0D triiodide hybrid halide perovskite for X-ray detection.

In the relentless pursuit of developing high-performance, stable and environmentally friendly materials for X-ray detection, we present a new class of Bi-based hybrid organic-inorganic perovskites. An X-ray detector based on a new zero-dimensional (0D) triiodide-induced lead-free hybrid perovskite, (DPA)2BiI9 (DPA = C5H16N22+), has been developed demonstrating outstanding detection performance, including high X-ray sensitivity (20 570 µC Gyair-1 cm-2), low detectable dose rate (0.98 nGyair s-1), fast response time (154/162 ns) and excellent long-term stability.

New insights into sulfur input induced methylmercury production and accumulation in paddy soil and rice.

Sulfur has a high affinity for mercury (Hg) and can serve as effective treating agent for Hg pollution. However, conflict effects between reducing Hg mobility and promoting Hg methylation by sulfur were found in recent studies, and there is a gap in understanding the potential mechanism of MeHg production under different sulfur-treated species and doses. Here, we investigated and compared the MeHg production in Hg-contaminated paddy soil and its accumulation in rice under elemental sulfur or sulfate treatment at a relatively low (500 mg·kg-1) or high (1000 mg·kg-1) level. The associated potential molecular mechanisms are also discussed with the help of density functional theory (DFT) calculation. Pot experiments demonstrate that both elemental sulfur and sulfate at high exposure levels increased MeHg production in soil (244.63-571.72 %) and its accumulation in raw rice (268.73-443.50 %). Coupling the reduction of sulfate or elemental sulfur and decrease of soil redox potential leads to the detachment of Hg-polysulfide complexes from the surface of HgS which can be explained by DFT calculations. Enhancement of free Hg and Fe release through reducing Fe(III) oxyhydroxides further promotes soil MeHg production. The results provide clues for understanding the mechanism by which exogenous sulfur promotes MeHg production in paddies and paddy-like environments and give new insights for decreasing Hg mobility by regulating soil conditions.

Highly efficient broadband white-light emission in two-dimensional semi-conductive hybrid lead chlorides.

White-light emission (WLE) materials based on organic-inorganic hybrid lead halides have drawn considerable attention because of their applications in light-emission equipment. Despite considerable efforts, there is still a lack of two-dimensional (2D) lead-chlorine white-light emitting halides with high photoluminescence quantum efficiency (PLQE). Herein, we report the preparation of a new 2D layered hybrid halide, [DTHPE]Pb4Cl10, which exhibits bright wide-band WLE, a high PLQE of 8.86% and high anti-water stability. To the best of our knowledge, the PLQE of [DTHPE]Pb4Cl10 exceeds that of most 2D lead chlorides. Furthermore, the emission intensity is unchanged even after continuous immersion in water for 7 days. Photoluminescence measurements indicate that the WLE originates from self-trapped excitons. [DTHPE]Pb4Cl10 is a promising visible-blind UV hybrid halide owing to its excellent photoelectric response. [DTHPE]Pb4Cl10 is an effective white-light emitting material for display applications. The coexistence of a high performance visible-blind UV response and high efficiency white-light emission provides attractive possibilities for potential applications in the multifunctional photoelectronic field.

Centimeter-sized lead-free iodide-based hybrid double perovskite single crystals for efficient X-ray photoresponsivity.

Hybrid organic-inorganic lead halide perovskites (HOIPs) possess significant photoelectric characteristics for solar energy conversion, but the presence of lead causes issues for eco-friendly applications. Halide double perovskites represent a green option for application in the optoelectronic field, especially X-ray detection systems. Despite the great efforts, the exploration of large-size lead-free iodide-based hybrid double perovskite single crystals for X-ray detection has been unsuccessful. Herein, we demonstrate that a large single crystal of the 2D (two-dimensional) semiconducting perovskite (C6H16N2)2CuBiI8·0.5H2O can serve as an X-ray detection candidate. A perovskite crystal, as large as 35 × 31 × 3 mm3, was grown using a low-cost, simple cooling solution approach. To the best of our knowledge, this is the first time a centimeter-sized 2D BiCu iodide double perovskite single crystal has been used for X-ray detection. The perovskite crystal exhibited unique properties for X-ray detection, such as a significant X-ray absorption coefficient, considerable µτ product, and low trap density. Moreover, X-ray detection with a sensitivity of 5.51 µC Gyair-1 cm-2 was achieved based on a single crystal. This work opens new ways to explore specially designed organic cations for stabilizing 2D HOIPs that show great potential in optoelectronics.

Transparent graphene electrodes based hybrid perovskites photodetectors with broad spectral response from UV-visible to near-infrared.

A new class of transparent graphene electrode based organic-inorganic halide perovskite photodetectors with broad spectral response is developed. These ultrasensitive devices exhibit high ON/OFF current ratio, high linear dynamic range, broad spectral range, excellent detection for weak light and easy fabrication with low-cost. Their semi-transparent feature and distinct photodetecting function for both sides would provide new applications affecting our daily lives.

High-Density Lewis Acid Sites in Porous Single-Crystalline Monoliths to Enhance Propane Dehydrogenation at Reduced Temperatures.

The non-oxidative dehydrogenation of propane to propylene plays an important role in the light-olefin chemical industry. However, the conversion and selectivity remain a fundamental challenge at low temperatures. Here we create and engineer high-density Lewis acid sites at well-defined surfaces in porous single-crystalline Mo2 N and MoN monoliths to enhance the non-oxidative dehydrogenation of propane to propylene. The top-layer Mo ions with unsaturated Mo-N1/6 and Mo-N1/3 coordination structures provide high-density Lewis acid sites at the surface, leading to the effective activation of C-H bonds without the overcracking of C-C bonds during the non-oxidative dehydrogenation of propane. We demonstrate a propane conversion of ≈11 % and a propylene selectivity of ≈95 % with porous single-crystalline Mo2 N and MoN monoliths at 500 °C.

Twisted Surfaces in Porous Single Crystals to Deliver Enhanced Catalytic Activity and Stability.

Porous single crystals which combine ordered lattice structures and disordered inter-connected pores would provide an alternative to create twisted surface in porous microstructures. Now, transition-metal nitride Nb4 N5 and MoN single crystals are grown on a 2 cm scale to create well-defined active structures at twisted surfaces. High catalytic activity and stability toward non-oxidative dehydrogenation of ethane to ethylene is observed. Unsaturated metal-nitrogen coordination structures including Nb-N1/5 , Nb-N2/5 , Mo-N1/3 , and Mo-N1/6 at the twisted surface mainly account for the C-H activation with chemisorption of H in molecular ethane at the twisted surface, which not only improves dehydrogenation performance but also avoids the deep cracking of ethane to enhance coking resistance. 11-25 % ethane conversion and 98-99 % ethylene selectivity is demonstrated without degradation being observed even after the operation of 50 hours.

Metallic porous nitride single crystals at two-centimeter scale delivering enhanced pseudocapacitance.

Pseudocapacitors that originate from chemisorption contain redox active sites mainly composed of transition metal ions with unsaturated coordination in lattice on the electrode surface. The capacitance is generally dictated by the synergy of the porous microstructure, electronic conduction and active sites in the porous electrode. Here we grow metallic porous nitride single crystals at 2-cm scale to enhance pseudocapacitance through the combination of large surface area with porous microstructure, high conductivity with metallic states and ordered active sites with unsaturated coordination at twisted surfaces. We show the enhanced gravimetric and areal pseudocapacitance and excellent cycling stability both in acidic and alkaline electrolyte with porous MoN, Ta5N6 and TiN single crystals. The long-range ordering of active metal-nitrogen sites account for the fast redox reactions in chemisorption while the high conductivity together with porous microstructure facilitate the charge transfer and species diffusion in electrodes.

Porous single-crystalline titanium dioxide at 2 cm scale delivering enhanced photoelectrochemical performance.

Porous single-crystalline (P-SC) titanium dioxide in large size would significantly enhance their photoelectrochemical functionalities owing to the structural coherence and large surface area. Here we show the growth of P-SC anatase titanium dioxide on an 2 cm scale through a conceptually different lattice reconstruction strategy by direct removal of K/P from KTiOPO4 lattice leaving the open Ti-O skeleton simultaneously recrystallizing into titanium dioxide. The (101) facet dominates the growth of titanium dioxide while the relative titanium densities on different parent crystal facets control the microstructures. Crystal growth in reducing atmospheres produces P-SC TinO2n-1 (n = 7~38) in magneli phases with enhanced visible-infrared light absorption and conductivity. The P-SC TinO2n-1 shows enhanced exciton lifetime and charge mobility. The P-SC TinO2n-1 boosts photoelectrochemical oxidation of benzene to phenol with P-SC Ti9O17 showing 60.1% benzene conversion and 99.6% phenol selectivity at room temperature which is the highest so far to the best of our knowledge.

Metallic Porous Iron Nitride and Tantalum Nitride Single Crystals with Enhanced Electrocatalysis Performance.

Altering a material's catalytic properties would require identifying structural features that deliver electrochemically active surfaces. Single-crystalline porous materials, combining the advantages of long-range ordering of bulk crystals and large surface areas of porous materials, would create sufficient active surfaces by stabilizing 2D active moieties confined in lattice and may provide an alternative way to create high-energy surfaces for electrocatalysis that are kinetically trapped. Here, a radical concept of building active metal-nitrogen moieties with unsaturated nitrogen coordination on a porous surface by directly growing metallic porous metal nitride (Fe3 N and Ta5 N6 ) single crystals at unprecedented 2 cm scale is reported. These porous single crystals demonstrate exceptionally high conductivity of 0.1-1.0 × 105 S cm-1 , while the atomic surface layers of the porous crystals are confirmed to be an Fe termination layer for Fe3 N and a Ta termination layer for Ta5 N6 . The unsaturated metal-nitrogen moieties (Fe6 -N and Ta5 -N3 ) with unique electronic structures demonstrate enhanced electrocatalysis performance and durability.

Broad-Band-Emissive Organic-Inorganic Hybrid Semiconducting Nanowires Based on an ABX3-Type Chain Compound.

Organic-inorganic hybrid lead halide (e.g., CH3NH3PbX3, where X = CI, Br, and I) nanowires (NWs) with remarkable electric and optical properties have recently garnered increasing attention, owing to their structural flexibility and tunability compared to inorganic semiconducting NWs. While most recently reported NWs are limited to methylammonium/formamidinium three-dimensional lead halide perovskites, it is urgent to develop new organic-inorganic hybrid semiconducting NWs. Here, broad-band-emissive single-crystal semiconductive NWs based on a new ABX3-type organic-inorganic chain hybrid, (2-methylpiperidine)lead tribromide, are reported. It is believed that this work will enrich the organic-inorganic hybrid semiconducting NWs and may provide potential applications for LED displaying.

Isomers of IC70BA and Their Photovoltaic Performance in Polymer Solar Cells.

Indene-C70 derivatives were synthesized, including indene-C70 mono-adduct (IC70MA), indene-C70 bis-adduct (IC70BA) and indene-C70 tris-adduct (IC70TA). All as-prepared fullerene adducts are in fact a mixture of isomers. The IC70BA mixture was further separated by high-performance liquid chromatography (HPLC) and two different IC70BA isomers were obtained. With the addition of the increased number of indene, the lowest unoccupied molecular orbital (LUMO) energy level of the C70 derivatives is also increased. IC70BA and its isomers have a slight difference in LUMO energy level, but show great differences in the absorption spectra. Polymer solar cells (PSCs) devices were fabricated under the same conditions with P3HT as donor, IC70BA and its isomer as acceptor, to examine the influence of the regioisomers on photovoltaic performance. The two IC70BA isomers exhibited varying power conversion efficiency (PCE) values of 2.80 and 3.18%, respectively, suggesting the molecular structure of the fullerene derivatives have an effect on polymer solar cells properties.

One-step electrodeposition of graphene loaded nickel oxides nanoparticles for acetaminophen detection.

An electrochemical sensor of acetaminophen (AP) based on electrochemically reduced graphene (ERG) loaded nickel oxides (Ni2O3-NiO) nanoparticles coated onto glassy carbon electrode (ERG/Ni2O3-NiO/GCE) was prepared by a one-step electrodeposition process. The as-prepared electrode was characterized by scanning electron microscopy, X-ray photoelectron spectroscopy and Raman spectroscopy. The electrocatalytic properties of ERG/Ni2O3-NiO modified glassy carbon electrode toward the oxidation of acetaminophen were analyzed via cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The electrodes of Ni2O3-NiO/GCE, ERG/GCE, and Ni2O3-NiO deposited ERG/GCE were fabricated for the comparison and the catalytic mechanism understanding. The studies showed that the one-step prepared ERG/Ni2O3-NiO/GCE displayed the highest electro-catalytic activity, attributing to the synergetic effect derived from the unique composite structure and physical properties of nickel oxides nanoparticles and graphene. The low detection limit of 0.02 µM (S/N=3) with the wide linear detection range from 0.04 µM to 100 µM (R=0.998) was obtained. The resulting sensor was successfully used to detect acetaminophen in commercial pharmaceutical tablets and urine samples.