Wide Temperature All-Solid-State Ti3 C2 Tx Quantum Dots/L-Ti3 C2 Tx Fiber Supercapacitor with High Capacitance and Excellent Flexibility.

Ti3 C2 Tx Quantum dots (QDs)/L-Ti3 C2 Tx fiber electrode (Q3 M7 ) with high capacitance and excellent flexibility is prepared by a wet spinning method. The assembled units Ti3 C2 Tx nanosheets (NSs) with large size (denoted as L-Ti3 C2 Tx ) is obtained by natural sedimentation screen raw Ti3 AlC2 , etching, and mechanical delamination. The pillar agent Ti3 C2 Tx QDs is fabricated by an ultrasound method. Q3 M7 fiber electrode gave a specific capacitance of 1560 F cm-3 , with a capacity retention rate of 79% at 20 A cm-3 , and excellent mechanical strength of 130 Mpa. A wide temperature all-solid-state the delaminated montmorillonite (F-MMT)/Polyvinyl alcohol (PVA) dimethyl sulfoxide (DMSO) flexible hydrogel (DHGE) (F-MMT/PVA DHGE) Q3 M7 fiber supercapacitor is assembled by using Q3 M7 fiber as electrodes and F-MMT/PVA DHGE as electrolyte and separator. It showed a volume specific capacitance of 413 F cm-3 at 0.5 A cm-3 , a capacity retention of 97% after 10 000 cycles, an energy density of 36.7 mWh cm-3 at a power density of 311 mW cm-3 , and impressive capacitance and flexibility over a wide temperature range of -40 to 60 °C. This work provides an effective strategy for designing and assembling wide temperature all-solid-state fiber supercapacitors with optimal balance of capacitive performance and flexibility.

Hyperbranched Polymer Dots with Strong Absorption and High Fluorescence Quantum Yield for In Vivo NIR-II Imaging.

In order to improve the fluorescence quantum yield (QY) of NIR-II-emitting nanoparticles, D-A-D fluorophores are typically linked to intramolecular rotatable units to reduce aggregation-induced quenching. However, incorporating such units often leads to a twisted molecular backbone, which affects the coupling within the D-A-D unit and, as a result, lowers the absorption. Here, we overcome this limitation by cross-linking the NIR-II fluorophores to form a 2D polymer network, which simultaneously achieves a high QY by well-controlled fluorophore separation and strong absorption by restricting intramolecular distortion. Using the strategy, we developed polymer dots with the highest NIR-II single-particle brightness among reported D-A-D-based nanoparticles and applied them for imaging of hindlimb vasculatures and tumors as well as fluorescence-guided tumor resection. The high brightness of the polymer dots offered exceptional image quality and excellent surgical results, showing a promising performance for these applications.

A traditional gynecological medicine inhibits ovarian cancer progression and eliminates cancer stem cells via the LRPPRC-OXPHOS axis.

BACKGROUND: Ovarian cancer (OC) is the most lethal malignant gynecological tumor type for which limited therapeutic targets and drugs are available. Enhanced mitochondrial oxidative phosphorylation (OXPHOS), which enables cell growth, migration, and cancer stem cell maintenance, is a critical driver of disease progression and a potential intervention target of OC. However, the current OXPHOS intervention strategy mainly suppresses the activity of the electron transport chain directly and cannot effectively distinguish normal tissues from cancer tissues, resulting in serious side effects and limited efficacy. METHODS: We screened natural product libraries to investigate potential anti-OC drugs that target OXPHOS. Additionally, LC-MS, qRT-PCR, western-blot, clonogenic assay, Immunohistochemistry, wound scratch assay, and xenograft model was applied to evaluate the anti-tumor mechanism of small molecules obtained by screening in OC. RESULTS: Gossypol acetic acid (GAA), a widely used gynecological medicine, was screened out from the drug library with the function of suppressing OXPHOS and OC progression by targeting the leucine-rich pentatricopeptide repeat containing (LRPPRC) protein. Mechanically, LRPPRC promotes the synthesis of OXPHOS subunits by binding to RNAs encoded by mitochondrial DNA. GAA binds to LRPPRC directly and induces LRPPRC rapid degradation in a ubiquitin-independent manner. LRPPRC was overexpressed in OC, which is highly correlated with the poor outcomes of OC and could promote the malignant phenotype of OC cells in vitro and in vivo. GAA management inhibits cell growth, clonal formation, and cancer stem cell maintenance in vitro, and suppresses subcutaneous graft tumor growth in vivo. CONCLUSIONS: Our study identified a therapeutic target and provided a corresponding inhibitor for OXPHOS-based OC therapy. GAA inhibits OC progression by suppressing OXPHOS complex synthesis via targeting LRPPRC protein, supporting its potential utility as a natural therapeutic agent for ovarian cancer.

The RNA-binding protein LRPPRC promotes resistance to CDK4/6 inhibition in lung cancer.

Kinase inhibitors against Cyclin Dependent Kinase 4 and 6 (CDK4/6i) are promising cancer therapeutic drugs. However, their effects are limited by primary or acquired resistance in virtually all tumor types. Here, we demonstrate that Leucine Rich Pentatricopeptide Repeat Containing (LRPPRC) controls CDK4/6i response in lung cancer by forming a feedback loop with CDK6. LRPPRC binds to CDK6-mRNA, increasing the stability and expression of CDK6. CDK6 and its downstream E2F Transcription Factor 1 (E2F1), bind to the LRPPRC promoter and elevate LRPPRC transcription. The activation of the LRPPRC-CDK6 loop facilitates cell cycle G1/S transition, oxidative phosphorylation, and cancer stem cell generation. Gossypol acetate (GAA), a gynecological medicine that has been repurposed as a degrader of LRPPRC, enhances the CDK4/6i sensitivity in vitro and in vivo. Our study reveals a mechanism responsible for CDK4/6i resistance and provides an enlightening approach to investigating the combinations of CDK4/6 and LRPPRC inhibitors in cancer therapy.

Unveiling the Effect of Organic Sulfur Sources on Synthesized MoS2 Phases and Electrocatalytic Hydrogen Evolution Performances.

Metallic-phase MoS2 exhibits Pt-comparable electrocatalytic hydrogen evolution reaction (HER) performance in acidic conditions. However, the controllable synthesis of metallic-phase MoS2 is quite challenging because the key factor determining the phase types of MoS2 during synthesis is still unclear. Herein, the effect of organic sulfur sources on the formed MoS2 phase is studied by use of thioacetamide (TAA), l-cysteine, and thiourea as sulfur sources. The TAA and l-cysteine produce metallic MoS2, while thiourea gives rise to semiconducting MoS2. Owing to the metallic phase and smaller size, the MoS2 prepared with TAA and l-cysteine has a higher electrocatalytic HER activity than the MoS2 obtained from thiourea. The HER overpotential of MoS2 synthesized with TAA is only 210 mV for reaching the current density of 10 mA/cm2, and the corresponding Tafel slope is 44 mV/decade. Further studies find that the decomposition temperature of sulfur precursors is the key factor for the formation of metallic MoS2. Sulfur precursors with a lower decomposition temperature release sulfur ions quickly, which in turn stabilize the metallic phase and inhibit the growth of MoS2 into large sizes. Our findings unveil the key factor for controlling the phase type of MoS2 synthesized from organic sulfur precursors and will be very helpful for the synthesis of MoS2 with high electrocatalytic activity.

Mitochondrial Protease Targeting Chimeras for Mitochondrial Matrix Protein Degradation.

Targeted protein degradation (TPD) is an emerging technique for protein regulation. Currently, all TPD developed in eukaryotic cells relies on either ubiquitin-proteasome or lysosomal systems, thus are powerless against target proteins in membrane organelles lacking proteasomes and lysosomes, such as mitochondria. Here, we developed a mitochondrial protease targeting chimera (MtPTAC) to address this issue. MtPTAC is a bifunctional small molecule that can bind to mitochondrial caseinolytic protease P (ClpP) at one end and target protein at the other. Mechanistically, MtPTAC activates the hydrolase activity of ClpP while simultaneously bringing target proteins into proximity with ClpP. Taking mitochondrial RNA polymerase (POLRMT) as a model protein, we have demonstrated the powerful proteolytic ability and antitumor application prospects of MtPTAC, both in vivo and in vitro. This is the first modularly designed TPD that can specifically hydrolyze target proteins inside mitochondria.

Size-Controlled Boron-Based Bifunctional Photocathodes for High-Efficiency Photo-Assisted Li-O2 Batteries.

Photo-assisted Li-O2 batteries are introduced as a promising strategy for reducing severe overpotential by directly employing photocathodes. Herein, a series of size-controlled single-element boron photocatalysts are prepared by the meticulous liquid phase thinning methods by combining probe and water bath sonication, and their bifunctional photocathodes in the photo-assisted Li-O2 batteries are systematically investigated. The boron-based Li-O2 batteries have shown incremental round-trip efficiencies as the sized reduction of boron under illumination. It is noteworthy that the completely amorphous boron nanosheets (B4 ) photocathode not only delivers an optimizing round-trip efficiency of 190% on the basis of the ultra-high discharge voltage (3.55 V) and ultra-low charge voltage (1.87 V) but also gives a high rate performance and ultralong durability with a round-trip efficiency of 133% after 100 cycles (200 h) compared with the other-sized boron photocathodes. This remarkable photoelectric performance of the B4 sample can be attracted to the synergistic effect on the suitable semiconductor property, high conductivity, and strengthened catalytic ability of boron nanosheets coated with ultrathin amorphous boron-oxides overlayer. This research can open a new avenue to facilitate the rapid development of high-efficiency photo-assisted Li-O2 batteries.

All-solid-state Ti3C2Tx neutral symmetric fiber supercapacitors with high energy density and wide temperature range.

All-solid-state Ti3C2Tx neutral symmetric fiber supercapacitors (PVA EGHG Ti3C2Tx FSCs) with high energy density and wide temperature range are constructed by using polyvinyl alcohol (PVA)-ethylene glycol hydrogel (EGHG)-sodium perchlorate (NaClO4) as electrolyte and separator, and Ti3C2Tx fiber as electrodes. Ti3C2Tx fiber is prepared using 130 mg mL-1 Ti3C2Tx nanosheet ink as an assembly unit in a coagulation bath of isopropyl alcohol (IPA) and distilled water with 5 wt% CaCl2 by a wet spinning method. The prepared Ti3C2Tx fiber exhibits a specific capacity of 385 F cm-3 and a capacitance retention of 94 % after 10,000 cycles in 1 M NaClO4 electrolyte. The assembled PVA EGHG Ti3C2Tx FSCs deliver a specific capacitance of 41 F cm-3, a volumetric energy density of 5 mWh cm-3, and a capacitance retention of 92 % after 500 times continuous bending. Furthermore, it shows good flexibility and excellent capacitance over a wide temperature range of -40 to 40 °C and maintains its electrochemical performance under varying degrees of bending. This study provides a viable strategy for designing and assembling all-solid-state neutral symmetric fiber supercapacitors with high energy density and wide temperature range.

RuCu Nanosheets with Ultrahigh Nanozyme Activity for Chemodynamic Therapy.

Nanoenzymes have been widely explored for chemodynamic therapy (CDT) in cancer treatment. However, poor catalytic efficiency of nanoenzymes, especially in the tumor microenvironment with insufficient H2 O2 and mild acidity, limits the effect of CDT. Herein, a new ultrathin RuCu nanosheet (NS) based nanoenzyme which has a large specific surface area and abundant channels and defects is developed. The RuCu NSs show superb catalytic efficiency for the oxidation of peroxidase substrate H2 O2 at a wide range of pH and their catalytic efficiency (kcat /Km = 177.2 m-1  s-1 ) is about 14.9 times higher than that of the single-atom catalyst FeN3 P. Besides being an efficient nanozyme as peroxidase, the RuCu NSs possess other two enzyme activities, not only disproportionating superoxide anion to produce H2 O2 but also consuming glutathione to keep a high concentration of H2 O2 in the tumor microenvironment for Fenton reaction. With these advantages, the RuCu NSs exhibit good performance to kill cancer cells and inhibit tumor growth in mice, demonstrating a promising potential as new CDT reagent.

Proteomic analysis reveals CAAP1 negatively correlates with platinum resistance in ovarian cancer.

The present study sought to investigate the correlation between CAAP1 and platinum resistance in ovarian cancer and to preliminarily explore the potential biological function of CAAP1. Proteomic analysis was used to analyze differentially expressed proteins in platinum-sensitive and -resistant tissue samples of ovarian cancer. The Kaplan-Meier plotter was used for prognostic analysis. Immunohistochemistry assay and chi-square test were employed to explore the relationship between CAAP1 and platinum resistance in tissue samples. Lentivirus transfection, immunoprecipitation-mass spectrometry, and bioinformatics analysis were used to determine the potential biological function of CAAP1. Based on results, the expression level of CAAP1 was significantly higher in platinum-sensitive tissues compared to that in resistant tissues. Chi-square test demonstrated that there is a negative correlation between high expression of CAAP1 and platinum resistance. Overexpression of CAAP1 increased cis­platinum sensitivity of the A2780/DDP cell line likely via the mRNA splicing pathway by interacting with the splicing factor AKAP17A. In summary, there is a negative correlation between high expression of CAAP1 and platinum resistance. CAAP1 might be a potential biomarker for platinum resistance in ovarian cancer. SIGNIFICANCE: Platinum resistance is a key factor affecting the survival of ovarian cancer patients. Understanding the mechanisms of platinum resistance is highly important for ovarian cancer management. Here, we performed the DIA- and DDA-based proteomics to analyze differentially expressed proteins in tissue and cell samples of ovarian cancer. We found that the protein identified as CAAP1, which was first reported to be involved in the regulation of apoptosis, may be negatively correlates with platinum resistance in ovarian cancer. In addition, we also found that CAAP1 enhanced the sensitivity of platinum-resistant cells to cis­platinum via the mRNA splicing pathway by interacting with the splicing factor AKAP17A. Our data would be useful to reveal novel molecular mechanisms of platinum resistance in ovarian cancer.

Atomically Dispersed Fe-N4 Sites and NiFe-LDH Sub-Nanoclusters as an Excellent Air Cathode for Rechargeable Zinc-Air Batteries.

The sluggish four-electron processes of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) limit the development of rechargeable Zn-air batteries (RZABs). Highly efficient ORR/OER bifunctional electrocatalysts are therefore highly desired for the commercialization of RZABs in large scale. Herein, the Fe-N4-C (ORR active sites) and NiFe-LDH clusters (OER active sites) are successfully integrated within a NiFe-LDH/Fe,N-CB electrocatalyst. The NiFe-LDH/Fe,N-CB electrocatalyst is first prepared by the introduction of Fe-N4 into carbon black (CB), followed by the growth of NiFe-LDH clusters. The cluster nature of NiFe-LDH effectively avoids the blocking of Fe-N4-C ORR active centers and affords excellent OER activity. The NiFe-LDH/Fe,N-CB electrocatalyst thus exhibits an excellent bifunctional ORR and OER performance, with a potential gap of only 0.71 V. The NiFe-LDH/Fe,N-CB-based RZAB exhibits an open-circuit voltage of 1.565 V and a specific capacity of 731 mAh gZn-1, which is much better than the RZAB composed of Pt/C and IrO2. Particularly, the NiFe-LDH/Fe,N-CB-based RZAB displays excellent long-term charging/discharging cyclic stability and rechargeability. Even at a large charging/discharging current density (20 mA cm-2), the charging/discharging voltage gap is only ∼1.33 V and exhibits an increase smaller than 5% after 140 cycles. This work provides a new low-cost bifunctional ORR/OER electrocatalyst with high activity and superior long-term stability and will be helpful to the commercialization of RZAB in large scale.

Integrative proteomic characterization of adenocarcinoma of esophagogastric junction.

The incidence of adenocarcinoma of the esophagogastric junction (AEG) has been rapidly increasing in recent decades, but its molecular alterations and subtypes are still obscure. Here, we conduct proteomics and phosphoproteomics profiling of 103 AEG tumors with paired normal adjacent tissues (NATs), whole exome sequencing of 94 tumor-NAT pairs, and RNA sequencing in 83 tumor-NAT pairs. Our analysis reveals an extensively altered proteome and 252 potential druggable proteins in AEG tumors. We identify three proteomic subtypes with significant clinical and molecular differences. The S-II subtype signature protein, FBXO44, is demonstrated to promote tumor progression and metastasis in vitro and in vivo. Our comparative analyses reveal distinct genomic features in AEG subtypes. We find a specific decrease of fibroblasts in the S-III subtype. Further phosphoproteomic comparisons reveal different kinase-phosphosubstrate regulatory networks among AEG subtypes. Our proteogenomics dataset provides valuable resources for understanding molecular mechanisms and developing precision treatment strategies of AEG.

Single-crystalline Mg-substituted Na4Mn3(PO4)2P2O7 nanoparticles as a high capacity and superior cycling cathode for sodium-ion batteries.

Mn-based mixed phosphate Na4Mn3(PO4)2(P2O7) (NMPP) is a promising cathode for high-potential, low-cost and eco-friendly sodium-ion batteries. However, this material still faces some bottleneck issues in terms of low conductivity, disturbance of impure crystalline phase, micron-sized agglomerated particles and the Mn3+ Jahn-Teller effect. Herein, a Mg-substituted NMPP (NM2.7Mg0.3PP)@C composite was constructed via modified solution combustion and subsequent calcination treatment. The obtained NM2.7Mg0.3PP presents a highly pure phase and single-crystalline characteristics. It is noteworthy that the sample shows a smaller particle size of 100-300 nm due to the Mg2+ incorporation, and the prepared NM2.7Mg0.3PP@C cathode exhibits considerable discharge capacity (119 mA h g-1), an improved rate capability and excellent long cycling stability of 1000 cycles. A series of measurements indicated that the Mg-substitution enhanced the electronic conductivity and ion diffusion rate, and effectively relieved the lattice distortion influenced by the multiphase transition from the Mn Jahn-Teller effect of the NM2.7Mg0.3PP@C cathode. In addition, NM2.7Mg0.3PP adopts an optimal 3Mg0.1-Mn1-Mn2-Mn3 crystal structure based on density functional theory (DFT) calculations and refined X-ray diffractometry results. These findings provide new insight into the design of highly stabilized and high-conductivity polyanionic cathodes for sodium-ion batteries.

Thiol oxidative stress-dependent degradation of transglutaminase2 via protein S-glutathionylation sensitizes 5-fluorouracil therapy in 5-fluorouracil-resistant colorectal cancer cells.

5-Fluorouracil (5-Fu) is a first-line drug for colorectal cancer (CRC) therapy. However, the development of 5-Fu resistance limits its chemotherapeutic effectiveness and often leads to poor prognoses of CRC. Transglutaminase 2 (TGM2), a member of the transglutaminase family, is considered to be associated with chemoresistance through apoptotic prevention in various cancers including CRC. TGM2 was found to be overexpressed in two 5-Fu-resistant CRC cell lines and down-regulated by increased thiol oxidative stress induced by inhibition of glutathione reductase (GR). The present study aimed to explore the role of TGM2 in 5-Fu-resistant CRC and the mechanism of action by which the elevated thiol oxidative stress down-regulates TGM2 protein level. The results revealed that 5-Fu-resistance induced by overexpression of TGM2 in CRC cells was reversed through up-regulation of thiol oxidative stress. Knockdown of TGM2 increased the chemosensitivity of CRC cells to 5-Fu. Thiol oxidative stress potentially enhanced the therapeutic effect of 5-Fu in the resistant CRC cells by promotion of 5-Fu-induced apoptosis through down-regulation of TGM2. The elevated thiol oxidative stress increased the S-glutathionylation of TGM2 and led to proteasomal degradation of TGM2. Furthermore, Cys193 was identified as the S-glutathionylation site in TGM2, and its mutation resulted in thiol oxidative stress-mediated CRC cell apoptotic resistance. TGM2-induced EMT was also suppressed by the elevated thiol oxidative stress. A xenograft tumor model confirmed the effect of thiol oxidative stress in the reversal of 5-Fu resistance in CRC cells in vivo. TGM2 protein expression level was found to be significantly higher in human CRC specimens than in non-cancerous colorectal tissues. Taken together, the present data suggest an important role of TGM2 in 5-Fu resistance in CRC cells. Up-regulation of thiol oxidative stress could be a potential therapeutic approach for treating 5-Fu-resistant CRC and TGM2 may serve as a potential therapeutic target of thiol oxidative stress.

PDZ-binding kinase aggravates pancreatic neuroendocrine neoplasm progression by activating the AKT/mTOR pathway.

The therapeutic effects of existing drug regimens against pancreatic neuroendocrine neoplasms (pNENs) remain limited, and identifying ideal therapeutic targets is warranted. PDZ binding kinase (PBK) may play an oncogenic role in most solid tumors. However, its function in pNEN remains unclear. In this study, pNEN samples and International Cancer Genome Consortium data were used to determine the clinical significance of PBK. Cell counting and CCK8 assays were used to assess cell proliferation. Flow cytometry was used to assess drug-induced apoptosis and cell cycle arrest. An in vivo PBK-targeting experiment was performed in mice bearing pNENs. Western blotting, quantitative PCR, and immunohistochemistry were performed to assess the molecular mechanisms. PBK was significantly upregulated in pNEN tissues compared with paracancerous tissues. Additionally, PBK was a poor prognostic factor for pNEN patients. PBK was found to promote the proliferation of pNEN cells by activating the AKT/mTOR pathway. Furthermore, PBK inhibition combined with everolimus treatment had enhanced antitumour effects on pNEN via inhibiting AKT/mTOR pathway and inducing G0/G1 phase cell cycle arrest. This study highlights that PBK plays an oncogenic role in and is a promising therapeutic target for pNEN.

Bifunctional Photoassisted Li-O2 Battery with Ultrahigh Rate-Cycling Performance Based on Siloxene Size Regulation.

Directly integrating the bifunctional photoelectrode into Li-O2 batteries has been considered an effective way to reduce the overpotential and promote electric energy saving. However, more regular investigations on various bifunctional photocatalysts have still been desired for high-performance photoassisted Li-O2 batteries. Herein, a systematic exploration of various-sized siloxene photocatalysts affected by Li-O2 batteries has been introduced. Compared with the utilization of larger-sized siloxene nanosheets (SNSs), the photoassisted Li-O2 battery with a siloxene quantum dot (SQD) photoelectrode delivers a superior round-trip efficiency of 230% based on the highest discharge potential up to 3.72 V and lowest charge potential of 1.60 V and enables the maintenance of a long-term cycling life with only 13% efficiency attenuation after 200 cycles at 0.075 mA/cm2. Furthermore, this system exhibits a record-high rate-cycling performance (162% round-trip efficiency, even at 3 mA/cm2) and a high discharge capacity of 2212 mAh/g at 1 mA/cm2. These ground-breaking performances could be attributed to the synergistic effect of the photocatalytic and electrocatalytic activities of SQD photocatalysts with the ideal conduction band/valence band values, the abundant defective sites, and the stronger O2 and lower LiO2 adsorption strengths of SQD photocatalysts. These systematic research studies highlight the significance of SQD bifunctional photocatalysts and could be extended to other photocatalysts for further high-efficiency photoelectric conversion and storage.

Chemo-Phototherapy with Carfilzomib-Encapsulated TiN Nanoshells Suppressing Tumor Growth and Lymphatic Metastasis.

The design of nanomedicine for cancer therapy, especially the treatment of tumor metastasis has received great attention. Proteasome inhibition is accepted as a new strategy for cancer therapy. Despite being a big breakthrough in multiple myeloma therapy, carfilzomib (CFZ), a second-in-class proteasome inhibitor is still unsatisfactory for solid tumor and metastasis therapy. In this study, hollow titanium nitride (TiN) nanoshells are synthesized as a drug carrier of CFZ. The TiN nanoshells have a high loading capacity of CFZ, and their intrinsic inhibitory effect on autophagy synergistically enhances the activity of CFZ. Due to an excellent photothermal conversion efficiency in the second near-infrared (NIR-II) region, TiN nanoshell-based photothermal therapy further induces a synergistic anticancer effect. In vivo study demonstrates that TiN nanoshells readily drain into the lymph nodes, which are responsible for tumor lymphatic metastasis. The CFZ-loaded TiN nanoshell-based chemo-photothermal therapy combined with surgery offers a remarkable therapeutic outcome in greatly inhibiting further metastatic spread of cancer cells. These findings suggest that TiN nanoshells act as an efficient carrier of CFZ for realizing enhanced outcomes for proteasome inhibitor-based cancer therapy, and this work also presents a "combined chemo-phototherapy assisted surgery" strategy, promising for future cancer treatment.

Few-layer Mg-deficient borophene nanosheets: I2 oxidation and ultrasonic delamination from MgB2.

By using I2 as an oxidant and CH3CN as a reaction medium, few-layer Mg-deficient borophene nanosheets (FBN) with a stoichiometric ratio of Mg0.22B2 are prepared by oxidizing MgB2 in a mixture of CH3CN and HCl for 14 days under nitrogen protection and followed by ultrasonic delaminating in CH3CN for 2 h. The prepared FBN possess a two-dimensional flake morphology, and they show a clear interference fringe with a d-spacing of 0.251 nm corresponding to the (208) plane of rhombohedral boron. While maintaining the hexagonal boron networks of MgB2, the FBN have an average thickness of about 4.14 nm (four monolayer borophene) and a lateral dimension of 500 nm, and the maximum Mg deintercalation rate can reach 78%. The acidity of the reaction system plays an important role; the HCl reaction system not only facilitates the oxidation of MgB2 by I2, but also increases the deintercalation ratio of Mg atoms. Etching of the Mg atom layer with HCl, the negative charge decrease of the boron layer by I2 oxidation, and the Mg chelating effect from CH3COOH due to the hydrolysis of CH3CN in an HCl environment led to a high deintercalation rate of the Mg atom. Density functional theory (DFT) calculations further support the result that the maximum deintercalation rate of Mg atoms is about 78% while maintaining the hexagonal layer structure of boron. This research solves the problems of low Mg atom deintercalation rate and hexagonal boron structure destruction when using the precursor MgB2 to produce borophene nanosheets, which is of great significance for large-scale novel preparation and application of borophene nanosheets.

A Schottky-Barrier-Free Plasmonic Semiconductor Photocatalyst for Nitrogen Fixation in a "One-Stone-Two-Birds" Manner.

Plasmonic photocatalysis has received much attention owing to attractive plasmonic enhancement effects in improving the solar-to-chemical conversion efficiency. However, the photocatalytic efficiencies have remained low mainly due to the short carrier lifetime caused by the rapid recombination of plasmon-generated hot charge carriers. Although plasmonic metal-semiconductor heterostructures can improve the separation of hot charge carriers, a large portion of the hot charge carriers are lost when they cross the Schottky barrier. Herein, a Schottky-barrier-free plasmonic semiconductor photocatalyst, MoO3- x , which allows for efficient N2 photofixation in a "one-stone-two-birds" manner, is demonstrated. The oxygen vacancies in MoO3- x serve as the "stone." They "kill two birds" by functioning as the active sites for the chemisorption of N2 molecules and inducing localized surface plasmon resonance for the generation of hot charge carriers. Benefiting from this unique strategy, plasmonic MoO3- x exhibits a remarkable photoreactivity for NH3 production up to the wavelength of 1064 nm with apparent quantum efficiencies over 1%, and a solar-to-ammonia conversion efficiency of 0.057% without any hole scavenger. This work shows the great potential of plasmonic semiconductors to be directly used for photocatalysis. The concept of the Schottky-barrier-free design will pave a new path for the rational design of efficient photocatalysts.

Efficient oxygen reduction electrocatalyst derived from facile Fe,N-surface treatment of carbon black.

The development of nonprecious metal-based electrocatalysts for oxygen reduction reaction (ORR) is a central task in renewable electrochemical energy conversion and storage technologies. Iron-nitrogen doped carbon-based (Fe-N/C) materials are promising alternatives to Pt-based ORR electrocatalysts. Owing to large specific surface area and outstanding electrical conductivity, carbon black is an inborn support for electrocatalysts. Unfortunately, the direct incorporation of Fe-Nx moieties onto the surface of carbon black has not been realized to date. Herein, Fe-Nx moieties are directly incorporated onto the surface of carbon black through surface modification and the following Fe and N co-doping. The obtained Fe and N co-doped carbon back (Fe-N/CB) catalyst has very large specific surface area and abundant accessible Fe-Nx moieties. As a result, Fe-N/CB electrocatalyst exhibits a more positive half-wave potential (0.86 V) than Pt/C. The Fe-N/CB catalyst also displays better stability and methanol resistance than Pt/C. The Zn-air battery with Fe-N/CB as cathodic catalyst shows a maximum power density of 68 mW cm-2 and a specific capacity of 676 mAh gZn-1. Our finding provides a convenient and low-cost approach to fabricating efficient M-N/C-based catalysts and will be helpful to the development of renewable electrochemical energy conversion and storage technologies.