Co3+-O-V4+ cluster in CoVOx nanorods for efficient and stable electrochemical oxygen evolution

The development of cost-efficient and long-term stable catalysts for the oxygen evolution reaction (OER) is crucial to produce clean and sustainable H2 fuels from water. Here we demonstrate a cobalt vanadium oxide (CoVOx-300) working as such an efficient and durable electrocatalyst. Such an active catalyst is beneficial from the balanced Co3+-O-V4+ active species, which show the high surface Co3+ contents with matched V4+ generated by rapid heat treatment. The CoVOx-300 with highest Co3+/Co2+ ratio of 1.4 and corresponding highest V4+/ V5+ ratio of 1.7 exhibits remarkable OER activity with an overpotential of 330 mV at current density of 10 mA cm−2 (η10), a shallow Tafel slope of only 46 mV dec-1 and a current density of 100 mA cm−2 at an overpotential of 0.38 V vs RHE, which is 20 times higher than the active CoOx-300 and 1000 times higher than VOx-300. The catalyst also shows excellent stability for 10 h in alkaline media and a 40 % reduced activation energy to the counterpart, CoOx-300. The overpotential (η10) of CoVOx-300 also shows nearly 70 and 80 mV lower than the corresponding CoOx-300 and CoVOx catalysts, respectively and 20 % lower Tafel slope than the commercial benchmark catalyst RuO2. Thus, this study for the first time demonstrates that surface Co3+-O-V4+ species play a crucial role in improving electrocatalytic properties and stability for water oxidation reaction and the approaches allow the rational design and synthesis of other active transition metal oxides toward efficient OER activity

Strong correlations and orbital texture in single-layer 1T-TaSe2

Strong electron correlation can induce Mott insulating behaviour and produce intriguing states of matter such as unconventional superconductivity and quantum spin liquids. Recent advances in van der Waals material synthesis enable the exploration of Mott systems in the two-dimensional limit. Here we report characterization of the local electronic properties of single- and few-layer 1T-TaSe2 via spatial- and momentum-resolved spectroscopy involving scanning tunnelling microscopy and angle-resolved photoemission. Our results indicate that electron correlation induces a robust Mott insulator state in single-layer 1T-TaSe2 that is accompanied by unusual orbital texture. Interlayer coupling weakens the insulating phase, as shown by reduction of the energy gap and quenching of the correlation-driven orbital texture in bilayer and trilayer 1T-TaSe2. This establishes single-layer 1T-TaSe2 as a useful platform for investigating strong correlation physics in two dimensions

MULTI-WAVELENGTH EMISSIONS FROM THE MILLISECOND PULSAR BINARY PSR J1023+0038 DURING AN ACCRETION ACTIVE STATE

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Efficient visible light-driven water oxidation and proton reduction by an ordered covalent triazine-based framework

Water oxidation is a rate-determining step in solar driven H2 fuel synthesis and is technically challenging to promote. Despite decades of effort, only a few inorganic catalysts are effective and even fewer are effective under visible light. Recently, attention has been paid to synthetic semiconducting polymers, mainly on graphitic C3N4, with encouraging hydrogen evolution performance but lower activity for water oxidation. Here, a highly ordered covalent triazine-based framework, CTF-1 (C8N2H4), is synthesised by a very mild microwave-assisted polymerisation approach. It demonstrates extremely high activity for oxygen evolution under visible light irradiation, leading to an apparent quantum efficiency (AQE) of nearly 4% at 420 nm. Furthermore, the polymer can also efficiently evolve H2 from water. A high AQE of 6% at 420 nm for H2 production has also been achieved. The polymer holds great potential for overall water splitting. This exceptional performance is attributed to its well-defined and ordered structure, low carbonisation, and superior band positions

The phylogenetically-related pattern recognition receptors EFR and XA21 recruit similar immune signaling components in monocots and dicots

During plant immunity, surface-localized pattern recognition receptors (PRRs) recognize pathogen-associated molecular patterns (PAMPs). The transfer of PRRs between plant species is a promising strategy for engineering broad-spectrum disease resistance. Thus, there is a great interest in understanding the mechanisms of PRR-mediated resistance across different plant species. Two well-characterized plant PRRs are the leucine-rich repeat receptor kinases (LRR-RKs) EFR and XA21 from Arabidopsis thaliana (Arabidopsis) and rice, respectively. Interestingly, despite being evolutionary distant, EFR and XA21 are phylogenetically closely related and are both members of the sub-family XII of LRR-RKs that contains numerous potential PRRs. Here, we compared the ability of these related PRRs to engage immune signaling across the monocots-dicots taxonomic divide. Using chimera between Arabidopsis EFR and rice XA21, we show that the kinase domain of the rice XA21 is functional in triggering elf18-induced signaling and quantitative immunity to the bacteria Pseudomonas syringae pv. tomato (Pto) DC3000 and Agrobacterium tumefaciens in Arabidopsis. Furthermore, the EFR:XA21 chimera associates dynamically in a ligand-dependent manner with known components of the EFR complex. Conversely, EFR associates with Arabidopsis orthologues of rice XA21-interacting proteins, which appear to be involved in EFR-mediated signaling and immunity in Arabidopsis. Our work indicates the overall functional conservation of immune components acting downstream of distinct LRR-RK-type PRRs between monocots and dicots

Quantum-Dot Light-Emitting Diodes with Nitrogen-Doped Carbon Nanodot Hole Transport and Electronic Energy Transfer Layer

Electroluminescence efficiency is crucial for the application of quantum-dot light-emitting diodes (QD-LEDs) in practical devices. We demonstrate that nitrogen-doped carbon nanodot (N-CD) interlayer improves electrical and luminescent properties of QD-LEDs. The N-CDs were prepared by solution-based bottom up synthesis and were inserted as a hole transport layer (HTL) between other multilayer HTL heterojunction and the red-QD layer. The QD-LEDs with N-CD interlayer represented superior electrical rectification and electroluminescent efficiency than those without the N-CD interlayer. The insertion of N-CD layer was found to provoke the Forster resonance energy transfer (FRET) from N-CD to QD layer, as confirmed by time-integrated and - resolved photoluminescence spectroscopy. Moreover, hole-only devices (HODs) with N-CD interlayer presented high hole transport capability, and ultraviolet photoelectron spectroscopy also revealed that the N-CD interlayer reduced the highest hole barrier height. Thus, more balanced carrier injection with sufficient hole carrier transport feasibly lead to the superior electrical and electroluminescent properties of the QD-LEDs with N-CD interlayer. We further studied effect of N-CD interlayer thickness on electrical and luminescent performances for high-brightness QD-LEDs. The ability of the N-CD interlayer to improve both the electrical and luminescent characteristics of the QD-LEDs would be readily exploited as an emerging photoactive material for high-efficiency optoelectronic devices.ope