Electronic-Structure Transformation of Platinum-Rich Nanowires as Efficient Electrocatalyst for Overall Water Splitting.

Platinum (Pt) has been widely used as cathodic electrocatalysts for the hydrogen evolution reaction (HER) but unfortunately neglected as an anodic electrocatalyst for the oxygen evolution reaction (OER) due to excessively strong bonding with oxygen species in water splitting electrolyzers. Herein we report that fine control over the electronic-structure and local-coordination environment of Pt-rich PtPbCu nanowires (NWs) by doping of iridium (Ir) lowers the overpotential of the OER and simultaneously suppresses the overoxidation of Pt in IrPtPbCu NWs during water electrolysis. In light of the one-dimensional morphology featured with atomically dispersed IrOx species and electronically modulated Pt-sites, the IrPtPbCu NWs exhibit an enhanced OER (175 mV at 10 mA cm-2) and HER (25 mV at 10 mA cm-2) electrocatalytic performance in acidic media and yield a high turnover frequency. For OER at the overpotential of 250 mV, the IrPtPbCu NWs show an enhanced mass activity of 1.51 A mg-1Pt+Ir (about 19 times higher) than Ir/C. For HER at the overpotential of 50 mV, NWs exhibit a remarkable mass activity of 1.35 A mg-1Pt+Ir, which is 2.6-fold relative to Pt/C. Experimental results and theoretical calculations corroborate that the doping of Ir in NWs has the capacity to suppress the formation of Ptx>4 derivates and ameliorate the adsorption free energy of reaction intermediates during the water electrolysis. This approach enabled the realization of a previously unobserved mechanism for anodic electrocatalysts.

High-entropy selenides derived from Prussian blue analogues as electrode materials for sodium-ion batteries.

Transition metal selenides (TMS) have received much attention as anode materials for sodium-ion batteries (SIBs) because of their high theoretical capacity and excellent redox reversibility. However, their further development is constrained by the dissolution of transition metal ions and substantial volume changes experienced during cycling. Herein, the high-entropy Prussian blue analogues were selenized by the vapor infiltration method, resulting in the formation of a core-shell structured high-entropy selenides (HESe-6). The core-shell structure with voids and abundant selenium vacancies on the surface effectively mitigates bulk expansion and enhances electronic conductivity. Furthermore, the high-entropy property endows an ultra-stable crystal structure and inhibits the dissolution of metal ions. The ex-situ EIS and in-situ XRD results show that HESe-6 is able to be reversibly transformed into highly conductive ultrafine metal particles upon Na+ embedding, providing more Na+ reactive active sites. In addition, despite the incorporation of up to seven different elements, it exhibits minimal phase transitions during discharge/charge cycles, effectively mitigating stress accumulation. HESe-6 could retain an ultralong-term stability of 765.83 mAh g-1 after 1000 loops even at 1 A g-1. Furthermore, when coupled with the Na3V2(PO4)2O2F cathode, it maintains a satisfactory charge energy density of 303 Wh kg-1 after 300 cycles, which shows promising application prospect in the future.

Solvent-Free Ultrafast Construction of Se-Deficient Heterojunctions of Bimetallic Selenides toward Flexible Sodium-Ion Full Batteries.

Flexible quasi-solid-state sodium ion batteries featuring their low-cost, high safety and excellent mechanical strength have attracted widespread interest in the field of wearable electronic devices. However, the development of such batteries faces great challenges including the construction of interfacial compatible flexible electrode materials and addressing the high safety demands of electrolyte. Here selenium-vacancies regulated bimetallic selenide heterojunctions anchored on waste cotton cloth-derived flexible carbon cloth (FCC) with robust interfacial C-Se-Co/Fe chemical bonds as a flexible anode material (CCFSF) is proposed by ultrafast microwave pyrolysis method. Rich selenium vacancies and CoSe2 /FeSe2-x heterostructures are synchronously formed that can significantly improve ionic and electronic diffusion kinetics. Additionally, a uniform carbon layer coating on the surface of Se-deficient heterostructures endows it with outstanding structural stability. The flexible cathode (PB@FCC) is also fabricated by directly growing Prussian blue nanoparticles on the FCC. Furthermore, an advanced flexible quasi-solid-state Na-ion pouch cell is assembled by coupling CCFSF anode, PB@FCC cathode with P(VDF-HFP)-based gel polymer electrolyte. The full cell not only demonstrates excellent energy storage performance but also robust mechanical flexibility and safety. The present work offers an effective avenue to achieve high safety flexible energy storage device, promoting the development of flexible wearable electronic devices.

Skin-Inspired Hair-Epidermis-Dermis Hierarchical Structures for Electronic Skin Sensors with High Sensitivity over a Wide Linear Range.

The quest for both high sensitivity and a wide linear range in electronic skin design is perpetual; unfortunately, these two key parameters are generally mutually exclusive. Although limited success in attaining both high sensitivity and a wide linear range has been achieved via material-specific or complicated structure design, addressing the conflict between these parameters remains a critical challenge. Here, inspired by the human somatosensory system, we propose hair-epidermis-dermis hierarchical structures based on a reduced graphene oxide/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) aerogel to reconcile this contradiction between high sensitivity and a wide linear range. This hierarchical structure enables an electronic skin (e-skin) sensor linear sensing range up to 30 kPa without sacrificing the high sensitivity (137.7 kPa-1), revealing an effective strategy to overcome the above-mentioned conflict. In addition, the e-skin sensor also exhibits a low detection limit (1.1 Pa), fast responsiveness (∼80 ms), and excellent stability and reproducibility (over 10 000 cycles); as a result, the e-skin platform is capable of detecting small air flow and monitoring human pulse and even sound-induced vibrations. This structure may boost the ongoing research on the structural design and performance regulation of emerging flexible electronics.

Construction of Bimetallic Selenides Encapsulated in Nitrogen/Sulfur Co-Doped Hollow Carbon Nanospheres for High-Performance Sodium/Potassium-Ion Half/Full Batteries.

Metallic selenides have been widely investigated as promising electrode materials for metal-ion batteries based on their relatively high theoretical capacity. However, rapid capacity decay and structural collapse resulting from the larger-sized Na+ /K+ greatly hamper their application. Herein, a bimetallic selenide (MoSe2 /CoSe2 ) encapsulated in nitrogen, sulfur-codoped hollow carbon nanospheres interconnected reduced graphene oxide nanosheets (rGO@MCSe) are successfully designed as advanced anode materials for Na/K-ion batteries. As expected, the significant pseudocapacitive charge storage behavior substantially contributes to superior rate capability. Specifically, it achieves a high reversible specific capacity of 311 mAh g-1 at 10 A g-1 in NIBs and 310 mAh g-1 at 5 A g-1 in KIBs. A combination of ex situ X-ray diffraction, Raman spectroscopy, and transmission electron microscopy tests reveals the phase transition of rGO@MCSe in NIBs/KIBs. Unexpectedly, they show quite different Na+ /K+ insertion/extraction reaction mechanisms for both cells, maybe due to more sluggish K+ diffusion kinetics than that of Na+ . More significantly, it shows excellent energy storage properties in Na/K-ion full cells when coupled with Na3 V2 (PO4 )2 O2 F and PTCDA@450 °C cathodes. This work offers an advanced electrode construction guidance for the development of high-performance energy storage devices.

Rational Construction of 2D Fe3 O4 @Carbon Core-Shell Nanosheets as Advanced Anode Materials for High-Performance Lithium-Ion Half/Full Cells.

Transition metal oxides have vastly limited practical application as electrode materials for lithium-ion batteries (LIBs) due to their rapid capacity decay. Here, a versatile strategy to mitigate the volume expansion and low conductivity of Fe3 O4 by coating a thin carbon layer on the surface of Fe3 O4 nanosheets (NSs) was employed. Owing to the 2D core-shell structure, the Fe3 O4 @C NSs exhibit significantly improved rate performance and cycle capability compared with bare Fe3 O4 NSs. After 200 cycles, the discharge capacity at 0.5 A g-1 was 963 mA h g-1 (93 % retained). Moreover, the reaction mechanism of lithium storage was studied in detail by ex situ XRD and HRTEM. When coupled with a commercial LiFePO4 cathode, the resulting full cell retains a capacity of 133 mA h g-1 after 100 cycles at 0.1 A g-1 , which demonstrates its superior energy storage performance. This work provides guidance for constructing 2D metal oxide/carbon composites with high performance and low cost for the field of energy storage.

Epigenome-wide DNA methylation assay reveals placental epigenetic markers for noninvasive fetal single-nucleotide polymorphism genotyping in maternal plasma.

BACKGROUND: The use of DNA methylation difference between maternal blood cell and fetal (placental) DNA is one of the main areas of interest for the development of fetal epigenetics markers in maternal plasma. STUDY DESIGN AND METHODS: We employed a methylation array (HumanMethylation450 array, Illumina, Inc.) to identify novel biomarkers that are specially hypermethylated in placental DNA versus maternal blood cells in a genome-wide basis. Validation by bisulfite genomic sequencing was performed and the priority was given to potential targets that harbor differential methylated CpG sites overlapped with at least two methylation-sensitive restriction enzyme (MSRE) recognizing sites, as well as one polymorphic single-nucleotide polymorphism (SNP), within a short DNA stretch. Three candidate regions of PSMB8, SKI, and CHST11 gene were selected for developing a preliminary polymerase chain reaction assay with MSRE digestion of maternal plasma DNA. SNP genotypes were confirmed by direct sequencing. RESULTS: We identified 2944 and 5218 fetal-specific hypermethylated CpG sites in the first- and third-trimester placenta, respectively, of which 2613 were overlapped, suggesting a consistency of differential methylation during the whole pregnancy. The array results were confirmed by bisulfite genomic sequencing. The preliminary tests in maternal plasma showed that postdigestion hypermathylated versions of these candidate molecules were detectable only in pregnant women. We further revealed that methylated targets in maternal plasma possessed the fetal SNP genotypes. CONCLUSION: The present studies systematically identified hypermethylated sites in fetal tissues and preliminarily demonstrated that some of the fetal epigenetic markers that contain informative SNPs have great potential for noninvasive fetal genetic diagnosis.

[Age estimation using content of sjTREC in human peripheral blood].

OBJECTIVE: To determine and verify the correlation formula of age estimation using the content of signal joint T-cell receptor excision DNA circle (sjTREC) in human peripheral blood and to discuss its application value in forensic biological practice. METHODS: The samples of peripheral blood stains were collected from 30 healthy unrelated individuals whose ages were known. The DNAs were extracted from the samples stored at room temperature after 4 weeks. The content of sjTREC was measured by real-time fluorescent quantitative PCR technique, and the TATA box binding protein (TBP) was selected as reference genes. The age of each sample was predicted with the formula which was Age = -7.181 5 Y-42.458 +/- 9.42 (Y = dCtTBP-sjTREC), and the result was compared with the real age of each individual to determine the accuracy of the formula. RESULTS: sjTREC and TBP gene were detectable in all 30 samples of peripheral blood. The contents of sjTREC in human peripheral blood showed a decreasing tendency with aging. The accuracy rate for the age estimation by this method was 76.67%. CONCLUSION: The method for the age estimation with the content of sjTREC was simple, fast, sensitive, and good species specific with important potential application prospect.