Eu 3+ -activated Sr 3 −x Ca x La(VO 4 ) 3 phosphors were fabricated via citric-acid-assisted sol combustion. Characterization of the Sr 3 −x Ca x La(VO 4 ) 3 :Eu 3+ samples with different concentrations of Ca 2+ revealed a hexagonal crystal structure belonging to the R -3 m space group. The amount of Ca 2+ added ( x ) was controlled within 0 ≤ x ≤ 2 to yield high-purity phosphors. Scanning electron microscopy results showed that an increase in Ca 2+ concentration resulted in a decrease in the particle size of Sr 3 −x Ca x La(VO 4 ) 3 :Eu 3+ , with the shape gradually changing from nearly equiaxed to lath-shaped. The Sr 2 CaLa(VO 4 ) 3 :Eu 3+ phosphor (denoted as SCLVO:Eu 3+ ) exhibited the strongest photoluminescence (PL) intensity at 618 nm among the samples under excitation of 394-nm near-UV (NUV) light. The study of Eu 3+ doping concentration confirmed that Eu 3+ could enter the lattice of the SCLVO matrix without altering its crystal structure. SCLVO:Eu 3+ was found to strongly absorb 394 nm NUV light and 464 nm blue light. The optimal concentration of the Eu 3+ dopant in the SCLVO host was 0.11, which resulted in the phosphor achieving an excellent PL intensity and a color purity of 98.68%. Tunable luminescence from the orange area (0.5280, 0.4522) of Commission Internationale de l'éclairage (CIE) to the red area (0.6313, 0.3650) was achieved by adjusting the concentration of Eu 3+ . Under 394 nm excitation, SCLVO:0.11Eu 3+ phosphor has a quantum yield (QY) of 28.2% and excellent thermal stability with 0.383 eV activation energy . Consequently, White-light-emitting diode (WLED) based on SCLVO:0.11Eu 3+ phosphor yielded a high color rendering index (CRI), low correlated color temperature (CCT), and CIE coordinates of 91.8, 5196 K, and (0.3407, 0.3612), respectively, under the 20 mA driven current. These results indicated the tremendous potential of SCLVO:0.11Eu 3+ phosphors for application in WLEDs excited by NUV or blue light.
Na Yang,Xu Guo,Jing Yu,Yu Zhang,Qi Liu,Jiahui Zhu,Hongsen Zhang,Jun Wang
The integration of external field-enhanced effects such as the photothermal effect has emerged as a promising strategy for improving the adsorption efficiency of adsorbents toward Cs + and Sr 2+ due to its energy saving and high efficiency. Herein, a multifunctional photothermal adsorbent is rationally designed and synthesized via a simple one-step hydrothermal method and electrostatic assembly by combining V, W co-doped MoS 2 , P-MXene, and biomass-derived carbon aerogel (VWMoS 2 /P-MXene/C). Doping of V and W induces the phase transition of MoS 2 to the more active 1T phase, providing more accessible active adsorption sites. Moreover, the 3D porous structure of the biomass-derived carbon aerogel offers sufficient water transport channels, accelerating the diffusion kinetics of Cs + and Sr 2+ . The excellent photothermal conversion capability of the VWMoS 2 /P-MXene/C composite drives water evaporation, which promotes the increase of local concentrations of Cs + and Sr 2+ in the water medium. This synergistic mechanism combining phase engineering and photothermal enhancement collectively contributes to the excellent performance in Cs + and Sr 2+ capture. The VWMoS 2 /P-MXene/C demonstrates adsorption capacities of 158.3 mg/g for Cs + and 110.1 mg/g for Sr 2+ within 1 h, respectively, under photothermal enhancement. Simultaneously, the adsorbent exhibits excellent ion selectivity and reusability. The possible adsorption mechanisms mainly involve surface complexation and electrostatic interactions. Moreover, VWMoS 2 /P-MXene/C demonstrates a long-term solar-driven desalination capability with an evaporation rate of 1.98 kg·m −2 ·h −1 in natural seawater. Notably, the VWMoS 2 /P-MXene/C also shows promising application potential for dye removal and oil adsorption. This work provides a universal strategy for designing multifunctional integrated adsorbents and promotes their practical applications in radioactive wastewater treatment and seawater desalination
Kiran Gupta,Baoling Yuan,Chen Chen,Naresh Varnakavi,Ming-Lai Fu
Novel composite of immobilized layered K 2x Mn x Sn 3−x S 6 (x = 0.5–0.95) (KMS-1) on the surface of reduced graphene oxide (r-GO), KMS-1/r-GO (KGO), has been fabricated by employing hydrothermal technique and used for the removal of radioactive Cs + and Sr 2+ ions from aqueous solutions. The KGO was characterized thoroughly with different characteristic techniques and found that the laminar KMS-1 nanoplate were immobilized on the surface of r-GO nanosheets, forming a highly porous stacked structure. Batch studies have been done for obtaining optimal experimental parameters and investigating the effect of adsorption time, initial concentration of pollutant, pH of solution, temperature, and competing anions on the removal properties. At room temperature, the maximum adsorption capacity of KGO was 338.18 mg·g −1 and 220.12 mg·g −1 for both Cs + and Sr 2+ , respectively. Langmuir isotherm and pseudo-second-order kinetic models were fitted well with experimental data of removed Cs + and Sr 2+ . Adsorption showed good selectivity of composite towards Cs + and Sr 2+ in the presence of co-existing ions (Ca 2+ and Mg 2+ ). The proposed adsorption mechanism involved ion exchange through the presence of K + ions in KMS-1 and formation of surface ionic interactions between r-GO and ions through COO X or S X (X denoted Cs + and Sr 2+ ). This study highlighted the facile applicability of novel material KGO and could be used as a new adsorbent for the removal of radioactive ions.
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