Surface Plasmon Resonance Effect Research Articles

Near-Infrared Luminescent Materials Incorporating Rare Earth/Transition Metal Ions: From Materials to Applications.

Near-infrared materials exhibiting high photoluminescence quantum yields present a promising avenue to broaden our capacity and threshold for detection and manipulation, extending beyond the visible emission range. The spotlight has shifted to near-infrared (NIR) luminescent materials emitting beyond 1000nm, with growing interest due to their unique characteristics. The ability of NIR-II emission (1000-1700nm) to penetrate deeply and transmit independently positions these NIR luminescent materials for applications in optical-communication devices, bioimaging, and photodetectors. The combination of rare earth metals/transition metals with a variety of matrix materials provides a new platform for creating new chemical and physical properties for materials science and device applications. In this review, we summarize the recent advancements in NIR emission activated by rare earth and transition metal ions and illustrate their role in applications spanning bioimaging, sensing, and optoelectronics. We start from the various synthesis techniques, including high-temperature solid-state, hydrothermal, and thermal decomposition methods, on how to delicately incorporate the rare-earth/transition metals to the NIR various matrixes, each imparting distinct characteristics to these luminescent materials. We then extend the discussion to strategies of enhancing excitation absorption and emission efficiency, spotlighting innovations like dye sensitization and surface plasmon resonance effects. Subsequently, a significant focus is placed on functionalization strategies and their applications. Finally, we provide a comprehensive analysis of the challenges and proposed strategies for rare earth/transition metal ion-doped near-infrared luminescent materials, summarizing the insights of each section. This article is protected by copyright. All rights reserved.

Integration of Co Single Atoms and Ni Clusters on Defect-Rich ZrO2 for Strong Photothermal Coupling Boosts Photocatalytic CO2 Reduction.

We report a solvothermal method for the synthesis of an oxygen vacancy-enriched ZrO2 photocatalyst with Co single atoms and Ni clusters immobilized on the surface. This catalyst presents superior performance for the reduction of CO2 in H2O vapor, with a CO yield reaching 663.84 μmol g-1 h-1 and a selectivity of 99.52%. The total solar-to-chemical energy conversion efficiency is up to 0.372‰, which is among the highest reported values. The success, on one hand, depends on the Co single atoms and Ni clusters for both extended spectrum absorption and serving as dual-active centers for CO2 reduction and H2O dissociation, respectively; on the other hand, this is attributed to the enhanced photoelectric and thermal effect induced by concentrated solar irradiation. We demonstrate that an intermediate impurity state is formed by the hybridization of the d-orbital of single-atom Co with the molecular orbital of H2O, enabling visible-light-driven excitation over the catalyst. In addition, Ni clusters play a crucial role in altering the adsorption configuration of CO2, with the localized surface plasmon resonance effect enhancing the activation and dissociation of CO2 induced by visible-near-infrared light. This study provides valuable insights into the synergistic effect of the dual cocatalyst toward both efficient photothermal coupling and surface redox reactions for solar CO2 reduction.

Localized surface-plasmon resonance effect as a new driver of Z-scheme electron transfer in cerium dioxide–graphitic carbon nitride heterojunctions

The intersecting interface between the two semiconductors of cerium dioxide (CeO2)–graphitic carbon nitride (g-C3N4) heterojunctions, which have demonstrated excellent photocatalytic activity, inhibits the rapid compounding of the photogenerated electron–hole pairs of g-C3N4. CeO2–g-C3N4 heterojunctions with Z-scheme and type-II electron-transfer routes were prepared via calcination in argon and air atmospheres, respectively. The built-in electric field theory cannot be used to explain the presence of a type-II electron-transfer route in CeO2–g-C3N4 heterojunctions. According the femtosecond transient absorption spectra, the localized surface-plasmon resonance (LSPR) effect of CeO2 drove the Z-scheme electron transfer in CeO2–g-C3N4 heterojunctions. The CeO2–g-C3N4 heterojunction exhibited a type-II electron-transfer route when the particle size of CeO2 increased, which attenuated the LSPR effect. The CeO2–g-C3N4 heterojunction with the Z-scheme electron-transfer route exhibited 4.4 times higher degradation efficiency for bamboo pulping wastewater than g-C3N4, and this result was attributed to the reduced complexation of photogenerated electron–hole pairs and extended photogenerated electron lifetime. Overall, this research provides a new idea for constructing Z-scheme electron-transfer heterojunctions.

Surface plasmon enhancement of 1D Ag nanowires modified electro-treated BiVO4 photoanode with abundant oxygen vacancies for solar water oxidation

The high carrier complexation rate is still one of the main obstacles for bismuth vanadate (BiVO4) to be used in photoelectrochemical (PEC) water oxidation. In this work, we used a simple method for dropping one dimension (1D) silver nanowires (Ag NWs) on the surface of electro-treated BiVO4 (Ag NWs/E-BiVO4). The photocurrent of Ag NWs/E-BiVO4 under AM 1.5 G illumination reaches to 3.12 mA/cm2 which is about 6.2 times than the pure BiVO4 photoelectrode. Meanwhile, the photogenerated charges injection efficiency of Ag NWs/E-BiVO4 photoelectrodes increasing from 12.7 % to 77.5 % than the pure BiVO4 photoelectrode. This is because the surface plasmon resonance (SPR) effect of 1D Ag nanowires enhanced the visible light absorption and provide more Ag active sites. Furthermore, the density functional theory (DFT) calculations show that the Ag NWs/E-BiVO4 have the best adsorption capacity for OH– and the electro-treated BiVO4 with rich oxygen vacancies greatly improves the electron transport efficiency which is benefit for improving the PEC catalytic performance. Thus, this work provides a simple method to enhance the PEC water splitting performance of BiVO4.

Synthesis of Structure-Adjustable R-Au/Pt-CdS Nanohybrids with Strong Plasmon Coupling and Improved Photothermal Conversion Performance

Noble metal nanomaterials with a localized surface plasmon resonance effect exhibit outstanding advantages in areas such as photothermal therapy and photocatalysis. As a unique plasmonic metal nanostructure, gold nanobipyramids have been attracting much interest due to their strong specific local electric field intensity, large optical cross sections, and high refractive index sensitivity. In this study, we propose a novel three-component hetero-nanostructure composed of rough gold nanobipyramids (R-Au NBPs), Pt, and CdS. Initially, purified gold nanobipyramids are regrown to form R-Au NBPs that have a certain degree of roughness. These R-Au NBP substrates with a rough surface provide more hotspots and strengthen the intensity of localized electric fields. Subsequently, Pt and CdS nanoparticles are selectively deposited onto the surface of R-Au NBPs. Pt nanoparticles can provide more active sites. Each component of this hetero-nanostructure directly contacts others, creating multiple electron transfer channels. This novel design allows for tunable localized plasmon resonance wavelengths ranging from the visible to near-infrared regions. These factors contribute to the final superior photothermal conversion performance of the R-Au/Pt-CdS nanohybrids. Under the irradiation of near-infrared light (1064 nm), the photothermal conversion efficiency of R-Au/Pt-CdS reached 38.88%, which is 4.49, 1.5, and 1.22 times higher than that of Au NBPs, R-Au NBPs, and R-Au NBPs/Pt, respectively.

Constructing interface chemical coupling S-scheme heterojunction MoO3-x@PPy for enhancing photocatalytic oxidative desulfurization performance: Adjusting LSPR effect via oxygen vacancy engineering

Construction of photocatalyst that combines excellent electron transfer and photoresponse capabilities to enhance photocatalytic performance remains a challenging task. In this work, interfacial Mo-N bonds and vacancy engineering collaborative modified MoO3-x@polypyrrole (MP) S-scheme heterojunction is rational designed for efficient photocatalytic oxidative desulfurization. The addition of polypyrrole introduces rich defects which inducing the localized surface plasmon resonance (LSPR) effect and enhancing light absorption. Furthermore, the combination facilitates the formation of Mo-N bonds. The modifications amplify the built-in electric field and conduct the efficacious separation of photogenerated carriers. With the synergism of LSPR effect and interfacial chemical Mo-N bonds, the optimal MP photocatalyst displays attractive desulfurization rate of 100% for dibenzothiophene (DBT) in 60 min under illumination, touching the objective of ultra-deep desulfurization. The study extends a novel understanding of the impact of LSPR effect and heterojunction interface charge transfer on the photocatalytic desulfurization ability.

High-efficient water splitting over an in-situ growth novel electrocatalyst of metal-organic framework-based nanostructures

Metal-organic frameworks (MOFs) as emerging material have drawn much attention to apply to the field of water splitting. In this paper, layered NiFe-MIL-53 and nanoflower-like CoFe-MOF-74 were sequentially grown on nickel foam through two-step in-situ growth to construct a MOF-74/MIL-53 heterojunction. On this basis, we used the localized surface plasmon resonance (LSPR) effect of gold nanoparticles (Au NPs) to significantly improve the oxygen evolution reaction performance of MOF-74/MIL-53 heterojunction. Under illumation, the obtained Au-MOF-74/MIL-53 exhibits a lower overpotential of 218 mV, which is far superior to commercial catalyst. The reaction kinetics are significantly enhanced due to the lower charge transfer resistance and the higher electric double layer capacitance. We confirmed the existence of charge transfer between Au NPs and MOFs, and at the same time, the deposition of Au NPs significantly reduced the charge transfer resistance of MOF-74/MIL-53. On the basis of our work, we provide a novel MOF-based electrocatalytic nanocomposite structure for efficient water splitting.

High-Efficiency Ag-Modified ZnO/g-C3N4 Photocatalyst with 1D-0D-2D Morphology for Methylene Blue Degradation

Photocatalysts with different molar ratios of Ag-modified ZnO to g-C3N4 were prepared through an electrostatic self-assembly method and characterized through techniques such as X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy. The resulting Ag-ZnO/g-C3N4 photocatalysts exhibited a unique 1D-0D-2D morphology and Z-type heterojunction. Moreover, g-C3N4 nanosheets with large layer spacing were prepared using acid treatment and thermal stripping methods. The Z-type heterostructure and localized surface plasmon resonance effect of Ag nanowires enabled high-speed electron transfer between the materials, while retaining large amounts of active substances, and broadened the light response range. Because of these features, the response current of the materials improved, and their impedance and photoluminescence reduced. Among the synthesized photocatalysts, 0.05Ag-ZnO/g-C3N4 (molar ratio of g-C3N4/ZnO: 0.05) exhibited the highest photocatalytic performance under UV–visible light. It degraded 98% of methylene blue in just 30 min, outperforming both g-C3N4 (21% degradation in 30 min) and Ag-ZnO (84% degradation in 30 min). In addition, 0.05Ag-ZnO/g-C3N4 demonstrated high cycling stability.

Tandem Electric-Fields Prolong Energetic Hot Electrons Lifetime for Ultra-Fast and Stable NO2 Detection.

Prolonging energetic hot electrons lifetimes and surface activity in the reactive site can overcome the slow kinetics and unfavorable thermodynamics of photo-activated gas sensors. However, bulk and surface recombination limit simultaneous optimization of both kinetics and thermodynamic. Here we deploy tandem electric-fields at (111)/(100)Au-CeO2 to ensure a sufficient driving force for carriers transfer and elucidate the mechanism of the relationship between charges transport and gas-sensing performance. The asymmetric structure of (111)/(100)CeO2 facet junction provide interior electric-fields, which facilitates electron transfer from (100)face to (111)face. This separation of reduction and oxidation reaction sites across different crystal faces helps inhibit surface recombination. The increased electron concentration at the (111)face intensifies the interface electric field, which promotes electron transfer to Au site. The local electric-field generated by the surface plasmon resonance effect promotes the generation of high energy hot-electrons, which maintains charge concentration in interface field by injecting into (111)/(100)CeO2, thereby provide thermodynamic contributions and inhibit bulk recombination. The tandem electric fields enable the (111)/(100)Au-CeO2 to rapidly detect 5ppm of NO2 at room temperature with stability maintained within 20 s. This article is protected by copyright. All rights reserved.

Achieving Visible Light Triggered Overall Water Splitting over Plasmonic Au/SrTiO3:Al Photocatalyst

The surface plasmon resonance (SPR) effect has garnered extensive attention in semiconductor photocatalysis for solar energy conversion, thanks to its remarkable optical properties. However, the majority SPR‐induced photocatalytic systems have been limited to achieving hydrogen evolution or oxygen evolution half reactions, and attaining overall water splitting on a SPR‐induced photocatalyst under visible light remains a formidable challenging. In this study, we employed a plasmonic photocatalyst Au/SrTiO3, and further enhanced its performance by doping aluminum (Al) into the SrTiO3 lattice (denoted as Au/SrTiO3:Al). By constructing reduction cocatalyst (RhCrOx) and oxidation cocatalyst (CoOOH), the Au/SrTiO3:Al photocatalyst successfully realizes photocatalytic overall water splitting with a stoichiometric ratio of H2 and O2 under visible light (λ ≥ 440 nm). We revealed that the introduction of Al species effectively modified the electronic structure of SrTiO3, thereby enhancing the hydrogen evolution reaction in Au/SrTiO3:Al. Simultaneously, the RhCrOx and CoOOH cocatalysts synergistically capitalized on the short‐lived hot electrons and holes generated by the plasmonic Au/SrTiO3:Al photocatalyst, enabling to realize photocatalytic overall water splitting. This work offers a promising avenue for the rational design of plasmon‐induced overall water splitting photocatalysts through the integration of suitable cocatalysts and surface/interface engineering strategies.

Inclusion of metal nanoparticles at the core-shell interface of GaAs0.99Bi0.01/ZnO/ITO core-shell nanowire solar cell for photovoltaic performance enhancement

Optoelectronic performance analysis of perpendicularly aligned conformally coated GaAs0.99Bi0.01/ZnO/ITO core–shell nanowire solar cell having a core length of 1 μm, core diameter of 160 nm, shell thickness of 10 nm and period of 280 nm, decorated with Au metal nanoparticles(MNPs) of variable diameters at the core–shell interface is done employing FDTD method. Diameter optimization of MNPs with four different diameters values around core GaAs0.99Bi0.01 nanowire is accomplished in terms of maximum short circuit current density (Jsc), which offered an optimized diameter combination of D1 = D2 = 50 nm and D3 = 34 nm, D4 = 10 nm, resulting in a maximum Jsc of 32.6 mA cm−2. A detailed analysis of the electric field profile including its top view and longitudinal view is presented to investigate the distribution of electric field upon optical illumination at different wavelength range. The overall photo generation rate profile is also presented to focus on the localized surface plasmon resonance effect caused by the metal nanoparticles (MNPs). In order to boost the electrical performance, a thin coating of electron selective ZnO shell is used around p type GaAs0.99Bi0.01core, which aids in charge carrier separation, thereby improving open circuit voltage (Voc) and overall power conversion efficiency (PCE). The electrical characteristics of bare NW and MNP decorated GaAs0.99Bi0.01/ZnO core–shell nanowire solar cell for different MNP diameters have been compared. For the optimized diameter combination, as stated above, a Voc of 941 mV, Jsc of 28 mA cm−2, FF of 84.35% and PCE of 22.19% is obtained for SRV of 105 cm s−1 at the interfaces and SRH recombination lifetime as less as 10 ns. For SRV of 105 cm s−1 at the interfaces and SRH recombination lifetime of 1 μs, this proposed structure can achieve a Voc of 1.06 V, Jsc of 31.5 mA cm−2, PCE of 29.37% and FF of 87.88% for equal diameters of D1 = D2 = D3 = D4 = 50 nm.

TiO2 nanotubes modification by photodeposition with noble metals: Characterization, optimization, photocatalytic activity, and by-products analysis

Self-organized TiO2 nanotubes (TNT) with 4µm length were obtained by anodization method and calcined to obtain an anatase crystallite phase. The photocatalysts were further decorated with Au, Ag, Pt or Pd nanoparticles (NPs), varying the metal loads (0.50, 0.75, 1, 2 and 5mol%) by photodeposition. The material characterization confirmed the presence of nanoparticles in the TNTs surface, signs of the localized surface plasmon resonance (LSPR) effect for some samples and a bandgap energy of 3.1-3.2eV. Photoluminescence measurements also confirmed that most of the samples with metallic nanoparticles had the recombination of photogenerated carriers lowered due to the trapping effect of the deposited metal NPs.The photoactivity was evaluated by phenol degradation using UV-Vis or visible radiation. Under UV-Vis, the best samples (2 and 5mol% of Au-TNTs and 0.75, 1, and 2mol% of Pd-TNTs) led to 97% phenol removal in 60min while pristine TNTs reached 92% removal. Under visible radiation, the pristine and the Au-TNTs led to about 3% removal, with the best sample being 2mol% Pd-TNTs with 14% removal in 60min. Similar results were obtained for 1 and 5mol% Pd-TNTs (12% and 13% of phenol removal, respectively). The by-products analysis showed that different degradation mechanisms and kinetic rates occur when different metal types, metal loads or types of radiation are considered.

Efficient gold recovery from low concentrated Au(S2O3)23− solution through enhanced photocatalysis via photothermal and surface plasmon resonance assistance on MoS2/MXene/Ag

Thiosulfate technique is the most promising method to recover gold from electronic waste (e-waste) and natural ores due to its non-toxicity and high leaching efficiency. However, the bad affinity between Au(S2O3)23− and traditional adsorbents leads to unsatisfied gold recovery performance from leaching solution. In this work, highly efficient recovery of gold from low concentrated Au(S2O3)23− solution was achieved through enhanced photocatalysis process on a novel MoS2/MXene/Ag adsorbent. During recovery procedure, Au(S2O3)23− was in-situ reduced to Au0 by photogenerated electrons and then anchored on MoS2/MXene/Ag. Under Au(S2O3)23− concentration <10 ppm, over 99 % gold recovery performance could achieve within 2 h. Experimental tests have proved that MXene made fully use of near infrared (NIR) light energy to exhibit better photothermal effect, and surface plasmon resonance (SPR) effect of Ag can simultaneously facilitate the separation of electron-hole pairs on MoS2. By means of external temperature input and rapid charge carrier transmission, plenty of electrons were excited from MoS2/MXene/Ag for Au(S2O3)23− recovery. This work paved a pathway for efficient Au(S2O3)23− recovery, which catered to the demand for green production of gold in the future.

Bi-Doped and Bi Nanoparticles Loaded CeO2 Derived from Ce-MOF for Photocatalytic Degradation of Formaldehyde Gas and Tetracycline Hydrochloride.

Bi/CeO2 (BC-x) photocatalysts are successfully prepared by solvothermal loading Bi nanoparticles and Bi-doped CeO2 derived by Ce-MOF (Ce-BTC). Formaldehyde gas (HCHO) and tetracycline hydrochloride (HTC) are used to evaluate the photocatalytic activity of the synthesized Bi/CeO2. For BC-1000 photocatalyst, the degradation of HTC by 420nm < λ < 780nm light reaches 91.89% for 90min, and HCHO by 350nm < λ < 780nm light reaches 94.66% for 120min. The photocatalytic cycle experiments prove that BC-1000 has good cyclic stability and repeatability. The results of photoluminescence spectra, fluorescence lifetime, photocurrent response, and electrochemical impedance spectroscopy showed that the SPR (Surface Plasmon Resonance) effect of Bi nanoparticles acted as a bridge and promoted electron transfer and enhanced the response-ability of Bi/CeO2 to visible light. Bi-doping produced more oxygen vacancies to provide adsorption sites for adsorbing oxygen and generated more ·O2 - thus promoting photocatalytic reactions. The mechanism of photocatalytic degradation is analyzed in detail utilizing active free radical capture experiments and electron paramagnetic resonance (EPR) characterization. The experimental results indicate that ·O2 - and h+ active free radicals significantly promote the degradation of pollutants.

Ultrasensitive dual-mode detection of amyloid β oligomer via Au NRs modulated photoelectrochemical/electrochemiluminescent response from HOFs/g-C3N4

In this work, a heterojunction composite of HOFs/g-C3N4 was synthesized using solution-plasticized self-assembly of g-C3N4 nanosheet on hydrogen-bonded organic frameworks (HOFs). HOFs/g-C3N4 was then used as a substrate material to construct a novel photoelectrochemical/electrochemiluminescent (PEC/ECL) biosensor for the detection of amyloid β oligomer (Aβo). HOFs/g-C3N4 composites were first drop-coated on the electrode surface. Subsequently, the Aβ aptamer was modified on the electrode surface via amide bonding. The target Aβo and the gold nanorods (Au NRs)-labeled Aβ recognition peptide (Au NRs-KLVFF) were simultaneously dropped onto the electrode surface, thus a “sandwich” dual-mode biosensor was constructed. In the PEC detection of the Aβo, the surface plasmon resonance effect of Au NRs enhanced the visible absorption of HOF/g-C3N4, and the sensor exhibited a "signal-on" photocurrent signal. Meanwhile, the ECL emission spectrum of HOF/g-C3N4 in ECL mode overlaps with the ultraviolet-visible (UV) absorption of Au NRs, and the sensor signal showed a “signal-off” ECL response. Under the optimal conditions experiments, the constructed dual-mode biosensor showed a wide detection range and low detection limit for Aβo. The proposed dual-mode detection method has a detection range of 10 fM to 10 nM with a detection limit of 5.97 fM for PEC detection and a detection range of 0.1 pM to 1.0 μM with a detection limit of 0.051 pM for ECL detection respectively. Additionally, the detection method achieved satisfactory results in the analysis of real samples. Dual-mode sensing platform provides a new strategy for HOFs application in PEC/ECL assay and sensitive detection of AβO.

Promoting the optoelectronic and nonlinear optics properties of MoS2 nanosheets via metal Al anchoring

Molybdenum disulfide (MoS2) has attracted much attention in the field of optoelectronic materials due to its stability and adjustable bandgap structure. However, improving the optoelectronic properties of MoS2 is still a challenging research. Herein, Al doped MoS2 (AMS) films were prepared by a simple single-step magnetron sputtering method. The bonding modes of Al implantation and auxiliary MoS2 were investigated by adjusting metal Al anchoring. The successful synthesis of AMS films was confirmed by the analysis of X-ray diffraction and X-ray photoelectron spectroscopy measurements to investigate the diffraction peaks of Al and Al2S3 and the valence electron structures of Al3+. Compared to MoS2, the A1g Raman peaks of AMS films are slightly blue-shifted, and the peak positions of both Mo3d and S2p are slightly shifted towards higher binding energies. This is attributed to the surface plasmon resonance effect produced by Al doping resulting in a large amount of electron transfer to the conduction band (CB) of MoS2. In addition, the density functional theory calculations reveal that Al doping of MoS2 results in a higher concentration of electrons in CB of MoS2, the band gap of MoS2 can be adjusted by changing the doping concentration of Al. The Z-scan results illustrated that MoS2 was converted from saturable absorption to reverse saturable absorption (RSA) by adjusting the sputtering power of Al. This is attributed to the fact that Al doping increases the electron concentration in the CB of MoS2, which promotes the RSA of the excited states and doping energy levels of AMS films. The values of the nonlinear absorption coefficients of AMS films are 2–5 times higher than those of MoS2, which significantly improves the nonlinear absorption performance of MoS2. The carrier relaxation process and kinetic mechanism of AMS films were investigated by transient absorption spectroscopy, moderate doping of Al can effectively improve the carrier lifetime. This implies that AMS films have good optoelectronic properties and have a wide application potential in optoelectronic devices.

Dealloying-Derived Self-Supporting Nanoporous Zinc Film with Optimized Macro/Microstructure for High-Performance Solar Steam Generation.

Solar steam generation (SSG) is a promising technology for the production of freshwater that can help alleviate global water scarcity. Nanostructured metals, known for their localized surface plasmon resonance effect, have generated significant interest, but low-cost metal films with excellent water evaporation properties are challenging. In this work, we present a one-step dealloying route for fabricating self-supporting black nanoporous zinc (NP-Zn) films with a bicontinuous ligament/channel structure, using Al-Zn solid solution alloys as the precursors. The influence of alloy composition on the formation and macro/microstructure of NP-Zn was investigated, and an optimal Al98Zn2 was selected. Additionally, in situ and ex situ characterizations were conducted to unveil the dealloying mechanism of Al98Zn2 and phase/microstructure evolution of NP-Zn during dealloying, including the phase transition of Al(Zn) → Zn, significant volume shrinkage (89.8%), and the development of high porosity (81.3%). The nanoscale ligament/channel structure and high porosity endow the NP-Zn films with good broadband absorption and superior hydrophilicity and, more importantly, give them excellent SSG performance. The NP-Zn2 film displays high evaporation efficiency, superior stability, and good seawater desalination performance. The efficient SSG performance, material abundance, and low cost suggest that NP-Zn films have promising applications in metal-based photothermal materials for SSG.

Construction of flexible BiOBr/W18O49/polyacrylonitrile discrete heterojunction nanofibers as a dual-functional photocatalyst for simultaneous hydrogen evolution and organic pollutant degradation

Dual-functional photocatalysis has attracted increasing attention due to its ability to achieve efficient synergistic hydrogen (H2) evolution and pollutant removal. Energy band structure engineering and surface morphology modification of photocatalysts is a useful strategy to improve the activity of photocatalysis. This paper uses a combination of electrospinning technology and hydrothermal method to prepare flexible BiOBr/W18O49/PAN discrete heterojunction flexible nanofibers (NFs) with staggered energy bands and spatially separated redox surfaces. The BiOBr/W18O49 heterojunction can improve carrier separation and migration, as evidenced by the photoluminescence and photoelectrochemical experiments. The localized surface plasmon resonance (LSPR) effect of W18O49 can achieve injection of “hot electrons” and lead to expanding the light absorption range according to the UV–visible-near infrared diffuse reflection spectra results. The discrete structure of BiOBr/W18O49/PAN NFs can provide spatially separated active sites for simultaneous photocatalytic redox reaction. As expected, the BiOBr/W18O49/PAN discrete heterojunction NFs greatly enhance the photocatalytic activity in simultaneous dual-functional reaction for H2 evolution and RhB degradation. The highest simultaneous H2 evolution rate and RhB degradation rate of BiOBr/W18O49/PAN NFs are 31.7 times and 34.1 times of BiOBr/PAN, respectively. The design and construction of this flexible discrete heterojunction NFs structures can provide novel ideas and directions for simultaneous dual-functional photocatalysts.

Nanopore arrays with TMOKE-enhanced high performance sensing

Magneto-plasmon sensing structure based on surface plasmon resonance (SPR) and magneto-optical (MO) effect has become a hot research topic in recent years. In this work, we propose a magneto-plasmon crystal consisting of an Au/Co double-layer nanoporous structure with optically thick Au film as a substrate. Due to the excitation of high-quality SPR, a Fano-like transverse magneto-optical Kerr (TMOKE) spectrum with subnanometer bandwidth is realized. A sensitivity of up to 677 nm RIU−1 is detected under subtle refractive index changes in air, and all the calculated figure of merits (FOM) are higher than 104 RIU−1. In addition, in order to highlight the superiority of the sensing performance of the MO plasmon (MOSPR) sensor, we compare the MOSPR sensor with the SPR sensor and calculate their FOM in different refractive index environments. The results show that the FOM of the MOSPR sensor is two orders of magnitude higher than that of the SPR sensor, which proves that the performance of the MOSPR sensor is significantly better than that of the SPR sensor and provides a theoretical basis for biosensing and gas detection based on magneto plasmon.

Experimental study on ultra-high sensitivity gold-based SPR sensor for refractive index and temperature measurement

We have experimentally demonstrated an ultra-high sensitivity gold-based fiber refractive index (RI) sensor whose main structure is composed of multimode fiber (MMF) and photonic crystal fiber (PCF). The gold film is deposited on V-shaped PCF by magnetron sputtering, and sensing experiments are performed based on the principle of surface plasmon resonance (SPR). Numerical simulation results indicate that the cladding mode of the V-shaped PCF is more capable of stimulating the SPR effect than the core mode. The experimental results show that the RI measurement range of the sensor is 1.333–1.421, with a maximum sensitivity of 10015 nm/RIU. In addition to RI sensing, sensing probes can be coated with polydimethylsiloxane (PDMS) on a gold film for temperature sensing. For temperature detection, the range is from 10 to 100 °C and the maximum sensitivity is 3.5 nm/℃. Besides high sensitivity in RI measurement, the proposed sensor also has good sensing performance in temperature sensing. With the advantages of high sensitivity, good stability, and easy preparation, this sensor has become an important reference in the field of high-performance sensing.