Direct Eight-Electron N2O Electroreduction to NH3 Enabled by an Fe Double-Atom Catalyst.

N2O is a dominant atmosphere pollutant, causing ozone depletion and global warming. Currently, electrochemical reduction of N2O has gained increasing attention to remove N2O, but its product is worthless N2. Here, we propose a direct eight-electron (8e) pathway to electrochemically convert N2O into NH3. As a proof of concept, using density functional theory calculation, an Fe2 double-atom catalyst (DAC) anchored by N-doped porous graphene (Fe2@NG) was screened out to be the most active and selective catalyst for N2O electroreduction toward NH3 via the novel 8e pathway, which benefits from the unique bent N2O adsorption configuration. Guided by theoretical prediction, Fe2@NG DAC was fabricated experimentally, and it can achieve a high N2O-to-NH3 Faradaic efficiency of 77.8% with a large NH3 yield rate of 2.9 mg h-1 cm-2 at -0.6 V vs RHE in a neutral electrolyte. Our study offers a feasible strategy to synthesize NH3 from pollutant N2O with simultaneous N2O removal.

Self-Tandem Electrocatalytic NO Reduction to NH3 on a W Single-Atom Catalyst.

We design single-atom W confined in MoO3-x amorphous nanosheets (W1/MoO3-x) comprising W1-O5 motifs as a highly active and durable NORR catalyst. Theoretical and operando spectroscopic investigations reveal the dual functions of W1-O5 motifs to (1) facilitate the activation and protonation of NO molecules and (2) promote H2O dissociation while suppressing *H dimerization to increase the proton supply, eventually resulting in a self-tandem NORR mechanism of W1/MoO3-x to greatly accelerate the protonation energetics of the NO-to-NH3 pathway. As a result, W1/MoO3-x exhibits the highest NH3-Faradaic efficiency of 91.2% and NH3 yield rate of 308.6 µmol h-1 cm-2, surpassing that of most previously reported NORR catalysts.

N6-Methyladenosine Demethylase FTO (Fat Mass and Obesity-Associated Protein) as a Novel Mediator of Statin Effects in Human Endothelial Cells.

BACKGROUND: N6-methyladenosine (m6A) plays a critical role in various biological processes. However, no study has addressed the role of m6A modification in the statin-induced protection of endothelial cells (ECs). METHODS: Quantitative real-time polymerase chain reaction and Western blotting analyses were used to study the expression of m6A regulatory genes in atorvastatin-treated ECs. Gain- and loss-of-function assays, methylated RNA immunoprecipitation analysis, and dual-luciferase reporter assays were performed to clarify the function of FTO (fat mass and obesity-associated protein) in ECs. RESULTS: Atorvastatin decreased FTO protein expression in ECs. The knockdown of FTO enhanced the mRNA and protein expression of KLF2 (Kruppel-like factor 2) and eNOS (endothelial NO synthase) but attenuated TNFα (tumor necrosis factor alpha)-induced VCAM-1 (vascular cell adhesion molecule 1) and ICAM-1 (intercellular adhesion molecule 1) expression, as well as the adhesion of monocytes to ECs. Conversely, FTO overexpression significantly upregulated the mRNA and protein levels of VCAM-1 and ICAM-1, downregulated those of KLF2 and eNOS, and strongly attenuated the atorvastatin-mediated induction of KLF2 and eNOS expression. Subsequent investigations demonstrated that KLF2 and eNOS are functionally critical targets of FTO. Mechanistically, FTO interacted with KLF2 and eNOS transcripts and regulated their expression in an m6A-dependent manner. After FTO silencing, KLF2 and eNOS transcripts with higher levels of m6A modification in their 3' untranslated regions were captured by YTHDF3 (YT521-B homology m6A RNA-binding protein 3), resulting in mRNA stabilization and the induction of KLF2 and eNOS protein expression. CONCLUSIONS: FTO might serve as a novel molecular target to modulate endothelial function in vascular diseases.

Electrocatalytic NO Reduction to NH3 on Mo2C Nanosheets.

Electrocatalytic reduction of NO to NH3 (NORR) emerges as a promising route for achieving harmful NO treatment and sustainable NH3 generation. In this work, we first report that Mo2C is an active and selective NORR catalyst. The developed Mo2C nanosheets deliver a high NH3 yield rate of 122.7 µmol h-1 cm-2 with an NH3 Faradaic efficiency of 86.3% at -0.4 V. Theoretical computations unveil that the surface-terminated Mo atoms on Mo2C can effectively activate NO, promote protonation energetics, and suppress proton adsorption, resulting in high NORR activity and selectivity of Mo2C.

Similar electronic state effect enables excellent activity for nitrate-to-ammonia electroreduction on both high- and low-density double-atom catalysts.

Double-atom catalysts (DACs) for harmful nitrate (NO3-) electroreduction to valuable ammonia (eNO3RR) is attractive for both environmental remediation and energy transformation. However, the limited metal loading in most DACs largely hinders their applications in practical catalytic applications. Therefore, exploring ultrahigh-density (UHD) DACs with abundant active metal centers and excellent eNO3RR activity is highly desired under the site-distance effect. Herein, starting from the experimental M2N6 motif deposited on graphene, we firstly screened the low-density (LD) Mn2N6 and Fe2N6 DACs with high eNO3RR activity and then established an appropriate activity descriptor for the LD-DAC system. By utilizing this descriptor, the corresponding Mn2N6 and Fe2N6 UHD-DACs with dynamic, thermal, thermodynamic, and electrochemical stabilities, are identified to locate at the peak of activity volcano, exhibiting rather-low limiting potentials of -0.25 and -0.38 V, respectively. Further analysis in term of spin state and orbital interaction, confirms that the electronic state effect similar to that of LD-DACs enable the excellent eNO3RR activity to be maintained in the UHD-DACs. These findings highlight the promising application of Mn2N6 and Fe2N6 UHD-DACs in nitrate electroreduction for NH3 production and provide impetus for further experimental exploration of ultrahigh-density DACs based on their intrinsic electronic states.

Tandem Electrocatalytic Nitrate Reduction to Ammonia on MBenes.

We demonstrate the great feasibility of MBenes as a new class of tandem catalysts for electrocatalytic nitrate reduction to ammonia (NO3 RR). As a proof of concept, FeB2 is first employed as a model MBene catalyst for the NO3 RR, showing a maximum NH3 -Faradaic efficiency of 96.8 % with a corresponding NH3 yield of 25.5 mg h-1 cm-2 at -0.6 V vs. RHE. Mechanistic studies reveal that the exceptional NO3 RR activity of FeB2 arises from the tandem catalysis mechanism, that is, B sites activate NO3 - to form intermediates, while Fe sites dissociate H2 O and increase *H supply on B sites to promote the intermediate hydrogenation and enhance the NO3 - -to-NH3 conversion.

Ambient Ammonia Synthesis via Electrochemical Reduction of Nitrate Enabled by NiCo2 O4 Nanowire Array.

NiCo2 O4 nanowire array on carbon cloth (NiCo2 O4 /CC) is proposed as a highly active electrocatalyst for ambient nitrate (NO3 - ) reduction to ammonia (NH3 ). In 0.1 m NaOH solution with 0.1 m NaNO3 , such NiCo2 O4 /CC achieves a high Faradic efficiency of 99.0% and a large NH3 yield up to 973.2 µmol h-1  cm-2 . The superior catalytic activity of NiCo2 O4 comes from its half-metal feature and optimized adsorption energy due to the existence of Ni in the crystal structure. A Zn-NO3 - battery with NiCo2 O4 /CC cathode also shows a record-high battery performance.

Designing Multifunctional Donor-Acceptor-Type Molecules to Passivate Surface Defects Efficiently and Enhance Charge Transfer of CsPbI2Br Perovskite for High Power Conversion Efficiency.

High-density and multitype surface defects of CsPbI2Br perovskite induce charge recombination and accumulation, hindering its device efficiency and stability. However, the surface defect types of CsPbI2Br perovskite are still unclear, and conventional organic molecules only passivate one specific defect and cannot achieve good overall passivation. Here, density functional theory is used to explore surface defect types and properties of CsPbI2Br with calculating the defect formation energy and electronic structure. Results show that the dominant deep-level defects are cationic defects (PbBr) under Br-poor conditions and anionic defects (Ii and Bri) under moderate and Br-rich conditions, originating from Pb-Pb bonding and I-I bonding. Multifunctional organic molecules containing donor and acceptor groups are used to passivate both cationic and anionic defects simultaneously. It turns out that the deep-level defects are effectively decreased by forming strong interaction of N-Pb, O-Pb, and halide-Pb bonds. Moreover, the electron and hole transfers from perovskite to molecules increase dramatically to -9.06 × 1012 and 2.60 × 1012 e/cm2 and maybe improve the efficiency of power conversion. Our findings not only reveal the surface defect properties of CsPbI2Br, but also offer an approach for designing new multifunctional passivators for perovskite solar cells with high conversion efficiency.

Tunable Photocatalytic Water Splitting Performance of Armchair MoSSe Nanotubes Realized by Polarization Engineering.

The photocatalytic properties of Janus transition metal dichalcogenide (TMD) nanotubes are closely correlated with the electrostatic potential difference between their inner and outer surfaces (ΔΦ). However, due to some distraction from the tubular structures, it remains a great challenge to calculate their ΔΦ directly. Here, we creatively work out the ΔΦ of Janus MoSSe armchair single-walled nanotubes (A-SWNTs) with their corresponding building block models by first-principles calculations. The ΔΦ increases as the diameter reduces. After considering ΔΦ, we find that all of these MoSSe A-SWNTs possess suitable band-edge positions required for water redox reactions and high solar-to-hydrogen (STH) conversion efficiencies. The built-in field induced by the ΔΦ promotes the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) to proceed separately on the inner and outer surfaces. Especially, the photoexcited carriers exhibit adequate driving forces for OER and HER. Besides, constructing a double-walled nanotube can dramatically increase ΔΦ, which also further improves the separation and redox capacity of photoexcited carriers as well as the STH conversion efficiency. Moreover, all of these MoSSe armchair nanotubes have outstanding optical absorption in the visible light range. Our studies provide an effective strategy to improve the photocatalytic water-splitting performance of Janus TMD nanotubes.

V (Nb) Single Atoms Anchored by the Edge of a Graphene Armchair Nanoribbon for Efficient Electrocatalytic Nitrogen Reduction: A Theoretical Study.

Efficient and low-cost electrocatalysts are urgently required for the electrocatalytic N2 reduction reaction (NRR) to produce valuable NH3. Single-atom catalysts (SACs) represent one class of promising candidates. Besides the defects on the basal plane, very recently, the one-dimensional edge universally existing in the finite graphene or carbon sheet has gained attention as the anchoring site for SACs, which may enable unique catalytic mechanism. Herein, using first-principles calculations, we systematically investigated the NRR over SACs of transition metals (Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Ru, Rh, Pd, Nb, Mo, and W) anchored by the N-modified edge of the graphene armchair nanoribbon (denoted as TM@GNR). Three criteria were employed to screen the best candidate from all the TM@GNR, including the high stability of TM@GNR, the preferable adsorption of N2 compared with H, and the lower applied potential for the first protonation of N2 compared with that of the active site. Accordingly, V(Nb)@GNR were theoretically demonstrated to be promising NRR electrocatalyst toward NH3 with low limiting potentials of -0.65 (-0.52) V, excellent selectivity of ∼100% (97%), and good stability. Particularly, NRR on the V@GNR and Nb@GNR precedes through a novel reaction mechanism with three spectator N2 molecules. Further analysis reveals that the strong capture and activation of N2 molecules by the edge-anchored V (Nb) atoms derives from their localized spin moment and atomic orbitals. Our studies emphasize the great potential of the edge of carbon materials to synthesize SACs for NRR and other reactions, and further reveal a novel NRR reaction mechanism on SACs.

Increasing electron density by surface plasmon resonance for enhanced photocatalytic CO2 reduction.

The photocatalytic CO2 reduction reaction is a multi-electron process, which is greatly affected by the surface electron density. In this work, we synthesize Ag clusters supported on In2O3 plasmonic photocatalysts. The Ag-In2O3 compounds show remarkedly enhanced photocatalytic activity for CO2 conversion to CO compared to pristine In2O3. In the absence of any co-catalyst or sacrificial agent, the CO evolution rate of optimal Ag-In2O3-10 is 1.56 µmol/g/h, achieving 5.38-folds higher than that of In2O3 (0.29 µmol/g/h). Experimental verification and DFT calculation demonstrate that electrons transfer from Ag clusters to In2O3 on Ag-In2O3 compounds. In Ag-In2O3 compounds, Ag clusters serving as electron donators owing to the SPR behaviour are not helpful to decline photo-induced charge recomnation rate, but can provide more electron for photocatalytic reaction. Overall, the Ag clusters promote visible-light absorption and accelerate photocatalytic reaction kinetic for In2O3, resulting in the photocatalytic activity enhancement of Ag-In2O3 compounds. This work puts insight into the function of plasmonic metal on enhancing photocatalysis performance, and provides a feasible strategy to design and fabricate efficient plasmonic photocatalysts.

Optimizing the Electronic Structure of ZnS via Cobalt Surface Doping for Promoted Photocatalytic Hydrogen Production.

Developing highly efficient semiconductor photocatalysts for H2 evolution is intriguing, but their efficiency is subjected to the following three critical issues: limited light absorption, low carrier separation efficiency, and sluggish H2 evolution kinetics. Element surface doping is a feasible strategy to synchronously break through the above limitations. In this study, we prepared a series of Co-surface-doped ZnS photocatalysts to systematically investigate the effects of Co surface doping on photocatalytic activity and electronic structure. The implantation of Co results in the emergence of the impurity level above the valence band (VB) and the upshifted conduction band (CB) and enhances its visible light absorption. Co gradient doping inhibits the combination and facilitates the migration of carriers. S atoms are proven to be reactive active sites for photocatalytic H2 evolution over both ZnS and Co-doped ZnS. Co doping alters the surface electronic structure and decreases the absolute value for the hydrogen binding free energy (ΔGH) of the adsorbed hydrogen atom on the catalyst. As a consequence, Co-surface-doped ZnS shows boosted photocatalytic H2 evolution activity relative to the undoped material. This work provides insights into the mechanistic understanding of the surface element doping modification strategy to developing efficient photocatalysts.

Absolute and Fast Removal of Viruses and Bacteria from Water by Spraying-Assembled Carbon-Nanotube Membranes.

Membrane separation is able to efficiently remove pathogens like bacteria and viruses from water based on size exclusion. However, absolute and fast removal of pathogens requires highly permeable but selective membranes. Herein, we report the preparation of such advanced membranes using carbon nanotubes (CNTs) as one-dimensional building blocks. We first disperse CNTs with the help of an amphiphilic block copolymer, poly(2-dimethylaminoethyl methacrylate)-block-polystyrene (PDMAEMA-b-PS, abbreviated as BCP). The PS blocks adsorb on the surface of CNTs via the π-π interaction, while the PDMAEMA blocks are solvated, thus forming homogeneous and stable CNT dispersions. We then spray the CNT dispersions on porous substrates, producing composite membranes with assembled CNT layers as the selective layers. We demonstrate that the optimized membrane shows 100% rejection to phage viruses and bacteria (Escherichia coli) while giving a water permeance up to ∼3300 L m-2 h-1 bar-1. The performance of the resultant BCP/CNT membrane outperforms that of state-of-the-art membranes and commercial membranes. The BCP/CNT membrane can be used for multiple runs and regenerated by water rinsing. Membrane modules assembled from large-area membrane sheets sustain the capability of absolute and fast removal of viruses and bacteria.

Electrocatalytic nitrogen reduction on the transition-metal dimer anchored N-doped graphene: performance prediction and synergetic effect.

Double-atom catalysts (DACs) have gained more and more attention to achieve efficient catalysts for the electrocatalytic nitrogen reduction reaction (NRR). It is expected that heteronuclear members could play an important role in the development of DACs, due to which the vast possible combinations of two different transition metal (TM) elements provide a large chemical composition space for the DAC design. Herein, to screen for efficient NRR DACs and, in particular, to further explore the synergetic effect as well as the TM combination pattern conductive to the NRR in the heteronuclear DACs, we have theoretically studied the NRR on TM dimer embedded N-doped porous graphene (TM = V, Cr, Mn, Fe, Co, Ni, and Cu), denoted as M1M2@NG, and both homonuclear and heteronuclear DACs have been considered. Our results indicate that most of the M1M2@NG systems exhibit comparable or better intrinsic NRR activity than the stepped Ru(0001) surface in terms of the calculated limiting potential. In particular, the heteronuclear DAC VCr@NG exhibiting metallic conductivity and high stability has an ultralow limiting potential of -0.24 V for the NRR and a strong capability of suppressing the competing hydrogen evolution reaction. Moreover, the synergetic effect for the heteronuclear DACs compared with the homonuclear counterparts has been studied in terms of energy and electronic structures. Based on this, we propose that combining a highly chemically active TM element (often the early TM) with another TM to form heteronuclear TM dimers on an appropriate substrate can help achieve efficient heteronuclear DACs for the NRR. Our studies not only highlight the important role of heteronuclear members in the application of DACs, but further provide a promising strategy to design efficient heteronuclear DACs for the NRR from the large chemical composition space.

Single-atom catalysts based on TiN for the electrocatalytic hydrogen evolution reaction: a theoretical study.

The electrocatalytic hydrogen evolution reaction (HER) for water splitting is crucial for the sustainable production of clean hydrogen fuel, while the high cost of Pt catalysts impedes its commercialization. Herein, we have performed a systematic theoretical study on the electrocatalytic HER over single-atom catalysts (SACs) based on low-cost TiN. Specifically, the TiN(100) surface with a Ti or N vacancy has been considered as the support. 20 transition-metal (TM) atoms and 3 nonmetallic atoms are embedded into the Ti or N vacancy, accordingly denoted as M@Tiv or M@Nv. All the single atoms can be stabilized by the surface vacancies, controlled by the adjustable chemical potential. Interestingly, for TM-embedded TiN(100), the hydrogen binding is much stronger over M@Nv than M@Tiv, which can be attributed to the more localized d states of the TM atoms anchored by the N vacancies, indicating a strong coordination effect. Among 43 catalysts, 10 (Ni, Zn, Nb, Mo, Rh@Tiv, and Au, Pd, W, Mo, B@Nv) were predicted to have high HER catalytic activity with near-zero hydrogen adsorption free energy. For the further gaseous hydrogen evolution, Zn@Tiv can adopt both Tafel (with an energy barrier of 0.68 eV) and Heyrovsky mechanisms, while the others may prefer the Heyrovsky mechanism. This work provides a promising strategy to realize cost-efficient electrocatalysts for the HER, and highlights the important role of the local coordination environment for SACs.

Honeycomb Carbon Nanofibers: A Superhydrophilic O2 -Entrapping Electrocatalyst Enables Ultrahigh Mass Activity for the Two-Electron Oxygen Reduction Reaction.

Electrocatalytic two-electron oxygen reduction has emerged as a promising alternative to the energy- and waste-intensive anthraquinone process for distributed H2 O2 production. This process, however, suffers from strong competition from the four-electron pathway leading to low H2 O2 selectivity. Herein, we report using a superhydrophilic O2 -entrapping electrocatalyst to enable superb two-electron oxygen reduction electrocatalysis. The honeycomb carbon nanofibers (HCNFs) are robust and capable of achieving a high H2 O2 selectivity of 97.3 %, much higher than that of its solid carbon nanofiber counterpart. Impressively, this catalyst achieves an ultrahigh mass activity of up to 220 A g-1 , surpassing all other catalysts for two-electron oxygen reduction reaction. The superhydrophilic porous carbon skeleton with rich oxygenated functional groups facilitates efficient electron transfer and better wetting of the catalyst by the electrolyte, and the interconnected cavities allow for more effective entrapping of the gas bubbles. The catalytic mechanism is further revealed by in situ Raman analysis and density functional theory calculations.

High-Performance Electrochemical NO Reduction into NH3 by MoS2 Nanosheet.

Electrochemical reduction of NO not only offers an attractive alternative to the Haber-Bosch process for ambient NH3 production but mitigates the human-caused unbalance of nitrogen cycle. Herein, we report that MoS2 nanosheet on graphite felt (MoS2 /GF) acts as an efficient and robust 3D electrocatalyst for NO-to-NH3 conversion. In acidic electrolyte, such MoS2 /GF attains a maximal Faradaic efficiency of 76.6 % and a large NH3 yield of up to 99.6 µmol cm-2 h-1 . Using MoS2 nanosheet-loaded carbon paper as the cathode, a proof-of-concept device of Zn-NO battery was assembled to deliver a discharge power density of 1.04 mW cm-2 and an NH3 yield of 411.8 µg h-1 mgcat. -1 . Calculations reveal that the positively charged Mo-edge sites facilitate NO adsorption/activation via an acceptance-donation mechanism and disfavor the binding of protons and the coupling of N-N bond.

Dynamic changes in insulin and glucagon during disease progression in rhesus monkeys with obesity-related type 2 diabetes mellitus.

AIMS: To investigate the progression of obesity-related type 2 diabetes mellitus (T2DM) in rhesus monkeys, especially dynamic changes in insulin and glucagon. MATERIALS AND METHODS: We followed a cohort of 52 rhesus monkeys for 7 years throughout the progression of obesity-related T2DM. Intravenous glucose tolerance tests were performed every 6 months to evaluate dynamic changes in glucose, insulin and glucagon levels. RESULTS: Obesity in rhesus monkeys increased the overall mortality and T2DM morbidity. During the progression of T2DM, glucagon remained consistently elevated, while insulin initially increased in compensation but then dropped to below normal levels when the monkeys developed overt T2DM. After a glucose challenge, both the first and second phases of insulin secretion increased during the early stage of T2DM; in later stages the first phase was delayed and the second phase was diminished. CONCLUSION: Our findings showed that, beside the decreased insulin level, hyperglucagonaemia also plays an important role in the development of T2DM.

Transition metal embedded C3N monolayers as promising catalysts for the hydrogen evolution reaction.

Transition metal (TM) doped or TM, N co-doped carbon materials have attracted increasing attention as efficient catalysts for the hydrogen evolution reaction (HER), to replace Pt or reduce the usage of Pt. By using first-principles calculations, the TM-embedded C3N monolayer (TM@C3N) has been theoretically investigated for HER, for which eighteen TMs are selected from the 3d, 4d, and 5d rows. The M-CC catalysts, with the TM atom embedded into the C-C double atomic vacancy, are the most stable among the various TM@C3N materials. All the M-CC catalysts show metallic conductivity and high thermal stability. The hydrogen binding free energy for the M-CC catalysts can be optimized to be close to 0 eV by choosing a suitable TM, and the kinetic barrier under the Tafel mechanism for further gaseous hydrogen evolution can be reduced to as low as 0.58 eV. These results suggest that the HER catalytic activities of the M-CC catalysts are likely comparable or even higher than those of the well-explored MoS2 nanostructures or Pt catalysts. Moreover, the HER activities of the M-CC catalysts can be illustrated by the electronic state distribution near the Fermi level of the catalytically active sites. This study provides a new possibility for cost-efficient HER catalysts of high activity and for the application of C3N nanostructures.

Central role of RIPK1-VDAC1 pathway on cardiac impairment in a non-human primate model of rheumatoid arthritis.

Rheumatoid arthritis (RA) is a chronic inflammatory disorder characterized by destructive polyarthritis and systemic complications. It increases cardiovascular morbidity and mortality. However, the mechanism underlying RA-related cardiac damage remains largely unknown. Here, we found and characterized a non-human primate (NHP) model with spontaneous RA similar to the human conditions. Compared with the control group, the cardiac function in RA monkeys showed progressively deterioration; histologically, we found significantly increased inflammatory cell infiltration, cell death, and fibrosis in RA monkey heart tissue. Mechanistically, the upregulated receptor-interacting protein kinase 1 (RIPK1) in RA monkey heart tissue bound to voltage-dependent anion-selective channel 1 (VDAC1), increased VDAC1 oligomerization, and subsequently induced cardiac cell death and functional impairment. These findings identified that RIPK1-VDAC1 pathway is a promising target to treat cardiac impairment in RA. This unique model of RA will provide a valuable tool for mechanistic and translational studies.