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The traditional chemical cross-linking method is based on the formation of covalent bonds between molecules to connect three-dimensional networks to enhance the strength of hydrogels. Although this method can significantly improve the mechanical properties, it also has many problems, such as irreversibility and fatigue. Therefore, the design and preparation of supramolecular hydrogels with high mechanical properties and good temperature resistance have very important research significance and practical value. This paper prepared a supramolecular gel with both temperature resistance and mechanical properties through hydrophobic association and hydrogen bonding, and evaluated its thermal stability, rheology, temperature resistance and pressure plugging ability. The results showed that the supramolecular gel had excellent thermal stability, and there was strong physical entanglement between its three-dimensional network structures, which made it difficult to be destroyed by increasing temperature. The excellent rheological properties of supramolecular gels enable them to maintain good viscoelastic changes in the linear viscoelastic region within the strain range of 0.1-30%. When the strain was greater than 30%, the supramolecular gel began to undergo different degrees of sol-gel phase transition, which showed that the energy storage modulus of supramolecular gel decreased. In addition, the energy storage modulus of supramolecular gel was always greater than the loss modulus in the whole frequency scanning range, and there was no intersection between the two gel and the gel always showed high elasticity. Meanwhile, the supramolecular gel still had good structure and strength after high temperature aging. Its tensile and compressive properties did not change significantly, but the color of the gel surface changed slightly, which could maintain good structural stability under high temperature environment. Supramolecular gel particles could be used as plugging materials for drilling fluid, and had excellent plugging ability of formation fractures and pores. The plugging ability of 1mm aperture plate model was up to 6.3MPa, and the plugging ability of 1mm seam width was up to 4.9MPa. Therefore, the development and application of supramolecular gel plays an important supporting role in drilling fluid plugging.

Structured AbstractPurposeRPE oxidative metabolism is critical for normal retinal function and is often studied in cell culture systems. Here, we show that conventional culture media volumes dramatically impact O2availability, limiting oxidative metabolism. We suggest optimal conditions to ensure cultured RPE is in a normoxic environment permissive to oxidative metabolism.MethodsWe altered the availability of O2to human primary RPE cultures directly via a hypoxia chamber or indirectly via the amount of medium over cells. We measured oxygen consumption rates (OCR), glucose consumption, lactate production,13C6-glucose flux, hypoxia inducible factor (HIF-1α) stability, intracellular lipid droplets after a lipid challenge, trans-epithelial electrical resistance, cell morphology, and pigmentation.ResultsMedium volumes commonly employed during RPE culture limit diffusion of O2to cells, triggering hypoxia, activating HIF-1α, limiting OCR, and dramatically altering cell metabolism, with only minor effects on typical markers of RPE health. Media volume effects on O2availability decrease acetyl-CoA utilization, increase glycolysis, and alter the size and number of intracellular lipid droplets under lipid-rich conditions.ConclusionsDespite having little impact on visible and typical markers of RPE culture health, media volume dramatically affects RPE physiology “under the hood”. As RPE-centric diseases like age-related macular degeneration (AMD) involve oxidative metabolism, RPE cultures need to be optimized to study such diseases. We provide guidelines for optimal RPE culture volumes that balance ample nutrient availability from larger media volumes with adequate O2availability seen with smaller media volumes.

Nitrogen and sulfur-co-doped ceria with a regular nanorod morphology was prepared by one-step calcination treatment. N and S dopants can generate new impurity level states and promote the photocatalytic performance of CeO2 for VOCs degradation.

A merger of copper catalysis and semiconductor photocatalysis using polymeric carbon nitride (PCN) for multi-type cross-coupling reactions was developed. This dual catalytic system enables mild C–H arylation, chalcogenation, and C–N cross-coupling reactions under visible light irradiation with a broad substrate scope. Good to excellent yields were obtained with appreciable site selectivity and functional group tolerance. Metal-free and low-cost PCN photocatalyst can easily be recovered and reused several times.

A novel cerium-based metal-organic framework crystal (Ce-TBAPy) was developed via a one-pot solvothermal method. Interestingly, the Ce-TBAPy photocatalyst material demonstrated an enhanced collaborative photoredox performance in terms of acetaldehyde degradation and water reduction, and the photoreaction rates of Ce-TBAPy shown about 5.06-times and 3.94-times higher, respectively, than those when untreated H4TBAPy was used. A significant finding is that the apparent quantum efficiency value of Ce-TBAPy for CO2 generation from CH3CHO decomposition performs 5.12% at 420 nm. The accumulation of abundant separated holes on the pyrene macrocycles could oxidize CH3CHO to CO2 easily. Meanwhile, cerium integration with TBAPy4− ligands to form a π-conjugated construction further resulted in sufficient photoinduced electrons and exhibited effective interfacial charge separation, which harvesting the reduction of H2O to H2 efficiently. The electronic localization influence arising from the formation of -COO-Ce functional groups in Ce-TBAPy and the direction of electron migration in the photocatalytic system were further confirmed by DFT calculation. This work provides an effective strategy to obtain rare earth-based MOF photocatalysts with dual redox functions and holds promise for advancing the prospect of using MOF materials to convert solar energy into chemical energy.

Pd–Ni/Au nanoshelled microsphere arrays with different Pd–Ni atomic ratios were successfully synthesized using the etched monolayer colloidal spheres as templates. Morphology and composition characterizations indicated that the prepared products consisted of polystyrene cores of Au and Pd–Ni metallic nanoshells with an overall diameter of 450 nm. Electrochemical measurements in an alkaline solution showed that the Pd–Ni/Au catalyst with Pd:Ni = 4:1 atomic ratio demonstrated an optimal catalytic activity with the peak current of 59.4 mA[Formula: see text], the lower oxidation peak potential and the higher stability. These results could be ascribed to the enhanced surface area which increased the number of electrocatalytic active sites, and the electronic interaction between Pd and Ni. This work provides new opportunities for the rational design of microsphere array catalysts for enhancing the catalytic performance in fuel cells.

Providing affordable safe drinking water and universal sanitation poses a grand challenge especially after the global COVID-19 pandemic. In this work, we developed atomically dispersed Au on potassium-incorporated polymeric carbon nitride (AuKPCN) that could simultaneously boost photocatalytic generation of ·OH and H2O2 with an apparent quantum efficiency over 90% at 400–420 nm. The introduction of potassium into the poly(heptazine imide) matrix formed strong K-N bonds, preventing Au from forming strong interactions with N. Instead, Au formed a bond with C, only having weak interactions with N on KPCN, which rendered Au with an oxidation number close to 0. The results of in-situ vibrational spectroscopy, isotopic experiments, transient absorption spectroscopy and time-dependent density functional theory (TDDFT) simulations revealed that the low-valent Au could append its 6s orbital into the band diagram of AuKPCN that formed a trapping level for generating highly localized holes under photoexcitation. These highly localized holes could boost the 1e− water oxidation reaction to form highly oxidative ·OH and simultaneously unbind the hydrogen atom in H2O molecule, which greatly promoted the hydrogenation process during the 2e− oxygen reduction reaction (ORR) to produce H2O2. The photogenerated ·OH on AuKPCN led to a more than 120-fold efficiency enhancement for visible-light-response superhydrophilicity as compared to that of the commercial TiO2. The onsite fixed-bed reactor under photo-illumination achieved a remarkable 132.5 LH2O m− 2 day− 1 water disinfection rate (lg6), which is about 30 times superior than the TiO2 photocatalytic advanced oxidation process in the most ideal case (H2O m− 2 day− 1; lg4).

Designing and synthesizing highly efficient and stable electrocatalysts for hydrogen evolution reaction (HER) is important for realizing the hydrogen economy. Tuning the electronic structure of the electrocatalysts is essential to achieve optimal HER activity, and interfacial engineering is an effective strategy to induce electron transfer in a heterostructure interface to optimize HER kinetics. In this study, ultrafine RhP2 /Rh nanoparticles are synthesized with a well-defined semiconductor-metal heterointerface embedded in N,P co-doped graphene (RhP2 /Rh@NPG) via a one-step pyrolysis. RhP2 /Rh@NPG exhibits outstanding HER performances under all pH conditions. Electrochemical characterization and first principles density functional theory calculations reveal that the RhP2 /Rh heterointerface induces electron transfer from metallic Rh to semiconductive RhP2 , which increases the electron density on the Rh atoms in RhP2 and weakens the hydrogen adsorption on RhP2 , thereby accelerating the HER kinetics. Moreover, the interfacial electron transfer activates the dual-site synergistic effect of Rh and P of RhP2 in neutral and alkaline environments, thereby promoting reorganization of interfacial water molecules for faster HER kinetics. Agency for Science, Technology and Research (A*STAR) Ministry of Education (MOE) This work was financially supported by the National Natural Science Foundation of China (Grant No. 22075195); Singapore Ministry of Education Academic Research Fund (AcRF) Tier 1: RG4/20 and RG2/21, Tier 2: MOET2EP10120-0002; Agency for Science, Technology and Research: AME IRG A20E5c0080; and the starting research fund of Suzhou University of Science and Technology for H.B.Y.

Ultrabroad spectral absorption is required for semiconductor photocatalysts utilized for solar-to-chemical energy conversion. The light response range can be extended by element doping, but the photocatalytic performance is generally not enhanced correspondingly. Here we present a solid alkali activation strategy to synthesize near-infrared (NIR) light-activated carbon-doped polymeric carbon nitride (A-cPCN) by combining the copolymerization of melamine and 1,3,5-trimesic acid. The prepared A-cPCN is highly crystalline with a narrowed bandgap and enhanced efficiency in the separation of photogenerated electrons and holes. Under irradiation with NIR light (780 nm ≥ λ ≥ 700 nm), A-cPCN shows an excellent photocatalytic activity for H2 generation from water with rate of 165 µmol g−1 h−1, and the photo-redox activity for H2O2 production (109 µmol g−1 h−1) from H2O and O2, whereas no observed photocatalytic activity over pure PCN. The NIR photocatalytic activity is due to carbon doping, which leads to the formation of an interband level, and the alkali activation that achieved shrinking the transfer distance of photocarriers. The current synergistic strategy may open insights to fabricate other carbon-nitrogen-based photocatalysts for enhanced solar energy capture and conversion.

Different from traditional metal-support heterogenous catalysts, inverse heterogeneous catalysts, in which the surface of metal is decorated by metal oxide, have recently attracted increasing interests owing to the unique interfacial effect and electronic structure. However, a deep insight into the effect of metal-oxide interaction on the catalytic performance still remains a great challenge. In our work, an inverse hematite/palladium (Fe2O3/Pd) hybrid nanostructure, i.e., the active Fe2O3 ultrathin oxide layers partially covering on the surface of Pd nanoparticles (NPs), exhibited superior electrocatalytic performance towards methanol oxidation reaction (MOR) as compared to the bare Pd NPs based on density functional theory calculation. The charge could transfer from Pd to Fe2O3 driven by the built-in potential at the interface of Pd and Fe2O3, which favors the downshift of d band center of Pd. With the assistance of interfacial hydroxyl OH*, the cleavage of O H and C H in CH3OH could take place much easily with lower barrier energy on Fe2O3/Pd than that on pure Pd via two electrons transferring reaction pathways. Our results highlight that the synergy of Pd and Fe2O3 at the interface could facilitate the electrochemical transformation of methanol into formaldehyde assisted with interfacial hydroxyl OH*.

Single-atom catalysts (SACs), with atomically dispersed metal atoms anchored on a typical support, representing the utmost utilization efficiency of the atoms, have recently emerged as promising catalysts for a variety of catalytic applications. The electronic properties of the active center of SACs are highly dependent on the local environment constituted by the single metal atom and its surrounding coordination elements. Therefore, engineering the coordination environment near single metal sites, from the first coordination shell to the second shell or higher, would be a rational way to design efficient SACs with optimized electronic structure for catalytic applications. The wide range of coordination configurations, guaranteed by the multiple choices of the type and heterogeneity of the coordination element (N, O, P, S, etc.), further offer a large opportunity to rationally design SACs for satisfactory activities and investigate the structure–performance relationship. In this review, the coordination engineering of SACs by varying the type of coordination element was elaborated and the photocatalytic water splitting of SACs was highlighted. Finally, challenging issues related to the coordination engineering of SACs and their photocatalytic applications were discussed to call for more efforts devoted to the further development of single-atom catalysis.

One of the most unique properties of two-dimensional carbides and nitrides of transition metals (MXenes) is their excellent water dispersibility and yet possessing superior electrical conductivity but their industrial-scale application is limited by their costly chemical synthesis methods. In this work, the niche feature of MXene was capitalized in the packed-bed electrochemical reactor (PBER) to produce MXene at an unprecedented reaction rate and yield with minimal chemical waste. A simple NH4F solution was employed as the green electrolyte which could be used repeatedly without any loss in its efficacy. Surprisingly, both fluoride and ammonium were found to play critical roles in the electrochemical etching, functionalization, and expansion of the layered parent materials (MAXs) through which the liberation of ammonia gas was observed. The electrochemically produced MXenes (eMXenes) with excellent conductivity, applied as supercapacitor electrodes, could deliver an ultra-high volumetric capacity (1408 F cm-3) and volumetric energy density (75.8 Wh L-1). This revolutionary green, energy efficient and scalable electrochemical route will not only pave the way for industrial-scale production of MXene but also open up a myriad of versatile electrochemical modifications for improved functional MXenes.

Artificial photosynthesis offers a promising strategy to produce hydrogen peroxide (H2O2)—an environmentally friendly oxidant and a clean fuel. However, the low activity and selectivity of the two-electron oxygen reduction reaction (ORR) in the photocatalytic process greatly restricts the H2O2 production efficiency. Here we show a robust antimony single-atom photocatalyst (Sb-SAPC, single Sb atoms dispersed on carbon nitride) for the synthesis of H2O2 in a simple water and oxygen mixture under visible light irradiation. An apparent quantum yield of 17.6% at 420 nm together with a solar-to-chemical conversion efficiency of 0.61% for H2O2 synthesis was achieved. On the basis of time-dependent density function theory calculations, isotopic experiments and advanced spectroscopic characterizations, the photocatalytic performance is ascribed to the notably promoted two-electron ORR by forming μ-peroxide at the Sb sites and highly concentrated holes at the neighbouring N atoms. The in situ generated O2 via water oxidation is rapidly consumed by ORR, leading to boosted overall reaction kinetics. Hydrogen peroxide is an interesting target for artificial photosynthesis, although its actual production via the two-electron oxygen reduction reaction remains limited. Now, a carbon nitride-supported antimony single atom photocatalyst has been developed with a superior performance for this process.

In this study, the novel triphenylphosphine-based covalent organic frameworks (P–COF-1) were firstly introduced into polymeric carbon nitride (PCN) to fabricate P–COF-1/PCN heterojunctions via intermolecular π-π interaction. The photocatalytic H2 production rate over the 9% P–COF-1/PCN heterojunctions is ca. 12 times as much as that of pure PCN. The photoelectrochemical measurements and theoretical calculation results show that due to the well-matched band structure between P–COF-1 and PCN, the photo-generated electrons tend to migrate from P–COF-1 into the conduction band of PCN through the interface of heterostructures. In addition to the π→π∗ electron transition of conjugated tri-s-triazine units in the 9% P–COF-1/PCN with band gap energy of 2.53 eV, the lone pair electrons of P transition to the π∗ orbitals of P–COF-1 (n→π∗) with lower band gap energy of 1.82 eV results in the effective separation of photo-generated carriers and more visible light absorption, and thus enhanced the photocatalytic hydrogen evolution.

Dry age-related macular degeneration (AMD) is marked by the accumulation of extracellular and intracellular lipid-rich deposits within and around the retinal pigment epithelium (RPE). Inducing autophagy, a conserved, intracellular degradative pathway, is a potential treatment strategy to prevent disease by clearing these deposits. However, mTOR inhibition, the major mechanism for inducing autophagy, disrupts core RPE functions. Here, we screened autophagy inducers that do not directly inhibit mTOR for their potential as an AMD therapeutic in primary human RPE culture. Only two out of more than thirty autophagy inducers tested reliably increased autophagy flux in RPE, emphasizing that autophagy induction mechanistically differs across distinct tissues. In contrast to mTOR inhibitors, these compounds preserved RPE health, and one inducer, the FDA-approved compound flubendazole (FLBZ), reduced the secretion of apolipoprotein that contributes to extracellular deposits termed drusen. Simultaneously, FLBZ increased production of the lipid-degradation product β-hydroxybutyrate, which is used by photoreceptor cells as an energy source. FLBZ also reduced the accumulation of intracellular deposits, termed lipofuscin, and alleviated lipofuscin-induced cellular senescence and tight-junction disruption. FLBZ triggered compaction of lipofuscin-like granules into a potentially less toxic form. Thus, induction of RPE autophagy without direct mTOR inhibition is a promising therapeutic approach for dry AMD.

Introducing oxygen vacancy (Vo) has been considered as an effective and significant method to accelerate the sluggish electrocatalytic nitrogen reduction reaction (NRR). In this work, a series of bimetallic zeolitic imidazolate frameworks based on ZIF-67 and ZIF-8 with varied ratios of Co/Zn have been applied as precursors to prepare Vo-rich Zn-doped Co3O4 nanopolyhedrons (Zn-Co3O4) by a low-temperature oxidation strategy. Zn-Co3O4 presents an ammonia yield of 22.71 μg h-1 mgcat.-1 with a high faradaic efficiency of 11.9% for NRR under ambient conditions. The remarkable catalytic performances are believed to result from the plentiful Vo as the Lewis acid sites and electron-rich Co sites to promote the adsorption and dissociation of N2 molecules. Remarkably, Zn-Co3O4 also demonstrates a high electrochemical stability. This work presents a guiding method for developing a stable and efficient electrocatalyst for the NRR.

The conversion of chemical feedstock materials into high value-added products accompanied with dehydrogenation is of great value in the chemical industry. However, the catalytic dehydrogenation reaction is inhibited by a limited number of expensive noble metal catalysts and lacks understanding of dehydrogenation mechanism. Here, we report the use of heterogeneous non-noble metal iron nanoparticles (NPs) incorporated mesoporous nitrogen-doped carbon to investigate the dehydrogenation mechanism based on experiment observation and density functional theory (DFT) method. Fe NPs catalyst displays excellent performance in the dehydrogenation of 1,2,3,4-tetrahydroquinoline (THQ) with 100% selectivity and 100% conversion for 10−12 h at room temperature. The calculated adsorption energy implies that THQ prefers to adsorb on Fe NPs as compared with absence of Fe NPs. What is more, the energy barrier of transition state is relatively low, illustrating the dehydrogenation is feasible. This work provides an atomic scale mechanism guidance for the catalytic dehydrogenation reaction and points out the direction for the design of new catalysts.

To solve serious energy and environmental crises caused by rapid industrial development, the formation of heterostructured photocatalysts is a promising approach for efficient and scalable H2 produ...

Introducing intrinsic defects in polymeric carbon nitride (PCN) without the addition of exotic atoms have been verified as an available strategy to boost the photocatalytic performance. This minireview focuses on the fundamental classifications and positive roles of intrinsic defects in PCN for photocatalysis applications. The intrinsic defects in PCN are classified into several types, such as nitrogen vacancy, carbon vacancy and derivative functional groups such as cyano, amino and cyanamide groups. The critical roles of these defects on the electronic configuration, charge transfer and surface properties of PCN are also carefully classified and elaborated. Furthermore, the photocatalysis applications of the defective PCN including photocatalytic water splitting, N2 fixation, H2 O2 production, CO2 reduction and NO removal are summarized. In the end, the challenges and opportunities of defect chemistry in PCN for photocatalysis field are presented.

Psoriasis is a chronic inflammatory skin disease, and the mechanism remains unknown. The present study found that the level of miR-205-5p was downregulated in psoriatic skin tissues. miR-205-5p inhibited proliferation in HaCaT cells. miR-205-5p impaired proliferation, migration and tube formation in human umbilical vein endothelial cells. Angiopoietin (Ang)-2, vascular endothelial growth factor (VEGFA) and bone morphogenetic protein and activin membrane-bound inhibitor (BAMBI) were confirmed as the targets of miR-205-5p. Moreover, miR-205-5p suppressed the phosphorylation of p38 and extracellular regulated protein kinase, and inhibited expression level of β-catenin. In vivo, miR-205-5p significantly alleviated imiquimod (IMQ)-induced psoriasis in mice, and deactivated mitogen-activated protein kinase (MAPK) and Wnt/β-catenin pathways. In summary, we demonstrated that miR-205-5p alleviated IMQ-induced psoriasis in mice by restraining epidermal hyperproliferation and excessive neovascularization. miR-205-5p may play its roles by targeting Ang-2, VEGFA and BAMBI, and deactivating the Wnt/β-catenin and MAPK signaling pathways. These findings may provide a potential therapeutic target for clinical treatment of psoriasis.

Three-dimensional Inverse opal periodic structure and high specific surface area have been widely applied in many fields. Herein, inverse opal tin dioxide (SnO2) was fabricated successfully via a s...