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Examinations of acoustic logging tools in the workshop are significant for checking the performance of every unit before field downhole measurements. It is more convenient to test the tools in a horizontally placed open trough rather than in a vertical closed pipe. To ensure the tools can excite and receive the signals from the trough well (i.e. the pipe waves), we should figure out the wave propagation in such an asymmetric structure. We aim for acoustic logging while drilling (LWD) signals from the fluid-filled trough. Both monopole and quadrupole wave fields are studied through the 3D finite difference model. For monopole acoustic logging, first-arrival full waves are the major concern. The propagation velocities of first-arriving pipe waves do not change with opening angles of the trough. The pipe wave speeds are exactly the same as those in closed pipes of the same sizes; while the amplitudes decrease with increasing opening angles. For quadrupole LWD, velocities of pipe waves have few correlations with opening angles and transducer azimuths. The quadrupole source can even excite the monopole collar waves in the trough, which become the first arrivals of the full waves. The quadrupole pipe waves show a trend of being weaker with increasing opening angles. If the opening angle of the trough is too large, the quadrupole pipe waves could totally be covered by other wavelets. To excite clearer pipe wave signals in the trough, it is suggested that an opening angle as small as possible is optimal for the tests.

Zeolitic imidazole frameworks (ZIF) and ultrathin layered double hydroxide nanosheets (LDHNS) have drawn growing attention in the electrocatalysis field. Combining the merits and maximizing the electrocatalytic activity of each building block in the corresponding composite is imperative but challenging. This work thus proposes a simple strategy for the in situ growth of ZIF-67 on ultrathin CoAl-LDHNS (LDHNS@ZIF-67) without an additional Co2+ source. Thanks to the ultrathin nature, CoAl-LDHNS provide more Co reactive sites for the ordered growth of ZIF-67 nanocrystals on this 2D matrix via coordination interactions between Co2+ and 2-methylimidazole. The obtained LDHNS@ZIF-67 provides more convenient pathways to rapid electron transportation between the basal electrode and analytes. Hence, the modified electrode can be applied for the truly simultaneous detection of naphthol isomers by differential pulse voltammetry. α-naphthol and β-naphthol exhibit irreversible oxidation peaks at 0.327 and 0.487 V vs. saturated calomel electrode, respectively, making their simultaneous detection feasible. The voltammetric responses of both isomers are linear in concentrations ranging from 0.3 to 150 μM with limits of detection of 62 and 94 nM, respectively. The sensor exhibits advantages including good reproducibility, stability, selectivity, and practicability for the simultaneous detection of naphthol isomers in real water samples.

Highly efficient and low-cost nanomaterials with multifunctions for oxygen evolution reaction (OER), hydrogen evolution reaction (OER) and oxygen reduction reaction (ORR) have been attracted tremendous attentions that play significant roles in energy storage and conversion. Herein, a facile strategy is developed to synthesize metal alloys (NiCo, CoFe) with their oxides supported on nitrogen-doped graphene (N-rGO/NiCo-NiO-CoO, N-rGO/CoFe-Co2FeO4). The obtained nanomaterials exhibit outstanding tri-functional performances for the above mentioned three kinds of reactions. Furthermore, the prepared composites, assembled in air cathodes, present excellent performance that are similar with Pt/C or Pt/C + IrO2 in primary and rechargeable zinc-air batteries. The prepared N-rGO/NiCo-NiO-CoO and N-rGO/CoFe-Co2FeO4 exhibit the specific capacities of 734 and 711 mA h gZn−1 at the current density of 20 mA cm−2, respectively. The rechargeable zinc-air batteries maintain excellent durability after cycling 33 h.

An effectively multifunctional electrocatalyst is crucial for catalyzing the reactions occurred at electrodes in zinc-air batteries and water splitting cells, such as oxygen evolution reaction (OER), hydrogen evolution reaction (HER), and oxygen reduction reaction (ORR). Herein, two non-noble metal-based multifunctional electrocatalysts of N-doped carbon nanotubes NCNT/CoFe-CoFe2O4 and NCNT/MnO-(MnFe)2O3 are prepared by a simple solvothermal procedure, followed by two-step annealing under the argon and ammonia atmosphere. The resultant electrocatalysts exhibit good trifunctional performances for HER, ORR, and OER. Notably, the NCNT/CoFe-CoFe2O4 and NCNT/MnO-(MnFe)2O3 assembled zinc-air batteries exhibit high energy densities of 727 and 776 W h kgZn-1 at the current density of 20 mA cm-2, respectively. Furthermore, the NCNT/CoFe-CoFe2O4-based rechargeable zinc-air battery remains excellent durability after discharge-charge cycle testing for 22 h, comparable to the noble metal-based catalyst (Pt/C + IrO2)-assembled zinc-air battery. Furthermore, the NCNT/CoFe-CoFe2O4 and NCNT/MnO-(MnFe)2O3-assembled water splitting cells need ∼1.65 and 1.70 V, respectively, to deliver a current density of 10 mA cm-2, lower than that of IrO2-Pt/C (1.71 V) and present excellent durability under long-term electrolysis. This work provides a facile strategy to prepare highly active multiple functional electrocatalysts for energy conversion and storage.

In this work, first-principles calculation based on density functional theory (DFT) was used to study the enhanced photocatalytic mechanism of TiO2 hybridized with pristine and defective g-C3N4 systematically. The theoretical investigations on both geometry structure and electronic properties, involving band structure, density of states, electron population and charge density difference, were carried out to characterize the improved property of TiO2. It was found that the combination TiO2 with g-C3N4 could be verified for high thermodynamic stability. The interaction between TiO2 and g-C3N4 led to form a built-in electric field at the interface, which facilitated the separation of electron-hole pairs and restrained photo-generated carrier recombination. Furthermore, electrons transiting from the highest occupied molecular orbital (HOMO) to the lowest unoccupied molecular orbital (LUMO) promoted the separation of electrons and holes. The effective separation of electron-hole pairs prolonged the lifetime of carries and enhanced the photocatalytic activity of TiO2/g-C3N4. The theoretical investigations could verify the experimental observation results [Chem. Sci., 5(2014), 3946–3951, Phys. Chem. Chem. Phys., 17(2015), 17406–17412] and illustrate the mechanisms of photocatalytic enhancement of TiO2/g-C3N4 composite photocatalysts. Furthermore, the calculated optical absorption curves demonstrated that the absorption edge of TiO2/g-C3N4 composites shifted to visible-light region and its photocatalytic activity increased under visible-light irradiation. The theoretical investigation might provide referable and valuable information for understanding the observed enhanced photocatalytic mechanism in experiments.

The development of highly efficient and inexpensive catalysts is still a tremendous challenge for the electrocatalytic nitrogen reduction reaction (NRR), which is a promising alternative to high-temperature and high-pressure industrial technologies for the synthesis of NH3. Herein, we report a facile and large scale strategy exploiting a porous non-precious bimetallic oxide of NiWO4 for the NRR under ambient conditions. Benefiting from the above-mentioned merits, the designed electrocatalyst achieved outstanding catalytic activities in both 0.1 M HCl (NH3 yield: (40.05 ± 1.45) μg h-1 mg-1cat., Faraday efficiency (FE): (19.32 ± 0.68)% at -0.3 V) and 0.1 Na2SO4 (NH3 yield: (23.14 ± 1.75) μg h-1 mg-1cat., Farady efficiency: (10.18 ± 0.62)% at -0.3 V), and these efficiencies are superior to most of the reported non-precious metals for the NRR. Furthermore, the prepared catalyst presented excellent stability in both acidic and neutral media for up to 20 h. This work opens a constructive avenue for optimizing the catalytic performance of metal oxides and other transition metal-based catalysts for NRRs.

Exploration and fabrication of low-cost but highly active electrocatalysts, alternatives to noble metals, have remained a challenge for overall water splitting reaction. To date, few studies have reported that the Earth-abundant pyrite FeS2 is catalytically active for hydrogen evolution reaction, while there is no study on the oxygen evolution reaction and overall water splitting reaction using pyrite FeS2 as an electrocatalyst. Here, we offer a facile hydrothermal approach for the synthesis of FeS2 nanoparticles by the reduction of FeCl3·6H2O with C5H10NS2Na·3H2O. The FeS2/C nanoparticles on Ni foam (NF) deliver 10 mA cm−2 at an overpotential of 240 mV towards the oxygen evolution reaction, which is lower than that of IrO2. It requires 202 mV to drive the hydrogen evolution reaction to reach 10 mA cm−2, while long-term durability and faster charge-transfer kinetics confirm the good hydrogen evolution reaction performance on FeS2/C/Ni foam. Moreover, the pyrite FeS2/C/nanoparticles on Ni foam are assembled as an anode and cathode in a two-electrode alkaline electrolyzer and show good overall water splitting efficiency with 1.72 V at 10 mA cm−2.

Electrocatalytic production of hydrogen from water is a promising and sustainable strategy. In this study, a simple and general strategy is demonstrated for the synthesis of a polymer-derived, heteroatom-doped carbon supporting MoS2–MoP nanosheets (MoS2–MoP/C), which acts as an efficient hydrogen evolution reaction (HER) catalyst. The unique composition of the MoS2–MoP/C enables catalysis of HER, demonstrating a Tafel slope of 58 mV dec−1 and overpotentials of 102 mV and 130 mV, and is therefore able to deliver current densities of 10 mA cm−2 and 20 mA cm−2, respectively. Moreover, the MoS2–MoP/C nanosheets demonstrate superior long-term durability in acid electrolytes and the developed strategy is easily adapted to large-scale production of efficient electrocatalysts. This excellent HER performance is likely attributed to electronic interactions between P and S, a relatively-high specific surface area of the electrocatalyst (162 m2 g−1), the characteristic nanosheet morphology, and high electrical conductivity, which promotes rapid charge transport and collection.

Developing inexpensive, active and durable nanomaterials for the oxygen reduction reaction (ORR) plays an important role in fuel cell research. In this work, a carbon supported dicobalt phosphide (Co2P) nanosheet (Co2P/C) electrocatalyst is prepared using a simple and low cost supramolecular gel assisted strategy. The nanomaterial obtained with a nanosheet morphology presents excellent electrocatalytic performance for ORR with comparable onset- and half-wave potential to a platinum/carbon (Pt/C) catalyst, indicating the significant role of Co2P for enhancing the electrocatalytic performance for ORR in an alkaline medium. Furthermore, the obtained catalyst exhibits outstanding long-term durability, methanol tolerance and a four electron pathway for ORR. The progress in this work will be scalable for the development of a non-precious metal electrocatalyst with a nanosheet structure for fuel cell applications.

Strontium iridate perovskites are attractive electrocatalysts for acidic water oxidation, but suffer from serious Sr-leaching during catalysis, which causes surface rearrangements that damage long-term applications. Herein, 6H phase SrIrO3 modified with laminar Sr2IrO4 (SrIrO) have been developed. Unlike the previous extreme chemical state changes of Ir, SrIrO maintained relatively stable surface Ir states during electrocatalysis. The layered nature of Sr2IrO4 enables the interlaminar Sr easily extracted from the crystal while remaining the in-plane IrO6 octahedral framework, thereby stabilizing the Ir state. The SrIrO displays extremely low overpotential of 245 mV for OER and 18.2 mV for HER at 10 mA cm−2, and outstanding catalytic stability. For acidic water splitting, SrIrO requires only 1.50 V to achieve 10 mA cm−2, surpassing most reported electrocatalysts. This work offers a new route for alleviating the surface rearrangements of perovskites, and exploring efficient and stable electrocalysts for hydrogen production via electrochemical water electrolysis.

Construction of bi-functional noble metal-free catalysts with low cost and high efficiency is greatly desired for hydrogen and oxygen evolution reactions. It is of vital importance to regulate the surface electron state of pyrite to improve the electrocatalytic performance towards overall water splitting. In this work, we provide a simple one-pot interface-regulated strategy to synthesize Ni3S4/NiS2/FeS2 nanoparticles with exposed interfacial structures between Ni-S and Fe-S, which can then affect the conductivity and activity of pyrite. Notably, Ni3S4/NiS2/FeS2 nanoparticles are highly active in the hydrogen evolution reaction with 197 mV at 10 mA/cm2. Superior oxygen evolution activity is observed for Ni3S4/NiS2/FeS2 nanoparticles with 1.46 V at 10 mA/cm2, outperforming RuO2 with 1.54 V. Impressively, Ni3S4/NiS2/FeS2 nanoparticles could efficiently drive water splitting into hydrogen and oxygen at a voltage of 1.68 V at 10 mA/cm2 in a two-electrode configuration and robust long-term stability was verified by continuous 20 h i-t tests without apparent loss in the current density. The outstanding catalytic activity could be traced back to the presence of interfacial structures between Ni-S and Fe-S. This work highlights that engineering heteroatoms into pyrite that can trigger the generation of interfacial structures, which beneficially accelerates electron transfer during the water splitting process.

Ru nanoparticles (NPs) and single atoms (SAs)‐based materials have been investigated as alternative electrocatalysts to Pt/C for hydrogen evolution reaction (HER). Exploring the dominant role of atomic‐ and nano‐ruthenium as active sites in acidic and alkaline media is very necessary for optimizing the performance. Herein, an electrocatalyst containing both Ru SAs and NPs anchored on defective carbon (RuSA+NP/DC) has been synthesized via a Ru–alginate metal–organic supramolecules conversion method. RuSA+NP/DC exhibits low overpotentials of 16.6 and 18.8 mV at 10 mA cm−2 in acidic and alkaline electrolytes, respectively. Notably, its mass activities are dramatically improved, which are about 1.1 and 2.4 times those of Pt/C at an overpotential of 50 mV in acidic and alkaline media, respectively. Theoretical calculations reveal that Ru SAs own the most appropriate H* adsorption strength and thus, plays a dominant role for HER in acid electrolyte, while Ru NPs facilitate the dissociation of H2O that is the rate‐determining step in alkaline electrolyte, leading to a remarkable HER activity., Defective carbon anchored Ru single atoms (SAs) and nanoparticles (NPs) is prepared, and exhibits super hydrogen evolution reaction (HER) activity in both acidic and alkaline media. Theoretical calculations reveal that Ru SAs are inclined to adsorption of H* that is critical for acidic HER, and Ru NPs facilitate the dissociation of H2O that is the rate‐determining step in alkaline medium.

D-band-center control engineering, particularly combining both cation and anion intercalations towards heterostructure formation with simultaneous usage of Ru, N as well as F species, for optimal electronic structure as efficient hydrogen evolution reaction (HER) catalysts remains a daunting challenge but critical for renewable-energy technologies. Herein, we lay emphasis on the design of active-site electronic structure based on d-band-center shift through the construction of Co4N-CoF2 heterostructure coupled with Ru doping (Ru/Co4N-CoF2). Solvothermal coordination reaction followed by annealing course causes cooccurrence of F, N, Ru in Co neighborhood. As-obtained Ru/Co4N-CoF2 exhibits superior HER activity in alkaline electrolyte with overpotential as low as 53 mV to yield a current density of 10 mA cm−2 which is close to that of commercial Pt/C, outperforming many transition-metal-based catalysts recent-reported. Moreover, it still presents good durability with continuous operation of 22 h in 1.0 M KOH. Such excellent performance is ascribed to appropriate electron structure of Ru/Co4N-CoF2 for optimized hydrogen binding abilities on Co/Ru sites as confirmed by synchrotron-based X-ray adsorption near-edge structure and X-ray photoelectron spectroscopies. This study not only establishes highly active electrocatalysts by impacting d-band center of active sites but also provides valuable insights into the synergistic-effect protocol of doping and heterostructure strategies for d-band-center shifting.

Pharmacological activity of one drug may be altered due to the concomitant administration of another drug, leading to unanticipated drug-drug interactions(DDIs). However, existing DDI prediction approaches are lacking in the following aspects: (1)scalability: they rely heavily on diverse drug-related features, leading to the unavailability of important features for most of the drugs when it comes to large-scale datasets. (2)robustness: they aim to approximate the interaction probability with the integration of diverse features. The model may be sensitive to pairwise similarity information of the test set. In this paper, we explore the promising application of graph representation learning for more accurate DDI prediction, establishing a brand new model to solve the two problems, achieving greater performance and keeping certain interpretability. Our experiments on the small-scale DDI dataset as well as the large-scale one illustrate that our model can achieve higher performance compared to various existing state-of-the-art approaches, which can indicate the scalability of our model. Moreover, our model can find the most important local atoms with the attention mechanism, which conform to domain knowledge with certain interpretability. Furthermore, the robust analysis show that the proposed method is insensitive to the pairwise similarity information of test datasets, and can retrieve interacting drug pairs even though their pairwise similarities are extremely low with a high recall rate and a considerable precision rate.

Noble metal-based catalysts are currently the most advanced electrocatalysts for many applications, such as for energy conversion and for chemical industry. Because of the high cost and scarcity of noble metals, reducing the usage is a practical way to achieve scalable applications. Herein, for the first time, three novel electrocatalysts composed of noble metal phosphide (IrP

It is highly essential but challengeable to explore the earth-abundant and low-cost oxygen evolution reaction catalysts to replace Ir- or/and Ru-based ones. In this article, we report an in situ growth of ultrathin NiFe layered double hydroxide nanosheets on reduced graphene oxide in formamide aqueous solution followed by simple chemical reduction. These ultrathin layered double hydroxide nanosheets in the composite occur in single- or multi-layer forms on reduced graphene oxide matrix. Consequently, the obtained catalyst exhibits the enhanced BET surface area and electrochemically active surface area, and low mass transfer resistance. This electrocatalyst displays the excellent OER activity with a small onset potential of 233 mV. Additionally, it only requires an overpotential of 254 mV to achieving current density of 10 mA cm−2, and can gives a current density of 70.60 mA cm−2 at overpotential of 300 mV in 0.1 M KOH. It also demonstrates the robust long-time electrochemical durability.

Design of cost-effective bifunctional electrocatalysts for both the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is vital for developing hydrogen energy for the future. Herein, a cost-effective phosphorus-doped Co-Fe-B material with chain-like structure (denoted as Co₁-Fe₁-B-P) is reported as an efficient and novel bifunctional electrocatalyst for the OER and HER, and was produced via a facile water-bath synthesis and subsequent phosphorization. For the OER, the as-prepared Co₁-Fe₁-B-P nanochains require an extremely low overpotential of about 225 mV at 10 mA cm⁻² and possess a small Tafel slope of 40 mV dec⁻¹ in alkaline media. Impressively, the HER properties of Co₁-Fe₁-B-P nanochains are superior to those of P-free Co-Fe-B in terms of overpotential at 10 mA cm⁻² (173 mV vs. 239 mV) and kinetic Tafel slope (96 mV dec⁻¹ vs. 105 mV dec⁻¹). The synergetic effect between Co-Fe-B and doped-P is mainly responsible for the satisfactory bifunctional performance, while the one-dimensional (1D) chain-like structure endows Co₁-Fe₁-B-P with abundant catalytically active sites that enhance the atom utilization efficiency. Moreover, the developed Co₁-Fe₁-B-P nanochains can be simultaneously utilized as both the cathode and anode for overall water-splitting, which requires a cell voltage of only 1.68 V to deliver 10 mA cm⁻². This work provides a feasible and promising protocol to realize metal borides as efficient electrocatalysts in energy-related applications. This work was supported by the Taishan Scholar Program of Shandong Province, China (ts201712045), the Key Research and Development Program of Shandong Province (2018GGX104001), the Natural Science Foundation of Shandong Province of China (ZR2017MB054 and ZR201807060818) and the Doctoral Fund of QUST (0100229001 and 010022873).

Atomically thick ultrathin nanomeshes (NMs) possessing the inherent advantages of both two-dimensional nanomaterials and porous nanomaterials are attracting increasing interest in catalysis and electrocatalysis. Herein, we report a direct chemical synthesis of atomically thick Ni(OH)2-NMs by a NaBH4 assisted cyanogel hydrolysis method, which overcomes the shortcoming of the post-etching method for NM synthesis. Various physical characterization methods show that the as-synthesized Ni(OH)2-NMs have 1.7 nm thickness, a big surface area, abundant nanoholes, and numerous surface/edge atoms with low-coordination numbers. The as-synthesized Ni(OH)2-NMs show a better electrocatalytic performance for the urea oxidation reaction than conventional Ni(OH)2 nanoparticles without holes in the alkaline electrolyte, including a lower onset oxidation potential, faster reaction kinetics, and higher mass activity.

It remains a tremendous challenge to develop a low-cost, earth-abundant, and efficient catalyst with multifunctional activities for the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR). Herein, a facile and scalable avenue was developed to prepare amorphous Co-P/Co-N-C supported on N, P co-doped porous carbon (Co-P/Co-N-C/NPC) with a large specific surface area (1462.9 m2 g-1 ) and abundant reactive sites including Co-P, Co-N and NPC. The prepared electrocatalyst exhibits outstanding catalytic performance for HER (η=234 mV at 10 mA cm-2 ), OER (η=374 mV at 10 mA cm-2 ), and ORR (E1/2 =0.89 V, vs. reversible hydrogen electrode). Benefiting from the excellent HER performance and outstanding OER activity, the Co-P/Co-N-C/NPC delivers a current density of 10 mA cm-2 for overall water splitting at a cell voltage of 1.59 V, which is comparable with the IrO2 -Pt/C couple electrode.

The hydrogen evolution reaction activity of carbon-supported Pt catalyst is highly dependent on Pt–C interfaces. Herein, we focus on the relationships between Pt activity and N/O-functionalized hollow carbon sphere (HCS) substrate in acidic media. The electrochemical dissolution of Pt counter electrode is performed to prepare Pt nanoparticles in low loading. The N groups are beneficial for homogeneously sized Pt nanoparticles, whereas the O groups lead to aggregated nanoparticles. Moreover, the proper electronegativity of the N groups may enable capturing of protons to create proton-rich Pt–C interfaces and transfer them onto the Pt sites. The O groups may also capture protons by hydrogen bonding, but the subsequent release of protons is more difficult due to a stronger electronegativity and result in an inferior Pt activity. Consequently, the N-doped HCS with a low Pt loading (1.7 μg cm–2 and 0.05 wt %) possesses a higher intrinsic activity compared with Pt on O-doped HCS. Moreover, it outperforms the co...

Although being of significance for water spitting, exploring the high-efficiency and low-cost electrocatalysts toward oxygen evolution reaction remains a considerable challenge. Here, we develop a facile bottom-up method for the direct growth of ultrathin CoFe layered double hydroxide nanosheets on oxidized carbon nanotube surface in formamide aqueous solution. The preparation strategy results in the ultrathin nature of hydrotalcite-like layers with less than 5 nm thickness. The resultant composite offers a larger electrochemically active surface area and faster mass transfer rate owing to the more exposed active sites. This electrocatalyst exhibits superior oxygen evolution reaction performance to the bulk form with lower onset potential, smaller Tafel slope, and robust durability in 0.1 M KOH solution. The better water oxidation activity can be attributable to the strong synergistic effects of CoFe layered double hydroxide nanosheets and oxidized carbon nanotubes because of their ultrathin assembling and more available catalytic centers.

The amorphous ternary MnCoB was synthesized at room temperature, which showed excellent oxygen evolution reaction (OER) activity and long‐term stability in 1.0 mol L-1 KOH solution. The obtained catalyst exhibited the lower overpotential (292 mV) and the Tafel slope was 92.4 mV dec-1 when the current density arrived 10 mA cm-2. Density functional theory (DFT) calculations elucidated its electrocatalytic activity and the favorable OER kinetics on MnCoB catalyst. Combined theoretical study with experimental observations, this work explained the OER activity mechanism of the catalyst, which was of important guiding significance for design, synthesis and performance of high efficiency electrocatalyst.

Cobalt-mediated activation of peroxymonosulfate (PMS) has been widely investigated for the effective oxidation of organic contaminants in wastewater. Herein, monometal- and bimetal-doped MCM-41 catalysts (Fe-MCM-41, Co-MCM-41, and FeCo-MCM-41) were synthesized by using one-pot hydrothermal method and attempted to degrade artificial methyl orange (MO) dye wastewater via PMS activation. The influences of initial PMS concentration, pH, catalyst dosage and reaction temperature on the degradation efficiency of MO were systematically examined. Compared with the contrasting catalysts, FeCo-MCM-41 exhibited extremely higher activity and lower amount of metal leaching in the degradation process. The excellent catalytic activity of FeCo-MCM-41 was ascribed to the high dispersion of metals and the synergistic effects of Co2+/Co3+ and Fe2+/Fe3+ redox cycles. A series of radical inhibition and electron paramagnetic resonance experiments revealed that both radical and non-radical pathways were involved in the degradation of MO. Singlet oxygen (1O2) was unveiled to be the dominant reactive oxygen species in the FeCo-MCM-41/PMS system. The possible degradation pathways were proposed based on the identification of intermediate products generated in the degradation process by LC-MS analyses.

Phototransistors based on organic photoactive materials combine tunable light absorption in the spectral region from ultraviolet to near-infrared with low-temperature processability over large areas on flexible substrates. However, they often exhibit low photoresponsivity because of low molar extinction coefficient of photoactive components. We report a simple, yet highly efficient solution method for enhancing the performance of organic phototransistors using ruthenium complex 1 (Ru-complex 1). An air-stable n-type organic semiconductor, N,N'-bis(2-phenylethyl)-perylene-3,4:9,10-tetracarboxylic diimide (BPE-PTCDI), has been deposited on a silicon wafer and a transparent polyimide (PI) substrate via thermal evaporation under vacuum. The BPE-PTCDI phototransistors functionalized with Ru-complex 1 exhibit ∼5000 times higher external quantum efficiency (EQE) than that of pristine BPE-PTCDI phototransistors, owing to the metal-ligand charge transfer (MLCT) from Ru-complex 1 to the active component of the device. In addition, a large 10 × 10 phototransistor array (2.5 × 2.5 cm(2)) has been prepared on a transparent PI substrate, showing distinct light mapping. The fabricated phototransistor array is highly flexible and twistable and works well under tensile and compressive strains. We believe that our simple method will pave a viable way for improvements in the photoresponsivity of organic semiconductors for applications in wearable organic optoelectronic devices.

Development of efficient bifunctional electrocatalysts from earth abundant elements, simultaneously active for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), remains to be a grand challenge for electrocatalysis. Herein we firstly synthesized a new type of bifunctional catalyst (NCNT/CoxMn1−xO) consisting of non-spinel cobalt–manganese oxide supported on N-doped carbon nanotubes through a simple non-surfactant assistant hydrothermal method. This hybrid catalyst exhibits much higher OER activity than that of IrO2, and comparable ORR activity to Pt/C with identical onset potential (0.96 V) in alkaline media. Furthermore, the NCNT/CoxMn1−xO catalyst was studied as a cathode in both primary and rechargeable zinc–air batteries demonstrating similar performance to commercial Pt/C or (Pt/C+IrO2), respectively. Primary zinc–air battery tests show a gravimetric energy density of 695 W h kg Zn - 1 , and the rechargeable battery exhibits a high round-trip efficiency evidenced by a low discharge–charge voltage gap (0.57 V) at a current density of 7 mA cm−2.

It is of tremendous significance to develop effective bifunctional electrocatalysts for electrochemical water-splitting to generate sustainable hydrogen energy. Herein, a facile and scalable strategy is evolved to design N doped bamboo-like carbon nanotube decorated with tri-metal nanoparticles (Fe–Ni–Cr/NC) for overall water-splitting in alkaline electrolyte. Coupling effects between different metals and intimately contact with the carbon matrix endow the obtained nanomaterial possesses splendid catalytic activity and stability for cathodic HER, anodic OER and overall water-splitting in alkaline electrolyte. The obtained Fe–Ni–Cr/NC exhibits the best catalytic performance for HER (284 mV@10 mA cm−2) relative to Fe–Cr/NC (368 mV), Ni–Cr/NC (314 mV) and Fe–Ni/NC (324 mV). For OER, a small overpotential of 210 mV is needed to drive 10 mAcm−2 which is superior to IrO2 (330 mV). Thus, the interactions between different metals act as paramount effects on promoting the catalytic activities. Benefiting from the outstanding catalytic performances for both HER and OER, the designed Fe–Ni–Cr/NC possesses splendid catalytic activity for overall water-splitting with a small potential of 1.64 V to deliver 10 mA cm−2. Moreover, the obtained nanomaterial also owns remarkable long-term stability in the measured electrolyte.

Despite the great success of word embedding, sentence embedding remains a not-well-solved problem. In this paper, we present a supervised learning framework to exploit sentence embedding for the medical question answering task. The learning framework consists of two main parts: 1) a sentence embedding producing module, and 2) a scoring module. The former is developed with contextual self-attention and multi-scale techniques to encode a sentence into an embedding tensor. This module is shortly called Contextual self-Attention Multi-scale Sentence Embedding (CAMSE). The latter employs two scoring strategies: Semantic Matching Scoring (SMS) and Semantic Association Scoring (SAS). SMS measures similarity while SAS captures association between sentence pairs: a medical question concatenated with a candidate choice, and a piece of corresponding supportive evidence. The proposed framework is examined by two Medical Question Answering(MedicalQA) datasets which are collected from real-world applications: medical exam and clinical diagnosis based on electronic medical records (EMR). The comparison results show that our proposed framework achieved significant improvements compared to competitive baseline approaches. Additionally, a series of controlled experiments are also conducted to illustrate that the multi-scale strategy and the contextual self-attention layer play important roles for producing effective sentence embedding, and the two kinds of scoring strategies are highly complementary to each other for question answering problems., 8 pages

Mastering of medical knowledge to human is a lengthy process that typically involves several years of school study and residency training. Recently, deep learning algorithms have shown potential in solving medical problems. Here we demonstrate mastering clinical medical knowledge at certificated-doctor-level via a deep learning framework Med3R, which utilizes a human-like learning and reasoning process. Med3R becomes the first AI system that has successfully passed the written test of National Medical Licensing Examination in China 2017 with 456 scores, surpassing 96.3% human examinees. Med3R is further applied for providing aided clinical diagnosis service based on real electronic medical records. Compared to human experts and competitive baselines, our system can provide more accurate and consistent clinical diagnosis results. Med3R provides a potential possibility to alleviate the severe shortage of qualified doctors in countries and small cities of China by providing computer-aided medical care and health services for patients., AI is used increasingly in medical diagnostics. Here, the authors present a deep learning model that masters medical knowledge, demonstrated by it having passed the written test of the 2017 National Medical Licensing Examination in China, and can provide help with clinical diagnosis based on electronic health care records.

Exploration of high-efficiency, economical, and ultrastable electrocatalysts for the oxygen reduction reaction (ORR) to substitute precious Pt is of great significance in electrochemical energy conversion devices. Single-atom catalysts (SACs) have sparked tremendous interest for their maximum atom-utilization efficiency and fascinating properties. Therefore, the development of effective synthetic methodology toward SACs becomes highly imperative yet still remains greatly challenging. Herein, a reliable SiO2 -templated strategy is elaborately designed to synthesize atomically dispersed Fe atoms anchored on N-doped carbon nanospheres (denoted as Fe-N-C HNSs) using the cheap and sustainable biomaterial of histidine (His) as the N and C precursor. By virtue of the numerous atomically dispersed Fe-N4 moieties and unique spherical hollow architecture, the as-fabricated Fe-N-C HNSs exhibit excellent ORR performance in alkaline medium with outstanding activity, high long-term stability, and superior tolerance to methanol crossover, exceeding the commercial Pt/C catalyst and most previously reported non-precious-metal catalysts. This present synthetic strategy will provide new inspiration to the fabrication of various high-efficiency single-atom catalysts for diverse applications.

Rational designing of the composition and structure of electrode material is of great significance for achieving highly efficient energy storage and conversion in electrochemical energy devices. Herein, MoS

Investigation of non-precious, highly-active and durable catalysts is an essential criteria for the development of electrocatalytic hydrogen evolution reaction (HER). In this work, reduced graphene oxide coupled with molybdenum phosphide (MoP-RGO) is prepared through a facile and scalable one-step strategy. Three strategies are developed to tune the electrocatalytic performance of MoP-RGO including optimize the pyrolysis temperature, add NaCl template and introduction of sulfur atoms. After the optimization, the overpotentials at 10 mA cm−2 reduced from 238 to 152 mV (alkaline electrolyte) and 232 to 144 mV (acid medium), respectively. This work mainly focus on exploiting various strategies to tune the electrocatalytic performance of non-precious catalysts for HER which can provide multiple avenues to develop efficient electrocatalysts.

Herein, nitrogen-doped carbon coated hollow Co

Electrocatalysis for the oxygen reduction reaction (ORR) at the cathode plays a critical role in fuel cells and metal-air batteries. However, the high-cost and sluggish kinetics of the catalytic reaction have hindered its development. Therefore, developing efficient catalysts to address these issues is of vital significance. In this work, we summarized the recent progress of nitrogen (N)-doped metal-free catalysts for the ORR, owing to their high catalytic activity (comparable to Pt/C) and cost-effectiveness. The synthetic strategy and the morphology structure to catalytic performance are mainly discussed. Furthermore, the design of N-doped nanomaterials with other heteroatoms in aiming to further enhance the ORR performance is also reviewed. At the end of the review, we provide a brief summary of the N-doped carbon-based catalysts in enhancing the ORR performance and give future perspectives for their further development.

Herein, nitrogen-doped carbon coated hollow Co9S8 microtubes (Co9S8@N–C microtubes) are prepared through a facile solvothermal procedure, followed by dopamine polymerization process together with a post-pyrolysis which present excellent electrocatalytic activity for oxygen reduction reaction (ORR). The Co9S8 within the hollow Co9S8@N–C microtubes presents a well-defined single-crystal structure with dominated (022) plane. To obtain desired electrocatalyst, the annealing temperature and the thickness of carbon layer tuned by changing the dopamine concentration are optimized systematically. The electrochemical results demonstrate that the coordination of the N-doped carbon layer, exposed (022) plane, and hollow architecture of Co9S8 microtubes calcined at 700 °C affords outstanding ORR performance to Co9S8@N–C microtubes. The moderate thickness of the carbon layer is crucial for improving ORR activity of Co9S8@N–C microtubes, while increasing or decreasing the thickness would result in activity decrease. More importantly, the N-doped carbon layer can protect inner Co9S8 from undergoing aggregation and dissolution effectively during the ORR, resulting in excellent electrocatalytic stability.

Oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) along with hydrogen evolution reaction (HER) have been considered critical processes for electrochemical energy conversion and storage through metal-air battery, fuel cell, and water electrolyzer technologies. Here, a new class of multifunctional electrocatalysts consisting of dominant metallic Ni or Co with small fraction of their oxides anchored onto nitrogen-doped reduced graphene oxide (rGO) including Co-CoO/N-rGO and Ni-NiO/N-rGO are prepared via a pyrolysis of graphene oxide and cobalt or nickel salts. Ni-NiO/N-rGO shows the higher electrocatalytic activity for the OER in 0.1 m KOH with a low overpotential of 0.24 V at a current density of 10 mA cm−2, which is superior to that of the commercial IrO2. In addition, it exhibits remarkable activity for the HER, demonstrating a low overpotential of 0.16 V at a current density of 20 mA cm−2 in 1.0 m KOH. Apart from similar HER activity to the Ni-based catalyst, Co-CoO/N-rGO displays the higher activity for the ORR, comparable to Pt/C in zinc-air batteries. This work provides a new avenue for the development of multifunctional electrocatalysts with optimal catalytic activity by varying transition metals (Ni or Co) for these highly demanded electrochemical energy technologies.

Fur Lithiumionenakkumulatoren mit hohen Energiedichten gibt es eine uberaus grose Nachfrage im Bereich tragbarer elektronischer Gerate und Elektrofahrzeuge. Weil die Energiedichten der Lithiumionenakkumulatoren vor allem vom verwendeten Kathodenmaterial abhangen, wird nach alternativen Kathodenmaterialien mit besserer Lithiumnutzung und hoherer spezifischer Energiedichte intensiv geforscht. Insbesondere Ni-reiche Lithium-Ubergangsmetalloxid-Schichtverbindungen konnen hohere Kapazitaten als das klassische LiCoO2 bei geringeren Kosten bereitstellen. Sie gelten als besonders vielversprechend, aber sie bergen noch grose Herausforderungen bezuglich Lebensdauer, Warmestabilitat und Sicherheit. Hier wird umfassend beschrieben, wie gezielte Veranderungen an der Struktur oder an den Grenzflachen in einer Leistungssteigerung von Ni-reichen Kathodenmaterialien resultieren. Die zugrundeliegenden Mechanismen und die noch zu bewaltigenden Herausforderungen werden ebenfalls diskutiert.

The reaction of nitric oxide with oxy-myoglobin (oxyMb) to form ferric myoglobin (metMb) and nitrate, and the metMb-catalyzed isomerization of peroxynitrite to nitrate, have long been assumed to proceed via the same iron-bound peroxynitrite intermediate (metMb(OONO)). More recent research showed that the metMb-catalyzed isomerization of peroxynitrite to nitrate produces detectable amounts of nitrogen dioxide and ferryl myoglobin (ferrylMb). This suggests a mechanism in which the peroxynitrite binds to the metMb, ferrylMb is transiently generated by dissociation of NO2, and nitrate is formed when the NO2 nitrogen attacks the ferrylMb oxo ligand. The presence of free NO2 and ferrylMb products reveals that small amounts of NO2 escape from myoglobin's interior before recombination can occur. Free NO2 and ferrylMb should also be generated in the reaction of oxyMb with NO, if the common intermediate metMb(OONO) is formed. However, this report presents a series of time-resolved UV/vis spectroscopy experiments in which no ferrylMb was detected when oxyMb and NO reacted. The sensitivity of the methodology is such that as little as 10% of the ferrylMb predicted from the experiments with metMb and peroxynitrite should have been detectable. These results lead to the conclusion that the oxyMb + NO and metMb + ONOO(-) reactions do not proceed via a common intermediate as previously thought. The conclusion has significant implications for researchers that propose a possible role of oxyMb in intracellular NO regulation, because it means that toxic NO2 and ferrylMb are not generated during NO oxidation by this species.

Nature Reviews Materials 1, 16064 (2016) In the originally published version of this article, the corresponding authorship was incorrectly assigned. This has been corrected in both the HTML and PDF versions of the article.

Metals and metal oxides are widely used as catalysts for materials production, clean energy generation and storage, and many other important industrial processes. However, metal-based catalysts suffer from high cost, low selectivity, poor durability, susceptibility to gas poisoning and have a detrimental environmental impact. In 2009, a new class of catalyst based on earth-abundant carbon materials was discovered as an efficient, low-cost, metal-free alternative to platinum for oxygen reduction in fuel cells. Since then, tremendous progress has been made, and carbon-based metal-free catalysts have been demonstrated to be effective for an increasing number of catalytic processes. This Review provides a critical overview of this rapidly developing field, including the molecular design of efficient carbon-based metal-free catalysts, with special emphasis on heteroatom-doped carbon nanotubes and graphene. We also discuss recent advances in the development of carbon-based metal-free catalysts for clean energy conversion and storage, environmental protection and important industrial production, and outline the key challenges and future opportunities in this exciting field. Reducing or even eliminating the need for precious-metal catalysts is crucial for the commercialization of clean energy technologies and various important industrial processes. Carbon materials have recently been shown to be cost-effective and efficient metal-free catalysts in clean energy generation and storage, environmental protection and chemical production.

Oxygen electrocatalysis, namely of the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER), governs the performance of numerous electrochemical energy systems such as reversible fuel cells, metal-air batteries, and water electrolyzers. However, the sluggish kinetics of these two reactions and their dependency on expensive noble metal catalysts (e.g, Pt or Ir) prohibit the sustainable commercialization of these highly innovative and in-demand technologies. Bifunctional perovskite oxides have emerged as a new class of highly efficient non-precious metal catalysts (NPMC) for oxygen electrocatalysis in alkaline media. In this review, we discuss the state-of-the-art understanding of bifunctional properties of perovskites with regards to their OER/ORR activity in alkaline media and review the associated reaction mechanisms on the oxides surface and the related activity descriptors developed in the recent literature. We also summarize the present strategies to modify their electronic structure and to further improve their performance for the ORR/OER through highlighting the new concepts relating to the role of surface redox chemistry and oxygen deficiency of perovskite oxides for the ORR/OER activity. In addition, we provide a brief account of recently developed advanced perovskite-nanocarbon hybrid bifunctional catalysts with much improved performances.

The study of catalytic water oxidation continues to be one of the most active areas of research across many sub-disciplines of chemistry. From efforts toward developing artificial photosynthetic assemblies to the exploration of nanoscale materials to be used as a photoanode for splitting water, a detailed understanding of the mechanistic details of water oxidation in photosystem II (PSII) is paramount for the rational design of an artificial model. In addition, insight into the model's mechanism of molecular-level water-oxidation catalysis will provide us with a unique opportunity to elucidate the mechanistic pathways of water oxidation in the oxygen-evolving complex (OEC) of PSII. In this review, the proposed mechanisms, catalytic activities and reaction kinetics of catalytic water oxidation with transition metal complexes in homogeneous systems published from 1979 to 2010, with an emphasis on the last decade, are discussed. These metal complexes include mononuclear, dinuclear and multinuclear manganese, ruthenium, iridium, iron and cobalt complexes. Electrodeposited cobalt complexes are a type of heterogeneous water-oxidation catalyst; however, these complexes are discussed herein because they are topological analogs of the Mn cluster in the OEC. M V O species (M = Mn, Ru) as the key active species in homogeneous catalytic evolution of O 2 are common feature in many catalysts, in which formation of the O O bond can be achieved either by intramolecular elimination of dioxygen from two M V O groups or by nucleophilic attack of OH − species on M V O groups. Another common feature appears from tetranuclear ruthenium complex 71 , manganese complex 10 and cobalt complex, all of these cubane structural complexes have self-repair properties similar to OEC–protein complex in nature.

Rational designing of the composition and structure of electrode material is of great significance for achieving highly efficient energy storage and conversion in electrochemical energy devices. Herein, MoS2 /NiS yolk-shell microspheres are successfully synthesized via a facile ionic liquid-assisted one-step hydrothermal method. With the favorable interface effect and hollow structure, the electrodes assembled with MoS2 /NiS hybrid microspheres present remarkably enhanced electrochemical performance for both overall water splitting and asymmetric supercapacitors. In particular, to deliver a current density of 10 mA cm-2 , the MoS2 /NiS-based electrolysis cell for overall water splitting only needs an output voltage of 1.64 V in the alkaline medium, lower than that of Pt/C-IrO2 -based electrolysis cells (1.70 V). As an electrode for supercapacitors, the MoS2 /NiS hybrid microspheres exhibit a specific capacitance of 1493 F g-1 at current density of 0.2 A g-1 , and remain 1165 F g-1 even at a large current density of 2 A g-1 , implying outstanding charge storage capacity and excellent rate performance. The MoS2 /NiS- and active carbon-based asymmetric supercapacitor manifests a maximum energy density of 31 Wh kg-1 at a power density of 155.7 W kg-1 , and remarkable cycling stability with a capacitance retention of approximately 100% after 10 000 cycles.