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Carbon dots (C-Dots) have many unique properties, which endow them with a promising platform from catalysis to biology applications. However, quantitative understanding of those properties of C-Dot...

In electrochemical energy storage and conversion systems, the anodic oxygen evolution reaction (OER) accounts for a large proportion of the energy consumption. The electrocatalytic urea oxidation reaction (UOR) is one of the promising alternatives to OER, owing to its low thermodynamic potential. However, owing to the sluggish UOR kinetics, its potential in practical use has not been unlocked. Herein, we developed a tungsten-doped nickel catalyst (Ni-WOx ) with superior activity towards UOR. The Ni-WOx catalyst exhibited record fast reaction kinetics (440 mA cm-2 at 1.6 V versus reversible hydrogen electrode) and a high turnover frequency of 0.11 s-1 , which is 4.8 times higher than that without W dopants. In further experiments, we found that the W dopant regulated the local charge distribution of Ni atoms, leading to the formation of Ni3+ sites with superior activity and thus accelerating the interfacial catalytic reaction. Moreover, when we integrated Ni-WOx into a CO2 flow electrolyzer, the cell voltage is reduced to 2.16 V accompanying with ≈98 % Faradaic efficiency towards carbon monoxide.

The strong metal–support interaction (SMSI) between metals and reducible supports (e.g., CeO2, TiO2, and SnO2), which has been widely investigated, plays a very important role in heterogeneous catalysis. We report the first example of SMSI between palladium (Pd) and gallium oxide (Ga2O3) within a PdGa nanoparticle (denoted as PdxGay NP, where x:y is the atomic ratio of Pd and Ga). The typical features of classic SMSI, such as electron transfer between Ga2O3 and Pd and suppression of H2 and CO adsorption, are successfully observed on PdxGay NPs. Detailed characterizations and control experiments demonstrate that the coexistence of PdGa alloy and Ga2O3 in PdxGay NPs plays a vital role in the formation of SMSI. To systematically study the effects of SMSI on catalytic performance, PdxGay NPs were used as “self-supported catalysts” for propyne semi-hydrogenation (PSH), a critical process for removing trace propyne from propylene in industry. It is shown that optimized Pd0.34Ga1 NPs give a propylene selectivity of 98.2% at a propyne conversion of 96.6% at 30 °C and atmospheric pressure, which is much higher than that of pure Pd NPs and Pd/Ga2O3 catalysts prepared by a conventional wet-impregnation method. The reaction paths of PSH on PdxGay NPs have been further revealed by density functional theory (DFT) calculations. This work may not only deepen the basic understanding of SMSI, but also promote the design and application of heterogeneous catalysts.

The sluggish redox conversion of sulfur species, especially under high sulfur loading, low-temperature, and low electrolyte/sulfur (E/S) ratio conditions, aggravates the shuttle effect that severely deteriorates the electrochemical performance of Li–S batteries. Herein, alloying metallic Ni with Fe increases the Ni–Ni(Fe) bond length and reduces the coordination number of Ni, realizing the upshift of the d-band center towards the Fermi level, and thus regulates sulfur species adsorbability to a rational level to accelerate their catalytic conversion. As a consequence, the Li–S batteries with Ni3Fe-modified separators exhibit superior rate performances (800 and 645 mA h g−1 at 10 and 15C, respectively) and excellent cycling stability (capacity decay of 0.05% per cycle over 800 cycles at 2.0C). Meanwhile, the stable operation of high areal capacity Li–S batteries under a high sulfur loading of 30 mg cm−2 and a low electrolyte/sulfur ratio of ∼7 µL mg−1 is realized. Besides, benefitting from the enhanced kinetics, the battery can work well at −10 °C, which is rarely achieved by conventional Li–S batteries. Our work provides a promising strategy for designing high-activity electrocatalysts for high-performance and low-temperature Li–S batteries.

The production of CO from the CO2 reduction reaction (CO2RR) is of great interest in the renewable energy storage and conversion, the neutral carbon emission, and carbon recycle utilization. Silver (Ag) is one of the catalytic metals that are active for electrochemical CO2 reduction into CO, but the catalysis requires a large overpotential to achieve higher selectivity. Constructing a metal-oxide interface could be an effective strategy to boost both activity and selectivity of the catalysis. Herein, density functional theory (DFT) calculations were first conducted to reveal the chemical insights of the catalytic performance on the interface between metal oxide and Ag(111) (MOx/Ag(111)). The results show that the *COOH intermediates can be more stabilized on the surfaces of MOx/Ag(111) than pure Ag(111). The hydrogen evolution reaction on MOx/Ag(111) can be suppressed due to the significantly higher Gibbs free energy for hydrogen adsorption (ΔGH*), thereby enhancing the selectivity toward CO2RR. A series of MOx/Ag composites with the unique interface based on the DFT results were then introduced though a two-step approach. The as-obtained MOx/Ag catalysts boosted both the CO activity and selectivity at a relatively positive potential range, especially in the case of MnO2/Ag. The reduction current density on the MnO2/Ag catalyst can reach 4.3 mA cm-2 at -0.7 V (vs RHE), which is 21.5 times higher than that on pure Ag, and the overpotential of CO2 to CO (390 mV) possesses is much lower than that on pure Ag NPs (690 mV). This study proposes an effective design strategy to construct a metal-oxide interface for CO2RR based on the synergistic effect between metals and MOx.

The conversion of light alkanes to olefins is crucial to the chemical industry. The quest for improved catalytic performance for this conversion is motivated by current drawbacks including: expensive noble metal catalysts, poor conversion, low selectivity, and fast decay of efficiency. The in situ visualization of complex catalysis at the atomic level is therefore a major advance in the rational framework upon building the future catalysts. Herein, the catalytic C-H bond activations of ethylbenzene on TiO2(110)-(1 × 1) were explored with high-resolution scanning tunneling microscopy and first-principles calculations. We report that the first C-H bond scission is a two-step process that can be triggered by either heat or ultraviolet light at 80 K, with near 100% selectivity of β-CH bond cleavage. This work provides fundamental understanding of C-H bonds cleavage of ethylbenzene on metal oxides, and it may promote the design of new catalysts for selective styrene production under mild conditions.

Single atom catalysts (SACs) have recently attracted great attention in heterogeneous catalysis and have been regarded as ideal models for investigating the strong interaction between metal and support. Despite the huge progress over the past decade, the deep understanding on the structure-performance correlation of SACs at a single atom level still remains to be a great challenge. In this study, we demonstrate that the variation in the coordination number of the Pt single atom can significantly promote the propylene selectivity during propyne semihydrogenation (PSH) for the first time. Specifically, the propylene selectivity greatly increases from 65.4% to 94.1% as the coordination number of Pt-O increases from ∼3.4 to ∼5, whereas the variation in the coordination number of Pt-O slightly influences the turnover frequency values of SACs. We anticipate that the present work may deepen the understanding on the structure-performance of SACs and also promote the fundamental research in single atom catalysis.

The structural transformation from symmetric cumulene to broken-symmetry polyyne within a one-dimensional (1-D) atomic carbon chain is a signature of Peierls distortion. Direct observation of such a structural transformation with single-bond resolution is, however, still challenging. Herein, we design a molecule with a cumulene moiety (Br2C═C═C═CBr2) and employ STM tip manipulation to achieve the molecular skeleton rearrangement from a cumulene to a diyne moiety (Br-C≡C-C≡C-Br). Furthermore, by an on-surface reaction strategy, thermally induced entire debromination (:C═C═C═C:) leads to the formation of a 1-D organometallic polyyne (-C≡C-C≡C-Au-) with a semiconducting characteristic, which implies that a Peierls-like transition may occur in a rationally designed molecular system with limited length.

Recent experimental study shows that the pre-lithiated MoS2 monolayer exhibits an enhanced electrochemical performance, coulombic efficiency of which is 26% higher than the pristine MoS2 based anode. The underlying mechanism of such significant enhancement, however, has not yet been addressed. By means of density functional theory (DFT) calculations, we systematically investigated the adsorption and diffusion behavior of lithium (Li) atoms on the MS2 (M = Mo, W, V) monolayers. On the pre-lithiated MS2 monolayers, the adsorption energy of extra Li ions are not significantly changed, implying the feasibility of multilayer adsorption. Of importance, the Li diffusion barriers on pre-lithiated MS2 are negligibly small because of the charge accumulation between the diffusing Li ions and the pre-lithiating Li layer. Correspondingly, we report that the pre-lithiation should be a general treatment which can be employed on many transition-metal di-chalcogenides to improve their storage capacities and charge-discharge performance in Li ion batteries. In addition, we propose that the pre-lithiated VS2 may serve as an outstanding anode material in LIBs.

The electrocatalytic reduction of nitrogen (N2) has recently emerged as an attractive technology for producing ammonia (NH3) under mild conditions. Nevertheless, achieving a high selectivity of N2 reduction with respect to hydrogen evolution at relatively low overpotential, and thus increasing the energy efficiency of ammonia production, has remained a key challenge. Herein, with systematic density functional theory (DFT) calculations, we report that the dipole of the NN triple bond in the adsorbed N2 molecule is a more efficient and accurate theoretical indicator compared with the previous ones for predicting the catalytic performance of active sites in the nitrogen reduction reaction (NRR). By screening single transition metal atoms anchored on two-dimensional phthalocyanine (2D Pc) organic frameworks, we show that 2D Mo-Pc is a promising single-atom-catalyst in the NRR with an extremely low onset potential of −0.25 V. The origin of such high catalytic activity can be interpreted by the large dipole moment introduced into the NN bond via strong Mo–N interactions. As a result, the injection of electrons into the anti-bonding orbitals of nitrogen molecules is promoted. In addition, the competing hydrogen evolution reaction (HER) can be effectively inhibited due to the unfavourable bonding interactions between the H and the single Mo atom.

The intramolecular dehalogenation reaction as an essential step is generally involved in the deprotection of carbon–carbon double bonds in solution chemistry. However, harsh reaction conditions oft...

The electrocatalytic urea oxidation reaction (UOR) provides more economic electrons than water oxidation for various renewable energy-related systems owing to its lower thermodynamic barriers. However, it is limited by sluggish reaction kinetics, especially by CO2 desorption steps, masking its energetic advantage compared with water oxidation. Now, a lattice-oxygen-involved UOR mechanism on Ni4+ active sites is reported that has significantly faster reaction kinetics than the conventional UOR mechanisms. Combined DFT, 18 O isotope-labeling mass spectrometry, and in situ IR spectroscopy show that lattice oxygen is directly involved in transforming *CO to CO2 and accelerating the UOR rate. The resultant Ni4+ catalyst on a glassy carbon electrode exhibits a high current density (264 mA cm-2 at 1.6 V versus RHE), outperforming the state-of-the-art catalysts, and the turnover frequency of Ni4+ active sites towards UOR is 5 times higher than that of Ni3+ active sites.

Controlling the orientations of molecules in self-assembled monolayers on surfaces is an effective means to construct high quality organic devices. Herein, we utilize linear polymer-modified step e...

Exploring new materials is essential in the field of material science. Especially, searching for optimal materials with utmost atomic utilization, ideal activities and desirable stability for catalytic applications requires smart design of materials’ structures. Herein, we report iridium metallene oxide: 1 T phase-iridium dioxide (IrO2) by a synthetic strategy combining mechanochemistry and thermal treatment in a strong alkaline medium. This material demonstrates high activity for oxygen evolution reaction with a low overpotential of 197 millivolt in acidic electrolyte at 10 milliamperes per geometric square centimeter (mA cmgeo−2). Together, it achieves high turnover frequencies of 4.2 sUPD−1 (3.0 sBET−1) at 1.50 V vs. reversible hydrogen electrode. Furthermore, 1T-IrO2 also shows little degradation after 126 hours chronopotentiometry measurement under the high current density of 250 mA cmgeo−2 in proton exchange membrane device. Theoretical calculations reveal that the active site of Ir in 1T-IrO2 provides an optimal free energy uphill in *OH formation, leading to the enhanced performance. The discovery of this 1T-metallene oxide material will provide new opportunities for catalysis and other applications., Identifying new, active material phases provides a promising avenue in the development of efficient catalysts. Here, authors demonstrate a metastable 1T-phase IrO2 metallene oxide as an oxygen evolution electrocatalyst in acidic electrolytes.

A deep understanding of the dynamics of photogenerated charge carriers is extremely important for promoting their germination in semiconductors to enhance the efficiency of solar energy conversion. In contrast to that of organic molecular heterojunctions (which are widely employed in organic solar cells), the charge transfer dynamics of purely inorganic molecular heterojunctions remains unexplored. Herein, we reveal the dynamics of charge transfer between inorganic semiconductor molecular heteroclusters by selecting a group of open-framework metal chalcogenides as unique structure models constructed from supertetrahedral T3-InS ([In10S20]) and T4-MInS ([M4In16S35], M = Mn or Fe) clusters. The staggered band gap alignment in T3-T4-MInS molecular heterojunctions enables the photogenerated charge carriers to be directionally transferred from T3-InS clusters to adjacent T4-MInS clusters upon irradiation or application of an external electric field. The simultaneous independence of and interactions between such two heteroclusters are investigated by theoretical calculations, steady- and transient-state absorption/photoluminescence spectroscopy, and surface photovoltage analysis. Moreover, the dynamics of cluster-to-cluster-to-dopant photogenerated charge transfer is deliberately elucidated. Thus, this work demonstrates the direct observation of charge transfer between molecular heterojunctions based on purely inorganic semiconductor clusters and is expected to promote the development of cluster-based semiconductors for solar cells., Charge transfer between inter-clusters is directly observed in inorganic molecular heterojunctions.

The metabolic reprogramming is a vital factor for the development of many type cancers, including colorectal cancer (CRC). Serine metabolic reprogramming is one of the prominent features of tumor metabolism. Yes-associated protein (YAP) participates in organ size control and tumorigenesis. However, the relationship between YAP and serine metabolism in CRC is unclear. In this study, RNA sequencing and metabolomics results represented significantly enriched glycine, serine and threonine metabolism pathways were significantly enriched in serine-starvation-resistant cells. Next, short-term serine deficiency inhibits YAP activation, whereas prolonged response in turn dephosphorylates and promotes YAP activity. Mechanistically, USP7 strengthen YAP stability under increased serine condition by regulating deubiquitinating. More interestingly, Verteporfin (VP) could effectively inhibit the proliferation of CRC both in cells and organoids, and even could modulate serine metabolism by reversely impeding USP7 expression. Clinically, YAP was significantly activated in colon tumor tissues and positively correlated to phosphoglycerate dehydrogenase (PHGDH) and USP7 expression. Our study uncovered the mechanisms by which serine metabolism regulates YAP via USP7 and identified the crucial role of YAP in regulating cell proliferation and tumor growth, and implied VP may provide a new idea for the treatment of CRC.

Half-Heusler alloys have recently received extensive attention because of their promising thermoelectric (TE) properties and great potential for applications requiring efficient thermoelectricity. Although the conversion efficiency of these materials can be greatly improved by doping, it is still far away from the real-life applications. Therefore, search for better parent TE compounds is deemed urgent. Using a high-throughput search method based on first-principles calculations in newly proposed 378 half-Heusler alloys, we identify nine nickel-based half-Heusler semiconductors as candidates and systematically study their mechanical, electronic, and transport properties. Their mechanical and dynamical stabilities are verified based on the calculated elastic constants and phonon spectra. The electronic structure calculations indicate the existence of direct energy gaps in the NiVZ (Z = Al, Ga, and In) and indirect energy gaps in the NiTiZ (Z = Si, Ge, and Sn) and NiScZ (Z = P, As, and Sb) compounds. Among them, NiVAl, NiVGa, and NiVIn exhibit a sharp slope of density of states near the Fermi level, which is predicted to be essential for a high TE performance. Further investigation on carrier concentration and temperature dependence of TE properties shows the high power factors of NiVAl, NiVGa, and NiVIn, which are responsible for their high figure of merit values. The highest maximum power factor of 5.152 mW m-1 K-2 and figure of merit of 0.309 are predicted for pristine half-Heusler NiVIn, which are larger than the values of some known pristine and doped half-Heusler TE materials. Our work opens up new avenues for rationally searching better TE materials among half-Heusler alloys for applications in fields requiring efficient thermoelectricity.

Pd is the only metal that can catalyze electrochemical CO2 reduction to formate at close-to-zero overpotential. It is unfortunately subjected to severe poisoning by trace CO as the side product and suffers from deteriorating stability and selectivity with increasing overpotential. Here, we demonstrate that alloying Pd with Cu in the form of two-dimensional nanodendrites could enable highly stable and selective formate production. Such unique bimetallic nanostructures are formed as a result of the rapid in-plane growth and suppressed out-of-plane growth by carefully controlling a set of experimental parameters. Thanks to the combined electronic effect and nanostructuring effect, our alloy product catalyzes CO2 reduction to formate with remarkable stability and selectivity under the working potential as cathodic as -0.4 V. Our results are rationalized by computational simulations, evidencing that Cu atoms weaken the *CO adsorption and stabilize the *OCHO adsorption on neighboring Pd atoms.

The development of highly selective catalysts has been remarkably relying on the understanding of catalytic active sites. Pd-catalyzed semihydrogenation of propyne has been a focus of research with...

The on-purpose dehydrogenation of light alkanes has received considerable interest for producing olefins from abundant and cheap feedstock. The prevalent catalysts have been limited to Pt–Sn/Al2O3 and Cr2O3/Al2O3. In this work, we demonstrate by density functional theory that two-dimensional Ru–phthalocyanine (2D Ru–Pc) is a potential single-atom catalyst for selective alkene production via direct C–H bond activations. By analyzing the reaction pathways and the electronic structures of the transition states, we show that the catalytic origin of 2D Ru–Pc in C–H bond activations is the highly exposed d orbitals of the single Ru atom. The alkene selectivity can be attributed to the weak Ru−π binding interaction between the produced alkene and the 2D Ru–Pc catalyst. The distinct catalytic selectivity of such a 2D Ru–Pc catalyst may inspire further investigations of selective dehydrogenation of light alkanes on single-metal catalysts.

Although scaled-up interventions and effective control efforts have drastically reduced malaria morbidity and mortality, malaria remains a serious threat to public health worldwide. Anopheles sinensis Wiedemann 1828 is a historically important vector of Plasmodium vivax (Haemosporida: Plasmodiidae) malaria in China. Insecticide resistance has become a major obstacle to vector-borne disease control. However, little is known about the insecticide resistance of An. sinensis in Wenzhou, an important coastal port city in Zhejiang province, China. The aim of this study was to examine insecticide resistance and mechanisms in An. sinensis field mosquito populations. Evidence of multiple insecticide resistance was found in An. sinensis adult female populations. Medium to high frequencies of target site kdr together with fixed ace-1 mutations was detected in both the Ruian and Yongjia populations. Both populations showed an association between kdr L1014 mutation and resistance phenotype when tested against deltamethrin and DDT. Significantly different metabolic enzyme activities were found between the susceptible laboratory strain and field-collected mosquitoes from both Ruian and Yongjia. Both field collected An. sinensis populations exhibited significantly higher P450 enzyme activity compared with the laboratory strain, while the field-collected resistant mosquitoes exhibited various GST and COE enzyme activities. These results indicate multiple resistance mechanisms in An. sinensis field populations. Effective implementation of insecticide resistance management strategies is urgently needed. The data collected in this study will be valuable for modeling insecticide resistance spread and vector-control interventions.

Electrolysis of water to generate hydrogen is an important issue for the industrial production of green and sustainable energy. The best electrocatalyst currently available for the hydrogen evolution reaction (HER) is platinum. We herein show that iridium can be manipulated to achieve a record high HER activity surpassing platinum in every aspect: a lower overpotential at any given current density, a higher current density, and mass activity for all bias potentials applied and a catalyst cost reduction of 50% for the same hydrogen generation rate. The superior HER activity was achieved by a binary Ir/Si nanowire catalyst design in which (as density functional theory calculations show) two distinct strategies act in synergy: (i) decreasing the size of the iridium nanoparticles to ∼2.2 nm and (ii) dividing the H2-generation process to three steps occurring on two different catalysts: H adsorption on iridium, H diffusion to silicon, and H2 desorption from silicon.

Rationale: Despite the promises of applying theranostic nanoagents for imaging-guided cancer therapy, the chronic retention of these nanoagents may cause safety concerns that hinder their future clinical applications. The metabolizable nanoagents with rapid renal excretion to avoid long-term toxicity is a possible solution for this issue. Method: Herein, we synthesize ultra-small metal-organic coordination polymer nanodots based on ruthenium ion (Ru3+) / phenanthroline (Phen) (Ru-Phen CPNs) with superior near-infrared (NIR) absorption. The size, photothermal conversion, cytotoxicity, photoacoustic imaging, in vivo & in vitro cancer treatment efficiency and biosafety are tested. Results: The size of the ultra-small Ru-Phen CPNs is 6.5 nm. The photothermal conversion efficiency is measured to be ~ 60.69 %, much higher than that of previously reported photothermal agents. The Ru-Phen CPNs could be employed for photoacoustic (PA, 808 nm) imaging-guided photothermal therapy (PTT, 808 nm, 0.5 W/cm2) with great performance. Notably, the intrinsic PA signals (808 nm) of Ru-Phen CPNs are observed in kidneys of treated mice, illustrating efficient renal clearance of those ultra-small CPNs. Moreover, the clearance of CPNs is further confirmed by detecting Ru levels in urine and feces. Conclusion: Our work presents a new type of ultra-small Ru-based CPNs with a record high photothermal conversion efficiency, efficient tumor retention after systemic administration, and rapid renal excretion to avoid long-term toxicity, promising for imaging-guided photothermal therapy.

Efficient catalysts for the alkaline hydrogen evolution reaction are continuously pursued to accelerate the kinetics of water splitting and enhance the conversion of renewable energy to chemical feedstock. Among numerous candidates, noble-metal-free Mo2C catalysts are favored because of their low cost, abundance and similar d-orbital electronic state to the state of the art platinum. However, due to the high empty d-orbital density of high-valence Mo species in Mo2C, the HER performance was impaired. We reason that introducing modulators into the Mo2C framework that could decrease the empty d-orbital density and valence states of Mo may be an efficient way to optimize the HER energetics. Herein, inspired by the versatile electronic structures of 3d metals, we carried out first principles calculations using 3d metal Co as a dopant of Mo2C to construct Co–Mo bimetallic carbide and found an enhanced HER activity after Co incorporation. We further synthesized a Co–Mo bimetallic carbide catalyst. The obtained catalysts achieved excellent alkaline HER performance with the lowest overpotential of −46 mV at −10 mA cm−2, a low Tafel slope of 46 mV dec−1 and great stability without any decay after a 500 hour reaction. The X-ray adsorption spectroscopy study showed that the valence state of Mo was decreased by the Co dopant and we propose that the decrease of Mo valence states should be the reason for the better HER performance of the bimetallic carbide than bulk Mo2C.

Chiral synthesis on surfaces has acquired tremendous interest. We herein report a novel approach of two-dimensional chiral transfer directed by metal-organic intermediate states on a silver surface. With initial deposition at low temperature, the achiral 4,4'-dihydroxybiphenyl molecules self-assemble into large scale two-dimensional networks with 4-fold symmetry via intermolecular hydrogen bonding. Fine controlled annealing, however, leads to the formation of tetramer-like chiral metal-organic hybrids, which self-organize into enantiomeric islands on the Ag(100) surface. Subsequent ortho C-C couplings of the reactants lead to dimer products. Of great importance, the chirality expressions of the dimer products are observed to be transferred directly from that of the tetramer intermediate states. The detailed reaction pathways are rationalized by DFT calculations and synchrotron-based XPS experiments, demonstrating the mechanisms of the chiral transfer.

Methionine is one of the essential amino acids. How tumor cells adapt and adjust their signal transduction networks to avoid apoptosis in a methionine-restricted environment is worthy of further exploration. In this study, we investigated the molecular mechanism of glioma response to methionine restriction, providing a theoretical basis for new treatment strategies for glioma.MethodsWe constructed methionine-restriction-tolerant cells in order to study the response of glioma to a methionine-restricted environment. The transcriptome analysis of the tolerant cells showed significant changes in MAT2A. Western blotting, immunohistochemistry, quantitative real-time PCR, colony formation assays, and other experiments were used to verify the role of MAT2A in glioma genesis. In addition, the regulatory mechanism of MAT2A mRNA nuclear export was investigated by transfection, plasma nucleation separation, and co-immunoprecipitation.ResultsUnder methionine restriction, glioma cells showed high expression of MAT2A, and an inhibitor of MAT2A reduced the proliferation of tumor cells. The expression of MAT2A was positively correlated with World Health Organization-grade glioma. High expression of MAT2A was related to increased transfer of its mRNA out of the nucleus. The expression of nuclear export regulatory molecule MTR4 could affect the export of MAT2A mRNA. In a methionine-restricted environment, ubiquitination of MTR4 was enhanced, and thus its protein level was reduced. The E3 ubiquitin ligase was verified to be SYVN1.ConclusionIn summary, methionine restriction leads to increased ubiquitination of MTR4, which promotes the transfer of MAT2A mRNA out of the nucleus and MAT2A protein expression. MAT2A promotes histone methylation, prompting cells to proliferate in a methionine-restricted environment.

In on-surface chemistry, the efficient preparation of metal-organic hybrids is regarded as a primary path to mediate controlled synthesis of well-ordered low-dimensional organic nanostructures. The fundamental mechanisms in forming these hybrid structures, however, are so far insufficiently explored. Here, with scanning tunneling microscopy, we studied the bonding behavior of the adsorbed phenol derivatives with different molecular lengths. We reveal that shorter molecules favor bonding with extracted metal adatoms and result in metal-organic hybrids, whereas longer molecules prefer to bond with lattice metal atoms. The conclusions are further confirmed by density functional theory calculations.

Nitrogen-doped graphene could catalyze the electrochemical reduction and evolution of oxygen, but unfortunately suffers from sluggish catalytic kinetics. Herein, for the first time, we report an onion-like carbon coated Co, N-doped carbon (OLC/Co-N-C) material, which possesses multilayers of highly curved nanostructures that form mesoporous architectures. These unique nanospheres are produced when surfactant micelles are introduced to synthesis precursors. Owing to the combined electronic effect and nanostructuring effect, our OLC/Co-N-C materials exhibit high bifunctional oxygen reduction/evolution reaction (ORR/OER) activity, showing a promising application in rechargeable Zn-air batteries. Experimental results are rationalized by theoretical calculations, showing that the curvature of graphitic carbon plays a vital role in promoting activities of meta-carbon atoms near graphitic N and ortho/meta carbon atoms close to pyridinic N.

Adipic acid (HOOC(CH2)4COOH, AA) is a crucial chemical in industrial manufactures and mainly produced by the oxidation of cyclohexane with air and nitric acid via a homogeneous two step path in industry. However, the conventional industrial method inevitably results in the generation of nitrous oxide (N2O, etc.), which is the main cause of the greenhouse effect and ozone depletion. Herein, we engineered five kinds of carbon dots (CDs) with different oxygen-containing functional groups on their surfaces, which were directly used as catalysts over the selective catalytic oxidation of cyclohexane. Among the five CDs, the hydroxyl-terminated CDs show the best catalytic activity with the conversion of cyclohexane ~ 29.43% and selectivity to AA ~ 95.89% under 130 °C, 20 atm with oxygen as oxidant. With the CDs directly as catalyst, the one-step efficient catalytic oxidation reaction for cyclohexane to AA was realized to replace the two-step routes. In addition, the density functional theory (DFT) computational results were performed to further prove that the more quantity of hydroxyl on CDs and the higher O2 pressure can boost the higher catalytic activity of CDs over oxidation of cyclohexane.

Developing high-performance electrocatalysts with in-depth understanding in reaction mechanisms require not only delicate synthetic technologies, but also advanced analytical methodologies. While catalytic performance can be boosted through the construction of porous nanostructures for enlarged surface area, mechanism studies generally depend on sophisticated in-situ characterization techniques. In the present work, we report a hierarchically porous nanostructure of chromium-doped nickel disulfide as an active electrocatalyst for water oxidation, which exhibits a low overpotential of 207 mV to drive 10 mA cm−2 in alkaline medium. The surface evolution at different reaction stages is revealed utilizing specifically designed ex-situ characterization approaches. An irreversible self-reconstruction from Cr-doped NiS2 to Cr, S co-doped Ni(OH)2 followed by a reversible transformation into NiOOH is observed in cyclic voltammetry processes, indicating that NiS2 plays a key role as pre-catalyst to generate highly active sites for electrocatalytic water oxidation.

Propane dehydrogenation (PDH) has been recognized as one of the most promising routes to produce propene in chemical industry. Recently, Pt–Ga2O3 catalysts have attracted great attention because of their high activity, high selectivity, and simple regeneration process. However, the lack of strategies to suppress Pt sintering has seriously impeded their practical applications. In this work, we have studied Pt sintering on Ga2O3 with different morphologies. Results showed that Pt sintering under high temperature treatment might be attributed to an oxidative process, in which metallic Pt was oxidized into volatile PtO2 that led to the formation of larger Pt particles. Compared to other shaped Ga2O3, rod-shaped Ga2O3 can trap Pt atoms and prevent the metallic Pt from being oxidized into PtO2, yielding a sintering-resistant Pt–Ga2O3 catalyst for PDH. This result can not only provide a highly stable catalyst for PDH, but also it can shed some light on fundamental research in catalysis.

The oxygen reduction reaction (ORR) is of significant importance in the development of fuel cells. Now, cobalt-nitrogen-doped chiral carbonaceous nanotubes (l/d-CCNTs-Co) are presented as efficient electrocatalysts for ORR. The chiral template, N-stearyl-l/d-glutamic acid, induces the self-assembly of well-arranged polypyrrole and the formation of ordered graphene carbon with helical structures at the molecular level after the pyrolysis process. Co was subsequently introduced through the post-synthesis method. The obtained l/d-CCNTs-Co exhibits superior ORR performance, including long-term stability and better methanol tolerance compared to achiral Co-doped carbon materials and commercial Pt/C. DFT calculations demonstrate that the charges on the twisted surface of l/d-CCNTs are widely separated; as a result the Co atoms are more exposed on the chiral CCNTs. This work gives us a new understanding of the effects of helical structures in electrocatalysis.

Experimentally, the values of band gaps of semiconductor nanoparticles are generally obtained by the absorption spectrum. Nevertheless, the determinations of the corresponding energy levels of the conduction bands (CBs) or valence bands (VBs) remain a challenge. Correspondingly, an accurate prediction of the CB or VB energy values is highly desired for designing and developing semiconductor devices. Herein, on the basis of the tight-binding approximation, we report a new linear equation that may quantitatively determine the energy levels of CB and VB of semiconductor nanoparticles based on their band gaps: and , where p and q are constants related with the crystal structures, and me and mh are the effective mass of electrons and holes, respectively. For single elements and binary crystals with tetrahedral and octahedral unit cells, which represent the majority of important semiconductors, the above equations can be simplified as: and . For Si nanoparticles, ECB,Si = 0.35 × (Eg – 1.1) – 4.0 and EVB,Si = −0.65 × (Eg – 1.1) – 5.1.

Pristine graphene is known to be nonmagnetic due to its π-conjugated electron system. However, we find that localized magnetic moments can be generated by chemically attaching boron atoms to the graphene sheets. Such spin-polarized states are evidenced by the spin-split of the density of states (DOS) peaks near the Fermi level in scanning tunneling spectroscopy (STS). In the vicinity of several coadsorbed boron atoms, the Coulomb repulsion between multiple spins leads to antiferromagnetic coupling for the induced spin states in the graphene lattice, manifesting itself as an increment of spin-down state at specific regions. Experimental observations and interpretations are rationalized by extensive density functional theory (DFT) simulations.

The synthetic challenges of radialenes have precluded their practical applications. Here, we report a one-step synthetic protocol of [4]radialene on a copper surface. High-resolution scanning tunneling microscopy measurements reveal that such catalytic reaction proceeds readily with high selectivity at the temperature below 120 K. First-principles calculations show that the reaction pathway is characterized by firstly the cooperative inter-molecular hydrogen tautomerization and then the C–C bond formation. The feasibility of such cyclotetramerization reaction can be interpreted by the surface effect of Cu(100), which firstly plays an important role in directing the molecular assembly and then serves as an active catalyst in the hydrogen tautomerization and C–C coupling processes. This work presents not only a novel strategy to the scant number of synthetic methods to produce [4]radialenes via a novel [1 + 1 + 1 + 1] reaction pathway, but also a successful example of C–C bond coupling reactions guided by the surface-induced C–H/π assembly., Radialenes have distinct structural, electronic and chemical properties from other hydrocarbons, but their synthesis remains a challenge. Here, the authors report a copper catalyzed one-step synthetic protocol of [4]radialene via the cyclotetramerization of phenylacetylene molecules upon thermal activation.

Pyroligneous acids can be used in herbicides, but the dosage used often more than 1000 kg ha−1. Five treatments including the application of bamboo, wood, straw vinegar, acetic acid and sulphuric acid at high dosages sprayed once every 6 days, for a total of 3 times. We then continuously monitored the changes in soil pH, moisture content and the activities of three soil hydrolase enzymes involving in urease, protease and sucrase. We found that after 1~3 days of spraying with all 5 kinds of acid, the soil pH was not immediately reduced, but from 3 days after application onward it was reduced by a maximum of 1.54~1.75, which showed that the soil had some buffering capacity. Over time, the pH began to return to the water control pH value, which showed that the soil also had good restorative capacity. After the second and third times of spraying, the pH change measured showed no cumulative effect, which demonstrated that the soil had adaptive capacity. We accidentally found that bamboo vinegar could improve the soil pH by a maximum of 0.65~1.02, while the other four acids reduced its pH. Bamboo vinegar was found to contain the 6 compounds while wood and straw vinegar contained none of these compounds. These compounds may be a new potential reagent(s) for improving the pH. Three soil sample processing methods tested for determining pH, including the moist soil test, oven-dry soil test and air-dried soil test, all produced extremely and significantly different pH values. Five acids were unable to significantly improve the water holding capacity of the soil; they had adverse effects on the activity of the urease enzymes while beneficial effects on the protease and sucrase enzymes. Therefore, pyroligneous acid and acetic acid have no effects on soil health as herbicides.

The development of highly efficient electrocatalysts for hydrogen evolution reaction is a fundamental undertaking of the hydrogen economy. Herein, we investigated the electrocatalytic performance of M/Si (M = Os, Rh, Pt, Pd, Re, Ru, Au or Ag) nanocomposites for hydrogen evolution reaction. The results show that Os/Si nanocomposites exhibit the best catalytic efficiency with a negligible onset overpotential (−25 mV), a small Tafel slope of −24 mV dec −1 and remarkable long-term stability. Of most importance, at a current density of the typical industrial production (−1000 mA cm −2 ), the energy conversion efficiency of the Os/Si nanocomposite is 29.3% higher than that of the commercial 40 wt% Pt/C. The density functional calculations reveal that such outstanding catalytic activity of the Os/Si catalyst arises from the thermodynamically more favorable hydrogen adsorption free energy (Δ G H* = −0.03 eV) at the osmium/silicon interfaces than that on platinum (Δ G H* = −0.09 eV) or osmium (Δ G H* = −0.26 eV).

Hydrogen evolution by electrocatalysis is an attractive method of supplying clean energy. However, it is challenging to find cheap and efficient alternatives to rare and expensive platinum based catalysts. Pt provides the best hydrogen evolution performance, because it optimally balances the free energies of adsorption and desorption. Appropriate control of these quantities is essential for producing an efficient electrocatalyst. We demonstrate, based on first principles calculations, a stepwise designed Rh-Au-Si ternary catalyst, in which adsorption (the Volmer reaction) and desorption (the Heyrovsky reaction) take place on Rh and Si surfaces, respectively. The intermediate Au surface plays a vital role by promoting hydrogen diffusion from the Rh to the Si surface. Theoretical predictions have been explored extensively and verified by experimental observations. The optimized catalyst (Rh-Au-SiNW-2) has a composition of 2.2:28.5:69.3 (Rh:Au:Si mass ratio) and exhibits a Tafel slope of 24.0 mV·dec–1. Its electrocatalytic activity surpasses that of a commercial 40 wt.% Pt/C catalyst at overpotentials above 0.19 V by exhibiting a current density of greater than 108 mA·cm–2. At 0.3 V overpotential, the turnover frequency of Rh-Au-SiNW-2 is 10.8 times greater than that of 40 wt.% Pt/C. These properties may open new directions in the stepwise design of highly efficient catalysts for the hydrogen evolution reaction (HER).

The hydrogen evolution reaction (HER) is a fundamental electrochemical reaction to produce hydrogen gas from the electrolysis of water, and has been regarded as an attractive solution to many energy challenges. In the past few decades, platinum has been widely demonstrated to split water into hydrogen gas at high reaction rates and low overpotentials. Nevertheless, decreasing the loading of Pt in the designed electrocatalysts is very significant. However, with low Pt loading, it is challenging to maintain excellent catalytic performance. Here we report a Pt–Au–Si ternary nanocomposite as a highly active catalyst for the HER. The optimal composition of Pt–Au–Si was determined to be 7.2 : 31.3 : 61.5 (Pt : Au : Si, mass ratio) with a Tafel slope of only 24 mV dec−1. To be specific, the mass activity of the Pt–Au–SiNW-2 catalyst was 6.5 fold that of a 40 wt% Pt/C catalyst at an overpotential of 60 mV. More importantly, the cathodic current density even surpassed 40 wt% Pt/C when the overpotential was larger than 0.17 V (the corresponding current density was 108 mA cm−2). The outstanding catalytic performance might be derived from the synergy of the respective properties of the three components: the fast hydrogen adsorption rate on Pt, the quick migration of the adsorbed hydrogen atoms on Au and the rapid hydrogen evolution rate on Si. This research opens up a novel strategy to prepare highly efficient catalysts for electrochemical hydrogen evolution reactions.

Defects are unavoidable during the synthesis of materials, especially for two-dimensional (2D) nanomaterials. They are usually seen as detrimental to device properties, but sometimes bring about new beneficial effects. In order to clarify the influence of defects on the structural and electronic properties, we have performed first-principles calculations to systematically investigate the structural stability, mobility and electronic properties of typical point defects in 2D arsenene (h-As), antimonene (h-Sb) and antimony arsenide (h-AsSb), including the Stone–Wales defects, single vacancies (SVs), double vacancies (DVs) and adatoms. To provide visual guidance for experimental observations, scanning tunnelling microscopy (STM) images are simulated. Compared to defects in graphene and silicene, these defects form more easily with lower formation energies, and SVs can diffuse very quickly to the edges with a lower diffusion barrier of less than 1 eV. Monolayer arsenene, antimonene and antimony arsenide are indirect band gap semiconductors, and the defective structures significantly reduce the band gaps. Most of the SV and adatom defects carry magnetic moments due to the dangling bonds resulting from the absent or extra atom. Our present results have demonstrated that the point defects induce significant effects on the electronic properties of pristine arsenene, antimonene and the antimony arsenide alloy, which should be considered in their future applications.

Direct methane conversion (DMC) to high value-added products is of significant importance for the effective utilization of CH4 to combat the energy crisis. However, there are ongoing challenges in DMC associated with the selective C−H activation of CH4. The quest for high-efficiency catalysts for this process is limited by the current drawbacks including poor activity and low selectivity. Here we show a cerium dioxide (CeO2) nanowires supported rhodium (Rh) single-atom (SAs Rh-CeO2 NWs) that can serve as a high-efficiency catalyst for DMC to oxygenates (i.e., CH3OH and CH3OOH) under mild conditions. Compared to Rh/CeO2 nanowires (Rh clusters) prepared by a conventional wet-impregnation method, CeO2 nanowires supported Rh single-atom exhibits 6.5 times higher of the oxygenates yield (1231.7 vs. 189.4 mmol gRh−1 h−1), which largely outperforms that of the reported catalysts in the same class. This work demonstrates a highly efficient DMC process and promotes the research on Rh single-atom catalysts in heterogeneous catalysis., Direct methane conversion to high value-added products is a promising way for highly-efficient utilization of methane. Here, the authors demonstrate that rhodium single-atom supported on cerium dioxide nanowires can selectively convert methane to oxygenates under mild conditions.

Many strategies to optimize molybdenum selenide based electrocatalysts for hydrogen evolution reaction (HER) have been explored; however, the modulation of molybdenum selenide on the molecular scale remains an ongoing challenge. Here, we synthesized a new molecular HER electrocatalyst based on a molybdenum-selenium cluster (Mo3Se13) and further realized its modulation by precise sulfur substitution at the molecular level to enhance the HER activity. The density functional theory (DFT) calculations demonstrated that the substituted sulfur could promote the hydrogen adsorption process and thus improve the HER performance. This work not only realizes the selective replacement of the bridging selenium atom with a sulfur atom in the molybdenum-selenium cluster for the first time but also provides a precise model for illustrating the structure-property relationship in electrocatalysis on the molecular level.

The energy conversion efficiency of water electrolysis is determined by the activity of selected catalysts. Ideal catalysts should possess not only porous architecture for high-density assembly of active sites but also a subtle electronic configuration for the optimized activity at each site. In this context, the development of stable porous hosting materials that allow the incorporation of various metal elements is highly desirable for both experimental optimization and theoretical comparison/prediction. Herein, MOF-derived spongy nanosheet arrays constructed by assembly of carbon encapsulated hetero-metal doped Ni2 P nanoparticles is presented as a superior bifunctional electrocatalyst for water splitting. This hierarchical structure can be stably retained when secondary metal dopants are introduced, providing a flexible platform for electronic modulation. The catalytic origin of activity enhancement via metal (Fe, Cr, and Mn) doping is deciphered through experimental and theoretical investigations. Combining the advantages in both morphological and electronic structures, the optimized catalyst NiMn-P exhibits remarkable activity in both hydrogen and oxygen evolution in the alkaline media, with an ultrasmall cell voltage of 1.49 V (at 10 mA cm-2 ) and high durability for at least 240 h.

The electrocatalytic splitting of water in neutral solution to produce hydrogen appears highly attractive for the development of hydrogen economy. The corresponding industrial applications, however, have not yet been realized due to the unsatisfactory energy conversion efficiency in the oxygen evolution reaction (OER), with the potential limiting step being the formation of HOO*. In the present work, we report that the functionalization of metal oxide electrocatalysts with thiocyanate groups is a novel, general and effective strategy for improving the catalytic performance of OER. Density Functional Theory (DFT) calculations show that mechanistic origin of such fucntioanlization is that the potenital limiting step of HOO* formation can be promoted via a cyanate assisted water dissociation. As a result, the SCN–Ru–RuO2/C3N4 may achieve the current density of 10 mA cm−2 in the neutral electrolyte at an overpotential of 342 mV, which is significantly lower than that of commercial RuO2 (545 mV). In addition, the SCN–Ru–RuO2/C3N4 anode is observed to outperform the commercial IrO2-anode-embedded electrolyzer in the PEMWE, indicating significant potential in realistic applications. The generalization of the activity enhancement due to thiocyanate functionalization in neutral medium can be demonstrated SCN–Ir/C3N4 and/or SCN–Co3O4/C3N4.