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Co and Fe Codoped WO <sub/>2.72</sub> as Alkaline‐Solution‐Available Oxygen Evolution Reaction Catalyst to Construct Photovoltaic Water Splitting System with Solar‐To‐Hydrogen Efficiency of 16.9%
摘要： Oxygen evolution electrode is a crucial component of efficient photovoltaic-water electrolysis systems. Previous work focuses mainly on the effect of electronic structure modulation on the oxygen evolution reaction (OER) performance of 3d-transition-metal-based electrocatalyst. However, high-atomic-number W-based compound with complex electronic structure for versatile modulation is seldom explored because of its instability in OER-favorable alkaline solution. Here, codoping induced electronic structure modulation generates a beneficial effect of transforming the alkaline-labile WO2.72 (WO) in to efficient alkaline-solution-stable Co and Fe codoped WO2.72 (Co&Fe-WO) with porous urchin-like structure. The codoping lowers the chemical valence of W to ensure the durability of W-based catalyst, improves the electron-withdrawing capability of W and O to stabilize the Co and Fe in OER-favorable high valence state, and enriches the surface hydroxyls, which act as reactive sites. The Co&Fe-WO shows ultralow overpotential (226 mV, J = 10 mA cm?2), low Tafel slope (33.7 mV dec?1), and good conductivity. This catalyst is finally applied to a photovoltaic-water splitting system to stably produce hydrogen for 50 h at a high solar-to-hydrogen efficiency of 16.9%. This work highlights the impressive effect of electronic structure modulation on W-based catalyst, and may inspire the modification of potential but unstable catalyst for solar energy conversion.
关键词： electrocatalysis,photovoltaic water splitting,oxygen evolution reaction,codoping,WO2.72
更新于2025-11-14 17:04:02
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Effects of Mg2+/Si4+ doping on luminescence of Y3Al5O12:Ce3+ phosphors
摘要： A series of Mg2+/Si4+ codoped Y3Al5O12:Ce3+ phosphors were synthesized by a sol-gel method. X-ray diffraction, scanning election microscope, energy dispersive spectroscopy and fluorescent spectrophotometer were used to characterize the synthesized phosphors. The influence of codoped Mg2+/Si4+ ions on luminescence of Y3Al5O12:Ce3+ was investigated. The X-ray diffraction, scanning election microscope and energy dispersive spectroscopy results indicate that Ce3+, Mg2+ and Si4+ substitute Y3+ site, in the tetrahedral site and the substitution has no obvious influence on the phase and microstructure. And the Mg2+/Si4+ substitution leads to the red shift of emission band and the decrease of emission intensity.
关键词： Mg2+/Si4+ codoping,Luminescence,Y3Al5O12:Ce3+
更新于2025-09-23 15:23:52
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Effect of potassium and magnesium codoping on the dielectric properties of BST powders
摘要： K and Mg codoped BST powders were prepared by a sol-gel method, and the effect of doped concentration on the dielectric performances was studied. For comparison, pure, Mg doped and K doped BST powders were studied. XRD shows all powders reveal complete diffraction peaks and ABO3 cubic perovskite polycrystalline structures. Compared to the pure BST powder, Mg doped BST powder shows a little weaker crystallization, 5%～15% K doped BST powders exhibit stronger crystallization, and the crystallization is getting stronger with increasing K doped concentrations from 2% to 15%. BST powder shows lattice parameter of 3.963 ?A, Mg doping corresponds to 3.963 ?A, 2%～20% K doping correspond to 3.963 ?A～3.967 ?A, and Mg and K codoping make lattice parameters increase from 3.967 ?A to 3.974 ?A. Mg2+ ion and K+ ion show acceptor doped mechanisms, Mg doping makes grains refine, and K doping makes grains grow. Pure BST powder and Mg doped BST powder show uniform grains with unclear grain boundaries, K doped BST powders can obtain uniform and dispersive grains with clear grain boundaries, but Mg and K codoping makes the uniformity and dispersity of the powders getting worse. Compared to pure BST powder, Mg doped BST powder shows smaller but more stable dielectric constant and dielectric loss, K doped powders tend to reveal larger and less stable dielectric constants and dielectric losses. Mg and K codoped BST powders show less than 35 dielectric constants, and lower than 0.02 dielectric losses. Dielectric properties are strongly dependent on the crystallization, doped mechanism and morphology. Mg doped and 2% Mg 2% K and 2% Mg 5% K codoped BST powders show low and stable dielectric constants and dielectric losses, thus can meet the requirements for tunable microwave applications and other applications.
关键词： dielectric property,codoping,Mg,K,BST powder
更新于2025-09-23 15:23:52
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Enhanced NIR-NIR luminescence from CaWO4: Nd3+/Yb3+ phosphors by Li+ codoping for thermometry and optical heating
摘要： Rare earth ions doped luminescent materials have demonstrated their potentiality as sensitive thermometers with good accuracy and high spatial resolution. Nevertheless, low luminescence efficiency, especially at high temperature, still limits the development of this thermometry technique. Here, Nd3+/Yb3+ codoped CaWO4 phosphors were synthesized using high temperature solid-state method, and Li+ ions were introduced aiming to improve the near-infrared (NIR) emissions from Nd3+ in the spectral range of 725-950 nm. The influence of Li+ codoping on the structure and NIR luminescence in CaWO4: Nd3+/Yb3+ when excited by a 980 nm laser diode was investigated. NIR-NIR emissions from Li+ codoped samples are successfully strengthened compared with that without Li+ ions, which is mainly attributed to the distortion of the crystal structure and the increase of crystalline size by Li+. The optical temperature sensing behavior of NIR luminescence from Nd3+ was studied based on fluorescence intensity ratio (FIR). Assisted by Li+ ions, the NIR-NIR emissions are observed to be effectively enhanced with the increment of temperature. And a new pair of thermally coupled levels in Nd3+ ions with excellent thermometry characteristics is explored, through which superior measurement sensitivity as well as accuracy could be achieved. In addition, light-induced temperature rise was realized in the phosphors, which makes CaWO4: Nd3+/Yb3+/Li+ excellent candidate for luminescence thermometry and optical heaters.
关键词： Li+ codoping,thermometry,Nd3+ ions,NIR luminescence
更新于2025-09-23 15:22:29
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The Performance Improvement of Using Hole Transport Layer with Lithium and Cobalt for Inverted Planar Perovskite Solar Cell
摘要： With the continuous development of solar cells, the perovskite solar cells (PSCs), whose hole transport layer plays a vital part in collection of photogenerated carriers, have been studied by many researchers. Interface transport layers are important for efficiency and stability enhancement. In this paper, we demonstrated that lithium (Li) and cobalt (Co) codoped in the novel inorganic hole transport layer named NiOx, which were deposited onto ITO substrates via solution methods at room temperature, can greatly enhance performance based on inverted structures of planar heterojunction PSCs. Compared to the pristine NiOx films, doping a certain amount of Li and Co can increase optical transparency, work function, electrical conductivity and hole mobility of NiOx film. Furthermore, experimental results certified that coating CH3NH3PbIxCl3?x perovskite films on Li and Co- NiOx electrode interlayer film can improve chemical stability and absorbing ability of sunlight than the pristine NiOx. Consequently, the power conversion efficiency (PCE) of PSCs has a great improvement from 14.1% to 18.7% when codoped with 10% Li and 5% Co in NiOx. Moreover, the short-circuit current density (Jsc) was increased from 20.09 mA/cm2 to 21.7 mA/cm2 and the fill factor (FF) was enhanced from 0.70 to 0.75 for the PSCs. The experiment results demonstrated that the Li and Co codoped NiOx can be a effective dopant to improve the performance of the PSCs.
关键词： codoping,nickle oxide,hole transport layer,perovskite solar cells,performance
更新于2025-09-23 15:21:01
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Effects of Gd3+ codoping on the enhancement of the luminescent properties of a NaBi(MoO4)2:Eu3+ red-emitting phosphors
摘要： A series of NaBi(MoO4)2:Eu3+ and NaBi(MoO4)2:Eu3+, Gd3+ phosphors were prepared using a sol-combustion method. NaBi(MoO4)2:Eu3+ with a tetragonal scheelite structure was obtained by heat treatment at 600–800 °C. The effects of the synthetic temperature and Eu3+ concentration on the luminescent properties of the NaBi(MoO4)2:Eu3+ phosphors were investigated. Under blue excitation at 464 nm, the NaBi(MoO4)2:Eu3+ sample exhibited a strong red emission peak at 618 nm, which originated from the 5D0→7F2 transition of Eu3+. Furthermore, Gd3+ ions were codoped into NaBi(MoO4)2:Eu3+ to enhance the luminescent intensity of NaBi(MoO4)2:Eu3+, Gd3+ due to energy transfer between Gd3+ and Eu3+. The results indicated that the NaBi(MoO4)2:Eu3+, Gd3+ red phosphor could be applied to white light-emitting diodes to achieve excellent properties, such as a high color rendering index and low correlated color temperature.
关键词： NaBi(MoO4)2,Energy transfer,Luminescence enhancement,Codoping,Red phosphors
更新于2025-09-19 17:15:36
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Precise size separation of water-soluble red-to-near-infrared-luminescent silicon quantum dots by gel electrophoresis
摘要： A gel electrophoresis, which is a standard method for separation and analysis of macromolecules such as DNA, RNA and proteins, is applied for the first time to silicon (Si) quantum dots (QDs) for the size separation. In the Si QDs studied, boron (B) and phosphorus (P) are simultaneously doped. The codoping induces negative potential on the surface of a Si QD and makes it dispersible in water. Si QDs with different B and P concentrations and grown at different temperatures (950°C - 1200°C) are studied. It is shown that a native polyacrylamide gel electrophoresis can separate codoped Si QDs by size. The capability of gel electrophoresis to immobilize size-separated QDs in a solid matrix makes detailed analyses of size-purified Si QDs possible. For example, photoluminescence (PL) studies of dried gel of Si QDs grown at 1100°C demonstrate that a PL spectrum of a Si QDs solution with the PL maximum around 1.4 eV can be separated into more than 15 spectra with the PL maximum changing from 1.2 to 1.8 eV depending on the migration distance. It is found that the relation between the PL peak energy and the migration distance depends on the growth temperature of Si QDs as well as the B and P concentration. For all the samples with different impurity concentrations and grown at different temperatures, a clear trend is observed in the relation between the full width at half maximum (FWHM) and the peak energy of the PL spectra in a wide energy range. The FWHM increases with increasing the peak energy and it is nearly twice larger than those observed for undoped Si QDs. The large PL FWHM of codoped Si QDs suggests that excitons are further localized in codoped Si QDs due to the existence of charged impurities.
关键词： codoping,size separation,silicon quantum dots,photoluminescence,gel electrophoresis
更新于2025-09-19 17:13:59
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Optimization of the electron transport in quantum dot light-emitting diodes by codoping ZnO with gallium (Ga) and magnesium (Mg)
摘要： In our study, to optimize the electron–hole balance through controlling the electron transport layer (ETL) in the QD-LEDs, four materials (ZnO, ZnGaO, ZnMgO, and ZnGaMgO NPs) were synthesized and applied to the QD-LEDs as ETLs. By doping ZnO NPs with Ga, the electrons easily inject due to the increased Fermi level of ZnO NPs, and as Mg is further doped, the valence band maximum (VBM) of ZnO NPs deepens and blocks the holes more e?ciently. Also, at the interface of QD/ETLs, Mg reduces non-radiative recombination by reducing oxygen vacancy defects on the surface of ZnO NPs. As a result, the maximum luminance (Lmax) and maximum luminance e?ciency (LEmax) of QD-LEDs based on ZnGaMgO NPs reached 43 440 cd m?2 and 15.4 cd A?1. These results increased by 34%, 10% and 27% for the Lmax and 450%, 88%, and 208% for the LEmax when compared with ZnO, ZnGaO, and ZnMgO NPs as ETLs.
关键词： electron transport layer,ZnO nanoparticles,quantum dot light-emitting diodes,Ga-Mg codoping,electron-hole balance
更新于2025-09-16 10:30:52
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Cu-S codoping TiO <sub/>2</sub> /SiO <sub/>2</sub> and TiO <sub/>2</sub> /SiO <sub/>2</sub> /Fe <sub/>3</sub> O <sub/>4</sub> core-shell nanocomposites as a novel purple LED illumination active photocatalyst for degradation of diclofenac: the effect of different scavenger agents and optimization
摘要： Cu-S co-doped TiO2/SiO2 as a novel photocatalyst which is active in visible light was synthesized by simple sol-gel method. Also, Fe3O4 nanoparticles were used as the core to create a magnetically separable photocatalyst. The prepared samples were characterized by XRD, BET, BJH, DRS-UV/Vis, PL, FESEM, EDX, TEM, XPS, and VSM analysis. The photocatalytic effect of synthesized samples was examined on diclofenac (as a model hazardous contaminant) degradation. The central composite design was employed to optimize the operational parameters including irradiation time, pH, photocatalyst mass, and diclofenac concentration, whose optimal values were 213.85 min, 4.31, 0.06 g, and 10.25 mg L?1 for irradiation time, pH, photocatalyst mass, and diclofenac concentration, respectively. Under the optimum conditions, the photocatalytic degradation percentages of diclofenac at desirability function value of 1.0 were found to be 99.56%. The photocatalytic activity of the nanoparticles was also studied under sunlight. Overall, the UV/Vis spectrophotometry and total organic carbon results indicated that the synthesized nanoparticles have an extraordinary photocatalytic activity for the degradation of diclofenac under both purple LED and solar lights. Furthermore, different scavenger agents were investigated.
关键词： Diclofenac,LED light,Photodegradation,Titanium dioxide,Codoping,Scavenger agents
更新于2025-09-11 14:15:04
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Synergistic Effect of Hydrochloric Acid and Phytic Acid Doping on Polyaniline-Coupled g-C <sub/>3</sub> N <sub/>4</sub> Nanosheets for Photocatalytic Cr(VI) Reduction and Dye Degradation
摘要： In this study, graphitic carbon nitride (g-C3N4) nanosheets (CNns) were modified using polyaniline (PANI) codoped with an inorganic (hydrochloric acid, HCl) and an organic (phytic acid, PA) acid. Our results revealed that these samples exhibited extended visible-light absorption and a three-dimensional (3D) hierarchical structure with a large specific surface area. They also inhibited photoluminescence emission, reduced electrical resistance, and provided abundant free radicals, resulting in high photocatalytic performance. The PANI/g-C3N4 sample demonstrated outstanding photocatalytic activity of a Cr(VI) removal capacity of 4.76 mg·min?1·gc ?1, which is the best record for the reduction of a 100 ppm K2Cr2O7 solution. Moreover, g-C3N4 coupled with PANI monotonically doped with HCl or PA did not demonstrate increased activity, suggesting that the codoping of HCl and PA plays a significant role in enhancing the performance. The improved photocatalytic activity of PANI/g-C3N4 can be attributed to the interchain and intrachain doping of PA and HCl over PANI, respectively, to create a 3D connected network and synergistically increase the electrical conductivity. Therefore, new insights into g-C3N4 coupled with PANI and codoped by HCl and PA may have excellent potential for the design of g-C3N4-based compounds for efficient photocatalytic reactions.
关键词： phytic acid,codoping,polyaniline,Cr(VI) reduction,hydrochloric acid,photocatalysis
更新于2025-09-11 14:15:04