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Monitoring acetic acid as a volatile organic compound, which is a key source of pollution, using metal oxides has a great demand and advantage in evaluating air quality. Herein, we present a facile route to modulate the α-Fe2O3/ZrO2 heterojunction for the detection of acetic acid, derived from the pyrolyzation of a zirconium-ferrocene metal–organic framework as the sacrificial precursor, coupled with reduced graphene oxide as the template. Resultantly, the α-Fe2O3/ZrO2 heterojunction exhibits a significant response with a maximum response of 61.5 to 100 ppm acetic acid at 225 °C, exceeding that of the Fe/Zr-0, in the top group of similar sensors. Furthermore, the sensing mechanism is elaborately investigated by X-ray photoelectron, photoluminescence, and Raman spectroscopy and theoretical calculations, possibly resulting from the coexistence of the heterojunction, phase junction and defects, which can accelerate the carrier transfer at the interface and maximize the adsorption of oxygen ions. This work presents a novel combinatorial strategy that opens up a possibility for improving the performance of gas sensors. [ABSTRACT FROM AUTHOR]

The pn junctions significantly affect the responsivity of photodetectors (PDs). However, the enhancement mechanism of the pn junction is still unclear. Herein, operando Raman spectroscopy was employed to study PDs with NiO/TiO2 pn junctions composed of p-NiO nanoparticles (NPs) and n-TiO2 nanotube arrays (TNAs). The results suggest that the built-in potential field of the NiO/TiO2 interface decreases the charge transfer resistance and changes the vibrational frequency of the phonon modes of TiO2, which is attributed to the electron–phonon coupling effect. Operando Raman spectroscopy is proved to be a powerful tool for manufacturing highly responsive PDs. [ABSTRACT FROM AUTHOR]

Two soft salts (S1 and S2) based on platinum(II) complexes with a near-infrared emission have been designed and synthesized. It has been demonstrated that S2 has a high photostability and a low cytotoxicity, and it has been successfully applied to in vivo imaging for the first time. [ABSTRACT FROM AUTHOR]

Ultralong organic phosphorescence (UOP) materials exhibiting persistent emission features can be used for applications such as information encryptions, bioimaging, and display. Until now, the molecular design of UOP materials has been mainly focused on intermolecular interactions without consideration of intramolecular interactions. Here, a series of highly twisted molecules exhibit non-radiative decay as low as 1.01 s−1 due to the restriction of the excited molecular motions through the synergy between intramolecular and intermolecular interactions in the molecular crystals. A unique insight regarding the importance of intramolecular interactions in suppressing non-radiative decay as well as the intermolecular interactions is provided in this contribution. Significantly, two of the phosphors display color-dynamic UOP emissions in a wide range (from pink to white then orange), which exhibit linearly tunable emissions after ceasing the excitation source. Moreover, due to the dual ultralong emission feature, a stable white-light persistent emission is realized for the first time in the molecular crystal. These findings provide the opportunity for the development of dynamic luminescence in organic materials. [ABSTRACT FROM AUTHOR]

As effective active sites for gas sensing, defects have been widely studied in recent years. However, reasonable regulation of defects in semiconductor metal oxides for gas sensing is a formidable challenge, and wide application of defect engineering still has limitations. Here, we synthesized ZIF/Zn(OH)m as precursors through annealing treatment, and obtained ZnO species with different defect ratios of donors. The gas-sensing tests displayed outstanding sensitivity (at the ppb level) and fine selectivity towards triethylamine at 275 °C with high electron donor ZnO, which was attributable to the donor-rich defects (zinc interstitial, Zni, and oxygen vacancy, VO) and higher adsorption energy of oxygen. The donor-related defects, as characterized by spectral measurements, reduce the band gap (determined from UV-visible and density functional theory (DFT) calculations), and enlarge the carrier concentration and electrical conductivity. Meanwhile, the enhanced adsorption capacity of oxygen (calculated by DFT) is conducive to the formation of more ionized oxygen. Our findings suggest that a defect molding strategy in metal oxides provides the possibility to improve the performance of gas sensors. [ABSTRACT FROM AUTHOR]

The role of aromatic π bridges (called π-linkers), which are used to connect multiple D and A groups in asymmetric thermally activated delayed fluorescence (TADF) emitters, remains a critical issue for the development of high-efficiency organic light-emitting diodes (OLEDs). In this work, based on our previous asymmetric TADF emitter (SCP) with electron donors carbazole (D) and phenothiazine (D′), we introduced different numbers of phenyl rings as π-linkers on both sides of SCP, leading to four D–A–D′ TADF emitters (PCz, 2PCz, PSz, and 2PSz) with different levels of conjugation. Experimental and theoretical results reveal that the π-linker distance has a significant effect on excited state regulation and thereby the optoelectronic properties. In comparison, the TADF emitters (PCz, and PSz) with shorter π-linkers exhibit higher photoluminescence quantum yields, due to effective suppression of conformation changes between ground state and excited state, and consequently higher device performance with external quantum efficiencies (EQEs) ranging from 20% to 30% achieved. This work provides an insight into the relationship between molecular design and optoelectronic properties of asymmetric TADF emitters. [ABSTRACT FROM AUTHOR]

Organic materials with persistent room-temperature phosphorescence (pRTP) have played an important role in many fields. However, it is difficult to simultaneously improve the efficiency and lifetime of pRTP via the introduction of simple groups. Herein, we synthesized OMe-SPh (τ = 58.1 ms and ΦP = 4.47%) by introducing a methoxy group into SPh (τ = 43.2 ms and ΦP = 2.48%). Moreover, further extension of the conjugate chain, i.e. OMe-SPhT, was achieved by dibenzothiophene, and OMe-SPhT possessed both a high efficiency and a long lifetime (τ = 171 ms and ΦP = 4.71%). In this case, we desired a balance of different excited-state configurations (nπ* and ππ*), which were verified via single-crystal X-ray diffraction analysis and theoretical time-dependent density functional theory calculations. In addition, the pRTP from neighbouring molecules exhibited a higher stability character than the phosphorescence from the traditional single molecule, especially at room temperature. Based on this property, OMe-SPhT achieved the real-time change in phosphorescence color in response to temperature. [ABSTRACT FROM AUTHOR]

A series of unsymmetrical diphenylketone derivatives with tunable dual-emissive and high-contrast mechanochromic properties are reported. These compounds show dual-emissive bands in both solution and the solid state, by combining traditional fluorescence (ca. 426–459 nm) and intermolecular thermally activated delayed fluorescence (ca. 565–575 nm). Various photophysical studies and single crystal analyses are undertaken to demonstrate the dual-emissive mechanism and effect of bulky groups on regulating dual emissions. In addition, OPNa, OPAn and OPPy show white-light emission with the CIEx,y coordinates (0.32, 0.33), (0.33, 0.32) and (0.30, 0.34) in the solid state and high-contrast mechanochromism from blue and cold white to yellow emission. These studies present an ingenious design strategy for the development of high-performance multifunctional and single-component white-light-emitting materials. [ABSTRACT FROM AUTHOR]

While lithium–sulfur (Li–S) batteries are poised to be the next generation of high-density energy storage devices, the intrinsic polysulfide shuttle has limited their practical applications. In order to fundamentally solve the problem, a well-designed host to simultaneously meet the requirements for both sufficient surface reaction and efficient conversion of polysulfides is urgently demanded. Herein, a 3D heterogeneous sulfur host, termed Ni-ZIF-8@CC, is fabricated by in situ deposition of nickel-doped zeolitic imidazolate framework-8 (Ni-ZIF-8) on carbon cloth (CC). Spectroscopic investigations show that polysulfides can be strongly adsorbed by the Ni-ZIF-8@CC host through the synergy between Ni–S and Li–N interactions, which is also verified by DFT simulations. The doped electrocatalytically active nickel species could furthermore significantly facilitate the kinetics of polysulfide redox reaction, attributed to fast lithium ion diffusion and reduced polarization potential. By combining these advantages, the electrodes exhibit a high areal capacity of up to 6.04 mA h cm−2 together with excellent cycling stabilities. [ABSTRACT FROM AUTHOR]

Currently, studies are increasingly focusing on the cytotoxic effects of anticancer drugs. Such investigations urgently warrant the assessment of single-cell viability. Here, we developed a novel method for quantifying single-cell viability with high selectivity by resonance Raman scattering. We report on this powerful tool that will allow researchers to study cellular metabolism at the level of a single cell. [ABSTRACT FROM AUTHOR]

As a class of smart materials, mechanofluorochromic (MFC) luminogens have promising applications in mechanosensors, security papers, and optical storage primarily based on their alternation in emission behaviors in response to mechanical stimuli. It has been discovered that most molecules having aggregation-induced emission (AIE) exhibit mechanofluorochromism. As one of the essential AIE cores, cyanoethylene has been widely used to build MFC molecules. This review focuses on the latest advances in the mechanofluorochromism of cyanoethylene derivatives with AIE properties, which incorporates mechanistic studies on mechanofluorochromism and MFC luminogens based on cyanoethylene. We hope that this review will provide a clear outlook on these novel functional materials to a broad range of scientists within exclusive disciplinary areas and attract more researchers to devote themselves to this exciting research area. [ABSTRACT FROM AUTHOR]

Charge transfer (CT) at the interfaces between titanium dioxide (TiO2) and gold (Au) is investigated by surface-enhanced Raman scattering (SERS) spectroscopy probed by a sandwiched molecule 4-mercaptobenzoic acid (4-MBA). For the first time, the contribution of surface plasmon resonance (SPR) to CT is studied by tuning the surface plasmon absorption of Au nanorods (NRs) from 530 nm to 793 nm. Moreover, the degrees of CT in the TiO2–MBA–Au assemblies are calculated and the maximum degree of CT is obtained when the excitation laser wavelength is resonant with the SPR absorption of the assemblies. Accordingly, we propose a CT pathway in these semiconductor–molecule–metal assemblies, and the mechanism by which SPR contributes to the CT at the interfaces is discussed. This study has established a simple and effective way of studying the influence of SPR on interfacial CT by using SERS, which is beneficial for further investigations on interfacial charge transfers. Our findings will have significant importance for the improvement of photoelectric devices and photocatalytic efficiency. [ABSTRACT FROM AUTHOR]

Inspired by the “tip effect”, we demonstrate that hollow cupric oxide spheres (HCOS) built from abundant protrusive crystal strips can be used as an effective host for Li–S batteries. The battery based on this novel host retained an excellent cycle performance over 500 cycles and delivered an improved rate capability. [ABSTRACT FROM AUTHOR]

Organic materials that exhibit thermally activated delayed fluorescence (TADF) are an attractive class of functional materials that have witnessed a booming development in recent years. Since Adachi et al. reported high-performance TADF-OLED devices in 2012, there have been many reports regarding the design and synthesis of new TADF luminogens, which have various molecular structures and are used for different applications. In this review, we summarize and discuss the latest progress concerning this rapidly developing research field, in which the majority of the reported TADF systems are discussed, along with their derived structure–property relationships, TADF mechanisms and applications. We hope that such a review provides a clear outlook of these novel functional materials for a broad range of scientists within different disciplinary areas and attracts more researchers to devote themselves to this interesting research field. [ABSTRACT FROM AUTHOR]

Charge transfer (CT) at the interfaces between titanium dioxide (TiO 2 ) and gold (Au) is investigated by surface-enhanced Raman scattering (SERS) spectroscopy probed by a sandwiched molecule 4-mercaptobenzoic acid (4-MBA). For the first time, the contribution of surface plasmon resonance (SPR) to CT is studied by tuning the surface plasmon absorption of Au nanorods (NRs) from 530 nm to 793 nm. Moreover, the degrees of CT in the TiO 2 -MBA-Au assemblies are calculated and the maximum degree of CT is obtained when the excitation laser wavelength is resonant with the SPR absorption of the assemblies. Accordingly, we propose a CT pathway in these semiconductor-molecule-metal assemblies, and the mechanism by which SPR contributes to the CT at the interfaces is discussed. This study has established a simple and effective way of studying the influence of SPR on interfacial CT by using SERS, which is beneficial for further investigations on interfacial charge transfers. Our findings will have significant importance for the improvement of photoelectric devices and photocatalytic efficiency.