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Developing electrode materials with excellent electrocatalytic properties for detecting pesticide residues plays a vital role in the safety of agricultural products and environmental applications. Herein, we designed a new electrochemical sensor on the basis of N-doped carbon hollow nanospheres modified with Sn/MoC Schottky junction (Sn/MoC@NC) for methyl parathion (MP) detection. The Sn/MoC@NC was prepared by self-assembled polymerization-anchoring strategy and high-temperature carbonization design. Sn/MoC Schottky junction and hollow nanosphere structure endow Sn/MoC@NC with a larger surface area, more active sites, and faster electron transfer, which is beneficial to enhancing its electrocatalytic performance. The structural characterizations and physicochemical properties of Sn/MoC@NC were explored through various microscopy, spectroscopic and electrochemical techniques. The experimental results confirmed that the calibration curve for current and MP concentration (0.05–10 μg/mL) was available under optimized conditions, and the sensitivity and detection limit were respectively determined to be 9.02 μA μM 1 cm 2 and 8.9 ng/mL. Furthermore, the constructed sensor displayed excellent selectivity, repeatability, and stability, which qualified it for use in detecting MP in grapes and tap water with satisfactory recovery. This work may provide some interesting prospects for constructing high-performance electrocatalysts for MP detection. [Display omitted] • Sn/MoC@NC Schottky catalyst was designed and synthesized for MP detection. • The self-assembled polymerization-anchoring strategy was proposed in this paper. • The coupling of of Schottky junction and nano hollow improve catalytic activity. • Sn/MoC@NC/GCE exhibits superior electrocatalytic reduction performance for MP. [ABSTRACT FROM AUTHOR]

The vital issue for semiconductor pressure sensors is how to improve the sensitivity of their piezoresistive behavior. In this work, aiming to substantially promote the sensitivity, ZnO/SiC nanowire heterojunctions with various ZnO piezoelectric shell thicknesses were constructed by adjusting the depositing times of atomic layer deposition (ALD). It was found that the thicknesses of coupled ZnO nanolayers played a profound effect on the response of the heterojunctions to the change of stresses, representing the tailored piezoresistive behaviors. Accordingly, the piezoresistive coefficient was optimized to ~ 9.47 × 10–11 Pa−1 with an enhanced ΔR/R0 value of ~ 0.88, once the ZnO nanolayer thickness is fixed at ~ 20 nm, superior to most of pressures sensors based on SiC nanomaterials. This work may provide a novel strategy for exploring advanced SiC-based pressure sensors by coupling with suitable thickness of the piezoelectric nanolayer to improve piezoresistive behaviors. The tailored piezoresistive performance of ZnO/SiC nanowire heterojunctions with a adjusted shell thicknesses of ZnO piezoelectric nanolayers was reported, which had an enhanced piezoresistive coefficient of 9.47 × 10–11 Pa−1 and a ΔR/R0 of 0.88. [ABSTRACT FROM AUTHOR]

Abstract: In present work, we report the fabrication of fabrication of ultrafine mesoporous TiO2 nanofibers via a versatile foaming‐assisted electrospinning method for efficient photocatalytic hydrogen production. The diameter and the porous structure could be precisely controlled, making the controlled fabrication of mesoporous ultrafine TiO2 nanofibers. As compared to P25 as well as other TiO2 nanofiber counterparts, the as‐prepared ultrafine mesoporous TiO2 nanofibers in 85 nm diameter yielded the highest activity photocatalytic H2 release rate of 710.8 μmol • g −1• h−1, suggesting their promising applications in clean energy production. [ABSTRACT FROM AUTHOR]

We demonstrate the controllable conduction band-edge reconfiguration in quasi-2D Dion-Jacobson α-CsPbI 3 perovskites enabled by dimensional engineering based on the rationally designed organic dipole moments and inorganic layer numbers, which endows the perovskites with fundamentally enhanced electron-hole separation toward efficient photovoltaic applications. [Display omitted] • The discovery of CB-edge reconfiguration in quasi-2D CsPbI 3 perovskites. • The achievement on controllable CB-edge reconfiguration. • The encouraged separation and in-plane transport of charge carriers. Generally, the band-edge configurations of ABX 3 perovskite (where A is MA+/FA+/Cs+ cation, B represents Pb2+ or Sn2+, and X is halogen, respectively) are constructed by the electronic states of B and X ions, implying that A-site cation has no significant contribution to the band edge. In current work, through first-principles calculation, we report the controllable conduction band (CB) edge reconfiguration of quasi-2D Dion-Jacobson α -CsPbI 3 perovskites enabled by dimensional engineering for making A-site cations affect perovskite CB edge, which is based on rationally designed organic chain length (m) of A-site organic spacer cations and inorganic layer numbers (n). It is discovered that the energy level of organic CB would be moved up with the increase of m , and that of inorganic CB would be shifted down with the raise of n , allowing the dimensional engineering of quasi-2D perovskites with controllable CB-edge configuration. Consequently, the achieved CB-edge reconfiguration could endow the quasi-2D perovskites with encouraged carrier separation and in-plane transfer. The discovery of CB-edge reconfiguration in quasi-2D perovskites by dimensional engineering, which is highly meaningful to direct the exploration of advanced perovskites for efficient solar cells. [ABSTRACT FROM AUTHOR]

The tailored doping levels towards the band gap tunability are one of the challenges to push forward the potential application of one-dimensional (1D) ZnO nanostructures in the opto/electric nanodevices. In present work, we reported the exploration of Mg-doped ZnO nanofibers via electrospinning of polyvinylpyrrolidone (PVP), Zn(CH 3 COO) 2 (ZnAc) and Mg(CH 3 COO) 2 (MgAc), followed by calcination in air. The resultant products were systematically characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscope (HRTEM), and X-ray photoelectron spectroscopy (XPS). The optical measurements (UV–vis) of the Mg-doped ZnO nanofibers suggested that the optical band gaps of the ZnO nanofibers could be tuned from 3.33 to 3.40 eV as a function of the Mg doing levels. This tunability of the band gap of ZnO nanofibers with an intentional impurity could eventually be useful for optoelectronic applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • An amine-response visual fluorescent tag was prepared by physical deposition. • Quantum dots with aggregation-induced emission effect acted as internal reference. • The tag can realize non-contact detection of biogenic amines. • The tag can be used for real-time and visual monitoring of seafood freshness. The method of monitoring the freshness of seafood is not satisfactory for ensuring food safety. Here, we develop a filter membrane-based smart fluorescent tag with excellent biogenic amine response, which can monitor the freshness of seafood in real time and visually. We use green fluorescent fluorescein as an indicator and red fluorescent carbon quantum dots (RQDs) with aggregation-induced emission property as an internal reference. After simple mixing, they are deposited on the commercial filter membrane by physical deposition method to prepare the fluorescent tag. When amine molecules are present, the molecular conformation of fluorescein changes and the fluorescence increases rapidly, while RQDs have no obvious response, thus achieving a clear fluorescence color response to biogenic amines. Under UV light of 254 nm and 365 nm, the fluorescent tag showed sensitive, rapid, and color-responsive to ammonia in a wide range of 250–2.5 × 104 ppm. To further verify the practical application potential, the fluorescent tag was used to monitor the freshness of shrimp and crab in situ in real time, and satisfactory results were achieved. More importantly, owing to the reversible conformational change of fluorescein, the fluorescent tag can be reused and manufactured at low cost, making it a more attractive platform for freshness monitoring in the field of food safety. [ABSTRACT FROM AUTHOR]

The realization of highly efficient perovskite solar cells (PSCs) in ambient air is considered to be advantageous for low‐cost commercial manufacturing. However, it is fundamentally difficult to achieve comparable device performance to that obtained in an inert atmosphere, especially when the ambient humidity is high. Here, an effective precursor engineering that simultaneously employs non‐halide lead acetate and lead thiocyanate lead sources for fabricating high‐quality methylammonium lead iodide perovskite films in ambient air with enhanced moisture tolerance, is reported. The presence of Ac– and SCN– ions not only enables the facile formation of homogeneous and highly crystalized perovskite films, but also directs the uniform growth of the crystals along the (110) direction. Accordingly, a 20.55% efficiency is demonstrated, one of the best results for air‐processed MAPbI3 PSCs, which is also the highest value achieved with non‐halide lead sources. Furthermore, the unencapsulated device shows fivefold prolonged air stability (3600 h) compared to the conventional PbI2‐based PSC. Together with the use of non‐toxic antisolvent, this strategy is fully compatible with ambient air operation and thus of great potential for practical applications. [ABSTRACT FROM AUTHOR]

Quasi‐2D CsPbI3 perovskites have emerged as excellent candidates for advanced photovoltaic technologies due to their fundamentally enhanced stability than conventional 3D counterparts. However, the applications of quasi‐2D perovskites are plagued with their poor out‐of‐plane carrier mobility induced by the intercalated insulating organic layers. In this work, a new strategy is explored to significantly enhance the out‐of‐plane charge transport in quasi‐2D Dion–Jacobson (DJ) CsPbI3 perovskites via leveraging the intercalation of aromatic diamine cations (p‐phenylenediamine, PPDA) with unique π‐conjugated bond based on the first‐principles calculations. The strong interactions between PPDA2+ cations and inorganic Pb‐I framework (i.e., I–I interaction, p‐π coupling, and H‐bonds) provide three carrier pathways to facilitate the out‐of‐plane charge transport. Furthermore, the restricted in‐plane and out‐of‐plane structural distortion induced by the π‐conjugated bond could improve the electronic coupling and charge mobility along the out‐of‐plane direction with reduced bandgaps. As a proof of concept, the calculated average photovoltaic conversion efficiency of such engineered DJ CsPbI3 perovskite solar cells is ≈17%, which is very close to the certificated champion efficiency of 3D α‐CsPbI3, underscoring their potential for solar cell applications. [ABSTRACT FROM AUTHOR]

In perovskite solar cells (PSCs), a defective perovskite (PVK) surface and cliff‐like energy offset at the interface always slow down the charge extraction; meanwhile, interface ion diffusion causes oxidation of the metal electrode, inducing device instability. Here, the in situ grown 2D‐(CH3NH2)3Sb2I9 (MA3Sb2I9) on the back surface of MAPbI3 results in a more robust interface. MA3Sb2I9 changes the MAPbI3 surface to p‐type and thus acts like a back surface field to drive charge extraction and suppress recombination, resulting in an obviously higher fill factor (FF) = 0.8 and power conversion efficiency (PCE) = 20.4% of SnO2/MAPbI3/MA3Sb2I9/Spiro‐OMeTAD (2,2′,7,7′‐Tetrakis[N,N‐di(4‐methoxyphenyl)amino]‐9,9′‐spirobifluorene) PSC than the pure MAPbI3 device. More importantly, strong chemical bonding of SbI prohibits ion diffusion, largely enhancing the thermal stability and longtime stability. Here, special 2D‐MA3Sb2I9 constructs' robust band alignment and chemical environment at the interface are highlighted for efficient and stable PSCs. [ABSTRACT FROM AUTHOR]

Abstract: The phase instability and large energy loss are two obstacles to achieve stable and efficient inorganic‐CsPbI3−xBrx perovskite solar cells. In this work, stable cubic perovskite (α)‐phase CsPbI2Br is successfully achieved by Pb(Ac)2 functioning at the grain boundary under low temperature. Ac− strongly coordinates with CsPbI2Br to stabilize the α‐phase and also make the grain size smaller and film uniform by fast nucleation. PbO is formed in situ at the grain boundary by decomposing Pb(Ac)2 at high‐temperature annealing. The semiconducting PbO effectively passivates the surface states, reduces the interface recombination, and promotes the charge transport in CsPbI2Br perovskite solar cells. A 12% efficiency and good stability are obtained for in situ PbO‐passivated CsPbI2Br solar cells, while Pb(Ac)2‐passivated device exhibits 8.7% performance and the highest stability, much better than the control device with 8.5% performance and inferior stability. This article highlights the extrinsic ionic grain boundary functionalization to achieve stable and efficient inorganic CsPbI3−xBrx materials and the devices. [ABSTRACT FROM AUTHOR]

Constructing semiconductor heterojunction with optimal structure and composition is highly desired to maximize the solar light utilization for photoelectrochemical (PEC) water splitting. Here, we reported the fabrication of BiVO 4 @ZnO heterojunction with a novel nanostructure for PEC water splitting via foaming-assisted electrospinning and subsequent atomic layer deposition (ALD) techniques. In such BiVO 4 @ZnO heterojunction, the isolated BiVO 4 nanoparticles were packaged within the ZnO microbelt matrix. During PEC water splitting, the BiVO 4 acts as the primary light absorber for wider solar spectral harvesting, and the ZnO prompts the transfer of the photo-excited high-energy electrons, which would render them with prolonged lifetime and enhanced separation of the photogenerated charge carriers. In addition, the microbelts architecture with a hollow channel can also effectively improve the interfacial charge separation and transportation. Accordingly, the PEC performances of BiVO 4 @ZnO hybrid microbelts were significantly enhanced with a photocurrent density up to ∼0.46 mA cm −2 (at 1.23 V vs. reversible hydrogen electrode (RHE) under simulated sunlight illumination), which is 15.3 times to that of pure BiVO 4 counterpart (∼0.03 mA cm −2 ). The photocurrent density of the BiVO 4 @ZnO electrode can be further increased to 1.07 mA cm −2 at 1.2 V vs. RHE by adding hole scavenger (NaSO 3 ) in the electrolyte solution under AM 1.5 G irradiation. [ABSTRACT FROM AUTHOR]

Abstract: Ionic movement is considered awful in perovskite solar cells (PSCs) for relating with the hysteresis and long‐term instability. However, the positive role of ions to enhance the energy band bending for high performance PSC is always overlooked, let alone reducing the hysteresis. In this work, LiI is doped in CH3NH3PbI3. It is observed that the aggregation of Li+/I− tunes the energy level of the perovskite and induces n/p doping in CH3NH3PbI3, which makes charge extraction quite efficient from perovskite to both NiO and [6,6]‐phenyl‐C61‐butyric acid methyl ester (PCBM) layer. Therefore, in NiO/LiI doped perovskite/PCBM solar cells, Li+ and I− modulate the interface energy band alignment to facilitate the electron/hole transport and reduce the interface energy loss. On the other hand, n/p doping enlarges Fermi energy level splitting of the PSCs to improve the photovoltage. The performance of LiI doped PSCs is much higher with reduced hysteresis compared to the undoped solar cells. This work highlights the positive effect of selective ionic doping, which is promisingly important to design the stable and efficient PSCs. [ABSTRACT FROM AUTHOR]

In this report, doping concentration-dependent photoluminescence (PL) properties of Mn-doped ternary Zn-In-S quantum dots (QDs) were studied by using steady-state and time-resolved PL spectroscopy. The QDs PL was firstly significantly intensified with the increasing Mn doping concentration and then decreased after the doping concentration increased up to 7.5 at.%. However, their decay lifetimes exhibit a monotone decrease with Mn doping concentration ranged from 0 to 10 at.%. It can be concluded that the PL intensity was mainly determined by two factors: one was the increased efficiency of energy transfer from host excitons to Mn ion accepter, and the other was the decreased efficiency of the emission from a Mn ion, which was caused by the increased component of exposed Mn ions on QDs surface and the accelerated interaction between adjacent dopants. The competition of above two exciton relaxation dynamics processes determined the trend of the PL intensity, while the latter was responsible for the monotonously decreased lifetime of the Mn ion emission with the increasing Mn doping concentration. [ABSTRACT FROM AUTHOR]

Dual emission quantum dots (QDs) have attracted considerable interest as a novel phosphor for constructing ratiometric optical thermometry because of its self-referencing capability. In this work, the exploration of codoped Zn-In-S QDs with dual emissions at ≈512 and ≈612 nm from intrinsic Cu and Mn dopants for ratiometric temperature sensing is reported. It is found that the dopant emissions can be tailored by adjusting the Mn-to-Cu concentration ratios, enabling the dual emissions in a tunable manner. The energy difference between the conduction band of the host and Cu dopant states is considered as the key for the occurrence of Mn ion emission. The as-constructed QD ratiometric temperature sensor exhibits a totally robust stability with a fluctuation of ≈ ICu/ Itot versus times lower than 1% and almost no hysteresis in cycles over a broad window of 100-320 K. This discovery represents that the present cadmium-free, intrinsic dual-emitting codoped QDs can open a new door for the synthesis of novel QDs with stable dual emissions, which poise them well for challenging applications in optical nanothermometry. [ABSTRACT FROM AUTHOR]

Nano-delivery systems play an important role in the development of nutritional supplements due to their efficient encapsulation and delivery properties for nutrients. Herein, we prepared protein-polysaccharide nanoparticles as a novel amphiphilic nano-delivery system based on gallic acid modified chitosan (GCS) and ovalbumin (OVA) by pH-driven and calcium ion crosslinking. The nanoparticles loaded with hydrophilic riboflavin (Rib) and hydrophobic quercetin (Que) as nutrient models were abbreviated as GCS-OVA-Rib NPs and GCS-OVA-Que NPs, respectively. Their encapsulation efficiencies for Rib and Que. were 66.36 % and 96.61 %, respectively. In addition, GCS-OVA-Rib NPs and GCS-OVA-Que NPs showed antioxidant activity as well as good stability and delivery capacity for Rib and Que. in simulated digestion with release ratios of 78.38 % and 84.15 %, respectively. More importantly, GCS-OVA-Rib/Que. NPs performed good biocompatibility for further applications. Overall, this work provides some useful insights for the design of novel amphiphilic nano-delivery systems based on polysaccharides and proteins. [Display omitted] [ABSTRACT FROM AUTHOR]

We report the synthesis and anode application for sodium-ion batteries (SIBs) of WS2 nanowires (WS2 NWs). WS2 NWs with very thin diameter of ≈25 nm and expanded interlayer spacing of 0.83 nm were prepared by using a facile solvothermal method followed by a heat treatment. The as-prepared WS2 NWs were evaluated as anode materials of SIBs in two potential windows of 0.01-2.5 V and 0.5-3 V. WS2 NWs displayed a remarkable capacity (605.3 mA h g−1 at 100 mA g−1) but with irreversible conversion reaction in the potential window of 0.01-2.5 V. In comparison, WS2 NWs showed a reversible intercalation mechanism in the potential window of 0.5-3 V, in which the nanowire-framework is well maintained. In the latter case, the interlayers of WS2 are gradually expanded and exfoliated during repeated charge-discharge cycling. This not only provides more active sites and open channels for the intercalation of Na+ but also facilitates the electronic and ionic diffusion. Therefore, WS2 NWs exhibited an ultra-long cycle life with high capacity and rate capability in the potential window of 0.5-3 V. This study shows that WS2 NWs are promising as the anode materials of room-temperature SIBs. [ABSTRACT FROM AUTHOR]

Perovskite solar cells as a hot research topic show the necessity of controlling the interface. In this work, an insulating alkyl chain layer is self-assembled at the perovskite/hole transport material interface, which successfully exhibits a dual function: blocking electron recombination and resisting moisture at the same time. Improved solar energy conversion efficiency and stability of the device are both achieved. [ABSTRACT FROM AUTHOR]

• A novel fluorescent probe based on red emission carbon dots was fabricated. • It was applied colorimetric and fluorometric dual-mode detection of nitrite. • It had a high sensitivity and a low detection limit. • It was successfully applied in detecting nitrite in meat products with satisfactory recoveries. • This dual-mode probe presented great advantages for detection of nitrite in food samples. Nitrite (NO 2 –) is widely present in the human environment and accurate, sensitive and selective detecting of nitrite is of vital significance for food safety and water quality. Herein, a novel red emission carbon dots (r-CDs) fluorescent probe was fabricated for dual-mode detection of nitrite, which was capable of both convenient colorimetric analysis and accurate fluorometric detection. When NO 2 – is added to the rose-red r-CDs solution, NO 2 – interacts with the amino groups which on the surface of r-CDs to form diazotized substance, resulting in that the colorimetric color of r-CDs solution realizes the transition from rose red to light purple, and the red fluorescence is gradually quenched. The detection limits of colorimetric and fluorescence for NO 2 – were 0.193 μM and 0.149 μM, respectively. Furthermore, the dual-readout probe revealed satisfactory recovery and reliability when analyzing the concentration of NO 2 – in ham and bacon samples.. [ABSTRACT FROM AUTHOR]

• Formation of (TMA) x FA 1-x Pb(PF 6) x I 3-x /FAPbI 3 heterojunction through interface ion exchange. • Strong hydrogen bonding and ion size effect stabilize the phase structure. • A champion efficiency of 21.43% was obtained with greatly enhanced device stability. Though formamidinium lead triiodide FAPbI 3 is hotly researched, it still suffers from chemical and phase instabilities, arising from inherent weak chemical bonding and easily transformed crystal configures respectively. This induces depraved opto-electronic properties and device instability, which is imperative to be solved. Here, chemical interaction enhancement in heterostructure of (TMA) x FA 1-x Pb(PF 6) x I 3-x /FAPbI 3 simultaneously improves the chemical and phase stability with preserving its inherent bandgap. Strong hydrogen bonding between PF 6 - and FA+ drastically reduces the α phase formation energy and diminishes the interface trap states. The resulting perovskite solar cells achieve improved efficiency of 21.43% compared with 19.32% of the control device. Meanwhile, ∼90% and 80% of the initial efficiency are maintained for unpacked devices after 1200 h storage (25 °C, 30% relative humidity) and 300 h maximum power point tracking (1 sun, 25 °C, N 2), outperforming the control one. This work highlights a robust interface construction method to overcome the inherent problem of FAPbI 3. [ABSTRACT FROM AUTHOR]

Fabrication of efficient Pb reduced inorganic CsPbI2Br perovskite solar cells (PSC) are an important part of environment‐friendly perovskite technology. In this work, 10% Pb reduction in CsPb0.9Zn0.1I2Br promotes the efficiency of PSCs to 13.6% (AM1.5, 1sun), much higher than the 11.8% of the pure CsPbI2Br solar cell. Zn2+ has stronger interaction with the anions to manipulate crystal growth, resulting in size‐enlarged crystallite with enhanced growth orientation. Moreover, the grain boundaries (GBs) are passivated by the Cs‐Zn‐I/Br compound. The high quality CsPb0.9Zn0.1I2Br greatly diminishes the GB trap states and facilitates the charge transport. Furthermore, the Zn4s‐I5p states slightly reduce the energy bandgap, accounting for the wider solar spectrum absorption. Both the crystalline morphology and energy state change benefit the device performance. This work highlights a nontoxic and stable Pb reduction method to achieve efficient inorganic PSCs. [ABSTRACT FROM AUTHOR]

A robust and stable ratiometric temperature sensor based on Zn‐In‐S quantum dots (QDs) with intrinsic dual‐dopant ion emissions is reported by W.Y. Yang, X.S. Fang, and co‐workers on page 7224. The environment‐friendly co‐doped QD sensor exhibits an excellent stability with almost no hysteresis in cycles. The device is promising for challenging applications in future optical nanothermometry. [ABSTRACT FROM AUTHOR]