ZnO/ZnS Nanoparticles on NaYF₄:Yb,Tm for Near-Infrared-Activated Photocatalytic Cr(VI) Reduction

Abstract

The essential requirement for photocatalysisutilization of sunlight energywas addressed by combining ZnO/ZnS nanoparticles (NPs) with NaYF4:Yb3+,Tm3+ upconversion nanoparticles (UCNPs) in a core–shell composite structure that can convert near-infrared (NIR) light to UV light through energy transfer (ET). The material was examined with advanced characterization techniques and computational methods, which allowed a better understanding of the interface and provided insights into possible conditions for the ET between UCNPs and ZnO, which has not been studied before. In addition, this work suggests a simple method for the in situ formation of a heterojunction on ZnO while it is attached to UCNP, which has not been applied to UCNP-coupled photocatalysts to date. The in situ-formed heterostructure of ZnO and ZnS was proven to enhance NIR-driven photocatalytic activity via efficient charge separation through the Z-scheme mechanism: 70% of Cr­(VI) reduction was obtained within 3 h of NIR laser irradiation with UCNP@ZnO/ZnS, while 48% reduction of Cr­(VI) was achieved by UCNP@ZnO. Reactive oxygen species (ROS) were detected during NIR-triggered photocatalysis, proving the energy conversion from UCNPsto photocatalysts.

Near-Infrared-Driven β-NaYF4:Yb,Tm,Gd/Ni-MOF Nanocomposites for Efficient Sterilization and Degradation of Organic Contaminants

“…Under the irradiation of 980 nm laser, Yb 3+ ions are excited first due to their higher absorption cross section compared to Tm 3+ and Gd 3+ ions, resulting in electrons being excited from 2 F 7/2 to the 2 F 5/2 state . Indirect excitation of Tm 3+ ions occurs through effective energy transfer from Yb 3+ , leading to the emission of three UV peaks at 280 nm ( 1 I 6 – 3 H 6 ), 345 nm ( 1 I 6 – 3 F 4 ), and 360 nm ( 1 D 2 – 3 H 6 ), two intense blue emission peaks at 452 nm ( 1 D 2 – 3 F 4 ) and 475 nm ( 1 G 4 – 3 H 6 ), as well as a red emission peak at 650 nm ( 1 G 4 – 3 F 4 ) . Moreover, an emission peak at 312 nm correlating with the 6 P 7/2 – 8 S 7/2 transition of the Gd 3+ ion was observed .…”

“…47 Indirect excitation of Tm 3+ ions occurs through effective energy transfer from Yb 3+ , leading to the emission of three UV peaks at 280 nm ( 1 I 6 − 3 H 6 ), 345 nm ( 1 I 6 − 3 F 4 ), and 360 nm ( 1 D 2 − 3 H 6 ), two intense blue emission peaks at 452 nm ( 1 D 2 − 3 F 4 ) and 475 nm ( 1 G 4 − 3 H 6 ), as well as a red emission peak at 650 nm ( 1 G 4 − 3 F 4 ). 48 Moreover, an emission peak at 312 nm correlating with the 6 P 7/2 − 8 S 7/2 transition of the Gd 3+ ion was observed. 49 − reaction.…”

Near-infrared responsive magnetic photocatalyst based on NaYF4:Yb3+/Er3+@Cu2O@MoS2@Fe3O4 for the efficient degradation of organic contaminants

“…18,19 A notable example of this is core-shell NaYF 4 :Yb 3+ ,Tm 3+ @TiO 2 nanoparticles, which have demonstrated exceptional photodegradation activity under both UV and NIR light exposure. 20 Moreover, researchers have rationally designed other upconversion material-semiconductor composite photocatalysts, such as b-NaYF 4 :Yb 3+ , Tm 3+ @BiOCl (NYF@BiOCl), 21 MoS 2 -NaYF 4 :Yb 3+ / Er 3+ , 22 b-NaYF 4 :Yb 3+ ,Tm 3+ /g-C 3 N 4 (NYT/C 3 N 4 ), 23,24 NaYF 4 :Yb, Tm@CdS, 25,26 NaYF 4 :Yb,Er/CdSe, 27 NaYF 4 :Yb 3+ ,Tm 3+ @ZnO 28,29 and NaYF 4 :Yb 3+ ,Tm 3+ @MOFs. 30 These composites are engineered to respond to near-infrared (NIR) light, enhancing their photocatalytic effectiveness.…”