Influenza A virus infection activates caspase-8 to enhance innate antiviral immunity by cleaving CYLD and blocking TAK1 and RIG-I deubiquitination.

Caspase-8, an aspartate-specific cysteine protease that primarily functions as an initiator caspase to induce apoptosis, can downregulate innate immunity in part by cleaving RIPK1 and IRF3. However, patients with caspase-8 mutations or deficiency develop immunodeficiency and are prone to viral infections. The molecular mechanism underlying this controversy remains unknown. Whether caspase-8 enhances or suppresses antiviral responses against influenza A virus (IAV) infection remains to be determined. Here, we report that caspase-8 is readily activated in A549 and NL20 cells infected with the H5N1, H5N6, and H1N1 subtypes of IAV. Surprisingly, caspase-8 deficiency and two caspase-8 inhibitors, Z-VAD and Z-IETD, do not enhance but rather downregulate antiviral innate immunity, as evidenced by decreased TBK1, IRF3, IκBα, and p65 phosphorylation, decreased IL-6, IFN-ß, MX1, and ISG15 gene expression; and decreased IFN-ß production but increased virus replication. Mechanistically, caspase-8 cleaves and inactivates CYLD, a tumor suppressor that functions as a deubiquitinase. Caspase-8 inhibition suppresses CYLD cleavage, RIG-I and TAK1 ubiquitination, and innate immune signaling. In contrast, CYLD deficiency enhances IAV-induced RIG-I and TAK1 ubiquitination and innate antiviral immunity. Neither caspase-3 deficiency nor treatment with its inhibitor Z-DEVD affects CYLD cleavage or antiviral innate immunity. Our study provides evidence that caspase-8 activation in two human airway epithelial cell lines does not silence but rather enhances innate immunity by inactivating CYLD.

Degradation mechanism and decomposition of sulfamethoxazole aqueous solution with persulfate activated by dielectric barrier discharge.

The present study focused on the degradation of sulfamethoxazole (SMX) aqueous solution and the toxicity of processing aqueous by the dielectric barrier discharge (DBD) activated persulfate (PS). The effects of input voltage, input frequency, duty cycle, and PS dosage ratio on the SMX degradation efficiency were measured. Based on the results of the Response Surface Methodology (RSM), SMX degradation efficiency reached 83.21% which is 10.54% higher than that without PS, and the kinetic constant was 0.067 min-1 in 30 min when the input voltage at 204 V (input power at 110.6 W), the input frequency at 186 Hz, the duty cycle at 63%, and the PS dosage ratio at 5.1:1. The addition of PS can produce more active particles reached 1.756 mg/L (O3), 0.118 mg/L (H2O2), 0.154 mmol/L (·OH) in 30 min. Furthermore, the DBD plasma system effectively activated an optimal amount of PS, leading to improved removal efficiency of COD, and TOC to 30.21% and 47.21%, respectively. Subsequently, eight primary by-products were pinpointed, alongside the observation of three distinct pathways of transformation. Predictions from the ECOSAR software indicated that most of the degradation intermediates were less toxic than SMX. The biological toxicity experiments elucidated that the treatment with the DBD/PS system effectively reduced the mortality of zebrafish larvae caused by SMX from 100% to 20.13% and improved the hatching rate from 55.69% to 80.86%. In particular, it is important to note that the degradation intermediates exhibit teratogenic effects on zebrafish larvae.

Highly Loaded Independent Pt0 Atoms on Graphdiyne for pH-General Methanol Oxidation Reaction.

The emergence of platinum-based catalysts promotes efficient methanol oxidation reactions (MOR). However, the defects of such noble metal catalysts are high cost, easy poisoning, and limited commercial applications. The efficient utilization of a low-cost, anti-poisoning catalyst has been expected. Here, it is skillfully used N-doped graphdiyne (NGDY) to prepare a zero-valent platinum atomic catalyst (Pt/NGDY), which shows excellent activity, high pH adaptability, and high CO tolerance for MOR. The Pt/NGDY electrocatalysts for MOR with specific activity 154.2 mA cm-2 (1449.3 mA mgPt -1 ), 29 mA cm-2 (296 mA mgPt -1 ) and 22 mA cm-2 (110 mA mgPt -1 ) in alkaline, acid, and neutral solutions. The specific activity of Pt/NGDY is 9 times larger than Pt/C in alkaline solution. Density functional theory (DFT) calculations confirm that the incorporation of electronegativity nitrogen atoms can increase the high coverage of Pt to achieve a unique atomic state, in which the shared contributions of different Pt sites reach the balance between the electroactivity and the stability to guarantee the higher performance of MOR and durability with superior anti-poisoning effect.

Graphdiyne-Induced Iron Vacancy for Efficient Nitrogen Conversion.

An iron vacancy-rich ferroferric oxide/graphdiyne heterostructure (IVR-FO/GDY) is rationally designed and fabricated for high-efficiency electrocatalytic nitrogen fixation to ammonia (ENFA). Experimental and theoretical results show that the GDY-induced iron vacancies in IVR-FO/GDY promote the electrocatalysis, and activate the local O sites to transfer electrons towards GDY to boost ENFA, resulting in promising electrocatalytic performances with a highest ammonia yield (YNH3 ) of 134.02 µg h-1 mgcat.-1 and Faradaic efficiency (FE) of up to 60.88%, as well as the high long-term stability in neutral electrolytes. The cationic vacancy activation strategy proposed in this work has strong general and universal guiding significance to the design of new efficient electrocatalysts for various electrochemical energy conversion reactions. Such defect engineering may be used efficiently in electrocatalysis, leading to the development and progress of energy industry.

Graphdiyne-based metal atomic catalysts for synthesizing ammonia.

Development of novel catalysts for nitrogen reduction at ambient pressures and temperatures with ultrahigh ammonia (NH3) yield and selectivity is challenging. In this work, an atomic catalyst with separated Pd atoms on graphdiyne (Pd-GDY) was synthesized, which shows fascinating electrocatalytic properties for nitrogen reduction. The catalyst has the highest average NH3 yield of 4.45 ± 0.30 mgNH3 mgPd -1 h-1, almost tens of orders larger than for previously reported catalysts, and 100% reaction selectivity in neutral media. Pd-GDY exhibits almost no decreases in NH3 yield and Faradaic efficiency. Density functional theory calculations show that the reaction pathway prefers to perform at the (Pd, C1, C2) active area because of the strongly coupled (Pd, C1, C2), which elevates the selectivity via enhanced electron transfer. By adjusting the p-d coupling accurately, reduction of self-activated nitrogen is promoted by anchoring atom selection, and side effects are minimized.

Graphdiyne@Janus Magnetite for Photocatalytic Nitrogen Fixation.

A highly active graphdiyne heterojunction with highly efficient photocatalysis is designed and fabricated. This catalyst demonstrates transformative properties on photocatalysis for ammonia synthesis. Such excellent properties are reigned from graphdiyne incorporating Fe site-specific magnetite resulting in a valence state transition within the catalyst. Our results show the strong advantages of graphdiyne in effectively regulating magnetite activity and coordination environments and also indicate that magnetite can selectively form two different valence tetrahedral coordination Fe and octahedral coordination Fe. The catalysts show remarkable catalytic performance for ammonia synthesis by photocatalysis, indicating transformative photocatalytic activity with an ammonia yield (Y NH 3 ) of unprecedented level of 1762.35±153.71 µmol h-1 gcat. -1 (the highest Y NH 3 could reach up to 1916.06 µmol h-1 gcat. -1 ). This work makes full use of the structural and property features of graphdiyne and opens up a new direction for photocatalysis in the field of catalysis.

Loading Copper Atoms on Graphdiyne for Highly Efficient Hydrogen Production.

Graphdiyne, as a magical support, can anchor zero valence metal atoms, providing us with an opportunity to develop emerging catalysts with the maximized active sites and selectivity. Herein we report high-performance atom catalysts (ACs), Cu0 /GDY, by anchoring Cu atoms on graphdiyne (GDY) for hydrogen evolution reaction (HER). The activity and selectivity of this catalyst are obviously superior to that of commercial 20 wt.% Pt/C, and the turnover frequency of 30.52 s-1 is 18 times larger than 20 wt.% Pt/C. Density functional theory (DFT) calculations demonstrate that the strong p-d coupling induced charge compensation leads to the zero valence state of the atomic-scaled transition metal catalyst. Our results show the strong advantages of graphdiyne-anchored metal atom catalysts in the field of electrochemical catalysis and opens up a new direction in the field of electrocatalysis.

A highly selective and active metal-free catalyst for ammonia production.

We report a facile surface-induced method for the in situ growth of single-/few-layered crystalline fluorographdiyne film on the surface of carbon fibers (cFGDY). The crystallized structure of cFGDY was directly confirmed by the scanning/transmission electron microscopy (SEM/TEM), high-resolution TEM (HRTEM) and computer simulation, selected area electron diffraction (SAED), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. cFGDY showed a 9-fold stacking mode. Our results show that cFGDY is a metal-free electrocatalyst with unique structure and excellent performance for ammonia production from nitrogen and water efficiently at room temperature and ambient pressure, achieving a high NH3 production rate and Faraday efficiency in neutral conditions. This work provides an efficient catalyst system with determined chemical and electronic structures for highly selective and active nitrogen reduction, serving as a promising platform towards the development of novel metal-free catalysts.

Graphdiyne Interface Engineering: Highly Active and Selective Ammonia Synthesis.

A freestanding 3D graphdiyne-cobalt nitride (GDY/Co2 N) with a highly active and selective interface is fabricated for the electrochemical nitrogen reduction reaction (ECNRR). Density function theory calculations reveal that the interface-bonded GDY contributes an unique p-electronic character to optimally modify the Co-N compound surface bonding, which generates as-observed superior electronic activity for NRR catalysis at the interface region. Experimentally, at atmospheric pressure and room temperature, the electrocatalyst creates a new record of ammonia yield rate (Y NH 3 ) and Faradaic efficiency (FE) of 219.72 µg h-1 mgcat. -1 and 58.60 %, respectively, in acidic conditions, higher than reported electrocatalysts. Such a catalyst is promising to generate new concepts, new knowledge, and new phenomena in electrocatalytic research, driving rapid development in the field of electrocatalysis.

Fluorographdiyne: A Metal-Free Catalyst for Applications in Water Reduction and Oxidation.

A highly efficient bifunctional metal-free catalyst was prepared by growth of three-dimensional porous fluorographdiyne networks on carbon cloth (p-FGDY/CC). Our experiments and density functional theory (DFT) calculations show the 3D p-FGDY/CC network is highly active and it is a high potential metal-free catalyst for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), as well as overall water splitting (OWS) under both acidic and alkaline conditions. The experimental and theoretical results show very good consistency; for example, in the HER process, p-FGDY/CC exhibits small overpotentials of 82 and 92 mV to achieve 10 mA cm-2 under alkaline and acidic conditions, respectively. This ensures an even higher selectivity for the adsorption/desorption of various O/H intermediate species. The essential key promotion accomplishes a bifunctional H2 O redox performance application under pH-universal electrochemical conditions.

Highly Efficient and Selective Generation of Ammonia and Hydrogen on a Graphdiyne-Based Catalyst.

The emergence of zerovalent atom catalysts has been highly attractive for catalytic science. For many years, scientists have explored the stability of zerovalent atom catalysts and demonstrated their unique properties. Here, we describe an atom catalyst (AC) with atomically dispersed zerovalent molybdenum atoms on graphdiyne (Mo0/GDY) with a high mass content of Mo atoms (up to 7.5 wt %) that was synthesized via a facile and scalable process. The catalyst shows both excellent selectivity and activity in the electrochemical reduction of nitrogen and in the hydrogen evolution reaction in aqueous solutions at room temperature and pressure. It is noted that this catalyst is the first bifunctional AC for highly efficient and selective ammonia and hydrogen generation. The catalytic process of our catalyst is well understood, the structure is defined, and the performance is excellent, providing a solid foundation for the generation and application of the new generation of catalysts.

Rationally engineered active sites for efficient and durable hydrogen generation.

The atomic-level understanding of the electrocatalytic activity is pivotal for developing new metal-free carbon electrocatalysts towards efficient renewable energy conversion. Here, by utilizing the amidated-carbon fibers, we demonstrate a rational surface modulation strategy on both structural and electronic properties, which will significantly boost the hydrogen evolution reaction activity of electrocatalysts. Theoretical calculations reveal the amidation decorated surface will promote significantly more 2D electrons towards the localization at the C=O branch. The modified surface displays a self-activated electron-extraction characteristic that was actualized by a fast reversible bond-switching between HO-C=Ccatalyst and O=C-Ccatalyst. Experimentally, this metal-free electrode exhibits outstanding hydrogen evolution reaction activities and long-term stabilities in both acidic and alkaline media, even surpassing the commercial 20 wt% Pt/C catalyst. Thus, this strategy can extend to a general blueprint for achieving precise tuning on highly efficient electron-transfer of hydrogen evolution reaction for broad applications under universal pH conditions.

Graphdiyne and its Assembly Architectures: Synthesis, Functionalization, and Applications.

Graphdiyne (GDY), a novel one-atom-thick carbon allotrope that features assembled layers of sp- and sp2 -hybridized carbon atoms, has attracted great interest from both science and industry due to its unique and fascinating structural, physical, and chemical properties. GDY-based materials with different morphologies, such as nanowires, nanotube arrays, nanosheets, and ordered stripe arrays, have been applied in various areas such as catalysis, solar cells, energy storage, and optoelectronic devices. After an introduction to the fundamental properties of GDY, recent advances in the fabrication of GDY-based nanostructures and their applications, and corresponding mechanisms, are covered, and future critical perspectives are also discussed.

Ultrathin Nanosheet of Graphdiyne-Supported Palladium Atom Catalyst for Efficient Hydrogen Production.

Atomic catalysts are promising alternatives to bulk catalysts for the hydrogen evolution reaction (HER), because of their high atomic efficiencies, catalytic activities, and selectivities. Here, we report the ultrathin nanosheet of graphdiyne (GDY)-supported zero-valent palladium atoms and its direct application as a three-dimensional flexible hydrogen-evolving cathode. Our theoretical and experimental findings verified the successful anchoring of Pd0 to GDY and the excellent catalytic performance of Pd0/GDY. At a very low mass loading (0.2%: 1/100 of the 20 wt % Pt/C), Pd0/GDY required only 55 mV to reach 10 mA cm-2 (smaller than 20 wt % Pt/C); it showed larger mass activity (61.5 A mgmetal-1) and turnover frequency (16.7 s-1) than 20 wt % Pt/C and long-term stability during 72 hr of continuous electrolysis. The unusual electrocatalytic properties of Pd0/GDY originate from its unique and precise structure and valence state, resulting in reliable performance as an HER catalyst.

Ultrathin Graphdiyne-Wrapped Iron Carbonate Hydroxide Nanosheets toward Efficient Water Splitting.

We employed a two-step strategy for preparing ultrathin graphdiyne-wrapped iron carbonate hydroxide nanosheets on nickel foam (FeCH@GDY/NF) as the efficient catalysts toward the electrical splitting water. The introduction of naturally porous GDY nanolayers on FeCH surface endows the pristine catalyst with structural advantages for boosting catalytic performances. Benefited from the protection of robust GDY nanolayers with intimate contact between GDY and FeCH, the combined material exhibits high long-term durability of 10 000 cycles for oxygen-evolution reaction (OER) and 9000 cycles for hydrogen evolution reaction (HER) in 1.0 M KOH. Such excellent bifunctional OER/HER performance makes FeCH@GDY/NF quite qualified for alkaline two-electrode electrolyzer. Remarkably, such electrocatalyst can drive 10 and 100 mA cm-2 at 1.49 and 1.53 V, respectively. These results demonstrate the decisive role of GDY in the improvement of electrocatalytic performances, and open up new opportunities for designing cost-effective, efficient, and stable electrocatalysts for sustainable oxygen/hydrogen generation.

Overall water splitting by graphdiyne-exfoliated and -sandwiched layered double-hydroxide nanosheet arrays.

It is of great urgency to develop efficient, cost-effective, stable and industrially applicable electrocatalysts for renewable energy systems. But there are still few candidate materials. Here we show a bifunctional electrocatalyst, comprising graphdiyne-exfoliated and -sandwiched iron/cobalt layered double-hydroxide nanosheet arrays grown on nickel foam, for the oxygen and hydrogen evolution reactions. Theoretical and experimental data revealed that the charge transport kinetics of the structure were superior to iron/cobalt layered double-hydroxide, a prerequisite for improved electrocatalytic performance. The incorporation with graphdiyne increased the number of catalytically active sites and prevented corrosion, leading to greatly enhanced electrocatalytic activity and stability for oxygen evolution reaction, hydrogen evolution reaction, as well as overall water splitting. Our results suggest that the use of graphdiyne might open up new pathways for the design and fabrication of earth-abundant, efficient, functional, and smart electrode materials with practical applications.

Efficient Hydrogen Production on a 3D Flexible Heterojunction Material.

A novel heterojunction material, with electron-rich graphdiyne as the host and molybdenum disulfide as the catalytic center (eGDY/MDS), to produce ultraefficient hydrogen-evolution reaction (HER) at all pH values is described. It is a surprise that the metallic conductor combined from two semiconductor materials, eGDY and MDS, leads to optimal free energy (ΔGH ) and enhancement in the intrinsic HER catalytic performances. The calculated and experimental results indicate that eGDY/MDS shows greatly enhanced catalytic activities and high stabilities in both acidic and alkaline conditions; these approach the outstanding performances of the state-of-the-art noble-metal-based catalysts. The eGDY/MDS shows better activity than Pt/C in alkaline media and remarkable enhancement in photocurrent density. The high catalytic activity of eGDY/MDS originates from facilitated electronic transfer kinetics, high conductivity, more exposed catalytic active sites, and excellent mass transport.