Search

Lattice disorder engineering on highly crystalline texture toward high-efficiency N2-to-NH3 electrocatalysis is tremendously challenging. Here, abundant lattice disturbances were established on an ultrafine Nb2O5 nanoparticle by Cu substitution. Cu-Nb2O5 anchored on a carbon material (Cu-Nb2O5@C) exhibits excellent activity and high selectivity for N2 electroreduction to NH3 with a yield rate of 28.07 μg h-1 mg-1 and a faradaic efficiency (FE) of 13.25% at -0.2 V vs. reversible hydrogen electrode (RHE) in acidic electrolyte. Cu-Nb2O5@C presents superb durability with no obvious change in catalyst constituents and structure after N2 reduction as confirmed by ex situ characterization studies. The excellent catalytical performance should originate from structural superiority of lattice turbulence for more active sites and optimized electronic state as well as good conductivity of carbon support. Meanwhile, in neutral electrolyte, the NH3 FE also reaches up to 10.29% at the same potential.

Designing bifunctional electrocatalysts with high-efficiency for catalyzing oxygen and hydrogen evolution is immensely desirable but challenging. Herein, a newly designed hybrid bifunctional electrocatalyst, FexNi4−xPy coupled with N,P-codoped carbon nanotubes (N, P-CNTs), is developed by a facile pyrolysis-phosphorization process. The FexNi4−xPy/N, P-CNT catalyst shows a small overpotential of 266 mV to attain the benchmark 10 mA cm−2, low Tafel slope, and excellent stability for OER in 1.0 M KOH electrolyte, preceding that of commercial IrO2. Moreover, the FexNi4−xPy/N, P-CNT catalyst also exhibits admirable activity and robust stability towards HER in alkaline media. The advantageous characteristics of high electrical conductivity, multicomponent active sites, and anchoring effects of carbon nanotubes synergistically contribute to the excellent electrocatalytic activities and stability of FexNi4−xPy/N, P-CNTs towards OER and HER. This study may pioneer a unique avenue to synthesize novel electrocatalysts featuring multicomponent active sites for applications in renewable energy techniques.

Designing highly efficient, stable and low-cost bifunctional electrocatalysts based on in situ microstructure evolution, especially achieving partial lattice dislocation on a highly crystalline texture, to catalyze the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is challenging. Herein, catalysts with the Ni3Fe alloy embedded in Ni3FeN ultrathin nanosheets (∼1 nm) were fabricated through thermal ammonolysis treatment of cation-vacant monolayered NiFe layered double hydroxides. The emergence of the Ni3Fe alloy during the annealing process unavoidably leads to strain output to adjacent microstructures in ultrathin nanosheets, contributing to the formation of lattice dislocations. Such lattice defects, combining the ultrathin 2D morphology and synergistic interfacial effect between Ni3FeN and Ni3Fe, endow the electrocatalyst (d-Ni3FeN/Ni3Fe) with excellent electrocatalytic performance for both the OER and HER in alkaline media, requiring overpotentials of 250 mV and 125 mV to drive a current density of 10 mA cm−2 in 1 M KOH, respectively. The water electrolyzer with d-Ni3FeN/Ni3Fe as the cathode and anode yields a current density of 10 mA cm−2 at a low cell voltage of 1.61 V, and exhibits excellent durability of over 90 h, outperforming the commercial IrO2‖Pt/C cell. The present study offers a new trial of lattice defect engineering to develop high-performance non-precious bifunctional electrocatalysts for overall water splitting.

Designing a conductive amorphous buffer layer between crystals (or lowering the crystallinity of one component) to minimize lattice-strain influence between a highly crystalline substance and nearby constituents, thus ensuring good electronic structure towards multiphase synergistic electro-catalysis, is of tremendous importance for the construction of high-performance catalysts. Here, combining solvothermal and calcination strategies, oxygen vacancy-abundant amorphous MoO3 and non-crystal MoO2 were implanted into amorphous N,P-doped carbon as MoOx/NPC to hybridize sub-10 nm crystalline ruthenium dots (Ru-MoOx/NPC). Amorphous NPC bridges MoOx with Ru crystal to avoid the direct contact of MoOx and Ru, thus weakening the lattice strain influence. The electrochemical measurement results show that Ru-MoOx/NPC exhibits excellent catalytical capacity towards hydrogen evolution reaction (HER), which only needs overpotentials of 30 mV and 27 mV to deliver the current density of 10 mA cm−2 in alkaline and acid electrolytes, respectively, outperforming numerous recent-reported catalysts. Such superior HER activity can be attributed to structural advantages of abundant oxygen deficiency, small-sized Ru dots, conductive amorphous NPC, and weakened lattice-strain for the maximum protection of key components. This study not only presents a well-defined nanostructure with high HER activity but also offers insight into the weakening of lattice-strain effects to support the catalytical property.

Electronic coupling with the support plays a crucial role in boosting the intrinsic catalytic activity of a single-atom catalyst. Herein, the three-dimensional (3D) hierarchical Co(OH)F nanosheet arrays modified by single-atom Ru (SA-Ru/Co(OH)F) are prepared by a facile one-step hydrothermal method under mild conditions, which exhibit excellent activity with an overpotential of 200 and 326 mV at 10 and 500 mA cm−2, respectively, as well as robust stability for oxygen evolution reaction (OER) in 1.0 mol L−1 KOH electrolyte. The study of electronic structures and surface chemical states before and after OER testing reveals that the strong electronic coupling between single-atom Ru and Co(OH)F induces the charge redistribution in SA-Ru/Co(OH)F and suppresses the excessive oxidation of Ru into higher valence state (more than +4) under high OER potential. This work provides a strategy to stabilize single-atom Ru by Co(OH)F that can enhance the activity and durability for OER under large current densities.

Facilitating the dissociation of water and desorption of hydrogen are both crucial challenges for improving the hydrogen evolution reaction (HER) in alkaline media. Herein, we report the synthesis of heterostructure of Ru2 P/WO3 @NPC (N, P co-doped carbon) by a simple hydrothermal reaction using ruthenium and tungsten salts as precursors, followed by pyrolyzing under an Ar atmosphere. The Ru2 P/WO3 @NPC electrocatalyst exhibits an outstanding HER activity with an overpotential of 15 mV at a current density of 10 mA cm-2 and excellent durability in a 1.0 M KOH solution, outperforming state-of-the-art Pt/C and most reported electrocatalysts. Experimental results combined with density functional calculations reveal that the electron density redistribution in Ru2 P/WO3 @NPC is achieved by electron transfer from NPC to Ru2 P/WO3 and from Ru2 P to WO3 , which directly promotes the dissociation of water on W sites in WO3 and desorption of hydrogen on Ru sites in Ru2 P.

In this work, an adsorbent, which we call MnPT, was prepared by combining MnO2, polyethylenimine and tannic acid, and exhibited efficient performance for Cu(II) and Cr(VI) removal from aqueous solution. The oxygen/nitrogen-containing functional groups on the surface of MnPT might increase the enrichment of metal ions by complexation. The maximum adsorption capacities of MnPT for Cu(II) and Cr(VI) were 121.5 and 790.2 mg·g−1, respectively. The surface complexation formation model was used to elucidate the physicochemical interplay in the process of Cu(II) and Cr(VI) co-adsorption on MnPT. Electrostatic force, solvation action, adsorbate-adsorbate lateral interaction, and complexation were involved in the spontaneous adsorption process. Physical electrostatic action was dominant in the initial stage, whereas chemical action was the driving force leading to adsorption equilibrium. It should be noted that after adsorption on the surface of MnPT, Cr(VI) reacted with some reducing functional groups (hydroxylamine-NH2) and was converted into Cr(III). The adsorption capacity declined by 12% after recycling five times. Understanding the adsorption mechanism might provide a technical basis for the procedural design of heavy metal adsorbents. This MnPT nanocomposite has been proven to be a low-cost, efficient, and promising adsorbent for removing heavy metal ions from wastewater.

One drug's pharmacological activity may be changed unexpectedly, owing to the concurrent administration of another drug. It is likely to cause unexpected drug-drug interactions (DDIs). Several machine learning approaches have been proposed to predict the occurrence of DDIs. However, existing approaches are almost dependent heavily on various drug-related features, which may incur noisy inductive bias. To alleviate this problem, we investigate the utilization of the end-to-end graph representation learning for the DDI prediction task. We establish a novel DDI prediction method named GCN-BMP (Graph Convolutional Network with Bond-aware Message Propagation) to conduct an accurate prediction for DDIs. Our experiments on two real-world datasets demonstrate that GCN-BMP can achieve higher performance compared to various baseline approaches. Moreover, in the light of the self-contained attention mechanism in our GCN-BMP, we could find the most vital local atoms that conform to domain knowledge with certain interpretability.

Developing high-efficiency electrocatalysts for artificial nitrogen fixation at room temperature and atmospheric pressure is fundamentally important but challenging. Herein, MoFe-PC (PC, phosphorus-doped carbon) microspheres, synthesized by facile one-step pyrolysis–phosphating of bimetallic metal–organic framework (MOF) precursors, were used as a cost-efficient catalyst for the electrocatalytic nitrogen reduction reaction (NRR). With the advantageous characteristics of the multicomponent active sites and porous structure inherited from the MOF precursor, the MoFe-PC catalyst achieves a peak NH3 yield rate of 34.23 μg h−1 mgcat.−1 with a high faradaic efficiency (FE) of 16.83% at −0.5 V vs. a reversible hydrogen electrode (RHE) in 0.1 M HCl under ambient conditions, exceeding those of most of the previously reported noble metal- or non-noble metal-based NRR electrocatalysts under the same conditions. The changes of the surface composition and structure of the catalyst before and after NRR testing are monitored by ex situ XPS and XANES. The Mo and Fe oxides and PC in the hybrids are both active in the NRR, synergistically enhancing the NRR performance.

MoS2-based nanomaterials are considered promising effective electrocatalysts to replace precious metal catalysts for hydrogen evolution reaction. However, understanding the effect of MoO2 in MoS2-based catalysts for hydrogen evolution reaction is ambiguous. In this paper, MoS2 nanoflowers of 210–430 nm in diameter were hydrothermally synthesized by the reduction of α-MoO3 particles with KSCN in a hydrochloric acid medium. Similarly, MoO2–MoS2-B nanoflowers and MoO2–MoS2-R nanoflowers were fabricated using α-MoO3 nanobelts and h-MoO3 microrods as Mo sources, respectively. Systematic studies on synthetic parameters verified that the formation of MoS2 nanoflowers is favored with high acidity, low MoO3/KSCN ratio and high temperature. The resultant nanoflowers served as electrocatalysts to drive hydrogen evolution in acidic solution. The MoS2 nanoflowers showed a relatively higher activity with a potential of 256 mV at 10 mA cm−2 compared to MoO2–MoS2-B nanoflowers (283 mV) and MoO2–MoS2-R nanoflowers (305 mV). Furthermore, MoS2 nanoflower catalysts maintained high stability after 1000 cycles and long-term durability for 5 h. The high catalytic activity could be ascribed to the large exposure of the Mo–S species and small amounts of Mo–O species on the MoS2-based catalyst surface.

Developing a highly efficient and cost-effective electrocatalyst for catalyzing the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is fundamentally important for the practical application of the overall water splitting technique. Herein, a bifunctional electrocatalyst constituted by FexNiy and CeO2 nanoparticles supported on the N-doped nanocarbon (NC) is fabricated by a simple one-pot pyrolysis of the homogeneous mixture of Fe, Ni, Ce nitrates and melamine. The synergistic effect of each component in the FexNiy/CeO2/NC gives rise to outstanding electrocatalytic activities and stability toward the HER and OER. For hydrogen evolution, the FexNiy/CeO2/NC shows a smaller overpotential of 260 mV to achieve a current density of 50 mA cm−2 in a 1 M KOH electrolyte. More significantly, a small overpotential of 240 mV for FexNiy/CeO2/NC affords an oxygen evolution current density of 10 mA cm−2, far lower than that of the benchmark IrO2. The practicability and electrocatalytic activity of the prepared FexNiy/CeO2/NC under practical operation conditions are also investigated. In particular, the FexNiy/CeO2/NC-based overall water splitting cell only needs a cell voltage of 1.70 V to output 10 mA cm−2 in alkaline electrolytes, comparable to that of the IrO2∥Pt/C cell. The present study may pioneer a new avenue for developing novel bifunctional electrocatalysts with high-performance and low cost for water splitting.

Developing effective bifunctional electrocatalysts for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) has a pivotal role in large-scale application of hydrogen energy. Herein, a facile and scalable strategy is developed to prepare in situ supported MoS2 coupled with CoB with Se doping on carbon cloth (MoS2/CoB–Se/CC) via a solvothermal process and subsequent selenylation treatment. For the HER, MoS2/CoB–Se/CC delivers the smallest overpotential (93 mV) to reach 10 mA cm−2 compared to MoS2/CoB/CC (158 mV), MoS2/CC (234 mV), and CoB/CC (410 mV) in 1 M KOH, indicating that the coupling effects of MoS2 and CoB with Se doping are responsible for boosting the catalytic performance. Impressively, the designed MoS2/CoB–Se/CC also presents outstanding catalytic activity for the OER, with only a small overpotential of 270 mV needed to drive 10 mA cm−2. Moreover, the developed MoS2/CoB–Se/CC used as both anode and cathode also shows remarkable catalytic performance for overall water-splitting, with a small cell voltage of 1.58 V needed to drive 10 mA cm−2. This work provides an efficient and promising protocol to design bifunctional electrocatalysts for overall water-splitting.

Developing low-cost and highly efficient electrocatalysts for overall water splitting is of far-reaching significance for new energy conversion. Herein, dual-cation Fe, Al-co-doped NiSe2 nanoparticles on reduced graphene oxide (Fe, Al-NiSe2/rGO) were prepared as a bifunctional electrocatalyst for overall water splitting. The dual-cation doping can induce a stronger electronic interaction between the foreign atoms and host catalyst, for optimizing the adsorption energy of reaction intermediates. Meanwhile, the leaching out of Al from the crystal structure of the target product during the alkaline wash creates more defects and increases the active site exposure. As a result, the Fe, Al-NiSe2/rGO catalyst exhibits excellent catalytic activities for both the OER and HER with an overpotential of 272 mV @η10 for the OER in 1.0 M KOH and 197 mV @η10 for the HER in 0.5 M H2SO4, respectively. A two-electrode electrolyzer using Fe, Al-NiSe2/rGO as the anode and cathode shows a low voltage of 1.70 V at the current density of 10 mA cm−2. This study emphasizes the synergistic contribution of the dual-cation co-doping effect and more defects created by Al leaching to boost the performance of water splitting.

It is vital to tailor the surface structure and composition of nanocatalysts, which greatly affect the catalytic activity through the exposure of specific atom coordination environment. To date, less progress has been made in tuning the interface structures of pyrite for promoting the catalytic activity towards overall water splitting. Herein, we developed a facile one-spot strategy to make carbon-layer-coated CoS2-FeS2 heterojunction nanosheets. The carbon layer and interface structures between Co-S and Fe-S were characterized via high resolution transmission electron microscopy. It exhibited a high OER activity with 1.47 V at 10 mA cm-2, which was superior to that of the commercial RuO2. Meanwhile, the carbon-layer-coated CoS2-FeS2 heterojunction nanosheets with the overpotential of 210 mV at 10 mA cm-2 was more active than FeS2 nanosheets with 240 mV in the hydrogen evolution reaction. Notably, it enhanced the catalytic activity towards the overall water splitting with the voltage of 1.66 V at 10 mA cm-2 using a two-electrode system. The remarkable long-term stability was verified by a slight change in the current density of 6 mA cm-2 for 26 h. The prominent catalytic activity could be related to the exposure of the carbon layer and interface structures. This work demonstrates that engineering the interface structure is essential for boosting the overall water splitting activity.

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.

The table-based fact verification task has recently gained widespread attention and yet remains to be a very challenging problem. It inherently requires informative reasoning over natural language together with different numerical and logical reasoning on tables (e.g., count, superlative, comparative). Considering that, we exploit mixture-of-experts and present in this paper a new method: Self-adaptive Mixture-of-Experts Network (SaMoE). Specifically, we have developed a mixture-of-experts neural network to recognize and execute different types of reasoning -- the network is composed of multiple experts, each handling a specific part of the semantics for reasoning, whereas a management module is applied to decide the contribution of each expert network to the verification result. A self-adaptive method is developed to teach the management module combining results of different experts more efficiently without external knowledge. The experimental results illustrate that our framework achieves 85.1% accuracy on the benchmark dataset TabFact, comparable with the previous state-of-the-art models. We hope our framework can serve as a new baseline for table-based verification. Our code is available at https://github.com/THUMLP/SaMoE., Accepted by Findings of ACL 2022

Developing high-efficiency and earth-abundant electrocatalysts for electrochemical seawater-splitting is of great significance but remains a grand challenge due to the presence of high-concentration chloride. This work presents the synthesis of a three-dimensional core-shell nanostructure with an amorphous and crystalline NiFe-layered double hydroxide (NiFe-LDH) layer on sulfur-modified nickel molybdate nanorods supported by porous Ni foam (S-NiMoO

Ru nanoparticles have been demonstrated to be highly active electrocatalysts for the hydrogen evolution reaction (HER). At present, most of Ru nanoparticles-based HER electrocatalysts with high activity are supported by heteroatom-doped carbon substrates. Few metal oxides with large band gap (more than 5 eV) as the substrates of Ru nanoparticles are employed for the HER. By using large band gap metal oxides substrates, we can distinguish the contribution of Ru nanoparticles from the substrates. Here, a highly efficient Ru/HfO

The oxygen evolution reaction (OER) is a key reaction for many electrochemical devices. To date, many OER electrocatalysts function well in alkaline media, but exhibit poor performances in neutral and acidic media, especially the acidic stability. Herein, sodium-decorated amorphous/crystalline RuO

Rational design and feasible synthesis of economical, efficient and durable electrocatalysts as alternatives to precious metal-based catalysts toward the oxygen reduction reaction (ORR) is extremely desirable for the advancement of future sustainable energy devices. Herein, we demonstrate a feasible hydrogel-bridged nitridation method to construct a 3D hierarchical carbon nanohybrid consisting of uniform Fe3N nanoparticles immobilized by N-doped carbon nanosheet frameworks (abbreviated as Fe3N@N–C). Lyophilization and subsequent nitridation treatment of the hydrogel formed by chitosan and K3[Fe(CN)6] result in the formation of Fe3N@N–C catalyst. The firm coupling of well-dispersed Fe3N nanoparticles with the carbon nanosheet frameworks confers the synthesized Fe3N@N–C catalyst with abundant Fe–N–C active sites, robust mechanical strength and improved reaction kinetics. Consequently, the Fe3N@N–C catalyst shows excellent ORR activity, superb stability and remarkable tolerance to methanol in alkaline condition, as compared with commercial Pt/C catalyst. Remarkably, when applied as an air cathode catalyst in a primary Zn-air battery, the Fe3N@N–C catalyst displays comparable performance to the commercial Pt/C catalyst with high power density and specific capacity. The proposed strategy in this work is anticipated to inspire the future design of cost-effective yet high-performance electrocatalysts for advanced electrochemical applications.

High-purity hydrogen can be generated by hydrolysis of sodium borohydride and used for operating portable proton exchange membrane fuel cells. The monolith supported catalyst is suitable for practical NaBH4-based hydrogen generation system due to its simple reactor structure miniaturizing for small size applications and easy separation from the spent solution. In the present study, a structured catalyst was prepared by wash-coating the Al2O3 sol over the wall of cordierite monolith followed by depositing Pt using incipient wet impregnation method; then the monolithic catalysts were characterized by XRF, XRD, SEM, HRTEM and XPS. The catalytic activity of the Pt-based monolithic catalyst towards hydrolysis of NaBH4 was tested using a flow reactor under ambient conditions in an autothermal manner. The characterization results show that Pt nanoparticles are highly dispersed on the surface of the Al2O3-coated layer. A continuous and stable hydrogen generation can be obtained by feeding the reactant (10 wt% NaBH4–5 wt % NaOH) into the tube reactor loaded with the monolithic catalyst at feed rates of 0.5–2.0 mL min−1.

The exploration of highly active and stable nonprecious electrocatalysts for the hydrogen evolution reaction (HER) is of great significance for the advancement of diverse sustainable energy storage and conversion systems. Herein, we demonstrate a facile one-pot hydrothermal synthesis of ultrafine and monodisperse NiS/NiS2 heteronanoparticles (ca. 3.2 nm) uniformly in situ grown on N-doped reduced graphene oxide nanosheets (denoted as NiS/NiS2@N-rGO hereafter). In such unique NiS/NiS2@N-rGO sample, the tiny-sized NiS/NiS2 heteronanoparticles with abundant intimate interfacial contacts allow the effective modification of the electronic structure and more exposure of catalytically active sites. Moreover, the conductive N-rGO support could serve as a “highway” of in-plane charge transfer and facilitate the mass diffusion during the electrocatalytic process. As a consequence, the resultant NiS/NiS2@N-rGO catalyst exhibits a superior HER performance with an overpotential of 148 mV to deliver a current density of 10 mA cm−2 in 1.0 M KOH solution. The NiS/NiS2@N-rGO catalyst could also endure long-term operation for 12 h with negligible activity attenuation and morphological change. The present study provides a feasible approach to explore efficient and robust non-noble metal-based electrocatalysts for a variety of renewable electrochemical applications.

Developing highly efficient and low-cost nonprecious electrocatalysts for hydrogen evolution reaction (HER) has a pivotal impact on the emergence of hydrogen energy. Herein, quaternary electrocatal...

A nanocomposite of PC/Sb/SbPO4 (PC, phosphorus-doped carbon) exhibits a high activity and an excellent selectivity for efficient electrocatalytic conversion of N2 to NH3 in both acidic and neutral electrolytes under ambient conditions. At a low reductive potential of -0.15 V versus the reversible hydrogen electrode (RHE), the PC/Sb/SbPO4 catalyst achieves a high Faradaic efficiency (FE) of 31 % for ammonia production in 0.1 m HCl under mild conditions. In particular, a remarkably high FE value of 34 % is achieved at a lower reductive potential of -0.1 V (vs. RHE) in a 0.1 m Na2 SO4 solution, which is better than most reported electrocatalysts towards the nitrogen reduction reaction (NRR) in neutral electrolyte under mild conditions. The change in surface species and electrocatalytic performance before and after N2 reduction is explored by an ex situ method. PC and SbPO4 are both considered as the active species that enhanced the performance of NRR.

Replacing the commercial Pt/C with non-precious metal-based electrocatalysts in the proton exchange membrane fuel cells and metal-air batteries is still challenging. Herein, an electrocatalyst (described as Fe-N-C/Fe100-x-y-zPxOyNz/NPC, NPC is N, P co-doped carbon) composed of multiple active components, such as NPC, iron-based porous hollow spheres and Fe-N-C, is reported, which exhibits an excellent activity that is comparable to state-of-the-art Pt/C for half-cell and full zinc-air battery in alkaline media. This catalyst exhibits an excellent activity with a half-wave potential of 0.86 V for the ORR in alkaline media, which is 10 mV more positive than to that of Pt/C (0.85 V), and a gravimetric energy density for zinc-air battery is up to 675 Wh Kgzn−1. The excellent activity is attributed to the synergetic effect of active NPC, iron-based porous hollow spheres (Fe100-x-y-zPxOyNz) and Fe-N-C in its structure. In addition, phosphoric acid groups are partially remained in the structure for our catalyst that make the catalyst excellent hydrophilicity. This work adds a new member into family of non-precious metal-based ORR electrocatalysts.

Developing highly efficient and economically sustainable electrocatalysts with bifunctions for the oxygen reduction reaction and oxygen evolution reaction is crucially important in practical implementation of rechargeable zinc-air batteries. Herein, a novel Cu-based electrocatalyst composed of Cu97P3-x-yOxNy nanoparticles supported on N, P co-doped carbon is synthesized straightforward by the annealing of the Cu-phytic acid gel under an argon and ammonia gases atmosphere. The Cu97P3-x-yOxNy/N, P co-doped carbon catalyst displays the outstanding catalytic performance for both the oxygen evolution reaction and oxygen reduction reaction in alkaline solution, which is ascribed to the synergistic effect of Cu97P3-x-yOxNy and N, P co-doped carbon. Meanwhile, the primary and rechargeable zinc-air batteries assembled by the Cu97P3-x-yOxNy/N, P co-doped carbon catalyst exhibit a high specific capacity and remarkable charge-discharge cycle stability, which are comparable to that of the benchmark Pt/C and IrO2. The energy density of the catalyst reaches to 737 Wh kgZn−1. To the best of our knowledge, few Cu-based electrocatalysts is reported for rechargeable zinc-air batteries.

An effective and scalable strategy was used to develop cobalt sulfide microtubes composed of nanosheets coated with an N-doped carbon shell (Co9S8@N-C) as an anode material for Li-ion batteries. The conductive carbon shell can provide fast transport of ions and electrons within the electrode, while remarkably enhancing the structural integrity of the electrode. Moreover, the volume expansion and aggregation of Co9S8 can be inhibited during lithiation-delithiation due to the intimate contact between Co9S8 and the carbon shell. Benefiting from this structure, the Co9S8@N-C manifested outstanding electrochemical performance including an initial specific capacity of 1654 mAh g−1 higher than that of Co9S8 (1350 mAh g−1) at a current density of 100 mA g−1, excellent rate capability, and superior cycling stability at 500 mAh g−1 for 2000 cycles. This electrochemical performance can be attributed to its superior conductivity, robust nanostructure, and relatively large surface area, rendering it a promising candidate for use as an anode material in Li-ion batteries.

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 (IrP2, Pd3P, or PtP2) nanoparticles with N,P-codoped nanocarbon were synthesized by the pyrolysis of mixtures of IrCl4, PdCl2, or PtCl4 with phytic acid under an ammonia atmosphere. With an ultralow loading of Pd (1.5 μg), Pt (1.4 μg), or Ir (1.6 μg) on the electrode, the Pd3P/NPC, PtP2/NPC, and IrP2/NPC catalysts, respectively, exhibited excellent trifunctional catalytic activities for the oxygen reduction reaction, hydrogen evolution reaction, and oxygen evolution reaction. Notably, the IrP2/NPC-, Pd3P/NPC-, and PtP2/NPC-based water-splitting cells required only 1.62, 1.65, and 1.68 V, respectively, to deliver the current density of 10 mA cm-2. Furthermore, the IrP2/NPC-, Pd3P/NPC-, and PtP2/NPC-based zinc-air batteries exhibited higher specific capacities than that of Pt/C. IrP2/NPC exhibited a comparable performance to that of Pt/C-IrO2 for use in rechargeable zinc-air batteries.

Metal–organic frameworks (MOFs) have gained significant attention as precursors for the fabrication of porous hybrid materials. However, a systematic investigation into the preparation of MOF-derived composites with high catalytic performance for hydrolysis of NaBH4 is very limited. In this work, we report the fabrication of Co@C composites using Co-MOF as the starting precursor. Physicochemical properties of the as-prepared Co@C catalysts are well characterized by XRD, BET, SEM, XPS, and HRTEM. The results of catalytic performance tests show that the Co@C-700 catalyst exhibits optimal activity among the Co@C catalysts prepared at different carbonization temperatures and retains 93.1% of its initial catalytic activity after five cycles. The cobalt nanoparticles are found to be highly dispersed and encapsulated in porous carbon, which might be responsible to the good stability of Co@C catalyst.

We have developed a facile quaternarization strategy to an ultrathin lamellar g-C3N4 ionic liquid nanostructure (IL-CNNS) via a nucleophilic substitution between the tertiary amino groups in tri-s-triazine subunits and n-butyl bromide. After functionalization, the obtained IL-CNNS composite exhibits the enhanced conductivity, dispersibility and stability owing to the formation of IL structure. This composite has been characterized by several spectroscopic techniques (FT-IR, XRD, XPS, TGA and TEM). The IL-CNNS modified electrode displays the larger effective surface area and the faster electron transfer rate, hence resulting in the superior electrocatalytic activity toward 2,4-Dichlorophenol (2,4-DCP). Under the optimal conditions, the proposed 2,4-DCP sensor gives rise to the wide linear range from 0.02 to 160 μM with a low detection limit (6.21 nM, S/N = 3) by amperometric method. The developed sensor has been applied to detect 2,4-DCP in water samples with satisfactory recoveries and stability. This quaternarization strategy may open up a new avenue to fabricate the layered carbon nitride IL nanostructure for electrochemical sensing applications.

Highly dispersed and stable catalysts comprising Ru nanoparticles supported on boron-doped amphiphilic core-shell mesoporous molecular sieves (MMS-C@MMS-NH2/B/Ru) with alkyl-modified hydrophobic silica core and NH2-functionalized hydrophilic silica shell are successfully prepared for use in hydrogenation of alpha-pinene for the first time. Dodecyl-modified MMS-C-12@MMS-NH2/B/Ru exhibits the best catalytic activity under mild hydrogenation conditions. The abundant -NH2 functional groups on the molecular sieve surface and their amphipathy allow the sieves to facilitate attachment of more Ru nanoparticles, and to simplify their dispersion in the water-organic reaction medium. Moreover, B-doped molecular sieves may adjust their acidity to meet the needs of alpha-pinene hydrogenation. Under mild reaction conditions (25 degrees C, 1 MPa H-2, and 1 h), alpha-pinene can be completely converted with 99 % selectivity to cis-pinane, because every nanocomposite is equivalent to a microreactor. The catalytic activity does not change much over 5 cycles, indicating that Ru nanoparticles are stably loaded on the molecular sieves.

Considerable efforts have been made to tailor the crystalline structure and morphology of tungsten oxide. The activity of tungsten oxide was not only associated with the geometrical structure of the catalysts but also determined by the active surface. In this work, WO3 nanocuboids were fabricated through hydrothermal treatment of commercial WO3 with the aid of H2O2. It was found that WO3·0.33H2O nanocuboids were formed at the initial stage and vanished with high temperature; while WO3 nanocuboids were produced at 240 °C. Experiments revealed that WO3 nanocuboids possessed much more amounts of coordinative unsaturated W sites than the WO3·0.33H2O nanocuboids. Due to the unsaturated coordination environment, the WO3 nanocuboids show a higher photocatalytic activity in the methylene blue degradation.

Rationally designed and synthesized non-noble metal-based multifunctional electrocatalysts with outstanding activity and durability for oxygen evolution reaction (OER), hydrogen evolution reaction (HER), and oxygen reduction reaction (ORR) are critical to the commercialization of energy-related devices. Herein, two trifunctional electrocatalysts composed of Ni–NiM2O4 (M = Mn or Fe) supported on N-doped carbon nanotubes (NCNT) were in situ synthesized by pyrolysis of NiMn- and NiFe-based precursors, respectively, under a NH3/Ar atmosphere. The hybrids exhibit robust trifunctional catalytic performance for HER, OER and ORR in an alkaline electrolyte. Especially, NCNT/Ni–NiMn2O4 exhibits excellent performance for zinc–air batteries with a high specific capacity of 502 mA h g−1 and a maximum power density of 105 mW cm−2, comparable to that of the Pt/C-based zinc–air battery. This study provides a feasible strategy for preparing highly efficient trifunctional electrocatalysts by in situ coupling metal/metal spinel oxide composites with high conductivity nanocarbon.

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.

Developing an efficient and inexpensive non-precious electrocatalyst to reduce the overpotential of hydrogen evolution reaction (HER) is of critical importance for the large scale production of hydrogen energy. Herein, a two-dimensional layered molybdenum-based catalyst coupled with N-doped carbon was prepared through a facile and scalable hydrothermal-low temperature pyrolysis strategy. Particularly, the content of carbon source and pyrolysis temperature have an extremely important influence on the composition of the catalyst. Moveover, the relationship between chemical composition and catalytic performance was investigated systematically. Impressively, the optimal electrocatalyst possesses excellent catalytic performance in terms of the low overpotential (121 mV) with a small Tafel slope (54 mV dec−1). More importantly, This work provide an avenue to the future design and preparation of other molybenum based electrocatalysts.

It is an urgent requirement to develop non-precious metal-based catalysts with excellent electrocatalytic activity and stability to accelerate the development of hydrogen generation via energy-efficient routes. Herein, a facile and scalable strategy was developed to synthesize both rod-like Co(OH)F and Co–P nanoarrays supported on Ni-foam, denoted as Co(OH)F/NF and Co–P/NF, respectively. Electrochemical measurements demonstrate that Co–P/NF exhibits excellent electrocatalytic performance for the hydrogen evolution reaction (HER), delivering a low overpotential of 70 mV and 43 mV at 10 mA cm−2 in alkaline and acid media, respectively. Furthermore, the as-prepared Co(OH)F/NF contributes to an outstanding oxygen evolution reaction (OER) performance with a low oxidation potential of about 1.5 V at 10 mA cm−2. In addition, the Co(OH)F/NF also can enable highly efficient urea oxidation reaction (UOR) electrocatalysis, which can be utilized to substitute OER to lower the overpotential and thus reduce electrical energy consumption during H2-production. As a proof of concept, full water-splitting measurements were performed with Co–P/NF and Co(OH)F/NF as cathode and anode, respectively, in 1 M KOH with 0.7 M urea. The Co–P/NF‖Co(OH)F/NF electrode is capable of producing a current density of 20 mA cm−2 at a cell potential of only 1.42 V, which is 230 mV less than that for the urea-free counterpart, demonstrating its potential feasibility in practical applications of energy-efficient hydrogen production.

Highly efficient and stable bifunctional electrocatalysts for ORR and OER are essential for fabricating rechargeable zinc–air batteries. Herein, we prepared metal-free N,P-codoped hydrophilic carbon nanosheets (NPC-“Li”) as effective bifunctional electrocatalysts using LiCl as the medium, in which phytic acid was used as the source of phosphorous and carbon, and ammonia atmosphere as the source of nitrogen. Furthermore, micrometer-sized agglomerations of carbon materials were significantly restrained using LiCl. NPC-“Li” exhibits superior bifunctional catalytic activity for both ORR and OER. In addition, the NPC-“Li”-based primary zinc–air battery shows a high energy density of 908 Wh kgZn−1, and the rechargeable battery shows excellent charge–discharge cycle efficiency.

Rechargeable lithium-iodine (Li-I2) battery is a promising energy storage system because of the high energy and power density. However, the shuttle effects of iodine species and the unstable features of I2 block the practical applications of Li-I2 batteries. Herein, a dual heteroatom doped porous carbon cloth is fabricated as the host material for lithium iodide (LiI). Specifically, the self-standing nitrogen, phosphorus co-doped carbon cloth with high LiI loading exhibits a large specific capacity (221 mAh·g−1 at 1 C), excellent rate capability (95.8% capacity retention at 5 C) and superior long cycling stability (2,000 cycles with a capacity retention of 96%). Electrochemical kinetic analysis confirms the dominant contribution of capacitive effects at high scan rates, which is responsible for the good high-rate performance. The improved electrochemical performance mainly stems from two unique features of nitrogen, phosphorus co-doped porous carbon cloth. Heteroatom doping provides extra active sites for strong adsorption of iodine species while the highly porous structure with large surface area favors the capacitive effects at high rates. This work provides a facile yet efficient approach to regulating both redox reaction and capacitive effects via adjusting surface composition and pore structure of carbon materials for enhanced battery performance.

Preparing non-noble metal and metal-free electrocatalysts as the alternatives to noble metal-based materials, such as Pt/C, IrO2, is very necessary for energy conversion and storage. Carbon-based nanomaterials are promising candidates because of their low-cost, good electrical conductivity, and high surface area. Among the carbon nanomaterials, graphene and carbon nanotube are more excellent as the electrocatalysts for oxygen electrode reactions, especially heteroatoms doped graphene and carbon nanotube. Herein, we developed a bifunctional electrocatalyst composed of nitrogen, sulfur co-doped graphene oxide and multi-walled carbon nanotube (N, S-GCNT), which exhibit good performance for catalyzing oxygen reduction and evolution reactions. These properties are comparable to those of noble-based catalysts such as Pt/C and IrO2, which are attributed to the synergetical effect of doped N, S because they modified the polarity of carbon in the graphene and carbon nanotube. This work provides a simple way to prepare high performance carbon-based metal-free catalysts for the applications in energy-related reactions.

Lattice disorder engineering on highly crystalline texture toward high-efficiency N2-to-NH3 electrocatalysis is tremendously challenging. Here, abundant lattice disturbances were established on an ultrafine Nb2O5 nanoparticle by Cu substitution. Cu-Nb2O5 anchored on a carbon material (Cu-Nb2O5@C) exhibits excellent activity and high selectivity for N2 electroreduction to NH3 with a yield rate of 28.07 μg h-1 mg-1 and a faradaic efficiency (FE) of 13.25% at -0.2 V vs. reversible hydrogen electrode (RHE) in acidic electrolyte. Cu-Nb2O5@C presents superb durability with no obvious change in catalyst constituents and structure after N2 reduction as confirmed by ex situ characterization studies. The excellent catalytical performance should originate from structural superiority of lattice turbulence for more active sites and optimized electronic state as well as good conductivity of carbon support. Meanwhile, in neutral electrolyte, the NH3 FE also reaches up to 10.29% at the same potential.

ICD-9-CM Volume 3 (ICD-9-CM-3), as a subset of the ICD-9-CM, is a standard system used to classify operations and medical procedures for billing purposes. With the gradual maturity of the DRG system, the precise coding of ICD-9-CM-3 is increasingly important for both hospital revenue and patients’ health. In this paper, a method based on BERT and NER capturing Multi-Features for automatic Chinese ICD-9-CM-3 Coding (BNMF) is proposed to support doctors to make decisions so that traditional manual coding in hospitals can be replaced. The method is designed focusing on short text information from electronic medical records (EMR) and make decisions by combining the semantic features of the clinical text, the structured features of Chinese ICD-9-CM-3, and the axis knowledge of Chinese ICD-9-CM-3 text. Meanwhile, fusion of spatial and temporal features is made to better capture semantic features. The experiments demonstrate that the efficiency of our framework is higher than those of state-of-the-art methods in the field of classification of the short medical corpus.

This paper describes our system for verifying statements with tables at SemEval-2021 Task 9. We developed a two-stage verifying system based on the latest table-based pre-trained model GraPPa. Multiple networks are devised to verify different types of statements in the competition dataset and an adaptive model ensembling technique is applied to ensemble models in both stages. A statement-slot-based symbolic operation module is also used in our system to further improve the performance and stability of the system. Our model achieves second place in the 3-way classification and fourth place in the 2-way classification evaluation. Several ablation experiments show the effectiveness of different modules proposed in this paper.

It is imperative but challenging to develop non-noble metal-based bifunctional electrocatalysts for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). Our work reports a core-shell nanostructure that is constructed by the electrodeposition of ultrathin NiFe-LDH nanosheets (NiFe-LDHNS) on Cu