Efficient Photoelectrochemical Hydrogen Generation Based on Core Size Effect of Heterostructured Quantum Dots.

Colloidal quantum dots (QDs) are shown to be effective as light-harvesting sensitizers of metal oxide semiconductor (MOS) photoelectrodes for photoelectrochemical (PEC) hydrogen (H2) generation. The CdSe/CdS core/shell architecture is widely studied due to their tunable absorption range and band alignment via engineering the size of each composition, leading to efficient carrier separation/transfer with proper core/shell band types. However, until now the effect of core size on the PEC performance along with tailoring the core/shell band alignment is not well understood. Here, by regulating four types of CdSe/CdS core/shell QDs with different core sizes (diameter of 2.8, 3.1, 3.5, and 4.8 nm) while the thickness of CdS shell remains the same (thickness of 2.0 ± 0.1 nm), the Type II, Quasi-Type II, and Type I core/shell architecture are successfully formed. Among these, the optimized CdSe/CdS/TiO2 photoelectrode with core size of 3.5 nm can achieve the saturated photocurrent density (Jph) of 17.4 mA cm-2 under standard one sun irradiation. When such cores are further optimized by capping alloyed shells, the Jph can reach values of 22 mA cm2 which is among the best-performed electrodes based on colloidal QDs.

Multi-Scale Engineered 2D Carbon Polyhedron Array with Enhanced Electrocatalytic Performance.

Electrocatalyst engineering from the atomic to macroscopic level of electrocatalysts is one of the most powerful routes to boost the performance of electrochemical devices. However, multi-scale structure engineering mainly focuses on the range of atomic-to-particle scale such as hierarchical porosity engineering, while catalyst engineering at the macroscopic level, such as the arrangement configuration of nanoparticles, is often overlooked. Here, a 2D carbon polyhedron array with a multi-scale engineered structure via facile chemical etching, ice-templating induced self-assembly, and high-temperature pyrolysis processes is reported. Controlled phytic acid etching of the carbon precursor introduces homogeneous atomic phosphorous and nitrogen doping, as well as a well-defined mesoporous structure. Subsequent ice-templated self-assembly triggers the formation of a 2D particle array superstructure. The atomic-level doping gives rise to high intrinsic activity, while the well-engineered porous structure and particle arrangement addresses the mass transport limitations at the microscopic particle level and macroscopic electrode level. As a result, the as-prepared electrocatalyst delivers outstanding performance toward oxygen reduction reaction in both acidic and alkaline media, which is better than recently reported state-of-the-art metal-free electrocatalysts. Molecular dynamics simulation together with extensive characterizations indicate that the performance enhancement originates from multi-scale structural synergy.

Lattice Oxygen Activation through Deep Oxidation of Co4N by Jahn-Teller-Active Dopants for Improved Electrocatalytic Oxygen Evolution.

Triggering the lattice oxygen oxidation mechanism is crucial for improving oxygen evolution reaction (OER) performance, because it could bypass the scaling relation limitation associated with the conventional adsorbate evolution mechanism through the direct formation of oxygen-oxygen bond. High-valence transition metal sites are favorable for activating the lattice oxygen, but the deep oxidation of pre-catalysts suffers from a high thermodynamic barrier. Here, taking advantage of the Jahn-Teller (J-T) distortion induced structural instability, we incorporate high-spin Mn3+ ( t 2 g 3 e g 1 ${{t}_{2g}^{3}{e}_{g}^{1}}$ ) dopant into Co4N. Mn dopants enable a surface structural transformation from Co4N to CoOOH, and finally to CoO2, as observed by various in situ spectroscopic investigations. Furthermore, the reconstructed surface on Mn-doped Co4N triggers the lattice oxygen activation, as evidenced experimentally by pH-dependent OER, tetramethylammonium cation adsorption and online electrochemical mass spectrometry measurements of 18O-labelled catalysts. In general, this work not only offers the introducing J-T effect approach to regulate the structural transition, but also provides an understanding about the influence of the catalyst's electronic configuration on determining the reaction route, which may inspire the design of more efficient catalysts with activated lattice oxygen.

Surface Stoichiometry Control of Colloidal Heterostructured Quantum Dots for High-Performance Photoelectrochemical Hydrogen Generation.

Manipulating the separation and transfer behaviors of charges has long been pursued for promoting the photoelectrochemical (PEC) hydrogen generation based on II-VI quantum dot (QDs), but remains challenging due to the lack of effective strategies. Herein, a facile strategy is reported to regulate the recombination and transfer of interfacial charges through tuning the surface stoichiometry of heterostructured QDs. Using this method, it is demonstrated that the PEC cells based on CdSe-(Sex S1- x )4 -(CdS)2 core/shell QDs with a proper Ssurface /Cdsurface ratio exhibits a remarkably improved photocurrent density (≈18.4 mA cm-2 under one sun illumination), superior to the PEC cells based on QDs with Cd-rich or excessive S-rich surface. In-depth electrochemical and spectroscopic characterizations reveal the critical role (hole traps) of surface S atoms in suppressing the recombination of photogenerated charges, and further attribute the inferior performance of excessive S-rich QDs to the impeded charge transfer from QDs to TiO2 and electrolyte. This work puts forward a simple surface engineering strategy for improving the performance of QDs PEC cells, providing an efficient method to guide the surface design of QDs for their applications in other optoelectronic devices.

Perfect Talbot self-imaging effect of aperiodic gratings.

We propose and investigate a class of aperiodic grating structure which can achieve perfect Talbot effect under certain conditions. The aperiodic grating structure is obtained by the superposition of two or more sine terms. In the case of two sine terms, the Talbot effect can be realized when the period ratio of two terms is arbitrary. While in the case of more than two sine terms, the period ratios of each term must meet certain extra conditions. The theory has been further verified by numerical simulations. It expands the field of Talbot effect and is of potential significance for subsequent research applications such as optical imaging and measurement.

A Bio-Inspired Spiking Neural Network with Few-Shot Class-Incremental Learning for Gas Recognition.

The sensitivity and selectivity profiles of gas sensors are always changed by sensor drifting, sensor aging, and the surroundings (e.g., temperature and humidity changes), which lead to a serious decline in gas recognition accuracy or even invalidation. To address this issue, the practical solution is to retrain the network to maintain performance, leveraging its rapid, incremental online learning capacity. In this paper, we develop a bio-inspired spiking neural network (SNN) to recognize nine types of flammable and toxic gases, which supports few-shot class-incremental learning, and can be retrained quickly with a new gas at a low accuracy cost. Compared with gas recognition approaches such as support vector machine (SVM), k-nearest neighbor (KNN), principal component analysis (PCA) +SVM, PCA+KNN, and artificial neural network (ANN), our network achieves the highest accuracy of 98.75% in five-fold cross-validation for identifying nine types of gases, each with five different concentrations. In particular, the proposed network has a 5.09% higher accuracy than that of other gas recognition algorithms, which validates its robustness and effectiveness for real-life fire scenarios.

Strengthened d-p Orbital Hybridization through Asymmetric Coordination Engineering of Single-Atom Catalysts for Durable Lithium-Sulfur Batteries.

Although single-atom catalysts (SACs) have been largely explored in lithium-sulfur (Li-S) batteries, the commonly reported nonpolar transition metal-N4 coordinations only demonstrate inferior adsorption and catalytic activity toward shuttled lithium polysulfides (LiPSs). Herein, single Fe atoms with asymmetric coordination configurations of Fe-N3C2-C were precisely designed and synthesized as efficient immobilizer and catalyst for LiPSs. The experimental and theoretical results elucidate that the asymmetrically coordinated Fe-N3C2-C moieties not only enhance the LiPSs anchoring capability by the formation of extra π-bonds originating from S p orbital and Fe dx2-y2/dxy orbital hybridization but also boost the redox kinetics of LiPSs with reduced Li2S precipitation/decomposition barrier, leading to suppressed shuttle effect. Consequently, the Li-S batteries assembled with Fe-N3C2-C exhibit high areal capacity and cycling stability even under high sulfur loading and lean electrolyte conditions. This work highlights the important role of coordination symmetry of SACs for promoting the practical application of Li-S batteries.

[Genetic analysis of a child with Focal segmental glomerulosclerosis and neurodevelopmental syndrome].

OBJECTIVE: To explore the genetic characteristics of a child with Focal segmental glomerulosclerosis and neurodevelopmental syndrome (FSGSNEDS). METHODS: A child with FSGSNEDS who had visited Shengli Oilfield Central Hospital on September 15, 2019 was selected as the study subject. Clinical data of the child was collected, and trio-whole exome sequencing (trio-WES), Sanger sequencing, chromosomal karyotyping analysis, and copy number variation sequencing (CNV-seq) were used to analyze the child and his parents. RESULTS: The child, a 3-year-old boy, had manifested developmental delay, nephrotic syndrome, and epilepsy. Trio-WES and Sanger sequencing showed that he has carried a heterozygous c.1375C＞T (p.Q459*) variant of the TRIM8 gene, for which both his parents were of the wild type. Based on guidelines from the American College of Medical Genetics and Genomics (ACMG), the variant was predicted to be pathogenic. No abnormality was found in the chromosomal karyotyping and CNV-seq results of the child and his parents. CONCLUSION: The child was diagnosed with FSGSNEDS, for which the c.1375C＞T variant of the TRIM8 gene may be accountable.

Thermodynamics-Kinetics-Balanced Metal-Organic Framework for In-Depth Radon Removal under Ambient Conditions.

Radon (Rn), a ubiquitous radioactive noble gas, is the main source of natural radiation to human and one of the major culprits for lung cancer. Reducing ambient Rn concentration by porous materials is considered as the most feasible and energy-saving option to lower this risk, but the in-depth Rn removal under ambient conditions remains an unresolved challenge, mainly due to the weak van der Waals (vdW) interaction between inert Rn and adsorbents and the extremely low partial pressure (<1.8 × 10-14 bar, <106 Bq/m3) of Rn in air. Adsorbents having either favorable adsorption thermodynamics or feasible diffusion kinetics perform poorly in in-depth Rn removal. Herein, we report the discovery of a metal-organic framework (ZIF-7-Im) for efficient Rn capture guided by computational screening and modeling. The size-matched pores in ZIF-7-Im abide by the thermodynamically favorable principle and the exquisitely engineered quasi-open apertures allow for feasible kinetics with little sacrifice of sorption thermodynamics. The as-prepared material can reduce the Rn concentration from hazardous levels to that below the detection limit of the Rn detector under ambient conditions, with an improvement of at least two orders of amplitude on the removal depth compared to the currently best-performing and only commercialized material activated charcoal.

Bone Repairment via Mechanosensation of Piezo1 Using Wearable Pulsed Triboelectric Nanogenerator.

Bone repair in real time is a challenging medical issue for elderly patients; this is mainly because aged bone marrow mesenchymal stem cells (BMSCs) possess limited osteogenesis potential and repair capacity. In this study, triboelectric stimulation technology is used to achieve bone repair via mechanosensation of Piezo1 by fabricating a wearable pulsed triboelectric nanogenerator (WP-TENG) driven by human body movement. A peak value of 30 µA has the optimal effects to rejuvenate aged BMSCs, enhance their osteogenic differentiation, and promote human umbilical vein endothelial cell tube formation. Further, previous studies demonstrate that triboelectric stimulation of a WP-TENG can reinforce osteogenesis of BMSCs and promote the angiogenesis of human umbilical vein endothelial cells (HUVECs). Mechanistically, aged BMSCs are rejuvenated by triboelectric stimulation via the mechanosensitive ion channel Piezo1. Thus, the osteogenesis potential of BMSCs is enhanced and the tube formation capacity of HUVECs is improved, which is further confirmed by augmented bone repair and regeneration in in vivo investigations. This study provides a potential signal transduction mechanism for rejuvenating aged BMSCs and a theoretical basis for bone regeneration using triboelectric stimulation generated by a WP-TENG.

Next Generation Sequencing Detects Premeiotic Errors in Human Oocytes.

Autosomal aneuploidy is the leading cause of embryonic and foetal death in humans. This arises mainly from errors in meiosis I or II of oogenesis. A largely ignored source of error stems from germinal mosaicism, which leads to premeiotic aneuploidy. Molecular cytogenetic studies employing metaphase fluorescence in situ hybridization and comparative genomic hybridisation suggest that premeiotic aneuploidy may affect 10-20% of oocytes overall. Such studies have been criticised on technical grounds. We report here an independent study carried out on unmanipulated oocytes that have been analysed using next generation sequencing (NGS). This study confirms that the incidence of premeiotic aneuploidy in an unselected series of oocytes exceeds 10%. A total of 140 oocytes donated by 42 women gave conclusive results; of these, 124 (88.5%) were euploid. Sixteen out of 140 (11.4%) provided evidence of premeiotic aneuploidy. Of the 140, 112 oocytes were immature (germinal vesicle or metaphase I), of which 10 were aneuploid (8.93%); the remaining 28 were intact metaphase II - first polar body complexes, and six of these were aneuploid (21.4%). Of the 16 aneuploid cells, half contained simple errors (one or two abnormal chromosomes) and half contained complex errors. We conclude that germinal mosaicism leading to premeiotic aneuploidy is a consistent finding affecting at least 10% of unselected oocytes from women undergoing egg collection for a variety of reasons. The importance of premeiotic aneuploidy lies in the fact that, for individual oocytes, it greatly increases the risk of an aneuploid mature oocyte irrespective of maternal age. As such, this may account for some cases of aneuploid conceptions in very young women.

Efficient degradation of naproxen by persulfate activated with zero-valent iron: performance, kinetic and degradation pathways.

Degradation of naproxen (NAP) by persulfate (PS) activated with zero-valent iron (ZVI) was investigated in our study. The NAP in aqueous solution was degraded effectively by the ZVI/PS system and the degradation exhibited a pseudo-first-order kinetics pattern. Both sulfate radical (SO4 •-) and hydroxyl radical (HO•) participate in the NAP degradation. The second-order rate constants for NAP reacting with SO4 •- and HO• were (5.64 ± 0.73) × 109 M- 1 s- 1 and (9.05 ± 0.51) × 109 M- 1 s- 1, respectively. Influence of key parameters (initial pH, PS dosage, ZVI dosage, and NAP dosage) on NAP degradation were evaluated systematically. Based on the detected intermediates, the pathways of NAP degradation in ZVI/PS system was proposed. It was found that the presence of ammonia accelerated the corrosion of ZVI and thus promoted the release of Fe2+, which induced the increased generation of sulfate radicals from PS and promoted the degradation of NAP. Compared to its counterpart without ammonia, the degradation rates of NAP by ZVI/PS were increased to 3.6-17.5 folds and 1.2-2.2 folds under pH 7 and pH 9, respectively.

Removal of toxic metals using ferrate(VI): a review.

Heavy metal contamination of water resources is a critical issue which adversely affects humans. Ferrate(VI) (FeVIO4 2-, Fe(VI)), as a new type of green multifunctional water treatment agent, has shown promising potential for environmental decontamination. A complete understanding of the interactions between ferrate(VI) and toxic metals can be conducive to the further development of ferrate(VI) technology for application to wastewater treatment. This review first introduces the purification of ferrate(VI) technology for toxic metals including free heavy metals and metal complexes briefly. The effective parameters are then analyzed and discussed in detail. Subsequently, the reactivity and mechanisms of ferrate(VI) with toxic metals are emphatically described. Finally, possible research challenges and directions for ferrate(VI) technology applied to wastewater treatment in the future are summarized.

Noble-metal-free tungsten oxide/carbon (WOx/C) hybrid manowires for highly efficient hydrogen evolution.

Developing active, stable, and low-cost electrocatalysts to generate hydrogen is a great challenge in the fields of chemistry and energy. Nonprecious metal catalysts comprised of inexpensive and earth-abundant transition metals are regarded as a promising substitute for noble metal catalysts used in hydrogen evolution reaction (HER), but are still practically unfeasible mainly due to unsatisfactory activity and durability. Here we report a facile two-step preparation method for WOx nanowires with high concentration of oxygen vacancies (OVs) via calcination of W-polydopamine compound precursors. The resulting hybrid material possesses a uniform and ultralong 1D nanowires structure and a rough and raised surface, which can effectively improve the specific surface area. The products exhibit excellent performance for H2 generation: the required overpotentials for 1 and 10 mA cm-2 are 18 and 108 mV, the Tafel slope is 46 mV/decade, and the electrochemically active surface area is estimated to be ∼77.0 m2 g-1. After 1000 cycles, the catalyst works well without significant current density drop. Our experimental results verified metallic transition metal oxides as superior non-Pt electrocatalysts for practical hydrogen evolution reactions.

Loading the FeNiOOH cocatalyst on Pt-modified hematite nanostructures for efficient solar water oxidation.

A FeNiOOH-decorated hematite photoanode has been prepared using a facile electrodeposition method, with a significant cathodic shift of the onset potential (up to 190 mV) compared to the pristine sample. Synchrotron radiation based techniques have been used to identify the composition of the catalyst indicating the presence of FeOOH and NiOOH (FeNiOOH). The enhanced performance can be attributed to the better oxidation evolution reaction kinetics with the FeNiOOH cocatalyst. The FeNiOOH-decorated hematite is very stable for a long time. Moreover, the cocatalyst can be well coupled to the Pt-modified hematite photoanode achieving a high photocurrent of 2.21 mA cm(-2) at 1.23 V vs. RHE. The good catalytic properties and the facile preparation method suggest that the decoration of FeNiOOH is a favorable strategy to improve the performance of hematite.

The origin of luminescence from di[4-(4-diphenylaminophenyl)phenyl]sulfone (DAPSF), a blue light emitter: an X-ray excited optical luminescence (XEOL) and X-ray absorption near edge structure (XANES) study.

The electronic structure and optical properties of di[4-(4-diphenylaminophenyl)phenyl]sulfone (denoted as DAPSF), a highly efficient fluorophor, have been investigated using X-ray excited optical luminescence (XEOL) and X-ray absorption near edge structure (XANES) spectroscopy at excitation energies across the C, N, O K-edges and the sulfur K-edge. The results indicate that the blue luminescence is mainly related to the sulfur functional group.

Cux Co1-x O Nanoparticles on Graphene Oxide as A Synergistic Catalyst for High-Efficiency Hydrolysis of Ammonia-Borane.

Ammonia-borane (AB) is an excellent material for chemical storage of hydrogen. However, the practical utilization of AB for production of hydrogen is hindered by the need of expensive noble metal-based catalysts. Here, we report Cux Co1-x O nanoparticles (NPs) facilely deposited on graphene oxide (GO) as a low-cost and high-performance catalyst for the hydrolysis of AB. This hybrid catalyst exhibits an initial total turnover frequency (TOF) value of 70.0 (H2 ) mol/(Cat-metal) mol⋅min, which is the highest TOF ever reported for noble metal-free catalysts, and a good stability keeping 94 % activity after 5 cycles. Synchrotron radiation-based X-ray absorption spectroscopy (XAS) investigations suggested that the high catalytic performance could be attributed to the interfacial interaction between Cux Co1-x O NPs and GO. Moreover, the catalytic hydrolysis mechanism was studied by in situ XAS experiments for the first time, which reveal a significant water adsorption on the catalyst and clearly confirm the interaction between AB and the catalyst during hydrolysis.

Nanoparticle Superlattices as Efficient Bifunctional Electrocatalysts for Water Splitting.

The solar-driven water splitting process is highly attractive for alternative energy utilization, while developing efficient, earth-abundant, bifunctional catalysts for both oxygen evolution reaction and hydrogen evolution reaction has remained as a major challenge. Herein, we develop an ordered CoMnO@CN superlattice structure as an efficient bifunctional water-splitting electrocatalyst, in which uniform Co-Mn oxide (CoMnO) nanoparticles are coated with a thin, continuous nitrogen-doped carbon (CN) framework. The CoMnO nanoparticles enable optimized OER activity with effective electronic structure configuration, and the CN framework serves as an excellent HER catalyst. Importantly, the ordered superlattice structure is beneficial for enhanced reactive sites, efficient charge transfer, and structural stability. This bifunctional superlattice catalyst manifests optimized current densities and electrochemical stability in overall water splitting, outperforming most of the previously reported single- or bifunctional electrocatalysts. Combining with a silicon photovoltaic cell, this CoMnO@CN superlattice bifunctional catalyst enables unassisted solar water splitting continuously for ∼5 days with a solar-to-hydrogen conversion efficiency of ∼8.0%. Our discovery suggests that these transition metal oxide-based superlattices may serve as a unique structure modality for efficient bifunctional water splitting electrocatalysts with scale-up potentials.

Operando spectroscopic analysis of an amorphous cobalt sulfide hydrogen evolution electrocatalyst.

The generation of chemical fuel in the form of molecular H2 via the electrolysis of water is regarded to be a promising approach to convert incident solar power into an energy storage medium. Highly efficient and cost-effective catalysts are required to make such an approach practical on a large scale. Recently, a number of amorphous hydrogen evolution reaction (HER) catalysts have emerged that show promise in terms of scalability and reactivity, yet remain poorly understood. In this work, we utilize Raman spectroscopy and X-ray absorption spectroscopy (XAS) as a tool to elucidate the structure and function of an amorphous cobalt sulfide (CoSx) catalyst. Ex situ measurements reveal that the as-deposited CoSx catalyst is composed of small clusters in which the cobalt is surrounded by both sulfur and oxygen. Operando experiments, performed while the CoSx is catalyzing the HER, yield a molecular model in which cobalt is in an octahedral CoS2-like state where the cobalt center is predominantly surrounded by a first shell of sulfur atoms, which, in turn, are preferentially exposed to electrolyte relative to bulk CoS2. We surmise that these CoS2-like clusters form under cathodic polarization and expose a high density of catalytically active sulfur sites for the HER.

Facile synthesis of Cr-decorated hexagonal Co3O4 nanosheets for ultrasensitive ethanol detection.

Cr-decorated hexagonal Co3O4 nanosheets were synthesized by a facile hydrothermal method on a SiO2/Si substrate, followed by a simple physical deposition of Cr film and a thermal annealing treatment. The Co3O4 nanosheets possess a porous and polycrystalline structure consisting of Co3O4 nanoparticles; Cr2O3 nanoparticles are uniformly formed on the surface of the Co3O4 nanosheets after the annealing treatment. The ethanol-sensing properties of the Cr-decorated hexagonal Co3O4 nanosheets were investigated in detail, and compared to pure hexagonal Co3O4 nanosheets, they show unique sensing properties toward ethanol, including high response (5.4) even when the ethanol concentration is as low as 10 ppm, ultrafast response (1 s) and recovery (7 s) rates, and good selectivity at a 300 °C operating temperature. These properties make the Cr-decorated hexagonal Co3O4 nanosheets good candidates for ethanol detection.