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International audience; Efficient and durable electrocatalysts are instrumental in enabling nextgeneration fuel cell technologies. At present, expensive precious metals are used as state-of-the-art catalysts. In this report, cost-effective nanosized tantalum-based alternatives are synthesized for the first time via a green and scalable laser pyrolysis method as bifunctional catalysts for direct peroxide-peroxide fuel cells. This rapid laser pyrolysis strategy allows for the production of nanoparticles at a laboratory scale of grams per hour, compatible with a detailed exploration of the functional properties of assynthesized nanoparticles. By varying the precursor ratio between ammonia and tantalum ethanolate, five tantalum-based nanomaterials (TaNOC) are prepared with crystalline phases of Ta$_2$ O$_5$ , Ta$_4$ N$_5$ , Ta$_3$ N$_5$ , and TaN in tunable ratios. Electrochemical studies in neutral and alkaline conditions demonstrate that Ta$_4$ N$_5$ is the active component for both H$_2$ O$_2$ oxidation and reduction. Kinetic isotope effect studies show that protons are involved at or before the rate-determining step. Long-term stability studies indicate that Ta$_3$ N$_5$ grants surfactant-free TaNOC-enhanced longevity during electrocatalytic operations. Taken together, bifunctional TaNOC can act as active and robust electrocatalysts for H$_2$ O$_2$ reduction and oxidation. Laser pyrolysis is envisioned to produce refractory metal nanomaterials with boosted corrosion resistance for energy catalysis.

Positioning basic/acid groups near molecular catalyst has been become a popular strategy to modulate proton-coupled electron transfer (PCET) reactions in energy conversion and storage. However, the detailed understanding of the real role played by basic/acid groups remains lacking. Here, we report the immobilization of a novel copper (II) dipicolylamine, CuL, catalyst bearing a phosphonic anchor on metal oxide electrode to investigate the activity of oxygen reduction reaction (ORR) in aqueous solution. The catalytic current of ORR by CuL catalyst was significantly enhanced by 3 times as a carboxylate-terminated ligand was integrated onto metal oxide surfaces acting as a co-catalyst. Extensive experimental and theoretical studies reveal that hydrogen bond formed between proximal carboxylate of co-catalyst and Cu-OOH intermediate generated via protonation of Cu-O2 adduct by bulk buffer solution aids O-O bond cleavage, thereby promoting the four-electron four-proton reduction of dioxygen into water reaching a Faradaic efficiency of 97.6%. Our finding is in stark contrast to the typical assignment on the role of basic groups near catalyst that features proton shuttling to facilitate protonation of metal-O2 intermediate forming metal-OOH intermediate. This work offers a new strategy to enhance simultaneously the activity and selectivity of surface-supported non-precious metal electrocatalysts that are important toward realizing alternative energy conversion schemes.

Net-zero carbon strategies and green synthesis methodologies are key to realizing the United Nations' sustainable development goals (SDGs) on a global scale. An electrocatalytic glycerol oxidation reaction (GOR) holds the promise of upcycling excess glycerol from biodiesel production directly into precious hydrocarbon commodities that are worth orders of magnitude more than the glycerol feedstock. Despite years of research on the GOR, the synthesis process of nanoscale electrocatalysts still involves (1) prohibitive heat input, (2) expensive vacuum chambers, and (3) emission of toxic liquid pollutants. In this paper, these knowledge gaps are closed via developing a laser-assisted nanomaterial preparation (LANP) process to fabricate bimetallic nanocatalysts (1) at room temperature, (2) under an ambient atmosphere, and (3) without liquid waste emission. Specifically, PdCu nanoparticles with adjustable Pd:Cu content supported on few-layer graphene can be prepared using this one-step LANP method with performance that can rival state-of-the-art GOR catalysts. Beyond exhibiting high GOR activity, the LANP-fabricated PdCu/C nanomaterials with an optimized Pd:Cu ratio further deliver an exclusive product selectivity of up to 99% for partially oxidized C

Efficient O2 reduction reaction (ORR) for selective H2O generation enables advanced fuel cell technology. Non-precious metal (NPM) catalysts are viable and attractive alternatives to state-of-the-art Pt-based materials that are expensive. Cu complexes inspired by Cu-containing O2 reduction enzymes in nature have yet to reach their desired ORR catalytic performance. Here, the concept of mechanical interlocking is introduced to the ligand architecture to enforce dynamic spatial restriction on the Cu coordination site unachievable using other structural means. The utility of the kinetic effects from mechanical bond in transition metal catalysis is just about to emerge, and here the catenane ligands govern the O2 adduct binding mode, thereby steering the selectivity to generate H2O as the major product via the 4e– pathway, rivaling the selectivity of Pt. The kinetic effects from the interlocked catenane ligand also promotes product elimination and boosts the onset potential by 130 mV, the mass activity by 1.8 times, and the turnover frequency (TOF) by 1.5 folds as compared to the non-interlocked counterpart. Our Cu catenane complex represents one of the first examples to take advantage of mechanical interlocking to afford electrocatalysts with enhanced activity and selectivity. The mechanistic insights gained through this integrated experimental and theoretical study are envisioned to be of practical value not just to the area of ORR energy catalysis, but also with broad implications on interlocked metal complexes that are of critical importance to the general fields in redox reactions involving proton-coupled electron transfer (PCET) steps

We develop a scanning probe microscopic technique to characterize the electric gap with a spatial resolution of nanometre scale. The technique probes the electric gap by monitoring the change of the local quantum capacitance via the Coulomb force at the mesoscopic scale. We showcase this technique on several 2D semiconductors and van der Waals heterostructures at ambient conditions.

Electronic gaps play an important role in the electric and optical properties of materials. Although various experimental techniques, such as scanning tunnelling spectroscopy and optical or photoemission spectroscopy, are normally used to perform electronic band structure characterizations, it is still challenging to measure the electronic gap at the nanoscale under ambient conditions. Here we report a scanning probe microscopic technique to characterize the electronic gap with nanometre resolution at room temperature and ambient pressure. The technique probes the electronic gap by monitoring the changes of the local quantum capacitance via the Coulomb force at a mesoscopic scale. We showcase this technique by characterizing several 2D semiconductors and van der Waals heterostructures under ambient conditions.

The development of renewable energy schemes requires the scalable production of highly robust electrocatalysts using a sustainable synthesis process that does not generate toxic liquid wastes. Here...

Consumer grade supercapacitors as power supply resources require outstanding electrode materials with large conductivity, high durability and retention rates, as well as large capacity. Graphene is a promising functional material as an electrical double layer capacitance electrode due to its large surface area, high chemical stability and moderate conductivity. However, the existing graphene synthesis methods, including CVD and chemical exfoliation, are limited to lab scale production. Although laser induced graphene has demonstrated outstanding performance as an electrode material for microsupercapacitors, its difficulty to attach to the metallic current collector limits its application as a large capacity electrode material. Herein, laser induced forward transfer of graphene is developed for additively depositing laser induced graphene onto nickel foam as a composite electrode. The laser annealing enhanced the lattice matching between the extended Basal plane of graphene and Ni (111) resulting in its high electrical conductivity (359 712 S m−1), high retention rate (over 98% capacitance retention after 10 000 cycles), and large areal specific capacitance (995 mF cm−2) and power density (9.39 mW cm−2). The assembled supercapacitors with these additively printed electrodes can work as a USB charger with a stable 5 V output voltage, for charging smart phones and other smart devices.

Background and Objectives: The stable stand structure of mixed plantations is the basis of giving full play to forest ecological function and benefit. However, the monocultural Eucalyptus plantations with large-scale and successive planting that caused ecological problems such as reduced species diversity and loss of soil nutrients have presented to be unstable and vulnerable, especially in typhoon-prone areas. The objective of this study was to evaluate the nonspatial structure difference and the stand stability of pure and mixed-Eucalyptus forests, to find out the best mixed pattern of Eucalyptus forests with the most stability in typhoon-prone areas. Materials and Methods: In this study, we randomly investigated eight plots of 30 m × 30 m in pure and mixed-Eucalyptus (Eucalyptus urophylla S. T. Blake × E. grandis W. Hill) plantations of different tree species (Neolamarckia cadamba (Roxb.) Bosser, Acacia mangium Willd., and Pinus elliottii var. Elliottii Engelm. × P. caribaea Morelet) on growth status, characterized and compared the distribution of nonspatial structure of the monoculture and mixtures, and evaluated the stand quality and stability from eight indexes of the nonspatial structure, including preservation rate, stand density, height, diameter, stem form, degree of stem inclination, tree-species composition, and age structure. Results: Eucalyptus surviving in the mixed plantation of Eucalyptus and A. mangium (EA) and in the mixed plantation of Eucalyptus and P. elliottii × P. caribaea (EP) were 5.0% and 7.6% greater than those in pure Eucalyptus plantation (EE), respectively, while only the stand preservation rate of EA was greater (+2.9%) than that of the pure Eucalyptus plantation. The proportions of all mixtures in the height class greater than 7 m were fewer than that of EE. The proportions of EA and mixed plantation of Eucalyptus and N. cadamba (EN) in the diameter class greater than 7 m were 10.6% and 7.8%, respectively, more than that of EE. EN had the highest ratio of branching visibly (41.0%), EA had the highest ratio of inclined stems (8.1%), and EP had the most straight and complete stem form (68.7%). The stand stability of the mixed plantation of Eucalyptus and A. mangium presented to be optimal, as its subordinate function value (0.76) and state value (ω = 0.61) of real stand were the largest. Conclusions: A. mangium is a superior tree species to mix with Eucalyptus for a more stable stand structure in the early growth stage to approach an evident and immense stability and resistance, which is of great significance for the forest restoration of Eucalyptus in response to extreme climate and forest management.

Background: Stable stand structure of mixed plantations is the basis of giving full play to forest ecological function and benefit, and the pure Eucalyptus plantations with large-area and successive planting have presented to be unstable and vulnerable in typhoon-prone area. In this study, we investigated eight 30 m × 30 m plots randomly in pure and mixed eucalyptus forests on growth status, characterized and compared the distribution of non-spatial structure of mixtures with that of mono-species plantation, and evaluated the stand quality and stability from eight indexes including preservation rate, stand density, height, diameter, stem form, degree of slant, tree species composition and age structure, so as to find out the best mixed composition and pattern of eucalyptus and other tree species in typhoon-prone area. Results: Eucalyptus surviving in the mixed forest of Eucalyptus and A. mangium (EA) and the mixed forest of Eucalyptus and P. elliottii × P. caribaea (EP) were 5.0% and 7.6% greater than those in pure Eucalyptus forest (E) respectively, while only the stand preservation rate of EA was greater (+2.9%) than that of pure Eucalyptus forest. The proportions of all mixtures on the height class that greater than 7 m were fewer than that of monoculture. The proportion of EA and EN (mixed forest of Eucalyptus and N.cadamba) on the diameter class that greater than 7 m were 10.6% and 7.8% respectively more than that of monoculture. EN got a highest ratio of branching visibly (41%), EA got a highest ratio of slant stems (8.1%) and EP got a most straight and complete stem form (68.7%). The stand stability of the mixed forest of Eucalyptus and A. mangium presents to be optimal for its subordinate function value (0.76) and status value (ω = 0.607) of real stand were the largest. Conclusion: A. mangium is a most superior tree specie to mix with Eucalyptus for a more stable stand structure in the early growth stage to approach an evident and immense stability and resistance, which is of great significance for the forest restoration of Eucalyptus in response to extreme climate and on the forest management.

The superior provenance is a prerequisite for ecological restoration, and a better mastery on the growth rhythms of Ormosia species is fundamental to reforest effectively. For the selection of better provenance and the formulation of artificial cultivation methods, the height and the ground diameter of Ormosia hosiei Hemsl. et Wils., O. xylocarpa Chun ex L. Chen and O. henryi Prain seedlings of different provenances were monitored in the first year. The results showed that their dynamic growths presented a slow-fast-slow trend that fit a “S” growth curve by the logistic mathematical model, and the growth of Ormosia species seedlings of different provenances significantly differed. The accumulated growth increment of O. xylocarpa was the largest (averagely 45.50 cm) and the accumulated growth increment of O. henryi was the least (averagely 20.33 cm). Thus, O. hosiei of Jiujiang provenance, O. xylocarpa of Liping provenance and O. henryi of Longquan provenance have a stronger adaptability for future artificial cultivation in Jiangxi China. RESUMO A origem melhor é um pré-requisito para a restauração ecológica, e um melhor domínio dos ritmos de crescimento das espécies Ormosia é fundamental para reflorescimento com eficácia. Para a seleção de melhor origem e a formulação de métodos artificiais de cultivo, a altura e o diâmetro do solo de mudas Ormosia hosiei Hemsl. et Wils., O. xylocarpa Chun ex L. Chen e O. henryi Prain de diferentes origens foram monitoradas no primeiro ano. Os resultados mostraram que seus crescimentos dinâmicos tiveram uma tendência lenta-rápida-lenta que se correspondia a uma curva de crescimento “S” no modelo matemático logístico, e o crescimento de espécies de mudas Ormosia de diferentes origens diferiram significativamente. O incremento de crescimento acumulado de O. xylocarpa foi o maior (em média de 45,50 cm) e o incremento de crescimento acumulado de O. henryi foi o menor (em média de 20,33 cm). Assim, O. hosiei da origem de Jiujiang, O. xylocarpa da origem de Liping e O. henryi da origem de Longquan têm uma adaptabilidade mais forte para o futuro cultivo artificial em Jiangxi, China.

Wearable sensing technologies are vital for realizing personalized health monitoring. Noninvasive human sweat sampling is essential for monitoring an individual's physical state using rich physiological data. However, existing wearable sensing technologies lack the controlled capture of body sweat and in performing on-device measurement without inflammatory contact. Herein, we report the development of a wearable sweat-capture device using patterned graphene arrays with controlled superwettability and electrical conductivity for simultaneously capturing and electrochemically measuring sweat droplets. The sweat droplets exhibited strong attachment on the superhydrophilic graphene patterns, even during moderate exercising. The captured sweat droplets present strong electrochemical signals using graphene films as the working electrode and metal pins as the counter electrode arrays assembled on 3D printed holders, at the detection limit of 6 μM for H2O2 sensing. This research enables full-body spatiotemporal mapping of sweat, which is beneficial for a broad range of personalized monitoring applications, such as drug abuse detection, athletics performance optimization, and physiological wellness tracking.

Genomic loci related with resistance to gall-inducing insects have not been identified in any plants. Here, association mapping was used to identify molecular markers for resistance to the gall wasp Leptocybe invasa in two Eucalyptus species. A total of 86 simple sequence repeats (SSR) markers were screened out from 839 SSRs and used for association mapping in E. grandis. By applying the mixed linear model, seven markers were identified to be associated significantly (P ≤ 0.05) with the gall wasp resistance in E. grandis, including two validated with a correction of permutation test (P ≤ 0.008). The proportion of the variance in resistance explained by a significant marker ranged from 3.3% to 37.8%. Four out of the seven significant associations in E. grandis were verified and also validated (P ≤ 0.073 in a permutation test) in E. tereticornis, with the variation explained ranging from 24.3% to 48.5%. Favourable alleles with positive effect were also mined from the significant markers in both species. These results provide insight into the genetic control of gall wasp resistance in plants and have great potential for marker-assisted selection for resistance to L. invasa in the important tree genus Eucalyptus.

Identification of loci or genes under natural selection is important for both understanding the genetic basis of local adaptation and practical applications, and genome scans provide a powerful means for such identification purposes. In this study, genome-wide simple sequence repeats markers (SSRs) were used to scan for molecular footprints of divergent selection in Eucalyptus grandis, a hardwood species occurring widely in costal areas from 32° S to 16° S in Australia. High population diversity levels and weak population structure were detected with putatively neutral genomic SSRs. Using three FST outlier detection methods, a total of 58 outlying SSRs were collectively identified as loci under divergent selection against three non-correlated climatic variables, namely, mean annual temperature, isothermality and annual precipitation. Using a spatial analysis method, nine significant associations were revealed between FST outlier allele frequencies and climatic variables, involving seven alleles from five SSR loci. Of the five significant SSRs, two (EUCeSSR1044 and Embra394) contained alleles of putative genes with known functional importance for response to climatic factors. Our study presents critical information on the population diversity and structure of the important woody species E. grandis and provides insight into the adaptive responses of perennial trees to climatic variations.

The difference in and correlation among major characters of eucalypt (species) hybrid clones were studied by investigating and analyzing the performance of 27 different eucalypt clones at 3-year old. Clones significantly differed in the mean annual volume growth and had significant interaction with the conditions of the test sites. A clone’s tree form index had significant negative correlation with the yield the pattern of the correlation between the major characters was different. Tree height and DBH had significant genetic and phenotypic correlation. As expected, DBH was the main factor in determining the plantation yield. Combined evaluation was given to the clones studied by using tree form index and unrestricted index selection. Eighteen superior clones including ECl, CH3 and CHI were selected for developing eucalypt plantations.