Ionic liquid-derived Fe, N, S, F multiple heteroatom-doped carbon materials for enhanced oxygen reduction reaction.

Heteroatoms doped carbon catalysts have been intensively studied to take the place of Platinum based catalysts for oxygen reduction reaction (ORR) because of their ideal catalytic activity. Herein, the microporous-mesoporous carbon material catalysts doped with Fe, N, S and F were synthesized through a plain one-pot pyrolysis method with ionic liquid 1-butyl-3-methyli-midazolium bis((trifluoromethyl)sulfonyl)imide ([Bmim][TF2N]) and melamine as precursors. Electrochemical analysis shows that the ORR activity and stability of the obtained catalysts are obviously better than Pt/C under alkaline condition. Meanwhile, the catalysts show similar ORR activity and much better durability in 0.1 M HClO4comparing to Pt/C. Moreover, the tolerance of methanol in both basic and acid solutions is greatly better than Pt/C. The high activity is ascribed to the large specific surface area, porous structure and the synergistic effect between S, F, pyridine N, graphite N and Fe-Nx. The high stability possibly comes from the appropriate graphitization and the carbon-coating effect. The strategy proposed here has the advantages of facile, low cost, high efficiency and easy large-scale production, which provides new ideas for the preparation of high-performance Fe-N-C electrocatalysts.

Interface Modulation of MoS2 /Metal Oxide Heterostructures for Efficient Hydrogen Evolution Electrocatalysis.

Developing efficient earth-abundant MoS2 based hydrogen evolution reaction (HER) electrocatalysts is important but challenging due to the sluggish kinetics in alkaline media. Herein, a strategy to fabricate a high-performance MoS2 based HER electrocatalyst by modulating interface electronic structure via metal oxides is developed. All the heterostructure catalysts present significant improvement of HER electrocatalytic activities, demonstrating a positive role of metal oxides decoration in promoting the rate-limited water dissociation step for the HER mechanism in alkaline media. The as-obtained MoS2 /Ni2 O3 H catalyst exhibits a low overpotential of 84 mV at 10 mA cm-2 and small charge-transfer resistance of 1.5 Ω in 1 m KOH solution. The current density (217 mA cm-2 ) at the overpotential of 200 mV is about 2 and 24 times higher than that of commercial Pt/C and bare MoS2 , respectively. Additionally, these MoS2 /metal oxides heterostructure catalysts show outstanding long-term stability under a harsh chronopotentiometry test. Theoretical calculations reveal the varied sensitivity of 3d-band in different transition oxides, in which Ni-3d of Ni2 O3 H is evidently activated to achieve fast electron transfer for HER as the electron-depletion center. Both electronic properties and energetic reaction trends confirm the high electroactivity of MoS2 /Ni2 O3 H in the adsorption and dissociation of H2 O for highly efficient HER in alkaline media.

Increasing Stability and Activity of Core-Shell Catalysts by Preferential Segregation of Oxide on Edges and Vertexes: Oxygen Reduction on Ti-Au@Pt/C.

We describe a new class of core-shell nanoparticle catalysts having edges and vertexes covered by refractory metal oxide that preferentially segregates onto these catalyst sites. The monolayer shell is deposited on the oxide-free core atoms. The oxide on edges and vertexes induces high catalyst stability and activity. The catalyst and synthesis are exemplified by fabrication of Au nanoparticles doped by Ti atoms that segregate as oxide onto low-coordination sites of edges and vertexes. Pt monolayer shell deposited on Au sites has the mass and specific activities for the oxygen reduction reaction about 13 and 5 times higher than those of commercial Pt/C catalysts. The durability tests show no activity loss after 10 000 potential cycles from 0.6 to 1.0 V. The superior activity and durability of the Ti-Au@Pt catalyst originate from protective titanium oxide located at the most dissolution-prone edge and vertex sites and Au-supported active and stable Pt shell.

Stable production of hydrogen peroxide over zinc oxide @ zeolitic imidazolate Framework-8 composite catalysts.

A promising method of producing hydrogen peroxide (H2O2) is the electrochemical two-electron water oxidation reaction (2e- WOR). In this process, it is important to design electrocatalysts that are both earth abundant and environmentally friendly, as well as offering high stability and production rates. The research of WOR catalysts, such as the extensively used transition metal oxides, is mainly focused on the modification of transition metal elements. Few studies pay attention to the protective heterostructure of metal oxides. Here, we demonstrate for the first time an organometallic skeleton protection strategy to develop highly stable WOR catalysts for H2O2 generation. Unlike the pure ZnO and zeolite imidazole framework-8 (ZIF-8) catalysts, ZnO@ZIF-8 enabled the production of hydrogen peroxide at high voltages. The experimental results demonstrate that the ZnO@ZIF-8 catalyst stably generates H2O2 even under a high voltage of 3.0 V vs. RHE, with a yield reaching 2845.819 µmolmin-1 g-1. ZnO@ZIF-8 shows a relatively low overpotential, with a current density of 10 mA cm-2 and an overpotential of 110 mV. The ZnO@ZIF-8 catalyst's maximal FE value was 4.72 %. Moreover, the ZnO@ZIF-8 catalyst exhibits remarkable durability even after an extended 60-hour stability test. Operando Raman and theoretic calculation analyses reveal that the metal-organic skeleton being encapsulated on the metal oxide surface synergizes with each other, not only expanding the electrochemical surface area, but also adjusting the catalyst metal sites' adsorption capacity. A novel approach to the modification of 2e- WOR metal oxide catalyst is presented in this work.

In Situ Reconstruction of High-Entropy Heterostructure Catalysts for Stable Oxygen Evolution Electrocatalysis under Industrial Conditions.

Despite of urgent needs for highly stable and efficient electrochemical water-splitting devices, it remains extremely challenging to acquire highly stable oxygen evolution reaction (OER) electrocatalysts under harsh industrial conditions. Here, a successful in situ synthesis of FeCoNiMnCr high-entropy alloy (HEA) and high-entropy oxide (HEO) heterocatalysts via a Cr-induced spontaneous reconstruction strategy is reported, and it is demonstrated that they deliver excellent ultrastable OER electrocatalytic performance with a low overpotential of 320 mV at 500 mA cm-2 and a negligible activity loss after maintaining at 100 mA cm-2 for 240 h. Remarkably, the heterocatalyst holds outstanding long-term stability under harsh industrial condition of 6 m KOH and 85 °C at a current density of as high as 500 mA cm-2 over 500 h. Density functional theory calculations reveal that the formation of the HEA-HEO heterostructure can provide electroactive sites possessing robust valence states to guarantee long-term stable OER process, leading to the enhancement of electroactivity. The findings of such highly stable OER heterocatalysts under industrial conditions offer a new perspective for designing and constructing efficient high-entropy electrocatalysts for practical industrial water splitting.

Simultaneous adsorption and biodegradation of oxytetracycline in wastewater by Mycolicibacterium sp. immobilized on magnetic biochar.

Due to the adverse effects of long-term oxytetracycline (OTC) residues in aquatic environments, an effective treatment is urgently needed. Immobilized microbial technology has been widely explored in the treatment of various organic pollutants in aquatic environments with its excellent environmental adaptability. Nevertheless, studies on its application in the removal of antibiotics are relatively scarce and not in sufficient depth. Only a few studies have further investigated the final fate of antibiotics in the immobilized bacteria system. In this study, a novel kind of OTC-degrading bacteria Mycolicibacterium sp. was immobilized on straw biochar and magnetic biochar, respectively. Magnetic biochar was proved to be a more satisfactory immobilization carrier due to its superior property and the advantage of easy recycling. Compared with free bacteria, immobilized bacteria had stronger environmental adaptability under different OTC concentrations, pH, and heavy metal ions. After 5 cycles, immobilized bacteria could still remove 71.8% of OTC, indicating that it had a stable recyclability. Besides, OTC in real swine wastewater was completely removed by immobilized bacteria within 2 days. The results of FTIR showed that bacteria were successfully immobilized on biochar and O-H, N-H, and C-N groups might be involved in the removal of OTC. The fate analysis indicated that OTC was removed by simultaneous adsorption and biodegradation, while biodegradation (92.8%) played a dominant role in the immobilized bacteria system. Meanwhile, the amount of adsorbed OTC (7.20%) was rather small, which could effectively decrease the secondary pollution of OTC. At last, new degradation pathways of OTC were proposed. This study provides an eco-friendly and effective approach to remedy OTC pollution in wastewater.

Fabricating carbon quantum dots of graphitic carbon nitride vis ultrasonic exfoliation for highly efficient H2O2 production.

A promising and sustainable approach for producing hydrogen peroxide is the two-electron oxygen reduction reaction (2e- ORR), which uses very stable graphitic carbon nitride (g-C3N4). However, the catalytic performance of pristine g-C3N4 is still far from satisfactory. Here, we demonstrate for the first time the controlled fabrication of carbon quantum dots (CQDs)-modified graphitic carbon nitride carbon (g-C3N4/CQDs-X) by ultrasonic stripping for efficient 2e- ORR electrocatalysis. HRTEM, UV-vis, EPR and EIS analyses are in good consistent which prove the in-situ generation of CQDs. The effect of sonication time on the physical properties and ORR activity of g-C3N4 is discussed for the first time. The g-C3N4/CQDs-12 catalyst shows a selectivity of up to 95% at a potential of 0.35 V vs. RHE, which is much higher than that of the original g-C3N4 catalyst (88%). Additionally, the H2O2 yield is up to 1466.6 mmol g-1 in 12 h, which is twice as high as the original g-C3N4 catalyst. It is discovered that the addition of CQDs through ultrasonic improves the g-C3N4 catalyst's electrical conductivity and electron transfer capability in addition to its high specific surface area and distinctive porous structure, speeding up the reaction rate. This research offers a green method for enhancing g-C3N4 activity.

Rationally Reconstructed Metal-Organic Frameworks as Robust Oxygen Evolution Electrocatalysts.

Reconstructing metal-organic framework (MOFs) toward a designed framework structure provides breakthrough opportunities to achieve unprecedented oxygen evolution reaction (OER) electrocatalytic performance, but has rarely, if ever, been proposed and investigated yet. Here, the first successful fabrication of a robust OER electrocatalyst by precision reconstruction of an MOF structure is reported, viz., from MOF-74-Fe to MIL-53(Fe)-2OH with different coordination environments at the active sites. Due to the radically reduced eg -t2g crystal-field splitting in Fe-3d and the much suppressed electron-hopping barriers through the synergistic effects of the O species the efficient OER of in MIL-53(Fe)-2OH is guaranteed. Benefiting from this desired electronic structure, the designed MIL-53(Fe)-2OH catalyst exhibits high intrinsic OER activity, including a low overpotential of 215 mV at 10 mA cm-2 , low Tafel slope of 45.4 mV dec-1 and high turnover frequency (TOF) of 1.44 s-1 at 300 mV overpotential, over 80 times that of the commercial IrO2 catalyst (0.0177 s-1 ).Consistent with the density functional theory (DFT) calculations, the real-time kinetic simulation reveals that the conversion from O* to OOH* is the rate-determining step on the active sites of MIL-53(Fe)-2OH.

Metal-Based Electrocatalysts for Selective Electrochemical Nitrogen Reduction to Ammonia.

Ammonia (NH3) plays a significant role in the manufacture of fertilizers, nitrogen-containing chemical production, and hydrogen storage. The electrochemical nitrogen reduction reaction (e-NRR) is an attractive prospect for achieving clean and sustainable NH3 production, under mild conditions driven by renewable energy. The sluggish cleavage of N≡N bonds and poor selectivity of e-NRR are the primary challenges for e-NRR, over the competitive hydrogen evolution reaction (HER). The rational design of e-NRR electrocatalysts is of vital significance and should be based on a thorough understanding of the structure-activity relationship and mechanism. Among the various explored e-NRR catalysts, metal-based electrocatalysts have drawn increasing attention due to their remarkable performances. This review highlighted the recent progress and developments in metal-based electrocatalysts for e-NRR. Different kinds of metal-based electrocatalysts used in NH3 synthesis (including noble-metal-based catalysts, non-noble-metal-based catalysts, and metal compound catalysts) were introduced. The theoretical screening and the experimental practice of rational metal-based electrocatalyst design with different strategies were systematically summarized. Additionally, the structure-function relationship to improve the NH3 yield was evaluated. Finally, current challenges and perspectives of this burgeoning area were provided. The objective of this review is to provide a comprehensive understanding of metal-based e-NRR electrocatalysts with a focus on enhancing their efficiency in the future.

Tiny Ni Nanoparticles Embedded in Boron- and Nitrogen-Codoped Porous Carbon Nanowires for High-Efficiency Water Splitting.

The integration of nickel (Ni) nanoparticle (NP)-embedded carbon layers (Ni@C) into the three-dimensional (3D) hierarchically porous carbon architectures, where ultrahigh boron (B) and nitrogen (N) doping is a potential methodology for boosting Ni catalysts' water splitting performances, was achieved. In this study, the novel 3D ultrafine Ni NP-embedded and B- and N-codoped hierarchically porous carbon nanowires (denoted as Ni@BNPCFs) were successfully synthesized via pyrolysis of the corresponding 3D nickel acetate [Ni(AC)2·4H2O]-hydroxybenzeneboronic acid-polyvinylpyrrolidone precursor networks woven by electrospinning. After optimizing the pyrolysis temperatures, various structural and morphological characterization analyses indicate that the optimal Ni@BNPCFs-900 networks own a large surface area, abundant micro/mesopores, and vast carbon edges/defects, which boost doping a large amount of B (5.81 atom %) and N (5.84 atom %) dopants into carbon frameworks with 6.36 atom % of BC3, pyridinic-N (pyridinic-N-Ni), and graphitic-N active sites. Electrochemical measurements demonstrate that Ni@BNPCFs-900 reveals the best hydrogen evolution reaction (HER) and oxygen reduction reaction catalytic activities in an alkaline solution. The HER potential at 10 mA cm-2 [E10 = -164.2 mV vs reversible hydrogen electrode (RHE)] of the optimal Ni@BNPCFs-900 is just 96.2 mV more negative than that of the state-of-the-art 20 wt % Pt/C (E10 = -68 mV vs RHE). In particular, the OER E10 and Tafel slope of the optimal Ni@BNPCFs-900 (1.517 V vs RHE and 19.31 mV dec-1) are much smaller than those of RuO2 (1.557 V vs RHE and 64.03 mV dec-1). For full water splitting, the catalytic current density achieves 10 mA cm-2 at a low cell voltage of 1.584 V for the (-) Ni@BNPCFs-900||Ni@BNPCFs-900 (+) electrolysis cell, which is 10 mV smaller than that of the (-) 20 wt % Pt/C||RuO2 (+) benchmark (1.594 V) under the same conditions. The synergistic effects of 3D hierarchically porous structures, advanced charge transport ability, and abundant active centers [such as Ni@BNC, BC3, pyridinic-N (pyridinic-N-Ni), and graphitic-N] are responsible for the excellent water-splitting catalytic activity of the Ni@BNPCFs-900 networks. Especially, because of the remarkable structural and chemical stabilities of 3D hierarchically porous Ni@BNPCFs-900 networks, the (-) Ni@BNPCFs-900||Ni@BNPCFs-900 (+) water electrolysis cell displays an excellent stability.

Manganese Oxide/Iron Carbide Encapsulated in Nitrogen and Boron Codoped Carbon Nanowire Networks as Accelerated Alkaline Hydrogen Evolution and Oxygen Reduction Bifunctional Electrocatalysts.

Along with the widespread applications of various energy storage and conversion devices, the prices of precious metal platinum (Pt) and transition-metal cobalt/nickel keep continuously growing. In the future, designing high-efficiency nonprecious-metal catalysts based on low-cost iron (Fe) and manganese (Mn) metals for hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR) is fairly critical for commercial applications of hydrogen fuel cells. In this study, for the first time, we design novel three-dimensional (3D) hybrid networks consisting of manganese oxide (MnO)-modified, iron carbide (Fe3C)-embedded, and boron (B)/nitrogen (N) codoped hierarchically porous carbon nanofibers (denoted FeMn@BNPCFs). After optimizing the pyrolysis temperatures, the optimal FeMn@BNPCFs-900 catalyst displays the best HER and ORR catalytic activities in an alkaline solution. As expected, the HER onset potential (Eonset) and the potential at a current density of -10 mA cm-2 for FeMn@BNPCFs-900 in 1.0 M KOH are just 36 and 194 mV more negative than the state-of-the-art 20 wt % Pt/C catalyst with more superior stability. In particular, the FeMn@BNPCFs-900 catalyst shows excellent ORR catalytic activity with a more positive Eonset (0.946 V vs RHE), a more positive half-wave potential (E1/2 = 0.868 V vs RHE), better long-term stability, and higher methanol tolerance surpassing the commercial 20 wt % Pt/C (Eonset = 0.943 V vs RHE, E1/2 = 0.854 V vs RHE) and most previously reported precious-metal-free catalysts in 0.1 M KOH. The synergistic effects of 3D hierarchically macro-/mesoporous architectures, advanced charge transport capacity, abundant carbon defects/edges, abundant B (2.3 atom %) and N (4.9 atom %) dopants, uniformly dispersed Fe3C@BNC NPs, and MnO nanocrystallines are responsible for the excellent HER/ORR catalytic activities of the FeMn@BNPCFs-900 catalyst.

[Retrospective study of adverse reactions of Niuhuang Jiedu tablet (pill) and risk control based on literature analysis].

In this retrospective study, 56 cases of adverse reactions caused by Niuhuang Jiedu tablet (pill) were statistically analyzed in respects of genders, ages, routes of administration, clinical manifestations, etc. We pinpointed that the main factors related to safety problems of Niuhuang Jiedu tablet (pill) are irrational drug use and drug quality, and put forward suggestions for strengthening the surveillance and administration of Niuhuang Jiedu tablet (pill) and improving clinical rational use.

[Thinking about evaluation of proprietary Chinese medicines containing toxic herbs during switch process of non-prescription drugs].

To enhance the scientific and fair evaluation about proprietary Chinese medicines containing toxic herbs during the switch process of non-prescription drugs, and to ensure those medicines to be used safely by the public in their self-medication. Combined with current research status of toxic herbs, the experience and knowledge accumulated in the practical work of selection and switch of OTC Chinese medicines for years, thinking about the feasible standards about evaluation and management of proprietary Chinese medicines containing toxic herbs at this stage. Initially established ideas and methods about evaluation of proprietary Chinese medicines containing toxic herbs during the switch process of non-prescription drugs. Basically solved the main problem currently faced by toxic herbs during the OTC switch process of proprietary Chinese medicines, effectively promoted the work on OTC switch, and had the important significance in making consumers use non-prescription drugs conveniently and safely.

Preparation of high-performance hydroxide exchange membrane by a novel ablation restriction plasma polymerization approach.

A novel approach of ablation restriction plasma polymerization has been successfully demonstrated for the first time in hydroxide exchange membrane synthesis. The membrane possesses high hydroxide conductivity, alkaline stability, and the ability of fully encompassing catalyst particles, without solubility in low boiling point water-soluble solvents.