Fiber Vector Light-Field-Based Tip-Enhanced Raman Spectroscopy.

Tip-enhanced Raman spectroscopy (TERS) has been extensively employed to investigate the light-matter interaction at the nanoscale. However, the current TERS strategies lack the ability to excite the low-background inhomogeneous electromagnetic field with significant enhancement of electric field, electric field gradient, and optomagnetic field, simultaneously. To overcome this, we developed a fiber vector light-field-based TERS strategy aimed at exploring the multipole Raman scattering processes of molecules.

Mechanistic insights into pH-sensitive photoluminescence of carbon dots: The role of carboxyl group.

We present a mechanistic study of pH-sensitive photoluminescence (PL) in two deliberately designed systems of carbon dots (CDs), which are relatively poor and rich in carboxyl groups anchored on their surfaces, denoted CDs-COOH(p) and CDs-COOH(r), respectively. The underlying PL mechanisms for the two contrasting CD systems are revealed to be different. As for CDs-COOH(p), the pH response of PL exhibits an asymmetric volcano-shaped pattern featuring dynamic and static quenching under acidic and alkaline conditions, dominated by the effects of hydrogen bonding and non-emissive ground-state complex, respectively.

Insights into the Semiconductor SERS Activity: The Impact of the Defect-Induced Energy Band Offset and Electron Lifetime Change.

The significant boost in surface-enhanced Raman scattering (SERS) by the chemical enhancement of semiconducting oxides is a pivotal finding. It offers a prospective path toward high uniformity and low-cost SERS substrates. However, a detailed understanding of factors that influence the charge transfer process is still insufficient.

Electron Transfer Mechanism at the Interface of Multi-Heme Cytochromes and Metal Oxide.

Electroactive microbial cells have evolved unique extracellular electron transfer to conduct the reactions via redox outer-membrane (OM) proteins. However, the electron transfer mechanism at the interface of OM proteins and nanomaterial remains unclear. In this study, the mechanism for the electron transfer at biological/inorganic interface is investigated by integrating molecular modeling with electrochemical and spectroscopic measurements.

Promoting Photocatalytic H Evolution through Retarded Charge Trapping and Recombination by Continuously Distributed Defects in Methylammonium Lead Iodide Perovskite.

Inspired by its great success in the photovoltaic field, methylammonium lead iodide perovskite (MAPbI ) has recently been actively explored as photocatalysts in H evolution reactions. However, the practical application of MAPbI photocatalysts remains hampered by the intrinsically fast trapping and recombination of photogenerated charges. Herein, we propose a novel strategy of regulating the distribution of defective areas to promote charge-transfer dynamics of MAPbI photocatalysts.

Intermolecular singlet fission in a radical dianion system in solution phase.

Singlet fission (SF) is a spin-allowed exciton multiplication process, in which a photogenerated singlet separates efficiently into two free triplets. Herein, we report an experimental study on the solution-phase intermolecular SF (xSF) in a prototype radical dianion system of PTCDA2-, which is produced from its neutral precursor PTCDA (i.e.

Tracking the Explosive Boiling Dynamics at the Alcohol/MXene Interface.

We demonstrate the real-time tracking of explosive boiling dynamics at the alcohol/MXene interface by monitoring the photoinduced lattice dynamics of MXene nanosheets dispersed in different alcohols. As revealed by ultrafast spectroscopy, the explosive boiling experiences three cascading stages, i.e.

Impact of cation modification on phonon-dressed exciton dynamics in a prototype two-dimensional hybrid organic-inorganic perovskite system.

Organic-cation engineering has recently proven effective in flexibly regulating two-dimensional hybrid organic-inorganic perovskites (2D HOIPs) to achieve a diversity of newly emerging applications. There have been many mechanistic studies based on the structural tunability of organic cations; nevertheless, those with an emphasis on the effect solely caused by the organic cations remain lacking. To this end, here we deliberately design a set of 2D HOIPs in which the inorganic layers are kept nearly intact upon cation modification, i.

Efficient Exciton Dissociation through the Edge Interfacial State in Metal Halide Perovskite-Based Photocatalysts.

Metal halide perovskites (MHPs) with superior optoelectronic properties have recently been actively pursued as catalysts in heterogeneous photocatalysis. Dissociating excitons into charge carriers holds the key to enhancing the photocatalytic performance of MHP-based photocatalysts, especially for those with strong quantum-confinement effects. However, attaining efficient exciton dissociation has been rather challenging.

High-temperature negative thermal quenching phosphors from molecular-based materials.

High-temperature negative thermal quenching (NTQ) phosphors are crucial to high-performance light-emitting devices. Herein, we report the high-temperature NTQ effect in deep-red to near-infrared (NIR) emitting copper iodide cluster-based coordination polymers as unconventional phosphors, whose NTQ operating temperature can reach as high as 500 K, the highest temperature reached by NTQ molecular-based materials.

A Copper Iodide Cluster-Based Coordination Polymer as an Unconventional Zero-Thermal-Quenching Phosphor.

Phosphor-converted white light-emitting diodes (pc-wLEDs) are promising candidates for next-generation solid-state lighting and display technologies. However, most of the conventional phosphors in pc-wLED devices suffer from serious thermal quenching (TQ) at high temperatures. Herein, we investigate an unconventional high-efficiency metal-halide cluster-based phosphor with dynamic Cu-Cu interactions that can resist the TQ effect of photoluminescence.

Unpaired Electron Engineering Enables Efficient and Selective Photocatalytic CO Reduction to CH.

The photocatalytic CO reduction to CH reaction is a long process of proton-coupled charge transfer accompanied by various reaction intermediates. Achieving high CH selectivity with satisfactory conversion efficiency therefore remains rather challenging. Herein, we propose a novel strategy of unpaired electron engineering to break through such a demanding bottleneck.

Intermediate Complex-Mediated Interfacial Electron Transfer in a Radical Dianion/TiO Dye-Sensitized Photocatalytic System.

We present a mechanistic study of a PTCDA/TiO dye-sensitized photocatalytic system, in which the stable radical dianion PTCDA is formed via a two-step consecutive photoinduced electron transfer from its neutral precursor PTCDA (i.e., perylenetetracarboxylic dianhydride).

A Red-Emitting Cu(I)-Halide Cluster Phosphor with Near-Unity Photoluminescence Efficiency for High-Power wLED Applications.

Solid-state lighting technology, where light-emitting diodes (LEDs) are used for energy conversion from electricity to light, is considered a next-generation lighting technology. One of the significant challenges in the field is the synthesis of high-efficiency phosphors for designing phosphor-converted white LEDs under high flux operating currents. Here, we reported the synthesis, structure, and photophysical properties of a tetranuclear Cu(I)-halide cluster phosphor, (bppm = bisdiphenylphosphinemethane), for the fabrication of high-performance white LEDs.

Phononic Fine-Tuning in a Prototype Two-Dimensional Hybrid Organic-Inorganic Perovskite System.

The emerging two-dimensional (2D) lead-halide perovskite materials hold great promise for next-generation photovoltaic and optoelectronic applications, in which phonon engineering plays a crucial role. However, detailed mechanistic exploration related to phonon effects, especially from a dynamics perspective, remains rather limited. Herein, we present a systematic demonstration of phononic fine-tuning in a prototype 2D hybrid organic-inorganic perovskite (HOIP) system, i.

Designing a Redox Heterojunction for Photocatalytic "Overall Nitrogen Fixation" under Mild Conditions.

Ammonia and nitrates are the most fundamental and significant raw ingredients in human society. Till now, industrial synthetic ammonia by Haber-Bosch process and industrial synthetic nitrates by the Ostwald process have encountered increasingly serious challenges, i.e.

State-selective exciton-plasmon interplay in a hybrid WSe/CuFeS nanosystem.

The integration of confined exciton and localized surface plasmon in a hybrid nanostructure has recently stimulated extensive interests. The mechanistic insights into the elusive exciton-plasmon interplay at the nanoscale are of both fundamental and applicable values. Herein, by taking a hybrid WSe/CuFeS system as a prototype, in which the excitonic semiconductor WSe nanosheets are interfaced with the plasmonic semiconductor CuFeS nanocrystals to form a heterostructure, we design and perform an ultrafast dynamics study to glean information in this regard.

Ce-Doped WO Nanowires for Tuning N Activation toward Direct Nitrate Photosynthesis.

Nitrate acts as a fundamental raw material in modern industrial and agricultural fields. Recently, photocatalytic nitrogen oxidation into nitrate has been expected to be an alternative method to replace the industrial nitrate synthesis process, which encounters many challenges, i.e.

Negative/Zero Thermal Quenching of Luminescence Electronic Structural Transition in Copper-Iodide Cluster-Based Coordination Networks.

Photoluminescence (PL) intensity in organic or metal-organic emitters usually suffers from thermal quenching (TQ), which severely hinders their industrial applications. The development of negative thermal quenching (NTQ) and/or zero thermal quenching (ZTQ) materials depends on a better understanding of the mechanisms underpinning TQ in luminescent solids. In this work, we investigated the temperature dependence of thermally activated delayed fluorescence (TADF) in copper(I)-organic coordination polymers (CP) ligated with an imidazole or triazole derivative over a broad temperature range.

Hydrogen-Doping-Induced Metal-Like Ultrahigh Free-Carrier Concentration in Metal-Oxide Material for Giant and Tunable Plasmon Resonance.

The practical utilization of plasmon-based technology relies on the ability to find high-performance plasmonic materials other than noble metals. A key scientific challenge is to significantly increase the intrinsically low concentration of free carriers in metal-oxide materials. Here, a novel electron-proton co-doping strategy is developed to achieve uniform hydrogen doping in metal-oxide MoO at mild conditions, which creates a metal-like ultrahigh free-carrier concentration approaching that of noble metals (10 cm in H MoO versus 10 cm in Au/Ag).

Photoexcited Electron Dynamics of Nitrogen Fixation Catalyzed by Ruthenium Single-Atom Catalysts.

It is still a grand challenge to exploit efficient catalysts to achieve sustainable photocatalytic N reduction under ambient conditions. Here, we developed a ruthenium-based single-atom catalyst anchored on defect-rich TiO nanotubes (denoted Ru-SAs/Def-TNs) as a model system for N fixation. The constructed Ru-SAs/Def-TNs exhibited a catalytic efficiency of 125.

Negative thermal quenching of photoluminescence in a copper-organic framework emitter.

Negative thermal quenching (NTQ), an abnormal phenomenon that the intensity of photoluminescence (PL) increases with increasing temperature, has essentially been restricted to either bulk semiconductors or very low temperatures. Here, we report a delayed fluorescence copper-organic framework exhibiting negative thermal quenching (NTQ) of photoluminescence, which is driven by the fluctuation between the localized and delocalized form of its imidazole ligand. The process is completely reversible on cooling/heating cycles.

Ultraefficient Singlet Oxygen Generation from Manganese-Doped Cesium Lead Chloride Perovskite Quantum Dots.

Lead halide perovskites hold promise for photovoltaics, lasers, and light-emitting diode (LED) applications, being known as light-harvesting or -emitting materials. Here we show that colloidal lead halide CsPbCl perovskite quantum dots (PQDs), when incorporating divalent manganese (Mn) ions, are able to produce spin-paired singlet oxygen molecules with over-unit quantum yield (∼1.08) in air conditions.

Ketones as Molecular Co-catalysts for Boosting Exciton-Based Photocatalytic Molecular Oxygen Activation.

Excitonic processes in semiconductors open up the possibility for pursuing photocatalytic organic synthesis. However, the insufficient spin relaxation and robust nonradiative decays in semiconductors place restrictions on both quantum yield and selectivity of these reactions. Herein, by taking polymeric carbon nitride (PCN)/acetone as a prototypical system, we propose that extrinsic aliphatic ketones can serve as molecular co-catalysts for promoting spin-flip transition and suppressing non-radiative energy losses.

Efficient Exciton Dissociation in Heterojunction Interfaces Realizing Enhanced Photoresponsive Performance.

Excitonic effects, originating from the interactions between charge carriers, influence and even dominate the photoresponsive properties of low-dimensional materials. For efficient carrier-related photoresponse, it is imperative to develop appropriate strategies to promote exciton dissociation in these systems. Herein, by taking black phosphorus nanosheets/poly(3-hexylthiophene) (BP/P3HT) as a prototype, we propose that the construction of a heterojunction with a certain band alignment and transport property can facilitate exciton dissociation into free carriers.