strategy to tailor the reactivity of SFLPs. Herein, a one-step solvothermal synthesis is developed that enables isomorphic replacement of Lewis acidic site In3+ ions in In2O3 by single-site Bi3+ ions, thereby enhancing the propensity to activate CO2 molecules. The so-formed BixIn2-xO3 materials prove to be three orders of magnitude more photoactive for the reverse water gas shift reaction than In2O3 itself, while also exhibiting notable photoactivity towards methanol production. The increased solar absorption efficiency and efficient charge-separation and transfer of BixIn2-xO3 also contribute to the improved photocatalytic performance. These traits exemplify the opportunities that exist for atom-scale engineering in heterogeneous CO2 photocatalysis, another step towards the vision of the solar CO2 refinery.

Enhanced Visible Light-Driven Photocatalytic Activities and Photoluminescence Characteristics of BiOF Nanoparticles Determined via Doping Engineering.

We report a new type of highly efficient visible light-driven photocatalyst, Sm3+-activated BiOF nanoparticles, developed by a facile solid-state reaction technology. The corresponding phase compositions, morphological nature, and chemical states along with complementary theoretical calculation insights are investigated systematically. Upon 404 nm laser excitation, the photoluminescence performance of the synthesized nanoparticles is explored and the optimal properties are achieved in BiOF:xSm3+ (x = 0.07). The dipole-quadrupole interaction is attributed to the concentration quenching mechanism. Under visible light irradiation, the degradation of the RhB dye by utilizing the Sm3+-activated BiOF nanoparticles is studied. In comparison with the BiOF nanoparticles, the resultant compounds doped with Sm3+ ions demonstrate improved photocatalytic performance. Moreover, on the basis of density functional theory, the electronic structure of the BiOF impacted by Sm3+ ion doping is studied in detail by first-principles calculations, revealing the generation of an impurity energy level that is beneficial for enhancing the photocatalytic properties. Importantly, the h+ and •O2- active species play a deterministic role in promoting the degradation of the RhB dye. Compared to commercial ZnO nanoparticles, the developed nanoparticles exhibit superior photocatalytic activities, further elaborating that the Sm3+-activated BiOF nanoparticles are poised to be one of most promising visible light-driven photocatalyst candidates.

Infrared excited Er3+/Yb3+ codoped NaLaMgWO6 phosphors with intense green up-conversion luminescence and excellent temperature sensing performance.

The Er3+/Yb3+-codoped NaLaMgWO6 phosphors were synthesized via a traditional high-temperature solid-state reaction method. The temperature sensing performance was thoroughly investigated by studying the temperature-dependent up-conversion (UC) emission intensity ratio in the range of 293-533 K. A remarkable enhancement of green UC emission, as well as enhanced temperature sensitivity, were observed by increasing the Yb3+ concentration. The maximum absolute sensor sensitivity was 2.29% K-1 at 533 K. When the pump power of the 980 nm laser increased from 200 to 1000 mW, a slightly elevated temperature from 293-307 K was achieved in the compounds. Using the prepared phosphors and a 940 nm NIR chip, a green-emitting LED device was developed to confirm the applicability of our prepared phosphors for solid-state lighting. As a temperature probe, the prepared phosphor detected that the temperature increased from 286 K to 315 K when the drive current was increased from 90 mA to 300 mA. These results suggest that the Er3+/Yb3+-codoped NaLaMgWO6 phosphors have a potential application in solid-state lighting and optical thermometry.

Er3+-Activated NaLaMgWO6 double perovskite phosphors and their bifunctional application in solid-state lighting and non-contact optical thermometry.

Herein, Er3+-activated NaLaMgWO6 phosphors were prepared by a traditional high-temperature solid-state method. Based on the double perovskite structure of the NaLaMgWO6 host, we observe the desirable PL properties of Er3+. When excited at about 378 nm, the as-obtained materials can emit strong green light. When applied to a temperature sensor based on the fluorescence intensity ratio (FIR) principle, the prepared phosphors show excellent sensitivity ranging from 303 to 483 K. With elevated operation temperature, the sensitivity is about 2.23% K-1 at 483 K, resulting from the sensitive thermally coupled levels (2H11/2 and 4S3/2) of Er3+ ions in the double perovskite structure. The calculated relative sensitivity of the temperature sensor was 1.04% K-1 at 303 K. In particular, besides high sensitivity, its superior water resistance is an equally thrilling discovery. Therefore, it is demonstrated that the as-prepared Er3+-activated NaLaMgWO6 phosphors have promising potential applications in both near-UV solid-state lighting and non-contact optical thermometry.

Simultaneous bifunctional application of solid-state lighting and ratiometric optical thermometer based on double perovskite LiLaMgWO6:Er3+ thermochromic phosphors.

Realization of simultaneous, efficient bifunctional application of thermochromic phosphors on light emitting diodes (LEDs) and as ratiometric thermometers is significant. Herein, doped Er3+ ions are introduced as an activator into double perovskite LiLaMgWO6 host lattice. The developed phosphors can be efficiently excited by a near-ultraviolet LED chip and show bright green emission, mainly at 527 and 543 nm, as well as very low thermal quenching. Their chemical stability is studied, demonstrating excellent application potentials. Furthermore, the temperature sensing properties of LiLaMgWO6:0.01Er3+ were analyzed in the wide range of 303-483 K and show a good exponential relationship between ratiometric intensity and temperature (R 2 > 0.999), as well as high sensitivity (2.24% K-1). Such a system not only optimizes the performance in solid light emitting but also provides an excellent platform for designing high-sensitivity optical thermometry.

Break the Interacting Bridge between Eu3+ Ions in the 3D Network Structure of CdMoO4: Eu3+ Bright Red Emission Phosphor.

Eu3+ doped CdMoO4 super red emission phosphors with charge compensation were prepared by the traditional high temperature solid-state reaction method in air atmosphere. The interrelationships between photoluminescence properties and crystalline environments were investigated in detail. The 3D network structure which composed by CdO8 and MoO4 polyhedra can collect and efficiently transmit energy to Eu3+ luminescent centers. The relative distance between Eu3+ ions decreased and energy interaction increased sharply with the appearance of interstitial occupation of O2- ions ([Formula: see text]). Therefore, fluorescence quenching occurs at the low concentration of Eu3+ ions in the 3D network structure. Fortunately, the charge compensator will reduce the concentration of [Formula: see text] which can break the energetic interaction between Eu3+ ions. The mechanism of different charge compensators has been studied in detail. The strong excitation band situated at ultraviolet and near-ultraviolet region makes it a potential red phosphor candidate for n-UV based LED.

Tunable Luminescence in Sr2MgSi2O7:Tb3+, Eu3+Phosphors Based on Energy Transfer.

A series of Tb3+, Eu3+-doped Sr2MgSi2O7 (SMSO) phosphors were synthesized by high temperature solid-state reaction. X-ray diffraction (XRD) patterns, Rietveld refinement, photoluminescence spectra (PL), and luminescence decay curves were utilized to characterize each sample's properties. Intense green emission due to Tb3+ 5D4→7F5 transition was observed in the Tb3+ single-doped SMSO sample, and the corresponding concentration quenching mechanism was demonstrated to be a diople-diople interaction. A wide overlap between Tb3+ emission and Eu3+ excitationspectraresults in energy transfer from Tb3+ to Eu3+. This has been demonstrated by the emission spectra and decay curves of Tb3+ in SMSO:Tb3+, Eu3+ phosphors. Energy transfer mechanism was determined to be a quadrupole-quadrupole interaction. And critical distance of energy transfer from Tb3+ to Eu3+ ions is calculated to be 6.7 Šon the basis of concentration quenching method. Moreover, white light emission was generated via adjusting concentration ratio of Tb3+ and Eu3+ in SMSO:Tb3+, Eu3+ phosphors. All the results indicate that SMSO:Tb3+, Eu3+ is a promising single-component white light emitting phosphor.

Nanotunnel Structures within Metal Oxides Induce Active Sites for the Strong Self-Reduction of MnIV to MnII.

Zn2SiO4, Zn2GeO4, and CdAl2O4 possess high electron density in their six-membered-ring nanotunnels, manganese from MnO2 was successfully doped into them, and green or blue phosphors were produced in air. It is nanotunnel A with high electron density that induces active sites for the reduction of MnIV. MnIV is captured and reduced to MnII on active sites by seizing two electrons from native defect VO× (VO× + Mn4+ → VO·· + Mn2+). CdB4O7:0.02Mn2+ was also synthesized from MnO2 or MnCO3 to confirm the role of nanotunnels. Such inorganic crystals with unique nanotunnel structure may bring more amazing performances in the field of materials in the future.

Remote Control Effect of Li(+), Na(+), K(+) Ions on the Super Energy Transfer Process in ZnMoO4:Eu(3+), Bi(3+) Phosphors.

Luminescent properties are affected by lattice environment of luminescence centers. The lattice environment of emission centers can be effectively changed due to the diversity of lattice environment in multiple site structure. But how precisely control the doped ions enter into different sites is still very difficult. Here we proposed an example to demonstrate how to control the doped ions into the target site for the first time. Alkali metal ions doped ZnMoO4:Bi(3+), Eu(3+) phosphors were prepared by the conventional high temperature solid state reaction method. The influence of alkali metal ions as charge compensators and remote control devices were respectively observed. Li(+) and K(+) ions occupy the Zn(2) sites, which impede Eu and Bi enter the adjacent Zn(2) sites. However, Na(+) ions lie in Zn(1) sites, which greatly promoted the Bi and Eu into the adjacent Zn(2) sites. The Bi(3+) and Eu(3+) ions which lie in the immediate vicinity Zn(2) sites set off intense exchange interaction due to their short relative distance. This mechanism provides a mode how to use remote control device to enhance the energy transfer efficiency which expected to be used to design efficient luminescent materials.

Sr2ZnWO6:Eu³âº, Bi³âº, Li⁺: a potential white-emitting phosphor for near-ultraviolet white light-emitting diodes.

A series of Sr2ZnWO6 phosphors co-doped with Eu(3+), Bi(3+) and Li(+) were prepared using the Pechini method. The samples were tested using X-ray diffraction and luminescence spectroscopy. The results show that the samples can be effectively excited by near-ultraviolet (UV) and UV light. The introduction of Bi(3+) and Li(+) significantly enhances the fluorescence emission of Sr2ZnWO6 :Eu(3+) and changes the light emitted by the phosphors from bluish-green to white. When excited at 371 nm, Sr(2-x-z)Zn(1-y)WO6:xEu(3+), yBi(3+), zLi(+) (x = 0.05, y = 0.05, z = 0.05, 0.1 and 0.15) samples emit high-performance white light. Intense red-orange emission is also observed when excited by UV light. The obtained phosphor is a potential white-emitting phosphor that could meet the needs of excitation sources with near-UV chips. In addition, this phosphor might have promising application as a red-orange emitting phosphor for white light-emitting diodes based on UV light-emitting diodes.