Interfacial Charge-transfer Transitions Research Articles

Disinfection of bacteria and viruses under near infrared light by tunable self-assembled nanomaterial NH2-MIL-101-xAu based on photothermal and photodynamic mechanisms

In response to the threat posed by multi-drug resistant "superbugs", a synergistic approach of photothermal therapy (PTT) and photodynamic therapy (PDT) has been developed. In this work, NH2-MIL-101-xAu was prepared by introducing Au nanoparticles on the surface of NH2-MIL-101 n-type semiconductor by means of self-assembly. The introduction of Au nanoparticles greatly improves the light absorption and utilization of nanomaterials. Based on the surface plasma response (SPR), NH2-MIL-101-xAu has an efficient photothermal conversion ability, and under the irradiation of 808 nm (1 W/cm2), NH2-MIL-101–5.0Au (0.50 mg/mL) can be heated to 60℃ in 3 min. And the synergistic effect of plasma-induced interfacial charge-transfer transition and Schottky barriers dramatically enhances the photogenerated carrier separation of NH2-MIL-101-xAu, which in turn generates a large number of reactive oxygen species (ROS). Under the experimental conditions, NH2-MIL-101-xAu with the synergistic effect of PTT and PDT had the sterilization rate of 99.99999 % against Escherichia coli and Staphylococcus aureus, and the inactivation rate of Bacteriophage MS2 was more than 99.9 %. This study shows that NH2-MIL-101-xAu possessing a high degree of tunability is an effective PTT and PDT synergistic means of destroying pathogens, which is very helpful in the application of eliminating drug-resistant bacteria.

Interfacial Charge-Transfer Transitions in Phenol-Functionalized SrTiO3 for Highly Reducible Visible-Light Photocatalysts

Interfacial Charge-Transfer Transitions in Phenol-Functionalized SrTiO₃ for Highly Reducible Visible-Light Photocatalysts

Interfacial charge-transfer transitions enable photovoltaic conversion with CO2-fixation products.

We demonstrate that organic-inorganic interfacial charge-transfer transitions enable favourable photovoltaic conversion with CO2-fixation products such as aromatic carboxylic acids, verifying a new possibility of CO2-fixation products in the development of optoelectronic conversion materials.

Interfacial Charge-Transfer Transitions in Rutile TiO2 Nanoparticles Functionalized with Benzoic Acid Derivatives

Interfacial Charge-Transfer Transitions in Rutile TiO₂ Nanoparticles Functionalized with Benzoic Acid Derivatives

Adsorption, Electronic, and Optical Properties of TiO2–Pyridine Complexes: General Principles for Interfacial Charge-Transfer Transitions

Adsorption, Electronic, and Optical Properties of TiO₂–Pyridine Complexes: General Principles for Interfacial Charge-Transfer Transitions

Interfacial modification of GO-FePt hybrid film leads to giant ultrafast optical nonlinearity

Excellent optical nonlinearity is highly promising for the development of multifunctional ultrafast photonics techniques and integrated optoelectronic devices. However, existing numerous optical materials commonly suffer from several challenges, such as bad functional integration, slow response speed, and weak optical nonlinearity thus severely hindering their extensive applications. Here, we first engineer new scalable graphene oxide (GO)-FePt films by chemistry induced self-assembly and then demonstrate the enhanced ultrafast optical nonlinearity by resorting to their interfacial modifications. It is found that the FePt magnetic nanoparticles (NPs) are easily assembled on the surface of the GO by exchanging the surface ligands of the former with evaporated solvent, leading to good water solubility and super-paramagnetism. The femtosecond Z-scan test results show that both the nonlinear saturation absorption and optical Kerr refraction of the pure GO are subjected to reversion once the FePt NPs are introduced. More importantly, we can greatly enhance the ultrafast nonlinear optics response of as-prepared GO-FePt hybrid film by promoting the concentration of magnetic NPs. In addition, the associated optical nonlinearity can be further boosted with femtosecond vectorial beams excitation instead of the linearly polarized one. In principle, the enhanced optical nonlinearity may arise from direct metal-to-semiconductor interfacial charge transfer transition (DICTT) related to the difference in work function and Fermi level together with complicated interaction between the vectorial light fields and the hybrid films. The GO-based magnetic hybrid films with giant ultrafast optical nonlinearity have potential wide-ranging applications in integrated optoelectronics, ultrafast nanophotonics, opto-magnetic storage, and beyond.

Interfacial Charge-Transfer Transitions between ZnO Nanoparticles and Aliphatic Thiols

Interfacial Charge-Transfer Transitions between ZnO Nanoparticles and Aliphatic Thiols

Substituent effects on interfacial charge-transfer transitions in a TiO2-phenol complex

Interfacial charge-transfer transitions (ICTTs) between organic compounds and inorganic semiconductors have recently gained increasing interest for their potential applications in photoenergy conversions and chemical sensing. A TiO2-phenol complex is one of the most important systems for the fundamental research and applications of ICTTs. However, conflicting results have been reported on the substituent effects on ICTTs and the adsorption enthalpy of phenol. Here, we report the systematic substituent effects on ICTTs in the anatase TiO2-phenol system. In addition, we report the adsorption enthalpies of phenol and its derivatives on anatase TiO2 corrected for basis set superposition error.

High-performance broadband photodetector based on plasmonic semiconductor-semiconductor p-n Cu1.8S/AZO interface

Plasmonic semiconductor nanocrystals (NCs) provide intriguing optical properties which offer opportunities to extend the photo-response corresponding to photons with energies less than the semiconductor energy band gap. However, the performance of photodetectors based on individual plasmonic semiconductors is restricted due to very short-living photo-carriers, followed by carrier recombination (∼ 100 ps). Herein, a plasmonic semiconductor-semiconductor p-n interface (Cu1.8S/AZO NCs) was constructed representing 2-fold optical characteristics containing an inter-band electronic transition from the valence to conduction band in response to ultraviolet-visible (UV–vis) excitation and plasmon-induced interfacial charge-transfer transition (PICTT) in response to near infrared (NIR) excitation. We demonstrated that AZO NCs, are appropriate candidates to generate chemical interface damping (CID) of plasmons in Cu1.8S NCs as an acceptor, which is required for PICTT pathway. The device displayed outstanding broadband UV–vis–NIR photoresponsivity (R) and response-time (Trise/Tfall) as high as R = 51.48 A/W, Trise/Tfall= 130/100 ms in 390 nm, R = 37.2 A/W, Trise/Tfall= 50/60 ms in 535 nm, R = 45.6 A/W, Trise/Tfall= 400/10 ms in 750 nm and R = 38.7 A/W and Trise/Tfall= 60/50 ms in 950 nm. This study demonstrates the promising potential of plasmonic semiconductor-semiconductor p-n hybrid systems as high-performance broadband photodetectors (PDs).

SERS-active plasmonic metal NP-CsPbX3 films for multiple veterinary drug residues detection

Sensitive and multiple veterinary drug residues detection is of important for food safety. Herein, uniform plasmonic Au nanobipyramids@Ag nanorods (Au NBP@Ag NR)-CsPbX3 films with strong surface-enhanced Raman scattering (SERS) activity were constructed. The effects of different CsPbX3 (X = Cl, Br, I, or mixed halogens) quantum dots (QDs) on the SERS performances of plasmonic metal NP films were investigated. CsPbI3 QDs with large dielectric constant could be served as the dielectric media to retard the attenuation of electromagnetic evanescent wave, inducing strong electromagnetic strength for SERS enhancement. Plasmon-induced metal-to-perovskite interfacial charge transfer transition also contributed to SERS enhancement. SERS-active plasmonic Au NBP@Ag NR-CsPbI3 films had excellent sensitivity and high reproducibility for quantitative, accurate and multiple detection of chloramphenicol, diazepam and malachite green in food matrix. This work deepened the understanding of the SERS enhancement mechanisms of plasmonic metal NP-perovskite hybrid heterostructures, showing potential prospects in food safety monitoring.

Enhanced Charge Separation for Efficient Photocatalytic H2 Production by Long-Lived Trap-State-Induced Interfacial Charge Transfer.

Photogeneration of charge carriers in semiconductors provides the scientific fundamental for photocatalytic water splitting. However, an ongoing challenge is the development of a new mechanism promoting charge carrier separation. Here we propose a trap-state-induced interfacial charge-transfer transition mechanism (TSICTT), in which electrons in long-lived trap states recombine with holes on the valence band (VB) of the semiconductor, thus prolonging the electron lifetime. We demonstrate this concept in the Sr4Al14O25:Eu2+, Dy3+/CdS (SAO/CdS) heterostructure, where trapped electrons with a lifetime of up to several hours in the SAO persistent luminescence phosphor (PLP) can continuously consume holes on the VB of CdS nanoparticles (NPs). We discover that the interfacial interaction and the work function difference between SAO and CdS are crucial for the TSICTT, which finally contributes to the improved H2 production from 34.4 to 1212.9 μmol gCdS-1 h-1 under visible-light irradiation. This model introduces a new strategy to manipulate charge carrier transport for the effective utilization of solar energy.

Interfacial Charge-Transfer Transitions in Weakly Coupled TiO2 Complexes with Aromatic Monothiols for Visible-Light Photocatalytic Reactions

Interfacial Charge-Transfer Transitions in Weakly Coupled TiO₂ Complexes with Aromatic Monothiols for Visible-Light Photocatalytic Reactions

Detailed study of a TiO2-phenol complex using deuterated phenol

Interfacial charge-transfer transitions (ICTTs) between organic compounds and inorganic semiconductors have recently attracted much interest for their potential applications in photoenergy conversions and chemical sensing. A TiO2-phenol complex is one of the most fundamental ICTT systems. However, the adsorption structure and electronic and optical properties have not been scrutinized yet. Here, we examine the TiO2-phenol complex in detail using deuterated phenol. The experimental and computational vibrational analysis reveals that phenol is dissociatively adsorbed on TiO2 with deprotonation of the hydroxy group. The dissociative adsorption induces much stronger ICTT via d-π electronic couplings than the non-dissociative adsorption.

Directional Damping of Plasmons at Metal-Semiconductor Interfaces.

ConspectusOver the past decade, it has been shown that surface plasmons can enhance photoelectric conversion in photovoltaics, photocatalysis, and other optoelectronic applications through their plasmonic absorption and damping processes. However, plasmonically enhanced devices have yet to routinely match or exceed the efficiencies of traditional semiconductor devices. The effect of plasmonic losses dissipates the absorbed photoenergy mostly into heat and that has hampered the realization of superior next-generation plasmonic optoelectronic devices. Several approaches are being explored to alleviate this situation, including using gain to compensate for the plasmonic losses, designing and synthesizing alternative low-loss plasmonic materials, and reducing activation barriers in plasmonic devices and physical thicknesses of photoabsorber layers to lower the plasmonic losses. A newly proposed plasmon-induced interfacial charge-transfer transition (PIICTT) mechanism has proven to be effective in minimizing energy loss during interfacial charge transfer. The PIICTT leads to a damping of metallic plasmonics by directly generating excitons at the plasmonic metal/semiconductor heteronanostructures. This novel concept has been proven to overcome some of the limitations of electron-transfer inefficiencies, renewing a focus on surface plasmon damping processes with the goal that the plasmonic excitation energies of metal nanoparticles can be more efficiently transferred to the adjacent semiconductor components in the absence and presence of an effective interlayer of carrier-selective blocking layer (CSBL). Several theoretical and experimental studies have concluded that efficient plasmon-induced ultrafast hot-carrier transfer was observed in plasmonic-metal/semiconductor heteronanostructures. The PIICTT mechanism may well be a general phenomenon at plasmonic metal/semiconductor, metal/molecule, semiconductor/semiconductor, and semiconductor/molecule heterointerfaces. Thus, the PIICTT presents a new opportunity to limit energy loss in plasmonic-metal nanostructures and increase device efficiencies based on plasmonic coupling. The nonradiative damping of surface plasmons can impact the energy flux direction and thereby provide a new process beyond light trapping, focusing, and hot carrier creation.In this Account, we draw much attention to the benefits of interfacial plasmonic coupling, highlighting recent pioneering discoveries in which plasmon-induced interfacial charge- and energy-transfer processes enable the generation of hot charge carriers near the plasmonic-metal/semiconductor interfaces. This process is likely to increase the photoelectric conversion efficiency, constituting "plasmonic enhancement". We also discuss recent advances in the dynamics of surface plasmon relaxation and highlight exciting new possibilities for plasmonic metals and their interactions with strongly attached semiconductors to provide directional energy fluxes. While this new research area comes on the heels of much elaborate research on both metal and semiconductor nanomaterials, it provides a subtle but important refinement in understanding the optoelectronic properties of materials with far-reaching consequences from fundamental interface science to technological applications. We hope that this Account will contribute to a more systematic description of interface-coupled plasmonics, both fundamentally and in terms of applications toward the design of plasmonic heterostructured devices.

A Wearable PVA Film Supported TiO2 Nanoparticles Decorated NaNbO3 Nanoflakes‐Based SERS Sensor for Simultaneous Detection of Metabolites and Biomolecules in Human Sweat Samples

AbstractSweat is one of the non‐invasive diagnostic biofluids that provides critical information about human health. In this work, a wearable sweat sensor integrated with a polymer‐based fluid absorption layer modified with titanium oxide (TiO2) nanoparticles decorated sodium niobate (NaNbO3) nanoflakes in porous polyvinyl alcohol (PVA) film matrix is demonstrated for the detection of vital metabolites (such as glucose and urea) and biomolecules (ascorbic acid (AA) and uric acid (UA)) in human sweat samples via surface‐enhanced Raman scattering (SERS). The TiO2@NaNbO3/PVA (SERS patch) exhibits a low limit of detection (LOD) of 0.50, 0.80, 1.00, and 100 mm towards AA, glucose, UA, and urea, respectively. The SERS patch displays a high enhancement factor with a low accumulation time of 20s which can be ascribed to the surface coordination between the TiO2@NaNbO3 and the analytes leading to interfacial charge‐transfer transition (ICTT). Besides, the photo‐induced charge transfer (PICT) resonance significantly amplifies the SERS signal. The SERS patch is successful in the simultaneous determination of AA, glucose, UA, and urea in simulated sweat samples with minimal mutual interference. The high efficacy of the SERS patch proves it as an ideal platform for a wide range of wearable healthcare monitoring applications.

Aromatic-ring dependence of interfacial charge-transfer transitions between TiO2 nanoparticles and aromatic carboxylic acids

Interfacial charge-transfer transitions (ICTTs) between organic compounds and inorganic semiconductors enable the absorption of visible light with colourless organic molecules and direct charge separation for their potential applications in photoenergy conversions and chemical sensing. TiO2 nanocomplexes with aromatic carboxylic acids are one of the most important ICTT systems for photoenergy conversions. Here, we report the aromatic-ring dependence of ICTT in TiO2 nanocomplexes with benzoic acid, naphthalene-2-carboxylic acid, and anthrancene-2-carboxylic acid. Our research reveals the significant red-shift of ICTT by expanding the π-conjugated system from the benzene to anthracene ring and elucidates the mechanism.

Interfacial Charge-Transfer Transitions between TiO2 Nanoparticles and Benzoic Acid Derivatives

Interfacial charge-transfer transitions (ICTTs) between organic compounds and inorganic semiconductors have recently attracted increasing interest for their potential applications in photoenergy co...

Linkage Dependence of Interfacial Charge-Transfer Transitions in ZnO: Carboxylate versus Sulfur Linker.

Interfacial charge-transfer transitions (ICTTs) between organic compounds and inorganic semiconductors have recently attracted much attention due to the unique features of a wide range of visible light absorption with colorless organic molecules and direct interfacial charge separation for their potential applications in photoenergy conversions and chemical sensing. As the research on ICTT has almost been limited to titanium oxide semiconductors such as TiO2, the exploration of ICTT in other inorganic semiconductors is a high-priority issue. Recently, we demonstrated that ICTT is strongly induced by chemisorption of aromatic thiols on ZnO nanoparticles via the sulfur atom. Here, we report on ICTT in ZnO nanoparticles adsorbed with benzoic acid derivatives and the linkage dependence of ICTT in ZnO. We observed ICTT bands in the visible region upon adsorption of 4-(dimethylamino)benzoic acid (4-DMABA) and 3,4-dimethoxybenzoic acid (3,4-DMOBA) on ZnO nanoparticles via the carboxylate group. Notably, the ICTT absorption intensities are about 1 order of magnitude lower than those in the ZnO surface complexes with aromatic thiol compounds. Time-dependence density functional theory (TD-DFT) calculations well reproduce the linkage dependence of ICTT. This characteristic linkage dependence of ICTT in ZnO is attributed to the difference in the valence orbital of bridging atoms. The sulfur bridging atom with the larger 3p valence orbitals gives rise to strong electronic couplings between ZnO and adsorbates for ICTT, in contrast to very weak electronic couplings via the smaller 2p valence orbitals of the oxygen bridging atoms in the carboxylate linkage. Our research reveals the important linkage dependence of ICTT in ZnO and elucidates the mechanism.

Efficient visible light photocatalytic NO abatement over SrSn(OH)6 nanowires loaded with Ag/Ag2O cocatalyst

SrSn(OH)6 (SSOH) possesses a high oxidation potential in the valence band (VB), which is suitable for photocatalytic oxidation removal of pollutants. However, the electrons in the VB of these catalysts are difficult to transition to the conduction band (CB) under visible light, which makes it difficult to utilize sunlight effectively. In this work, Ag/Ag2O is loaded on the surface of SSOH nanowires, which stimulates the interfacial charge-transfer transition on SSOH. Compared with pure-phase SSOH, the NO abatement ratio of Ag/Ag2O-SSOH under visible light irradiation is increased to 45.10%. The e− in the VB of Ag2O are excited into the CB under visible light, and are further transferred to the Ag to react with O2 to produce superoxide radicals. The photo-excited e− in the VB of SSOH enter into the VB of Ag2O through interfacial charge-transfer transition to recombine with the photo-generated holes in the VB of Ag2O, thereby leaving photo-generated holes in the VB of SSOH. The holes in the VB of SSOH have sufficient oxidizing ability to oxidize the adsorbed hydroxyl groups into hydroxyl radicals. This work provides a new perspective for photocatalytic removal of pollutants by wide band gap photocatalyst under visible light.

Interfacial Charge-Transfer Transitions in TiO2 Nanoparticles Adsorbed with 4-Mercaptobenzenoic Acid: Carboxy versus Thiol Anchor and Adsorbate-to-TiO2 versus TiO2-to-Adsorbate Charge Transfer

Interfacial charge-transfer transitions (ICTTs) in surface coordination complexes of organic compounds with inorganic semiconductors enable the absorption of visible light with colorless organic molecules and direct photoinduced charge separation for applications in photoenergy conversions and biosensing. The surface complex of 4-mercaptobenzenoic acid (4-MBA) with TiO2 nanoparticles has attracted much attention for the surface-enhanced Raman scattering (SERS). However, the adsorption and electronic structures and optical properties of the TiO2–4-MBA surface complex remain to be clarified. Here, we examine the TiO2–4-MBA surface complex in detail experimentally and computationally. Upon adsorption of 4-MBA, TiO2 nanoparticles show a broad absorption band in the visible region. The IR vibrational analysis clearly indicates that 4-MBA adsorbs on TiO2 via the carboxylate group, contrary to the reported thiol linkage. Ionization potential measurements and time-dependent density functional theory (TD-DFT) calculations reveal that the absorption band is attributed to ICTT from the highest occupied molecular orbital (HOMO) of the adsorbed 4-MBA to the conduction band of TiO2, contrary to the reported TiO2-to-adsorbate photoinduced charge-transfer scheme. Our research clarifies the predominant adsorption mode of 4-MBA via the carboxylate linkage and organic-to-inorganic ICTT and suggests that the reported SERS originates from the ICTT.