Ultrasonication-Induced Strong Metal-Support Interaction Construction in Water Towards Enhanced Catalysis.

The development of facile methodologies to afford robust supported metal nanocatalysts under mild conditions is highly desirable yet challenging, particularly via strong metal-support interactions (SMSI) construction. State-of-the-art approaches capable of generating SMSI encapsulation mainly focus on high temperature annealing in reductive/oxidative atmosphere. Herein, ultra-stable metal nanocatalysts based on SMSI construction were produced by leveraging the instantaneous high-energy input from ultrasonication under ambient conditions in H2 O, which could rapidly afford abundant active intermediates, Ti3+ ions, and oxygen vacancies within the scaffolds to induce the SMSI overlayer formation. The encapsulation degree could be tuned and controlled via the reducibility of the solvents and the ultrasonication parameters. This facile and efficient approach could be further extended to diverse metal oxide supports and noble metal NPs leading to enhanced performance in hydrogenation reactions and CO2 conversion.

Photoinduced Strong Metal-Support Interaction for Enhanced Catalysis.

Strong metal-support interaction (SMSI) construction is a pivotal strategy to afford thermally robust nanocatalysts in industrial catalysis, but thermally induced reactions (>300 °C) in specific gaseous atmospheres are generally required in traditional procedures. In this work, a photochemistry-driven methodology was demonstrated for SMSI construction under ambient conditions. Encapsulation of Pd nanoparticles with a TiOx overlayer, the presence of Ti3+ species, and suppression of CO adsorption were achieved upon UV irradiation. The key lies in the generation of separated photoinduced reductive electrons (e-) and oxidative holes (h+), which subsequently trigger the formation of Ti3+ species/oxygen vacancies (Ov) and then interfacial Pd-Ov-Ti3+ sites, affording a Pd/TiO2 SMSI with enhanced catalytic hydrogenation efficiency. The as-constructed SMSI layer was reversible, and the photodriven procedure could be extended to Pd/ZnO and Pt/TiO2.

Cobalt Single Atoms Embedded in Nitrogen-Doped Graphene for Selective Oxidation of Benzyl Alcohol by Activated Peroxymonosulfate.

The development of novel single atom catalyst (SAC) is highly desirable in organic synthesis to achieve the maximized atomic efficiency. Here, a Co-based SAC on nitrogen-doped graphene (SACo@NG) with high Co content of 4.1 wt% is reported. Various characterization results suggest that the monodispersed Co atoms are coordinated with N atoms to form robust and highly effective catalytic centers to activate peroxymonosulfate (PMS) for organic selective oxidation. The catalytic performance of the SACo@NG/PMS system is conducted on the selective oxidation of benzyl alcohol (BzOH) showing high efficiency with over 90% conversion and benzaldehyde selectivity within 180 min under mild conditions. Both radical and non-radical processes occurred in the selective oxidation of BzOH, but the non-radical oxidation plays the dominant role which is accomplished by the adsorption of BzOH/PMS on the surface of SACo@NG and the subsequent electron transfer through the carbon matrix. This work provides new insights to the preparation of efficient transition metal-based single atom catalysts and their potential applications in PMS mediated selective oxidation of alcohols.

Theoretical Calculation Guided Design of Single-Atom Catalysts toward Fast Kinetic and Long-Life Li-S Batteries.

Lithium-sulfur (Li-S) batteries are promising next-generation energy storage technologies due to their high theoretical energy density, environmental friendliness, and low cost. However, low conductivity of sulfur species, dissolution of polysulfides, poor conversion from sulfur reduction, and lithium sulfide (Li2S) oxidation reactions during discharge-charge processes hinder their practical applications. Herein, under the guidance of density functional theory calculations, we have successfully synthesized large-scale single atom vanadium catalysts seeded on graphene to achieve high sulfur content (80 wt % sulfur), fast kinetic (a capacity of 645 mAh g-1 at 3 C rate), and long-life Li-S batteries. Both forward (sulfur reduction) and reverse reactions (Li2S oxidation) are significantly improved by the single atom catalysts. This finding is confirmed by experimental results and consistent with theoretical calculations. The ability of single metal atoms to effectively trap the dissolved lithium polysulfides (LiPSs) and catalytically convert the LiPSs/Li2S during cycling significantly improved sulfur utilization, rate capability, and cycling life. Our work demonstrates an efficient design pathway for single atom catalysts and provides solutions for the development of high energy/power density Li-S batteries.

Direct Cation Exchange in Monolayer MoS_{2} via Recombination-Enhanced Migration.

In addition to their unique optical and electronic properties, two-dimensional materials provide opportunities to directly observe atomic-scale defect dynamics. Here we use scanning transmission electron microscopy to observe substitutional Re impurities in monolayer MoS_{2} undergo direct exchanges with neighboring Mo atoms in the lattice. Density-functional-theory calculations find that the energy barrier for direct exchange, a process that has only been studied as a diffusion mechanism in bulk materials, is too large for either thermal activation or energy directly transferred from the electron beam. The presence of multiple sulfur vacancies next to the exchanged Re-Mo pair, as observed by electron microscopy, does not lower the energy barrier sufficiently to account for the observed atomic exchange. Instead, the calculations find that a Re dopant and surrounding sulfur vacancies introduce an ever-changing set of deep levels in the energy gap. We propose that these levels mediate an "explosive" recombination-enhanced migration via multiple electron-hole recombination events. As a proof of concept, we also show that Re-Mo direct exchange can be triggered via controlled creation of sulfur vacancies. The present experimental and theoretical findings lay a fundamental framework towards manipulating single substitutional dopants in two-dimensional materials.

Evolution of Oxyhalide Crystals under Electron Beam Irradiation: An in Situ Method To Understand the Origin of Structural Instability.

The oxyhalides have attracted growing interest because of their excellent photocatalytic performance. However, their structural instability hampers further development toward practical applications, a major challenge of current concerns. It is appealing to figure out the origin of structural instability and guide the design of advanced oxyhalide crystals for efficient photocatalysis. In this study, the decomposition of BiOCl crystals, a typical oxyhalide, is triggered by electron beam irradiation and investigated in situ by transmission electron microscopy. The results indicate that the instability originates from the unique layered structure of BiOCl crystals; the interlayer van der Waals bonds are easily broken under electron beam irradiation via the assistance of hydroxyl groups. This facilitates the formation of O/Cl-deficient BiO1- xCl1- y species, Bi metal nanoparticles, and nanobubbles (gaseous substance) that are confined between the adjacent layers. Surface reconstruction would be an effective way to stabilize the oxyhalide crystals.

Controlling Reaction Selectivity through the Surface Termination of Perovskite Catalysts.

Although perovskites have been widely used in catalysis, tuning of their surface termination to control reaction selectivity has not been well established. In this study, we employed multiple surface-sensitive techniques to characterize the surface termination (one aspect of surface reconstruction) of SrTiO3 (STO) after thermal pretreatment (Sr enrichment) and chemical etching (Ti enrichment). We show, by using the conversion of 2-propanol as a probe reaction, that the surface termination of STO can be controlled to greatly tune catalytic acid/base properties and consequently the reaction selectivity over a wide range, which is not possible with single-metal oxides, either SrO or TiO2 . Density functional theory (DFT) calculations explain well the selectivity tuning and reaction mechanism on STO with different surface termination. Similar catalytic tunability was also observed on BaZrO3 , thus highlighting the generality of the findings of this study.

Substitutional-interstitial structural transition in Cu-Pt nano-alloys.

Copper-platinum alloys are important binary alloys in catalysis. In this communication, we demonstrate that it is possible to preserve the thermal properties of platinum with a copper-platinum alloy by converting the substitutional alloy into an interstitial one. This conversion occurs when the size of the copper-platinum system is reduced down to the nanoscale. The size-dependent phase diagram of Cu-Pt for a spherical nanoparticle is calculated at various sizes (50, 10 and 5 nm) demonstrating that Cu-Pt alloyed nanoparticles can be formed all over the composition range. Experimentally, the electron microscopy characterization of copper-platinum alloyed nanoparticles synthesized by wet chemistry supports the predicted structural transition.

circRNA_141539 can serve as an oncogenic factor in esophageal squamous cell carcinoma by sponging miR-4469 and activating CDK3 gene.

The abnormal expression and regulation of circular RNA (circRNA) is involved in the occurrence and development of a variety of tumors. The current study aimed to determine the role of circRNA_141539 in esophageal squamous cell carcinoma (ESCC). CircRNA_141539 expression in ESCC was detected via circRNA chip analysis and verified via reverse transcription-quantitative PCR. Associations between circRNA_141539, patient clinicopathological characteristics and prognosis were also statistically analyzed. Additionally, the effects of circRNA_141539 on ESCC cell proliferation and invasion were assessed. A dual-luciferase assay was performed to analyze the interaction between circRNAs, microRNAs (miRs) and mRNAs. The results revealed that circRNA_141539 was significantly up-regulated in patients with ESCC. Furthermore, high circRNA_141539 expressions were significantly associated with TNM stage, differentiation and poor prognosis, revealing high diagnostic value (P<0.05). Furthermore, circRNA_141539 overexpression promoted cell proliferation and invasion, while circRNA_141539 silencing inhibited cell proliferation and invasion (P<0.05). The dual-luciferase reporter assay identified that circRNA_141539 directly binds to miR-4469 and also revealed that cyclin-dependent kinase-3 (CDK3) was negatively regulated by miR-4469. The results indicated that circRNA_141539 served as an oncogenic factor in ESCC by sponging miR-4469 and activating CDK3 expression. circRNA_141539 may present as a novel diagnostic and prognostic biomarker and a therapeutic target for patients with ESCC.

Iridium metallene oxide for acidic oxygen evolution catalysis.

Exploring new materials is essential in the field of material science. Especially, searching for optimal materials with utmost atomic utilization, ideal activities and desirable stability for catalytic applications requires smart design of materials' structures. Herein, we report iridium metallene oxide: 1 T phase-iridium dioxide (IrO2) by a synthetic strategy combining mechanochemistry and thermal treatment in a strong alkaline medium. This material demonstrates high activity for oxygen evolution reaction with a low overpotential of 197 millivolt in acidic electrolyte at 10 milliamperes per geometric square centimeter (mA cmgeo-2). Together, it achieves high turnover frequencies of 4.2 sUPD-1 (3.0 sBET-1) at 1.50 V vs. reversible hydrogen electrode. Furthermore, 1T-IrO2 also shows little degradation after 126 hours chronopotentiometry measurement under the high current density of 250 mA cmgeo-2 in proton exchange membrane device. Theoretical calculations reveal that the active site of Ir in 1T-IrO2 provides an optimal free energy uphill in *OH formation, leading to the enhanced performance. The discovery of this 1T-metallene oxide material will provide new opportunities for catalysis and other applications.

Facile benzene reduction promoted by a synergistically coupled Cu-Co-Ce ternary mixed oxide.

Hydrogenation of aromatic rings promoted by earth-abundant metal composites under mild conditions is an attractive and challenging subject in the long term. In this work, a simple active site creation and stabilization strategy was employed to obtain a Cu+-containing ternary mixed oxide catalyst. Simply by pre-treatment of the ternary metal oxide precursor under a H2 atmosphere, a Cu+-derived heterogeneous catalyst was obtained and denoted as Cu1Co5Ce5O x . The catalyst showed (1) high Cu+ species content, (2) a uniform distribution of Cu+ doped into the lattices of CoO x and CeO2, (3) formation of CoO x /CuO x and CeO2/CuO x interfaces, and (4) a mesoporous structure. These unique properties of Cu1Co5Ce5O x endow it with pretty high hydrogenation activity for aromatic rings under mild conditions (100 °C with 5 bar H2), which is much higher than that of the corresponding binary counterparts and even exceeds the performance of commercial noble metal catalysts (e.g. Pd/C). The synergetic effect plays a crucial role in the catalytic procedure with CeO2 functioning as a hydrogen dissociation and transfer medium, Cu+ hydrogenating the benzene ring and CoO x stabilizing the unstable Cu+ species. This will unlock a new opportunity to design highly efficient earth-abundant metal-derived heterogeneous catalysts via interface interactions.

Sinter-Resistant Nanoparticle Catalysts Achieved by 2D Boron Nitride-Based Strong Metal-Support Interactions: A New Twist on an Old Story.

Strong metal-support interaction (SMSI) is recognized as a pivotal strategy in hetereogeneous catalysis to prevent the sintering of metal nanoparticles (NPs), but issues including restriction of supports to reducible metal oxides, nonporous architecture, sintering by thermal treatment at >800 °C, and unstable nature limit their practical application. Herein, the construction of non-oxide-derived SMSI nanocatalysts based on highly crystalline and nanoporous hexagonal boron nitride (h-BN) 2D materials was demonstrated via in situ encapsulation and reduction using NaBH4, NaNH2, and noble metal salts as precursors. The as-prepared nanocatalysts exhibited robust thermal stability and sintering resistance to withstand thermal treatment at up to 950 °C, rendering them with high catalytic efficiency and durability in CO oxidation even in the presence of H2O and hydrocarbon simulated to realistic exhaust systems. More importantly, our generic strategy offers a novel and efficient avenue to design ultrastable hetereogeneous catalysts with diverse metal and support compositions and architectures.

[Erratum] circRNA_001275 upregulates Wnt7a expression by competitively sponging miR­370­3p to promote cisplatin resistance in esophageal cancer.

Following the publication of the above article, the authors have realized that certain intended corrections were not carried over to the published version of the article. First, the description of the results of Figs. 5 and 6 did not match the figures; Edu and Transwell invasion assays were intended to have been excluded from the manuscript during the proofreading stage, although these data were presented in the description of the results for Figs. 5 and 6. Consequently, the text for the "circRNA_001275 promotes cell proliferation" subsection of the Results section towards the end of p. 153 should have read as follows: "MTT assay was used to detect the effects of circRNA_001275 on cell proliferation. The results showed that cell viability was significantly increased in the circRNA_001275 OE group, and significantly decreased in the si circRNA_001275 group (both P<0.05, Fig. 5A and B), compared with the corresponding control groups." Furthermore, the text in the subsequent subsection ("circRNA_001275 inhibits cell apoptosis") should have read as follows: "Hoechst 33258 staining was used to detect the effects of circRNA_001275 on apoptosis. The apoptosis rate was significantly decreased in the circRNA_001275 OE group, and significantly increased in the si circRNA_001275 group (both P<0.05; Fig. 6), compared with the corresponding control group. Secondly, Fig. 5B was omitted from Fig. 5 in the published article; and thirdly, a higher­resolution version of Fig. 6 was submitted during the revision stages, although the version of this figure that was deemed to have been too low in quality was the one that appeared in the final proofs. The corrected / updated versions of Figs. 5 and 6 are shown opposite. The Editor of International Journal of Oncology regrets that certain of these errors were introduced into the article during the production stages, and apologizes both to the authors and to the readership. [the original article was published in International Journal of Oncology 57: 151­160, 2020; DOI: 10.3892/ijo.2020.5050].

circRNA_001275 upregulates Wnt7a expression by competitively sponging miR­370­3p to promote cisplatin resistance in esophageal cancer.

Circular RNAs (circRNAs) are aberrantly expressed in various tumors and are associated with tumorigenesis. The present study aimed to determine the role of circRNA_001275 in cisplatin­resistant esophageal cancer. Three pairs of cisplatin­resistant tissues and corresponding adjacent tissues were collected and subjected to circRNA chip analysis. Additionally, the effect of circRNA_001275 on cisplatin­resistant cells was investigated. The relationship between circRNA_001275, microRNAs (miRs) and target genes were analyzed using luciferase assays, and validated via reverse transcription­quantitative PCR (RT­qPCR) and western blotting. The results showed that circRNA_001275 was significantly upregulated in cisplatin­resistant esophageal cancer tissues and cells (P<0.05). Overexpression of circRNA_001275 promoted the proliferation and invasion, and decreased the apoptosis of cisplatin­resistant cells. On the other hand, circRNA_001275 silencing inhibited cell proliferation and invasion, and promoted cell apoptosis (P<0.05). Dual­luciferase reporter assays revealed that circRNA_001275 directly binds to miR­370­3p, and that Wnt family member 7A (Wnt7a) is targeted by miR­370­3p. RT­qPCR and western blotting further demonstrated that circRNA_001275 serves as an miR­370­3p sponge to upregulate Wnt7a expression. In conclusion, the present study revealed that circRNA_001275 was upregulated in cisplatin­resistant esophageal cancer and promoted cisplatin resistance by sponging miR­370­3p to upregulate Wnt7a expression. Therefore, circRNA_001275 may serve as a potential diagnostic biomarker and therapeutic target for patients with cisplatin­resistant esophageal cancer.

Harnessing strong metal-support interactions via a reverse route.

Engineering strong metal-support interactions (SMSI) is an effective strategy for tuning structures and performances of supported metal catalysts but induces poor exposure of active sites. Here, we demonstrate a strong metal-support interaction via a reverse route (SMSIR) by starting from the final morphology of SMSI (fully-encapsulated core-shell structure) to obtain the intermediate state with desirable exposure of metal sites. Using core-shell nanoparticles (NPs) as a building block, the Pd-FeOx NPs are transformed into a porous yolk-shell structure along with the formation of SMSIR upon treatment under a reductive atmosphere. The final structure, denoted as Pd-Fe3O4-H, exhibits excellent catalytic performance in semi-hydrogenation of acetylene with 100% conversion and 85.1% selectivity to ethylene at 80 °C. Detailed electron microscopic and spectroscopic experiments coupled with computational modeling demonstrate that the compelling performance stems from the SMSIR, favoring the formation of surface hydrogen on Pd instead of hydride.

High-performance electrolytic oxygen evolution with a seamless armor core-shell FeCoNi oxynitride.

Highly active, low-cost, and durable electrocatalysts for the water oxidation reaction are pivotal in energy conversion and storage schemes. Here we report a nitride-core, oxide-shell-armor structured FeCoNi oxynitride as an efficient oxygen evolution electrocatalyst with a homogeneous nitride (Fe0.70Co0.56Ni0.92N1.0O0.06) core and an oxide (Fe0.48Co0.1Ni0.21N0.05O1.0) shell. The catalyst demonstrated excellent activity for the oxygen evolution reaction with a current density of 10 mA cm-2 at a low overpotential of 0.291 V in alkaline media (1 M KOH), which is superior to the activities of commercial IrO2, RuO2, and Pt/C catalysts and comparable to those of state-of-the-art catalysts (e.g., NiFe-LDH, NiCo2O4, O-NiCoFe-LDH). Density functional theory simulations suggested that the incorporation of multiple metal elements can indeed improve the reaction energetics with a synergistic effect from the core-shell structure. This unique structure of a nitride-core with a oxide-shell presents a new form of multimetallic oxynitride with compelling performance in electrolytic oxygen evolution.

Iron Single Atoms on Graphene as Nonprecious Metal Catalysts for High-Temperature Polymer Electrolyte Membrane Fuel Cells.

Iron single atom catalysts (Fe SACs) are the best-known nonprecious metal (NPM) catalysts for the oxygen reduction reaction (ORR) of polymer electrolyte membrane fuel cells (PEMFCs), but their practical application has been constrained by the low Fe SACs loading (<2 wt%). Here, a one-pot pyrolysis method is reported for the synthesis of iron single atoms on graphene (FeSA-G) with a high Fe SAC loading of ≈7.7 ± 1.3 wt%. The as-synthesized FeSA-G shows an onset potential of 0.950 V and a half-wave potential of 0.804 V in acid electrolyte for the ORR, similar to that of Pt/C catalysts but with a much higher stability and higher phosphate anion tolerance. High temperature SiO2 nanoparticle-doped phosphoric acid/polybenzimidazole (PA/PBI/SiO2) composite membrane cells utilizing a FeSA-G cathode with Fe SAC loading of 0.3 mg cm-2 delivers a peak power density of 325 mW cm-2 at 230 °C, better than 313 mW cm-2 obtained on the cell with a Pt/C cathode at a Pt loading of 1 mg cm-2. The cell with FeSA-G cathode exhibits superior stability at 230 °C, as compared to that with Pt/C cathode. Our results provide a new approach to developing practical NPM catalysts to replace Pt-based catalysts for fuel cells.

Promoting Pt catalysis for CO oxidation via the Mott-Schottky effect.

CO oxidation is an important reaction both experimentally and industrially, and its performance is usually dominated by the charge states of catalysts. For example, CO oxidation on the platinum (Pt) surface requires a properly charged state for the balance of adsorption and activation of CO and O2. Here, we present "Mott-Schottky modulated catalysis" on Pt nanoparticles (NPs) via an electron-donating carbon nitride (CN) support with a tunable Fermi level. We demonstrate that properly-charged Pt presents an excellent catalytic CO oxidation activity with an initial conversion temperature as low as 25 °C and total CO conversion below 85 °C. The tunable electronic structure of Pt NPs, which is regulated by the Fermi level of CN, is a key factor in dominating the catalytic performance. This "Mott-Schottky modulated catalysis" concept may be extended to maneuver the charge state on other metal catalysts for targeted catalytic reactions.

Defect-Tailoring Mediated Electron-Hole Separation in Single-Unit-Cell Bi3 O4 Br Nanosheets for Boosting Photocatalytic Hydrogen Evolution and Nitrogen Fixation.

Solar photocatalysis is a potential solution to satisfying energy demand and its resulting environmental impact. However, the low electron-hole separation efficiency in semiconductors has slowed the development of this technology. The effect of defects on electron-hole separation is not always clear. A model atomically thin structure of single-unit-cell Bi3 O4 Br nanosheets with surface defects is proposed to boost photocatalytic efficiency by simultaneously promoting bulk- and surface-charge separation. Defect-rich single-unit-cell Bi3 O4 Br displays 4.9 and 30.9 times enhanced photocatalytic hydrogen evolution and nitrogen fixation activity, respectively, than bulk Bi3 O4 Br. After the preparation of single-unit-cell structure, the bismuth defects are controlled to tune the oxygen defects. Benefiting from the unique single-unit-cell architecture and defects, the local atomic arrangement and electronic structure are tuned so as to greatly increase the charge separation efficiency and subsequently boost photocatalytic activity. This strategy provides an accessible pathway for next-generation photocatalysts.

Isolated single atom cobalt in Bi3O4Br atomic layers to trigger efficient CO2 photoreduction.

The design of efficient and stable photocatalysts for robust CO2 reduction without sacrifice reagent or extra photosensitizer is still challenging. Herein, a single-atom catalyst of isolated single atom cobalt incorporated into Bi3O4Br atomic layers is successfully prepared. The cobalt single atoms in the Bi3O4Br favors the charge transition, carrier separation, CO2 adsorption and activation. It can lower the CO2 activation energy barrier through stabilizing the COOH* intermediates and tune the rate-limiting step from the formation of adsorbed intermediate COOH* to be CO* desorption. Taking advantage of cobalt single atoms and two-dimensional ultrathin Bi3O4Br atomic layers, the optimized catalyst can perform light-driven CO2 reduction with a selective CO formation rate of 107.1 µmol g-1 h-1, roughly 4 and 32 times higher than that of atomic layer Bi3O4Br and bulk Bi3O4Br, respectively.