Electrical-Driven Directed-Evolution of Copper Nanowires Catalysts for Efficient Nitrate Reduction to Ammonia.

The electrocatalytic conversion of nitrate (NO3 -) to NH3 (NO3RR) at ambient conditions offers a promising alternative to the Haber-Bosch process. The pivotal factors in optimizing the proficient conversion of NO3 - into NH3 include enhancing the adsorption capabilities of the intermediates on the catalyst surface and expediting the hydrogenation steps. Herein, the Cu/Cu2O/Pi NWs catalyst is designed based on the directed-evolution strategy to achieve an efficient reduction of NO3‾. Benefiting from the synergistic effect of the OV-enriched Cu2O phase developed during the directed-evolution process and the pristine Cu phase, the catalyst exhibits improved adsorption performance for diverse NO3RR intermediates. Additionally, the phosphate group anchored on the catalyst's surface during the directed-evolution process facilitates water electrolysis, thereby generating Hads on the catalyst surface and promoting the hydrogenation step of NO3RR. As a result, the Cu/Cu2O/Pi NWs catalyst shows an excellent FE for NH3 (96.6%) and super-high NH3 yield rate of 1.2 mol h-1 gcat. -1 in 1 m KOH and 0.1 m KNO3 solution at -0.5 V versus RHE. Moreover, the catalyst's stability is enhanced by the stabilizing influence of the phosphate group on the Cu2O phase. This work highlights the promise of a directed-evolution approach in designing catalysts for NO3RR.

Rhenium Suppresses Iridium (IV) Oxide Crystallization and Enables Efficient, Stable Electrochemical Water Oxidation.

IrO2 as benchmark electrocatalyst for acidic oxygen evolution reaction (OER) suffers from its low activity and poor stability. Modulating the coordination environment of IrO2 by chemical doping is a methodology to suppress Ir dissolution and tailor adsorption behavior of active oxygen intermediates on interfacial Ir sites. Herein, the Re-doped IrO2 with low crystallinity is rationally designed as highly active and robust electrocatalysts for acidic OER. Theoretical calculations suggest that the similar ionic sizes of Ir and Re impart large spontaneous substitution energy and successfully incorporate Re into the IrO2 lattice. Re-doped IrO2 exhibits a much larger migration energy from IrO2 surface (0.96 eV) than other dopants (Ni, Cu, and Zn), indicating strong confinement of Re within the IrO2 lattice for suppressing Ir dissolution. The optimal catalysts (Re: 10 at%) exhibit a low overpotential of 255 mV at 10 mA cm-2 and a high stability of 170 h for acidic OER. The comprehensive mechanism investigations demonstrate that the unique structural arrangement of the Ir active sites with Re-dopant imparts high performance of catalysts by minimizing Ir dissolution, facilitating *OH adsorption and *OOH deprotonation, and lowering kinetic barrier during OER. This study provides a methodology for designing highly-performed catalysts for energy conversion.

[Quality evaluation of Ginseng Radix et Rhizoma based on UPLC characteristic chromatogram and quantitative analysis of multi-components by single marker (QAMS)].

Based on UPLC characteristic chromatogram and quantitative analysis of multi-components by single marker(QAMS), the content of seven types of ginsenosides in Ginseng Radix et Rhizoma was simultaneously determined, and the quality of Ginseng Radix et Rhizoma was evaluated by the principal component analysis(PCA). The chromatographic separation was performed on the Acquity UPLC BEH C_(18) column(2.1 mm×100 mm, 1.7 µm) with the mobile phase of acetonitrile-water for gradient elution at the flow rate of 0.3 mL·min~(-1), the column temperature of 30 ℃, the detection wavelength of 203 nm, and the injection volume of 2 µL. The UPLC chromatogram was established with 19 batches of Ginseng Radix et Rhizoma samples from three producing areas by Similarity Evaluation System for Chromatographic Fingerprint of Traditional Chinese Medicine(version 2012). Thirteen characteristic peaks were determined and seven components were identified. SPSS 26.0 was used to conduct PCA on the characteristic peak areas. With the peak of ginsenoside Rb_1 as reference peak S, ginsenoside Rb_1 showed good durability of relative correction factor as compared with other ginsenosides. The QAMS method for the determination of seven ginsenosides in Ginseng Radix et Rhizoma was established. There was no significant difference in results between the QAMS method and the external standard method. As revealed by the results of PCA and the determination of the total content of seven ginsenosides, the four batches of Ginseng Radix et Rhizoma numbered S19, S18, S1, and S2 were of superior quality. The characteristic chromatogram and QAMS method for the determination of seven ginsenosides in this study were convenient and accurate, which greatly shortened the analysis time and improved the analysis efficiency. The findings of this study are expected to provide a basis for the overall quality evaluation of Ginseng Radix et Rhizoma.

Principal component analysis of MALDI-TOF MS of whole-cell foodborne pathogenic bacteria.

The rapid and accurate identification of foodborne pathogenic bacteria is of great importance for human health. Matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) can be used to rapidly and sensitively identify microorganisms but is limited by the expensive protein databases available. In this study, we established a whole-cell method for the identification of foodborne pathogenic bacteria, using MALDI-TOF MS and principal component analysis (PCA), which did not use protein extractions or expensive protein databases. Thirty strains comprising six common foodborne pathogenic bacteria, namely, Shigella flexneri, Escherichia coli, Staphylococcus aureus, Salmonella enteritidis, Pseudomonas aeruginosa, and Listeria monocytogenes were analyzed using MALDI-TOF MS. The culture time, matrix, and spotting method were optimized based on peak intensity and deviation. A PCA was performed to analyze the mass spectrometry results of six samples and proved capable of identifying significant changes in those samples. It was found that directly applying MALDI-TOF MS analysis to whole-cell bacteria, without protein extraction, exhibited rich peak contents and a high level of reproducibility. MALDI-TOF MS combined with PCA is a promising method of rapidly identifying pathogens in food products.

Rapid Electrochemical Cleaning Silver Nanowire Thin Films for High-Performance Transparent Conductors.

Silver nanowire (Ag-NW) thin films are of considerable interest for next-generation transparent conductors (TCs). However, their carrier transport properties are largely plagued by the residual polyvinylpyrrolidone (PVP) ligands on surface that were introduced during the synthesis of the Ag-NWs. Here we report a rapid electrochemical cleaning strategy to thoroughly remove the surface PVP ligands and greatly improve the carrier transport properties of the Ag-NW thin films while not affecting their transmittance. In particular, we show a negative electrochemical potential near the hydrogen adsorption/evolution regime can effectively displace all PVP ligands from the Ag-NW surface in 5-15 s, producing ultraclean interfaces between Ag-NW/Ag-NW junctions or Ag-NW film/active layer junction in a stacked optoelectronic device. We show that the removal of the PVP ligands can substantially reduce the sheet resistance of the Ag-NW thin film from 49 to 13 ohm/sq (with 90.91% transmittance at 550 nm) and reduce the interfacial resistance at the Ag-NW film/active layer interface by 94.3%. Such improved Ag-NW thin films can greatly enhance the sensitivity of the wearable strain sensor and the current collection efficiency of the vertically stacked devices constructed from the sandwiched thin films. These results demonstrate that the electrochemical cleaning approach is highly effective in removing surface ligands and improving both the in-plane and the out-of-plane carrier transport properties of the Ag-NW thin films, greatly facilitating their applications in electronic and optoelectronic devices.

Direct Room Temperature Welding and Chemical Protection of Silver Nanowire Thin Films for High Performance Transparent Conductors.

Silver nanowire (Ag-NW) thin films have emerged as a promising next-generation transparent electrode. However, the current Ag-NW thin films are often plagued by high NW-NW contact resistance and poor long-term stability, which can be largely attributed to the ill-defined polyvinylpyrrolidone (PVP) surface ligands and nonideal Ag-PVP-Ag contact at NW-NW junctions. Herein, we report a room temperature direct welding and chemical protection strategy to greatly improve the conductivity and stability of the Ag-NW thin films. Specifically, we use a sodium borohydride (NaBH4) treatment process to thoroughly remove the PVP ligands and produce a clean Ag-Ag interface that allows direct welding of NW-NW junctions at room temperature, thus greatly improving the conductivity of the Ag-NW films, outperforming those obtained by thermal or plasmonic thermal treatment. We further show that, by decorating the as-formed Ag-NW thin film with a dense, hydrophobic dodecanethiol layer, the stability of the Ag-NW film can be greatly improved by 150-times compared with that of PVP-wrapped ones. Our studies demonstrate that a proper surface ligand design can effectively improve the conductivity and stability of Ag-NW thin films, marking an important step toward their applications in electronic and optoelectronic devices.

Lightweight 3D Lithiophilic Graphene Aerogel Current Collectors for Lithium Metal Anodes.

Constructing three-dimensional (3D) current collectors is an effective strategy to solve the hindrance of the development of lithium metal anodes (LMAs). However, the excessive mass of the metallic scaffold structure leads to a decrease in energy density. Herein, lithiophilic graphene aerogels comprising reduced graphene oxide aerogels and silver nanowires (rGO-AgNW) are synthesized through chemical reduction and freeze-drying techniques. The rGO aerogels with large specific surface areas effectively mitigate local current density and delay the formation of lithium dendrites, and the lithiophilic silver nanowires can provide sites for the uniform deposition of lithium. The rGO-AgNW/Li symmetric cell presents a stable cycle of about 2000 h at 1 mA cm-2. When coupled with the LiFePO4 cathode, the assembled full cells exhibit outstanding cycle stability and rate performance. Lightweight rGO-AgNW aerogels, as the host for lithium metal, can significantly improve the energy density of lithium metal anodes.

Ultrafine Ir nanoparticles anchored on carbon nanotubes as efficient bifunctional oxygen catalysts for Zn-air batteries.

Ultrafine iridium particles anchored on nitrogen-doped CNTs were obtained from Ir(ppy)3 and CNTs using a simple annealing method and acted as highly efficient bifunctional oxygen catalysts for Zn-air batteries. A synergistic effect, efficient *OH adsorption and rapid *OOH deprotonation were demonstrated from in situ FTIR spectroscopy, EIS and activation energy measurements.

Immobilization of iron phthalocyanine on MOF-derived N-doped carbon for promoting oxygen reduction in zinc-air battery.

Functional carbon nanomaterials play a crucial role in the cathodic oxygen reduction reaction (ORR) for sustainable fuel cells and metal-air batteries. In this study, we propose an effective approach to immobilize iron phthalocyanines (FePc) by employing a porous N-doped carbon material, denoted as NC-1000, derived from a sheet-shaped coordination polymer. The resulting NC-1000 possesses substantial porosity and abundant pore defects. The nitrogen sites within NC-1000 not only facilitate FePc adsorption but also optimize the electron distribution at the Fe-N site. The FePc@NC-1000 composite material exhibits a significant number of active centers in the form of Fe-N4 moieties, showcasing satisfactory ORR activity. Specifically, it demonstrates an onset potential of 0.99 V, a positive half-wave potential of 0.86 V, a large limiting current of 5.96 mA cm-2, and a small Tafel slope of 44.41 mV dec-1. Additionally, theoretical calculations and experimental results confirm the favorable performance and durability of zinc-air batteries assembled using FePc@NC-1000, thereby highlighting their considerable potential for practical applications. Overall, this study provides a comprehensive exploration of the enhanced catalytic performance and increased stability of metal-organic framework-derived functional carbon nanomaterials as cost-effective, efficient, and stable catalysts for the ORR.

Efficient Electrocatalytic Nitrate Reduction to Ammonia Based on DNA-Templated Copper Nanoclusters.

In alkaline solutions, the electrocatalytic conversion of nitrates to ammonia (NH3) (NO3RR) is hindered by the sluggish hydrogenation step due to the lack of protons on the electrode surface, making it a grand challenge to synthesize NH3 at a high rate and selectivity. Herein, single-stranded deoxyribonucleic acid (ssDNA)-templated copper nanoclusters (CuNCs) were synthesized for the electrocatalytic production of NH3. Because ssDNA was involved in the optimization of the interfacial water distribution and H-bond network connectivity, the water-electrolysis-induced proton generation was enhanced on the electrode surface, which facilitated the NO3RR kinetics. The activation energy (Ea) and in situ spectroscopy studies adequately demonstrated that the NO3RR was exothermic until NH3 desorption, indicating that, in alkaline media, the NO3RR catalyzed by ssDNA-templated CuNCs followed the same reaction path as the NO3RR in acidic media. Electrocatalytic tests further verified the efficiency of ssDNA-templated CuNCs, which achieved a high NH3 yield rate of 2.62 mg h-1 cm-2 and a Faraday efficiency of 96.8% at -0.6 V vs reversible hydrogen electrode. The results of this study lay the foundation for engineering catalyst surface ligands for the electrocatalytic NO3RR.

Ag-Co3 O4 -CoOOH-Nanowires Tandem Catalyst for Efficient Electrocatalytic Conversion of Nitrate to Ammonia at Low Overpotential via Triple Reactions.

The electrocatalytic conversion of nitrate (NO3 ‾) to NH3  (NO3 RR) offers a promising alternative to the Haber-Bosch process. However, the overall kinetic rate of NO3 RR is plagued by the complex proton-assisted multiple-electron transfer process. Herein, Ag/Co3 O4 /CoOOH nanowires (i-Ag/Co3 O4  NWs) tandem catalyst is designed to optimize the kinetic rate of intermediate reaction for NO3 RR simultaneously. The authors proved that NO3 ‾ ions are reduced to NO2 ‾ preferentially on Ag phases and then NO2 ‾ to NO on Co3 O4  phases. The CoOOH phases catalyze NO reduction to NH3  via NH2 OH intermediate. This unique catalyst efficiently converts NO3 ‾ to NH3  through a triple reaction with a high Faradaic efficiency (FE) of 94.3% and a high NH3  yield rate of 253.7 µmol h-1  cm-2  in 1 M KOH and 0.1 M KNO3  solution at -0.25 V versus RHE. The kinetic studies demonstrate that converting NH2 OH into NH3  is the rate-determining step (RDS) with an energy barrier of 0.151 eV over i-Ag/Co3 O4  NWs. Further applying i-Ag/Co3 O4  NWs as the cathode material, a novel Zn-nitrate battery exhibits a power density of 2.56 mW cm-2  and an FE of 91.4% for NH3  production.

Inhibition of thioredoxin reductase by a novel series of bis-1,2-benzisoselenazol-3(2H)-ones: Organoselenium compounds for cancer therapy.

Thioredoxin reductase (TrxR) is critical for cellular redox regulation and is involved in tumor proliferation, apoptosis and metastasis. Its C-terminal redox-active center contains a cysteine (Cys497) and a unique selenocysteine (Sec498), which are exposed to solvent and easily accessible. Thus, it is becoming an important target for anticancer drugs. Selective inhibition of TrxR by 1,2-(bis-1,2-benzisoselenazol-3(2H)-one)ethane (4a) prevents proliferation of several cancer cell lines both in vivo and in vitro. Using the structure of 4a as a starting point, a series of novel bis-1,2-benzisoselenazol-3(2H)-ones was designed, prepared and tested to explore the structure-activity relationships (SARs) for this class of inhibitor and to improve their potency. Notably, 1,2-(5,5'-dimethoxybis(1,2-benzisoselenazol-3(2H)-one))ethane (12) was found to be more potent than 4a in both in vitro and in vivo evaluation. Its binding sites were confirmed by biotin-conjugated iodoacetamide assay and a SAR model was generated to guide further structural modification.

Pd/PdO Electrocatalysts Boost Their Intrinsic Nitrogen Reduction Reaction Activity and Selectivity via Controllably Modulating the Oxygen Level.

The electrocatalytic nitrogen reduction reaction (eNRR) is regarded as promising sustainable ammonia (NH3) production alternative to the industrial Haber-Bosch process. However, the current electrocatalytic systems still exhibit a grand challenge to simultaneously boost their eNRR activity and selectivity under ambient conditions. Herein, we construct Pd/PdO electrocatalysts with a controlled oxygen level by a facile electrochemical deposition approach at different gas atmospheres. Theoretical calculation results indicate that the introduction of an oxygen atom into a pure Pd catalyst would modulate the electron density of the Pd/PdO heterojunction and thus influence the adsorption energy for nitrogen and hydrogen. The calculation results and experiments show that the Pd/PdO heterojunction with a moderate oxygen level (O-M) exhibits optimal eNRR performance with a high NH3 yield of 11.0 µg h-1 mgcat-1 and a large Faraday efficiency (FE) of 22.2% at 0.03 V (vs RHE) in a 0.1 M KOH electrolyte. The moderate affinity of Pd to N in the Pd/PdO heterojunction and the inhibition of the hydrogen evolution reaction (HER) can facilitate the breaking of the triple bond of N2 and promote the protonation of N, which is confirmed by ex situ X-ray photoelectron spectroscopy (XPS) and in situ Raman spectroscopy. In situ Fourier transform infrared spectroscopy (FTIR) and density functional theory (DFT) calculations further disclose that the O-M catalysts prefer the distal association pathway during the eNRR process. This work opens a new way to construct heterostructures by controlling the oxygen level in other electrochemical fields.

Sulfur Reduction Catalyst Design Inspired by Elemental Periodic Expansion Concept for Lithium-Sulfur Batteries.

The key challenges facing the commercialization of lithium-sulfur (Li-S) batteries are shortening the lithium polysulfide (LiPS) intermediate existence time while accelerating solid-phase conversion reactions. Herein, inspired by highly efficient natural enzymes with Fe/N active sites for oxygen reduction reactions, we report a periodic expansion catalysis concept, i.e., Ru and P synergic stereoselectivity, for designing sulfur reduction reaction (SRR) catalysts. As a proof of concept, a RuP2-configuration molecular catalyst was exploited to assemble an interlayer in Li-S batteries that adsorbs LiPSs, optimizes Li+ migration paths, and catalyzes SRRs. Comprehensive investigation identified the elimination of steric hindrance and strong electron orbital couplings between metallic d band and nonmetallic p band as the main contributing factors of PEC for the SRRs. As a result, the Li-S battery with ∼0.5 wt % catalyst additive showed enhanced cycling stability even under a high sulfur loading (6.5 mg cm-2) and low electrolyte/sulfur ratio (9 µL mg-1).

IrO2-Stablized La2IrO6 perovskite nanotubes via corner-shared interconnections as highly-efficient oxygen evolution electrocatalysts.

One-dimensional nanotube heterostructures with IrO2-stabilized La2IrO6 is obtained by an electrospinning approach. The La2IrO6/IrO2 catalyst exhibits superior catalytic activity and strong stability for the oxygen evolution reaction. The synergistic cooperation between the two types of Ir as the active sites in La2IrO6/IrO2 is demonstrated by in situ Raman spectrum and DFT calculation.

Desolvation Synergy of Multiple H/Li-Bonds on an Iron-Dextran-Based Catalyst Stimulates Lithium-Sulfur Cascade Catalysis.

Traditional lithium-sulfur battery catalysts are still facing substantial challenges in solving sulfur redox reactions, which involve multistep electron transfer and multiphase transformations. Here, inspired by the combination of iron dextran (INFeD) and ascorbic acid (VC) as a blood tonic for the treatment of anemia, a highly efficient VC@INFeD catalyst is developed in the sulfur cathode, accomplishing the desolvation and enrichment of high-concentration solvated lithium polysulfides at the cathode/electrolyte interface with the assistance of multiple H/Li-bonds and resolving subsequent sulfur transformations through gradient catalysis sites where the INFeD promotes long-chain lithium polysulfide conversions and VC accelerates short-chain lithium polysulfide conversions. Comprehensive characterizations reveal that the VC@INFeD can substantially reduce the energy barrier of each sulfur redox step, inhibit shuttle effects, and endow the lithium-sulfur battery with high sulfur utilization and superior cycling stability even under a high sulfur loading (5.2 mg cm-2 ) and lean electrolyte (electrolyte/sulfur ratio, ≈7 µL mg-1 ) condition.