Boosting Interfacial Electron Transfer and CO2 Enrichment on ZIF-8/ZnTe for Selective Photoelectrochemical Reduction of CO2 to CO.

Artificial photosynthesis is an effective way of converting CO2 into fuel and high value-added chemicals. However, the sluggish interfacial electron transfer and adsorption of CO2 at the catalyst surface strongly hamper the activity and selectivity of CO2 reduction. Here, we report a photocathode attaching zeolitic imidazolate framework-8 (ZIF-8) onto a ZnTe surface to mimic an aquatic leaf featuring stoma and chlorophyll for efficient photoelectrochemical conversion of CO2 into CO. ZIF-8 possessing high CO2 adsorption capacity and diffusivity has been selected to enrich CO2 into nanocages and provide a large number of catalytic active sites. ZnTe with high light-absorption capacity serves as a light-absorbing layer. CO2 molecules are collected in large nanocages of ZIF-8 and delivered to the ZnTe surface. As evidenced by scanning electrochemical microscopy, the interface can effectively boost interfacial electron transfer kinetics. The ZIF-8/ZnTe photocathode with unsaturated Zn-Nx sites exhibits a high Faradaic efficiency for CO production of 92.9% and a large photocurrent of 6.67 mA·cm-2 at -2.48 V (vs Fc/Fc+) in a nonaqueous electrolyte at AM 1.5G solar irradiation (100 mW·cm-2).

Performance of a polymerization-based electrochemically assisted persulfate process on a real coking wastewater treatment.

Industrial wastewater should be treated with caution due to its potential environmental risks. In this study, a polymerization-based cathode/Fe3+/peroxydisulfate (PDS) process was employed for the first time to treat a raw coking wastewater, which can achieve simultaneous organics abatement and recovery by converting organic contaminants into separable solid organic-polymers. The results confirm that several dominant organic contaminants in coking wastewater such as phenol, cresols, quinoline and indole can be induced to polymerize by self-coupling or cross-coupling. The total chemical oxygen demand (COD) abatement from coking wastewater is 46.8% and the separable organic-polymer formed from organic contaminants accounts for 62.8% of the abated COD. Dissolved organic carbon (DOC) abatement of 41.9% is achieved with about 89% less PDS consumption than conventional degradation-based process. Operating conditions such as PDS concentration, Fe3+ concentration and current density can affect the COD/DOC abatement and organic-polymer yield by regulating the generation of reactive radicals. ESI-MS result shows that some organic-polymers are substituted by inorganic ions such as Cl-, Br-, I-, NH4+, SCN- and CN-, suggesting that these inorganic ions may be involved in the polymerization. The specific consumption of this coking wastewater treatment is 27 kWh/kg COD and 95 kWh/kg DOC. The values are much lower than those of the degradation-based processes in treating the same coking wastewater, and also are lower than those of most processes previously reported for coking wastewater treatment.

High defect tolerance ß-CsSnI3 perovskite light-emitting diodes.

All-inorganic lead-free CsSnI3 has shown promising potential in optoelectronic applications, particularly in near-infrared perovskite light-emitting diodes (Pero-LEDs). However, non-radiative recombination induced by defects hinders the optoelectronic properties of CsSnI3-based Pero-LEDs, limiting their potential applications. Here, we uncovered that ß-CsSnI3 exhibits higher defect tolerance compared to orthorhombic γ-CsSnI3, offering a potential for enhancing the emission efficiency. We further reported on the deposition and stabilization of highly crystalline ß-CsSnI3 films with the assistance of cesium formate to suppress electron-phonon scattering and reduce nonradiative recombination. This leads to an enhanced photoluminescence quantum yield up to ∼10%. As a result, near-infrared LEDs based on ß-CsSnI3 emitters are achieved with a peak external quantum efficiency of 1.81% and excellent stability under a high current injection of 1.0 A cm-2.

Steroidal saponins and homoisoflavonoids from the fibrous roots of ophiopogon japonicus and their anti-pulmonary fibrosis activities.

The chemical investigation of the fibrous roots of Ophiopogon japonicus afforded two new steroidal saponins, named ophiojaponin F (1) and ophiojaponin G (2), together with twelve known steroidal saponins (3-14) and ten known homoisoflavonoids (15-24). The structures of the isolated compounds were established unambiguously via spectroscopic analyses (NMR and HR-ESI-MS). Ophiojaponin F (1) is a 23-hydroxylated spirostanol saponin, and this type of steroidal saponin rarely been reported in liriopogons. All isolates were evaluated for their anti-pulmonary fibrosis activities on TGF-ß1-actived NIH3T3 cells for the first time. Among them, compounds 3, 4, 11-13, 15-19, 21 and 24 showed potential anti-pulmonary fibrosis effects with IC50 values ranging from 3.61 ± 0.86 µM to 21.33 ± 1.82 µM, and the main component ophiopogonin D (4) displayed the best activity with an IC50 value of 3.61 ± 0.86 µM. Thus, ophiopogonin D may be a potent candidate for the treatment of pulmonary fibrosis.

Regulating The Electronic Configuration of Low-Dimensional Hybrid Perovskites via Organic Cations for Self-Powered Ultraviolet Photodetectors.

Ultraviolet photodetectors (UPDs) based on low-dimensional halide perovskites have undergone rapid development. Here, regulation of the electronic configuration of low-dimensional hybrid perovskites are reported via organic cations for self-powered UPDs. For the first time, it is determine that the rational design of organic cation phenyl alkylammonium can effectively prevent phonon scattering thus increasing charge carrier extraction in low dimensional lead chlorine perovskite thin-films. As a result, the exciton-binding energy can be reduced to 62.91 meV in (PMA)2 PbCl4 perovskite films with a charge-carrier mobility of 0.335 cm2  V-1  s-1 . The fabricated (PMA)2 PbCl4 -based self-powered UPDs has achieved a high detectivity of 6.32 × 1013 jones with a low noise current of 0.35 pA Hz-1/2 under zero bias. A further demonstration of images with high UV to visible light rejection ratio under weak-light illumination of 70 nW cm-2 highlights the feasible potential application of low-dimensional perovskite.

All-Inorganic Perovskite NiTiO3/Cs3Sb2I9 Heterostructure for Photocatalytic CO2 Reduction to CH4 with High Selectivity.

Developing efficient and stable halide perovskite-based photocatalysts for highly selectivity reduction CO2 to valuable fuels remains a significant challenge due to their intrinsic instability. Herein, a novel heterostructure featuring 2D Cs3Sb2I9 nanosheets on a 3D flower-like mesoporous NiTiO3 framework using a top-down stepwise membrane fabrication technique is constructed. The unique bilayer heterostructure formed on the 3D mesoporous framework endowed NiTiO3/Cs3Sb2I9 with sufficient and close interface contact, minimizing charge transport distance, and effectively promoting the charge transfer at the interface, thus improving the reaction efficiency of the catalyst surface. As revealed by characterization and calculation, the coupling of Cs3Sb2I9 with NiTiO3 facilitates the hydrogenation process during catalytic, directing reaction intermediates toward highly selective CH4 production. Furthermore, the van der Waals forces inherent in the 3D/2D heterostructure with face-to-face contact provide superior stability, ensuring the efficient realization of photocatalytic CO2 reduction to CH4. Consequently, the optimized 3D/2D NiTiO3/Cs3Sb2I9 heterostructure demonstrates an impressive CH4 yield of 43.4 µmol g-1 h-1 with a selectivity of up to 88.6%, surpassing most reported perovskite-based photocatalysts to date. This investigation contributes to overcoming the challenges of commercializing perovskite-based photocatalysts and paves the way for the development of sustainable and efficient CO2 conversion technologies.

Progress and Challenges Toward Effective Flexible Perovskite Solar Cells.

The demand for building-integrated photovoltaics and portable energy systems based on flexible photovoltaic technology such as perovskite embedded with exceptional flexibility and a superior power-to-mass ratio is enormous. The photoactive layer, i.e., the perovskite thin film, as a critical component of flexible perovskite solar cells (F-PSCs), still faces long-term stability issues when deformation occurs due to encountering temperature changes that also affect intrinsic rigidity. This literature investigation summarizes the main factors responsible for the rapid destruction of F-PSCs. We focus on long-term mechanical stability of F-PSCs together with the recent research protocols for improving this performance. Furthermore, we specify the progress in F-PSCs concerning precise design strategies of the functional layer to enhance the flexural endurance of perovskite films, such as internal stress engineering, grain boundary modification, self-healing strategy, and crystallization regulation. The existing challenges of oxygen-moisture stability and advanced encapsulation technologies of F-PSCs are also discussed. As concluding remarks, we propose our viewpoints on the large-scale commercial application of F-PSCs.

Surface Modification in CsPb0.5Sn0.5I2Br Inorganic Perovskite Solar Cells: Effects of Bifunctional Dipolar Molecules on Photovoltaic Performance.

Inorganic tin-lead binary perovskites have piqued the interest of researchers as effective absorbers for thermally stable solar cells. However, the nonradiative recombination originating from the surface undercoordinated Sn2+ cations and the energetic offsets between different layers cause an excessive energy loss and deteriorate the perovskite device's performance. In this study, we investigated two thioamide derivatives that differ only in the polar part connected to their common benzene ring, namely, benzenecarbothioamide and 4-fluorophenylcarbothioamide (F-TBA). These two molecules were implemented as modifiers onto the inorganic tin-lead perovskite (CsPb0.5Sn0.5I2Br) surface in the perovskite solar cells. Modifiers that carry C═S and NH2 functional groups, equipped with lone electron pairs, can autonomously associate with surface Sn2+ through coordination and electrostatic attraction mechanisms. This interaction serves effectively to passivate the surface. In addition, due to the permanent dipole moment of the intermediate layer, an interfacial dipole field appears at the PCBM/CsPb0.5Sn0.5I2Br interface, reducing the electron extraction potential barrier. Consequently, the planar solar cell with an ITO/PEDOT:PSS/CsPb0.5Sn0.5I2Br/PCBM/BCP/Ag layered structure featuring an F-TBA surface post-treatment demonstrated a noteworthy power conversion efficiency of 14.01%. Simultaneously, after being stored for 1000 h in an inert atmosphere glovebox, the non-encapsulated CsPb0.5Sn0.5I2Br solar cells managed to preserve 94% of their original efficiency.

Single-Crystal Nanowire Cesium Tin Triiodide Perovskite Solar Cell.

This work reports for the first time a highly efficient single-crystal cesium tin triiodide (CsSnI3 ) perovskite nanowire solar cell. With a perfect lattice structure, low carrier trap density (≈5 × 1010 cm-3 ), long carrier lifetime (46.7 ns), and excellent carrier mobility (>600 cm2 V-1 s-1 ), single-crystal CsSnI3 perovskite nanowires enable a very attractive feature for flexible perovskite photovoltaics to power active micro-scale electronic devices. Using CsSnI3 single-crystal nanowire in conjunction with highly conductive wide bandgap semiconductors as front-surface-field layers, an unprecedented efficiency of 11.7% under AM 1.5G illumination is achieved. This work demonstrates the feasibility of all-inorganic tin-based perovskite solar cells via crystallinity and device-structure improvement for the high-performance, and thus paves the way for the energy supply to flexible wearable devices in the future.

Achieving High Responsivity and Detectivity in a Quantum-Dot-in-Perovskite Photodetector.

This work reports on quantum dots (QDs) in perovskite photodetectors showing high optoelectronic performance via quantum-dot-assisted charge transmission. The self-powered broad-band photodetector constructed with SnS QDs in FAPb0.5Sn0.5I3 perovskite can capture incoming optical signals directly at zero bias. The QDs-in-perovskite photodetector exhibits a high sensitivity in the wavelength range from 300 to 1000 nm. Its responsivity at 850 nm reaches 521.7 mA W-1, and a high specific detectivity of 2.57 × 1012 jones can be achieved, which is well beyond the level of previous self-powered broad-band photodetectors. The capability of quantum-dot-in-perovskite photodetectors as data receivers has been further demonstrated in a visible-light communication application.

Phenolic compounds from the flowers of Rosa hugonis Hemsl. and their neuroprotective effects.

The fragrant flowers of Rosa hugonis Hemsl. Contain abundant valuable rose oil and carotenoids. However, phytochemical investigation of this resource rich in phenolics with neuroprotective activity in vitro has been rarely reported. Purification of the 70% ethanol extracts from the flowers of R. hugonis by various chromatographic methods resulted in the isolation and characterization of five undescribed acylated flavonoid glycosides (Hugonisflavonoid A-E) together with forty known phenolics. The chemical structures of the undescribed compounds were elucidated by extensive analysis of their spectroscopic data and chemical methods. All the isolates were found from R. hugonis for the first time and evaluated for their neuroprotective effects on 6-OHDA induced injury in PC12 cells. Seventeen compounds displayed remarkable protective effects at concentrations of 10 µM. Hugonisflavonoid E can reduce excessive reactive oxygen species and up-regulate mRNA expression levels of superoxide dismutase 1 and catalase. Additionally, hugonisflavonoid E activated the phosphorylated proteins such as PDK1, Akt and GSk-3ß. These findings suggested that R. hugonis could be a potential source for neuroprotective agents.

Fabrication of High-Quality CsPbI3 Perovskite Films with Phosphorus Pentachloride Additive for Highly Stable Solar Cells.

Fully inorganic perovskite cesium lead triiodide (CsPbI3 ) has garnered much attention from researcher for photovoltaic application because of its excellent thermal stability compared with the inorganic-organic hybrid counterparts, along with the potential to serve as the top cell in tandem devices with silicon solar cell. However, the active α-phase cubic CsPbI3 spontaneously tends to transform into the non-perovskite δ-CsPbI3 when subjected to ambient condition. This work proposes an effective method to fabricate high-quality and stable α-phase cubic CsPbI3 films by introducing phosphorus pentachloride (PCl5 ) as an additive. PCl5 acts as colloidal binder for modulating crystallization dynamics of perovskites, resulting in high-quality film and a significantly suppressed phase transition. Finally, highly stable CsPbI3 perovskite solar cells can be achieved with a power conversion efficiency up to 17.85 %, and a long-term stability in N2 filled glove box.

Organics abatement and recovery from wastewater by a polymerization-based electrochemically assisted persulfate process: Promotion effect of chloride ion and its mechanism.

Ubiquitous chloride ion (Cl-) in wastewaters usually inhibits the degradation of organic contaminants and generates numerous toxic chlorinated products in conventional degradation-based advanced oxidation processes (AOPs). Herein, a more Cl- tolerant polymerization-based electrochemical AOP for organic contaminants abatement and simultaneous organic resource recovery was demonstrated with eight typical organic contaminants and two real industrial wastewaters for the first time. This process can significantly promote dissolved organic carbon (DOC) abatement in the presence of Cl-, differing greatly from conventional degradation-based processes. Compared to sulfate radical (SO4•-) (or hydroxyl radical (HO•)), dichloride radical (Cl2•-) derived from Cl- has moderate reactivity towards most contaminants, which facilitates the organics polymerization as it ensures the formation of polymerizable organic radicals while inhibiting their excessive degradation. Thus, high DOC abatement (over 75 %) and high organic resource recovery ratio (48-79 % separable organic-polymer yield) can be achieved for most contaminants. Both soluble chlorinated compounds and solid chlorinated polymers are formed in the presence of Cl-. The chlorinated products (e.g. chlorophenols) can be polymerized as new monomers, thus the concentration of dissolved organic chlorinated products is much lower than that in conventional degradation-based process. The tolerance of the present process to Cl- is tested in real coking wastewaters, and exceeding 60 % of the abated chemical oxygen demand (COD) is obtained in the form of recoverable organic-polymers.

Isoprenylated Flavonoids and 2-Arylbenzofurans from the Root Bark of Morus alba L. and Their Cytotoxic Activity against HGC27 Cancer Cells.

Three new compounds (1, 11, and 12), together with 32 known ones, were isolated from the root bark of Morus alba L. using various chromatographic methods. The structures of the undescribed compounds were elucidated based on 1D, 2D NMR, and HRESIMS dataanalysis, while the known ones were identified by comparison of their spectroscopic data with those reported in the literature. All the isolates were evaluated for their cytotoxic activities against human gastric cancer HGC27 cells by CCK-8 assay. Among them, compounds 5, 8, 10, and 30 exhibited cytotoxic activities on HGC27 cells with IC50 values of 33.76 ± 2.64 µM, 28.94 ± 0.72 µM, 6.08 ± 0.34 µM, and 10.24 ± 0.89 µM, respectively. Furthermore, compound 10 was confirmed to reduce proliferation ability, increase apoptosis rate, and inhibit cell migration pathway by annexin V/PI double staining experiment, transwell experiment, and Western blot analysis.

Sugar easters and xanthones from the roots of Polygala tenuifolia Willd. and their cytoprotective activity.

Six new sugar esters (1-6), named tenuifolisides F-G (1-2) and tenuifolioses W-Z (3-6), together with 16 known compounds (7-22) were isolated from the roots of Polygala tenuifolia. The chemical structures of the new compounds were elucidated by 1D, 2D NMR and HRESIMS techniques together with chemical methods. All the compounds were evaluated for the cytoprotective activity against hydrogen peroxide (H2O2)-induced oxidative stress in human keratinocyte HaCaT cells. Compounds 4, 5, 13, 20 and 22 showed strong cytoprotective effect.

Single-crystalline TiO2 nanoparticles for stable and efficient perovskite modules.

Despite the remarkable progress in power conversion efficiency of perovskite solar cells, going from individual small-size devices into large-area modules while preserving their commercial competitiveness compared with other thin-film solar cells remains a challenge. Major obstacles include reduction of both the resistive losses and intrinsic defects in the electron transport layers and the reliable fabrication of high-quality large-area perovskite films. Here we report a facile solvothermal method to synthesize single-crystalline TiO2 rhombohedral nanoparticles with exposed (001) facets. Owing to their low lattice mismatch and high affinity with the perovskite absorber, their high electron mobility and their lower density of defects, single-crystalline TiO2 nanoparticle-based small-size devices achieve an efficiency of 24.05% and a fill factor of 84.7%. The devices maintain about 90% of their initial performance after continuous operation for 1,400 h. We have fabricated large-area modules and obtained a certified efficiency of 22.72% with an active area of nearly 24 cm2, which represents the highest-efficiency modules with the lowest loss in efficiency when scaling up.

Controlling Quantum-Well Width Distribution and Crystal Orientation in Two-Dimensional Tin Halide Perovskites via a Strong Interlayer Electrostatic Interaction.

Two-dimensional (2D) tin halide perovskites have recently emerged as very promising materials for eco-friendly lead-free photovoltaic devices. However, the fine control of the bulky organic cations orderly embedding into the perovskite structure with a narrow quantum-well width distribution and favorable orientation is rather complicated. In this study, we proposed to introduce the F-substituted phenylethlammonium (PEA) cation (i.e., 4-fluorophenethylammonium FPEA) in 2D tin halide perovskite, which may mitigate phase polydispersity and crystal orientation, thus potentially increasing attainable charge-carrier mobility. A strong interlayer electrostatic attraction between electron-deficient F atoms and its adjacent phenyl rings aligns the crystal structure, working together with the validated dipole interaction. Therefore, the fluorination of organic cation leads to orderly self-assembly of solvated intermediates and promotes vertical crystal orientation. Furthermore, the interlayer electrostatic interaction serves as a supramolecular anchor to stabilize the 2D tin halide perovskite structure. Our work uncovers the effect of interlayer molecular interaction on efficiency and stability, which contributes to the development of stable and efficient low-toxicity perovskite solar cells.

Efficient and Stable Large-Area Perovskite Solar Cells with Inorganic Perovskite/Carbon Quantum Dot-Graded Heterojunction.

This work reports on a compositionally graded heterojunction for photovoltaic application by cooperating fluorine-doped carbon quantum dots (FCQDs in short) into the CsPbI2.5Br0.5 inorganic perovskite layer. Using this CsPbI2.5Br0.5/FCQDs graded heterojunction in conjunction with low-temperature-processed carbon electrode, a power conversion efficiency of 13.53% for 1 cm2 all-inorganic perovskite solar cell can be achieved at AM 1.5G solar irradiation. To the best of our knowledge, this is one of the highest efficiency reported for carbon electrode based all-inorganic perovskite solar cells so far, and the first report of 1 cm2 carbon counter electrode based inorganic perovskite solar cell with PCE exceeding 13%. Moreover, the inorganic perovskite/carbon quantum dot graded heterojunction photovoltaics maintained over 90% of their initial efficiency after thermal aging at 85° for 1056 hours. This conception of constructing inorganic perovskite/FCQDs graded heterojunction offers a feasible pathway to develop efficient and stable photovoltaics for scale-up and practical applications.

Effect of a Cocatalyst on a Photoanode in Water Splitting: A Study of Scanning Electrochemical Microscopy.

With a proper band gap of ∼2.4 eV for solar light absorption and suitable valence band edge position for oxygen evolution, scheelite-monoclinic bismuth vanadate (BiVO4) has become one of the most attractive photocatalysts for efficient visible-light-driven photoelectrochemical (PEC) water splitting. Several studies have indicated that surface modification of BiVO4 with a cocatalyst such as NiFe layered double hydroxide (LDH) can significantly increase the PEC water splitting performance of the catalyst. Herein, we experimentally investigated the charge transfer dynamics and charge carrier recombination processes by scanning electrochemical microscopy (SECM) with the feedback mode on the surface of BiVO4 and BiVO4/NiFe-LDH as model samples. The ratio of rate constants for photogenerated hole (kh+0) to electron (ke-0) via the photocatalyst of BiVO4/NiFe-LDH reacting with the redox couple is found to be five times larger than that of BiVO4 under illumination. In this case, the ratio of the rate constants kh+0/ke-0 stands for the interfacial charge recombination process. This implies the cocatalyst NiFe-LDH suppresses the electron back transfer greatly and finally reduces the surface recombination. Control experiments with cocatalysts CoPi and RuOx onto BiVO4 further verify this conclusion. Therefore, the SECM characterization allows us to make an overall analysis on the function of cocatalysts in the PEC water splitting system.

Realizing Compact Lithium Deposition via Elaborative Nucleation and Growth Regulation for Stable Lithium-Metal Batteries.

Metallic lithium (Li) has been regarded as an ideal candidate for anode materials in next-generation high-energy-density batteries. However, a ubiquitous spongy Li deposition results in low reversibility, huge interfacial impedance, and even safety issues, hindering its practical application. Herein, we proposed a bifunctional electrolyte (BiFE) to avoid the spongy Li deposition, in which lithium nitrate (LiNO3) facilitates a uniform granular Li nucleation via forming a kinetically favorable solid electrolyte interphase and silicon dioxide (SiO2) adsorbs anions to stabilize the electric field distribution near the electrode surface. Such a BiFE provides an even Li+ ion flux for the subsequent growth of electrochemical Li deposition, which was verified by ζ potential, Raman spectra, and specific capacitance characterizations, thus realizing a compact and uniform Li deposition via elaborative nucleation and growth regulation. An improved Li Coulombic efficiency of 99.1% can be achieved within BiFE. When used in Cu∥Li half-cells and Li∥Li symmetric cells, the high Li utilization prolonged the cycling life span to above 300 cycles and 1200 h, respectively. The compact Li deposition also resisted the corrosion of polysulfides to enhance the cycling performance of Li∥S full cells.