Engineering the Coordination Environment of Ir Single Atoms with Surface Titanium Oxide Amorphization for Superior Chlorine Evolution Reaction.

The chlorine evolution reaction (CER) is essential for industrial Cl2 production but strongly relies on the use of dimensionally stable anode (DSA) with high-amount precious Ru/Ir oxide on a Ti substrate. For the purpose of sustainable development, precious metal decrement and performance improvement are highly desirable for the development of CER anodes. Herein, we demonstrate that surface titanium oxide amorphization is crucial to regulate the coordination environment of stabilized Ir single atoms for efficient and durable chlorine evolution of Ti monolithic anodes. Experimental and theoretical results revealed the formation of four-coordinated Ir1O4 and six-coordinated Ir1O6 sites on amorphous and crystalline titanium oxides, respectively. Interestingly, the Ir1O4 sites exhibited a superior CER performance, with a mass activity about 10 and 500 times those of the Ir1O6 counterpart and DSA, respectively. Moreover, the Ir1O4 anode displayed excellent durability for 200 h, far longer than that of its Ir1O6 counterpart (2 h). Mechanism studies showed that the unsaturated Ir in Ir1O4 was the active center for chlorine evolution, which was changed to the top-coordinated O in Ir1O6. This change of active sites greatly affected the adsorption energy of Cl species, thus accounting for their different CER activity. More importantly, the amorphous structure and restrained water dissociation of Ir1O4 synergistically prevent oxygen permeation across the Ti substrate, contributing to its long-term CER stability. This study sheds light on the importance of single-atom coordination structures in the reactivity of catalysts and offers a facile strategy to prepare highly active single-atom CER anodes via surface titanium oxide amorphization.

Cobalt Single-Atom Reverse Hydrogen Spillover for Efficient Electrochemical Water Dissociation and Dechlorination.

Efficient water dissociation to atomic hydrogen (H*) with restrained recombination of H* is crucial for improving the H* utilization for electrochemical dechlorination, but is currently limited by the lack of feasible electrodes. Herein, we developed a monolithic single-atom electrode with Co single atoms anchored on the inherent oxide layer of titanium foam (Co1-TiOx/Ti), which can efficiently dissociate water into H* and simultaneously inhibit the recombination of H*, by taking advantage of the single-atom reverse hydrogen spillover effect. Experimental and theoretical calculations demonstrated that H* could be rapidly generated on the oxide layer of titanium foam, and then overflowed to the adjacent Co single atom for the reductive dechlorination. Using chloramphenicol as a proof-of-concept verification, the resulting Co1-TiOx/Ti monolithic electrode exhibited an unprecedented performance with almost 100 % dechlorination at -1.0 V, far superior to that of traditional indirect reduction-driven commercial Pd/C (52 %) and direct reduction-driven Co1-N-C (44 %). Moreover, its dechlorination rate constant of 1.64 h-1 was 4.3 and 8.6 times more active than those of Pd/C (0.38 h-1) and Co1-N-C (0.19 h-1), respectively. Our research sheds light on the rational design of hydrogen spillover-related electrocatalysts to simultaneously improve the H* generation, transfer, and utilization for environmental and energy applications.

Danger-associate peptide regulates root immunity in Arabidopsis.

Plant elicitor peptides (Peps) are recognized by two receptor-like kinases, PEPR1 and PEPR2, and trigger plant immunity responses and root growth inhibition. In this study, we reveal that the Pep-PEPR system triggers root immunity responses in Arabidopsis. Pep1 incubation initiated callose and lignin deposition in roots of wild type but not in that of pepr1 pepr2 mutant seedlings. The plasma membrane-associated kinase BIK1, which serves downstream of the Pep-PEPR signaling pathway, was essential for Pep1-induced root immunity responses. Interestingly, disruption of PEPR1/2-associated coreceptor BAK1 enhanced the deposition of both callose and lignin induced by Pep1 in roots. Ethylene and salicylic acid signaling are involved in Pep1-induced root immunity responses. Furthermore, we showed that the successful phytopathogen, P. syringae (DC3000) could effectively suppress Pep1-trigged root callose and lignin accumulation. These results demonstrated the endogenous Pep-triggered root immunity responses and pathogenic suppression of the Pep-PEPR signaling pathway.

Vacuolar Sugar Transporter TMT2 Plays Crucial Roles in Germination and Seedling Development in Arabidopsis.

Vacuolar sugar transporters transport sugar across the tonoplast, are major players in maintaining sugar homeostasis, and therefore play vital roles in plant growth, development, and biomass yield. In this study, we analyzed the physiological roles of the tonoplast monosaccharide transporter 2 (TMT2) in Arabidopsis. In contrast to the wild type (WT) that produced uniform seedlings, the tmt2 mutant produced three types of offspring: un-germinated seeds (UnG), seedlings that cannot form true leaves (tmt2-S), and seedlings that develop normally (tmt2-L). Sucrose, glucose, and fructose can substantially, but not completely, rescue the abnormal phenotypes of the tmt2 mutant. Abnormal cotyledon development, arrested true leaf development, and abnormal development of shoot apical meristem (SAM) were observed in tmt2-S seedlings. Cotyledons from the WT and tmt2-L seedlings restored the growth of tmt2-S seedlings through micrografting. Moreover, exogenous sugar sustained normal growth of tmt2-S seedlings with cotyledon removed. Finally, we found that the TMT2 deficiency resulted in growth defects, most likely via changing auxin signaling, target of rapamycin (TOR) pathways, and cellular nutrients. This study unveiled the essential functions of TMT2 for seed germination and initial seedling development, ensuring cotyledon function and mobilizing sugars from cotyledons to seedlings. It also expanded the current knowledge on sugar metabolism and signaling. These findings have fundamental implications for enhancing plant biomass production or seed yield in future agriculture.

Monodispersed and Organic Amine Modified La(OH)3 Nanocrystals for Superior Advanced Phosphate Removal.

Advanced phosphate removal is critical for alleviating the serious and widespread aquatic eutrophication, strongly depending on the development of superior adsorption materials to overcome low chemical affinity and sluggish mass transfer at low phosphate concentrations. Herein, the first synthesis of monodispersed and organic amine modified lanthanum hydroxide nanocrystals (OA-La(OH)3) for advanced phosphate removal by modulating inner Helmholtz plane (IHP), is reported. These OA-La(OH)3 nanocrystals with positively charged surfaces and abundant exposed La sites exhibit specific affinity toward phosphate, delivering a maximum adsorption capacity of 168 mg P g⁻1 and a wide pH adaptability from 3.0 to 11.0, as well as a robust anti-interference performance, far surpassing those of documented phosphate removal materials. The superior phosphate removal performance of OA-La(OH)3 is attributed to its protonated organic amine in IHP, which enhances the electrostatic attraction around the adsorbent-solution interface. Impressively, OA-La(OH)3 can treat ≈5 000 and ≈3 200 bed volumes of simulated and real phosphate-containing wastewater to below extremely strict standard (0.1 mg L⁻1) in a fixed-bed adsorption mode, exhibiting great potential for advanced phosphate removal. This study offers a facile modification strategy to improve phosphate removal performance of nanoscale adsorbents, and sheds light on the structure-reactivity relationship of La-based materials.

Highly selective urea electrooxidation coupled with efficient hydrogen evolution.

Electrochemical urea oxidation offers a sustainable avenue for H2 production and wastewater denitrification within the water-energy nexus; however, its wide application is limited by detrimental cyanate or nitrite production instead of innocuous N2. Herein we demonstrate that atomically isolated asymmetric Ni-O-Ti sites on Ti foam anode achieve a N2 selectivity of 99%, surpassing the connected symmetric Ni-O-Ni counterparts in documented Ni-based electrocatalysts with N2 selectivity below 55%, and also deliver a H2 evolution rate of 22.0 mL h-1 when coupled to a Pt counter cathode under 213 mA cm-2 at 1.40 VRHE. These asymmetric sites, featuring oxygenophilic Ti adjacent to Ni, favor interaction with the carbonyl over amino groups in urea, thus preventing premature resonant C⎓N bond breakage before intramolecular N-N coupling towards N2 evolution. A prototype device powered by a commercial Si photovoltaic cell is further developed for solar-powered on-site urine processing and decentralized H2 production.

Plant elicitor Peptides regulate root hair development in Arabidopsis.

Plant Elicitor Peptides (Peps) induce plant immune responses and inhibit root growth through their receptors PEPR1 and PEPR2, two receptor-like kinases. In our study, we found a previously unknown function of Peps that enhance root hair growth in a PEPRs-independent manner. When we characterized the expression patterns of PROPEP genes, we found several gene promoters of PROPEP gene family were particularly active in root hairs. Furthermore, we observed that PROPEP2 is vital for root hair development, as disruption of PROPEP2 gene led to a significant reduction in root hair density and length. We also discovered that PROPEP2 regulates root hair formation via the modulation of CPC and GL2 expression, thereby influencing the cell-fate determination of root hairs. Additionally, calcium signaling appeared to be involved in PROPEP2/Pep2-induced root hair growth. These findings shed light on the function of Peps in root hair development.

Spin polarized Fe1-Ti pairs for highly efficient electroreduction nitrate to ammonia.

Electrochemical nitrate reduction to ammonia offers an attractive solution to environmental sustainability and clean energy production but suffers from the sluggish *NO hydrogenation with the spin-state transitions. Herein, we report that the manipulation of oxygen vacancies can contrive spin-polarized Fe1-Ti pairs on monolithic titanium electrode that exhibits an attractive NH3 yield rate of 272,000 µg h-1 mgFe-1 and a high NH3 Faradic efficiency of 95.2% at -0.4 V vs. RHE, far superior to the counterpart with spin-depressed Fe1-Ti pairs (51000 µg h-1 mgFe-1) and the mostly reported electrocatalysts. The unpaired spin electrons of Fe and Ti atoms can effectively interact with the key intermediates, facilitating the *NO hydrogenation. Coupling a flow-through electrolyzer with a membrane-based NH3 recovery unit, the simultaneous nitrate reduction and NH3 recovery was realized. This work offers a pioneering strategy for manipulating spin polarization of electrocatalysts within pair sites for nitrate wastewater treatment.