Hollow-Carbon Confinement Annealing: A New Synthetic Approach to Make High-Entropy Solid-Solution and Intermetallic Nanoparticles.

High-entropy alloy (HEA) nanoparticles (NPs) have been emerging with superior compositional tunability and multielemental synergy, presenting a unique platform for material discovery and performance optimization. Here we report a synthetic approach utilizing hollow-carbon confinement in the ordinary furnace annealing to achieve the nonequilibrium HEA-NPs such as Pt0.45Fe0.18Co0.12Ni0.15Mn0.10 with uniform size ∼5.9 nm. The facile temperature control allows us not only to reveal the detailed reaction pathway through ex situ characterization but also to tailor the HEA-NP structure from the crystalline solid solution to intermetallic. The preconfinement of metal precursors is the key to ensure the uniform distribution of metal nanoparticles with confined volume, which is essential to prevent the thermodynamically favored phase separation even during the ordinary furnace annealing. Besides, the synthesized HEA-NPs exhibit remarkable activity and stability in oxygen reduction catalysis. The demonstrated synthetic approach may significantly expand the scope of HEA-NPs with uncharted composition and performance.

High air humidity dampens salicylic acid pathway and NPR1 function to promote plant disease.

The occurrence of plant disease is determined by interactions among host, pathogen, and environment. Air humidity shapes various aspects of plant physiology and high humidity has long been known to promote numerous phyllosphere diseases. However, the molecular basis of how high humidity interferes with plant immunity to favor disease has remained elusive. Here we show that high humidity is associated with an "immuno-compromised" status in Arabidopsis plants. Furthermore, accumulation and signaling of salicylic acid (SA), an important defense hormone, are significantly inhibited under high humidity. NPR1, an SA receptor and central transcriptional co-activator of SA-responsive genes, is less ubiquitinated and displays a lower promoter binding affinity under high humidity. The cellular ubiquitination machinery, particularly the Cullin 3-based E3 ubiquitin ligase mediating NPR1 protein ubiquitination, is downregulated under high humidity. Importantly, under low humidity the Cullin 3a/b mutant plants phenocopy the low SA gene expression and disease susceptibility that is normally observed under high humidity. Our study uncovers a mechanism by which high humidity dampens a major plant defense pathway and provides new insights into the long-observed air humidity influence on diseases.

A sweet story from Phytophthora-soybean interaction.

Phytopathogenic microbes obtain nutrients from host plants to support their growth and metabolism. A recent study by Zhu et al. revealed that the oomycete pathogen Phytophthora sojae upregulates the activity of soybean trehalose 6-phosphate synthase 6 (GmTPS6) and increases trehalose accumulation (through an effector PsAvh413) to promote nutritional gain.

CURLY LEAF modulates apoplast liquid water status in Arabidopsis leaves.

The apoplast of plant leaves, the intercellular space between mesophyll cells, is normally largely filled with air with a minimal amount of liquid water in it, which is essential for key physiological processes such as gas exchange to occur. Phytopathogens exploit virulence factors to induce a water-rich environment, or "water-soaked" area, in the apoplast of the infected leaf tissue to promote disease. We propose that plants evolved a "water soaking" pathway, which normally keeps a nonflooded leaf apoplast for plant growth but is disturbed by microbial pathogens to facilitate infection. Investigation of the "water soaking" pathway and leaf water control mechanisms is a fundamental, yet previously overlooked, aspect of plant physiology. To identify key components in the "water soaking" pathway, we performed a genetic screen to isolate Arabidopsis (Arabidopsis thaliana) severe water soaking (sws) mutants that show liquid water overaccumulation in the leaf under high air humidity, a condition required for visible water soaking. Here, we report the sws1 mutant, which displays rapid water soaking upon high humidity treatment due to a loss-of-function mutation in CURLY LEAF (CLF), encoding a histone methyltransferase in the POLYCOMB REPRESSIVE COMPLEX 2 (PRC2). We found that the sws1 (clf) mutant exhibits enhanced abscisic acid (ABA) levels and stomatal closure, which are indispensable for its water soaking phenotype and mediated by CLF's epigenetic regulation of a group of ABA-associated NAM, ATAF, and CUC (NAC) transcription factor genes, NAC019/055/072. The clf mutant showed weakened immunity, which likely also contributes to the water soaking phenotype. In addition, the clf plant supports a substantially higher level of Pseudomonas syringae pathogen-induced water soaking and bacterial multiplication, in an ABA pathway and NAC019/055/072-dependent manner. Collectively, our study sheds light on an important question in plant biology and demonstrates CLF as a key modulator of leaf liquid water status via epigenetic regulation of the ABA pathway and stomatal movement.

Hybrid Heterostructure Ni3 N|NiFeP/FF Self-Supporting Electrode for High-Current-Density Alkaline Water Electrolysis.

Exploring earth-abundant and efficient electrocatalysts for oxygen evolution reaction (OER) is an urgent need and significant to water electrolysis. Although great achievements have been made, it is still challenging to achieve industrial current density and stability. Herein, a hybrid heterostructure electrode based on Ni3 N and NiFeP over Fe foam substrate (Ni3 N|NiFeP/FF) is reported, along with 3D-interconnected hierarchical porous architecture, achieving the low overpotentials of 287, 178, and 290 mV at 500 mA cm-2 in 1 m KOH, 30 wt% KOH, and alkaline simulated seawater, respectively, with excellent durability at 800 mA cm-2 over 120 h, which can satisfy the requirements of industrial water electrolysis. Here, the hybrid heterostructure can ensure the low energy barrier of the catalytic active sites, the 3D-interconnected hierarchical porous architecture can facilitate the fast mass/ions/electrons transformation, which contributes together to boost the superb water splitting performance. Furthermore, the COMSOL simulations confirm the multiple merits of the designed electrode during the water electrocatalysis. The present work provides a new strategy in the design and engineering of high-performance electrodes for industrial water electrolysis.

Bimetallic Phosphide Heterostructure Coupled with Ultrathin Carbon Layer Boosting Overall Alkaline Water and Seawater Splitting.

Seawater electrolysis is promising for green hydrogen production but hindered by the sluggish reaction kinetics of both cathode and anode, as well as the detrimental chlorine chemistry environment. Herein, a self-supported bimetallic phosphide heterostructure electrode strongly coupled with an ultrathin carbon layer on Fe foam (C@CoP-FeP/FF) is constructed. When used as an electrode for the hydrogen and oxygen evolution reactions (HER/OER) in simulated seawater, the C@CoP-FeP/FF electrode shows overpotentials of 192 mV and 297 mV at 100 mA cm-2 , respectively. Moreover, the C@CoP-FeP/FF electrode enables the overall simulated seawater splitting at the cell voltage of 1.73 V to achieve 100 mA cm-2 , and operate stably during 100 h. The superior overall water and seawater splitting properties can be ascribed to the integrated architecture of CoP-FeP heterostructure, strongly coupled carbon protective layer, and self-supported porous current collector. The unique composites can not only provide enriched active sites, ensure prominent intrinsic activity, but also accelerate the electron transfer and mass diffusion. This work confirms the feasibility of an integration strategy for the manufacturing of a promising bifunctional electrode for water and seawater splitting.

Hollow Carbon Nanorod Confined Single Atom Rh for Direct Formic Acid Electrooxidation.

Nearly theoretical 100% atomic utilization (supposing each atom could serve as independent sites to play a role in catalyz) of single-atom catalysts (SACs) makes it highly promising for various applications. However, for most SACs, single-atom sites are trapped in a solid carbon matrix, which makes the inner parts hardly available for reaction. Herein, a hollow N-doped carbon confined single-atom Rh (Rh-SACs/HNCR) is developed via a coordination-template method. Both aberration-corrected scanning transmission electron microscopy and energy dispersive X-ray spectroscopy mapping confirm the uniform distribution of Rh single atoms. Owning to the unique hollow structure and effective carbon confinement, excessive conversion from pyridinic/pyrrolic N to graphic N is hindered. As a proof of concept, Rh-SACs/HNCR exhibits superior activity, stability, selectivity, and anti-poisoning capability in formic acid oxidation reaction compared with the counterpart Rh/C, Pd/C, and Pt/C catalysts. This work provides a powerful strategy for synthesizing hollow carbon confined single-atom catalysts apply in various energy-related systems.

Bacterial effectors manipulate plant abscisic acid signaling for creation of an aqueous apoplast.

Phytopathogens like Pseudomonas syringae induce "water soaking" in the apoplastic space of plant leaf tissue as a key virulence mechanism. Water soaking is commonly observed in diverse pathosystems, yet the underlying physiological basis remains largely elusive. Here, we show that one of the strong P. syringae water-soaking inducers, AvrE, alters the regulation of abscisic acid (ABA) to induce ABA signaling, stomatal closure, and, thus, water soaking. AvrE binds and inhibits the function of Arabidopsis type one protein phosphatases (TOPPs), which negatively regulate ABA by suppressing SnRK2s, a key node of the ABA signaling pathway. The topp12537 quintuple mutants display significantly enhanced water soaking after P. syringae inoculation, whereas the loss of the ABA pathway dampens P. syringae-induced water soaking and disease. Our study uncovers the hijacking of ABA signaling and stomatal closure by P. syringae effectors as key mechanisms of disease susceptibility.

A Low-Temperature Carbon Encapsulation Strategy for Stable and Poisoning-Tolerant Electrocatalysts.

Carbon encapsulation is an effective strategy for enhancing the durability of Pt-based electrocatalysts for the oxygen reduction reaction (ORR). However, high-temperature treatment is not only energy-intensive but also unavoidably leads to possible aggregation. Herein, a low-temperature polymeric carbon encapsulation strategy (≈150 °C) is reported to encase Pt nanoparticles in thin and amorphous carbonaceous layers. Benefiting from the physical confinement effect and enhanced antioxidant property induced by the surface carbon species, significantly improved stabilities can be achieved for polymeric carbon species encapsulated Pt nanoparticles (Pt@C/C). Particularly, a better antipoisoning capability toward CO, SOx , and POx is observed in the case of Pt@C/C. To minimize the thickness of the catalyst layer and reduce the mass transfer resistance, the high mass loading Pt@C/C (40 wt%) is prepared and applied to high-temperature polymer electrolyte membrane fuel cells (HT-PEMFCs). At 160 °C, a peak power density of 662 mW cm-2 is achieved with 40% Pt@C/C cathode in H2 -O2 HT-PEMFCs, which is superior to that with 40% Pt/C cathode. The facile strategy provides guidance for the synthesis of highly durable carbon encapsulated noble metal electrocatalysts toward ORR.

Efficient Electrochemical Production of H2O2 on Hollow N-Doped Carbon Nanospheres with Abundant Micropores.

Electrocatalytic two-electron (2e-) oxygen reduction reaction (ORR) has been regarded as an efficient strategy to achieve onsite H2O2 generation under ambient conditions. However, due to the sluggish kinetics and competitive reaction between 2e- and 4e- ORR, exploring more efficient ORR catalysts with dominant 2e- ORR selectivity is of significance. Herein, hollow N-doped carbon spheres (HNCS) with abundant micropores through a template-directed method are presented. Consequently, the selectivity of the HNCS reaches ∼91.9% at 0.7 V (vs RHE), and the output for H2O2 production is up to 618.5 mmol gcatalyst-1 h-1 in 0.1 M KOH solution. The enhanced performance of HNCS for H2O2 electrosynthesis could be attributed to the hollow structure and heteroatom/defect/pore incorporation. The strategy presented here could shed light on the design of efficient carbon-based materials for improved 2e- ORR.

Variable-valence metals catalyzed solid NaBiO3 nanosheets for oxidative degradation of norfloxacin, ofloxacin and ciprofloxacin: Efficiency and mechanism.

In this work, we report metal ions catalyzed oxidative degradation of three typical fluoroquinolones norfloxacin (NOR), ofloxacin (OFL) and ciprofloxacin (CIP) by using NaBiO3 nanosheets. It was found that variable-valence metal ions such as Cu2+, Fe2+, Mn2+, Ce3+, Ag+ and Co2+ could obviously enhanced degradation of NOR, OFL and CIP by NaBiO3. The pseudo-first-order kinetic rate for the degradation of 20 µmol L-1 NOR by NaBiO3 (2 mmol L-1) in the presence of 0.1 mmol L-1 Cu2+, Fe2+, Mn2+, Ce3+, Ag+ and Co2+ was 0.021, 0.084, 0.019, 0.23, 0.25 and 0.28 min-1, 2.1, 8.4, 19, 23, 25 and 28 times that by NaBiO3 without any metal ions. In comparison, Ca2+ and Fe3+ exhibited no obviously promotive or depressive effect for the degradation of NOR by NaBiO3. Singlet oxygen (1O2) was suggested as the main reactive species from NaBiO3 in the presence of metal ions by electron spin resonance technology and radicals scavenging experiments. The evolution of NaBiO3 was tracked with scanning electron microscope, energy dispersive spectrometer, X-ray diffraction, X-ray photoelectron spectroscopy and Raman spectroscopy. It was found that the metal ions were embedded into the crystal structure of NaBiO3 through ion-exchange between Na in NaBiO3 and metal ions. In the subsequent step, an electron transformation from lattice oxygen to Bi(V) sites was mediated by embedded variable-valence metal species, resulting in an enhanced generation of 1O2 from the crystal structure of NaBiO3. These results can shed light on the application of NaBiO3 for the organic pollutant decontamination.