N2 Fixation Research Articles

Effect of NPK through Chemical Fertilizers Combination with Farm Yard Manure (FYM) and Bio-fertilizers on Yield Attributes of Onion (Allium cepa L.) in Jaipur Region of Rajasthan, India

The field experiment was conducted in loamy sand soil of the Horticulture farm, Vivekanand Global University Jaipur, during Rabi season of 2020-21 and 2021-22. The experiment comprises of 32 treatment combinations replicated three times was laid out in split-plot design (SPD) with four fertility levels of NPK (0, 50, 75 and 100% of recommended dose of NPK) and two levels of FYM (without FYM and with FYM @ 25 t ha-1) were added in main plots. Four bio-fertilizer levels (No inculcation, N2 fixer Azotobacter, PSB inculcation and N2 fixer Azotobacter + PSB inoculation) were added in sub plots. The treatments comprised of Chemical fertilizers, FYM and biofertilizers with ten treatments Viz., F0- Control, F1-50% of recommended dose of NPK, F2-75% of recommended dose of NPK, F3-100% of recommended dose of NPK, M0- Without FYM, M1- With FYM @ 25 t ha -1, B0- No inoculation, B1- N2 fixer Azotobacter, B2- PSB inoculation and B3- N2 Fixer Azotobacter + PSB inoculation, respectively. The results of the study have clearly shown that application of chemical fertilizer up to 100% RDF increased the entire yield and its attributes viz. (neck length, bulb diameter, number of scales, fresh weight of bulb, volume of bulb). With application of FYM @ 25 t ha-1 yield significantly improved with its attributes. Use of biofertilizers (N2 fixers Azotobacter + PSB inoculation) in combination or alone increased all yield and its attributes. Integrated system approach is not only the liable for attaining fairly high productivity with substantial fertilizer economy but also a concept of soundness leading to sustainable agriculture .

Identification of QTLs for symbiotic nitrogen fixation and related traits in a soybean recombinant inbred line population.

The genetic architecture of symbiotic N fixation and related traits was investigated in the field. QTLs were identified for percent N derived from the atmosphere, shoot [N] and C to N ratio. Soybean [Glycine max (L.) Merr.] is cultivated worldwide and is the most abundant source of plant-based protein. Symbiotic N2 fixation (SNF) in legumes such as soybean is of great importance; however, yields may still be limited by N in both high yielding and stressful environments. To better understand the genetic architecture of SNF and facilitate the development of high yielding cultivars and sustainable soybean production in stressful environments, a recombinant inbred line population consisting of 190 lines, developed from a cross between PI 442012A and PI 404199, was evaluated for N derived from the atmosphere (Ndfa), N concentration ([N]), and C to N ratio (C/N) in three environments. Significant genotype, environment and genotype × environment effects were observed for all three traits. A linkage map was constructed containing 3309 single nucleotide polymorphism (SNP) markers. QTL analysis was performed for additive effects of QTLs, QTL × environment interactions, and QTL × QTL interactions. Ten unique additive QTLs were identified across all traits and environments. Of these, two QTLs were detected for Ndfa and eight for C/N. Of the eight QTLs for C/N, four were also detected for [N]. Using QTL × environment analysis, six QTLs were detected, of which five were also identified in the additive QTL analysis. The QTL × QTL analysis identified four unique epistatic interactions. The results of this study may be used for genomic selection and introgression of favorable alleles for increased SNF, [N], and C/N via marker-assisted selection.

Promoted photocatalytic performances over Ti3+-B co-doped TiO2/BN with high carrier transfer and absorption capabilities driven by SWCNT addition

Recently, carbon nanotubes have been widely used as supporting materials for semiconductor photocatalysts due to their excellent electron and mass transportation. Herein, we prepared a novel SWCNT-decorated Ti3+-B co-doped TiO2/BN (STBN) photocatalyst with the presence of single-walled carbon nanotubes (SWCNTs) during the hybridization of BN and TiB2. The effects of SWCNTs on the structural and photocatalytic properties were investigated. Adding SWCNTs enables excellent multifunctional photocatalytic performances (N2 fixation, H2 production, and MO degradation) compared with the TBN synthesized in the previous study. Introducing SWCNTs reduces the transfer resistance and makes the photogenerated carriers transfer more efficiently, thereby improving photocatalytic activity. More defect sites provide extra adsorption sites for reactants and photogenerated electrons, significantly improving the system's photocatalytic activity. The enhanced photocatalytic mechanism of SWCNT-decorated hybrid catalysts was proposed at last.

Fertilisation strategies and their influence on nutrient flows in organic apple orchards

AbstractIn organic fruit production, permitted fertilisers contain multiple nutrients with stoichiometries differing from the nutrient offtakes of the fruit trees. Furthermore, some pesticides contain nutrients resulting in additional inputs. These conditions may cause unbalanced nutrient supplies and thereby influence the long-term sustainability of the system. An analysis of nutrient management practices in organic apple farms was conducted in three Southern and one Northern German apple-growing region. Data on nutrient inputs (via fertilisers and pesticides) and outputs (via fruit) per orchard were collected along with soil samples from up to five orchards per farm on 19 farms. On average, farmers fertilised 37 kg N and harvested 23 Mg apples per ha and year. Nutrient budgets showed imbalances for N (+ 25 kg ha−1 year−1), P (+ 3 kg), K (− 4 kg), Ca (+ 37 kg), Mg (+ 4 kg), S (+ 53 kg), Na (+ 4 kg) and Cl (+ 3 kg). Base fertilisers like compost or manure contributed to higher nutrient inputs due to a larger P and K-to-N-ratio. Commercial organic fertilisers such as keratins or vinasse contained much lower ratios. The main S input sources were pesticides (46 kg). N inputs by base (p = 0.06) and commercial (p = 0.37) fertilisers had no significant effect on the yield. Balanced nutrition can best be achieved by applying a combination of 20% of the total N demand via base fertilisers, complemented with commercial fertilisers with low element-to-N-ratios (e. g. keratin fertilisers, vinasse or biological N2 fixation). No correlation was found between soil nutrient status and nutrient budgets. Site conditions and internal field nutrient flows (transfer of the inter-row biomass via mulching into the tree row) had a stronger influence on the soil nutrient content than fertilisation strategy. In addition, fruit orchards showed a spatial differentiation of soil nutrient contents. Elevated P and K contents above the recommended range in the tree row were found in 67% of the orchards, while tendencies of depletion were found in the inter-row area. Mulching schemes which transfer biomass from the inter-row area to the tree row need to be adapted to this condition.

Accelerated nitrogen cycling on Mediterranean seagrass leaves at volcanic CO2 vents

Seagrass meadows form highly productive and diverse ecosystems in coastal areas worldwide, where they are increasingly exposed to ocean acidification (OA). Efficient nitrogen (N) cycling and uptake are essential to maintain plant productivity, but the effects of OA on N transformations in these systems are poorly understood. Here we show that complete N cycling occurs on leaves of the Mediterranean seagrass Posidonia oceanica at a volcanic CO2 vent near Ischia Island (Italy), with OA affecting both N gain and loss while the epiphytic microbial community structure remains largely unaffected. Daily leaf-associated N2 fixation contributes to 35% of the plant’s N demand under ambient pH, while it contributes to 45% under OA. Nitrification potential is only detected under OA, and N-loss via N2 production increases, although the balance remains decisively in favor of enhanced N gain. Our work highlights the role of the N-cycling microbiome in seagrass adaptation to OA, with key N transformations accelerating towards increased N gain.

Photoexcitation assisted oxygen vacancy for enhancing nitrogen fixation with Fe-CeO2

Photoexcitation assisted oxygen vacancy for enhancing N2 fixation was investigated with Fe-CeO2 as photocatalysts. Fe substituted doping of CeO2 promoted the formation of oxygen vacancies (Vo). 5 % Fe-CeO2 exhibited the highest Vo concentration with photocatalytic nitrogen fixation efficiency of 176 μmol·g−1·h−1. The oxygen vacancy could induce the formation of the oxygen vacancy level, which could reduce the band gap energy, attract electrons, and hinder the electron hole recombination. More importantly, the oxygen vacancy level could be used as a springboard to reduce the energy required for N2 activation. In addition, calcination and acid-wash were used to regulate the concentration of surface oxygen vacancies (Vo-s) and bulk oxygen vacancies (Vo-b), respectively. The results showed that acid-wash only reduced the Vo-s concentration, while calcination reduced both the Vo-s and the Vo-b concentration, and the high concentration of Vo and Vo-s was beneficial for photocatalytic nitrogen fixation. The regulation strategy of Vo had guiding significance for improving the photocatalytic performance of metal oxide photocatalysts.

Plant responses to elevated CO2 under competing hypotheses of nitrogen and phosphorus limitations.

The future ecosystem carbon cycle has important implications for biosphere-climate feedback. The magnitude of future plant growth and carbon accumulation depends on plant strategies for nutrient uptake under the stresses of nitrogen (N) versus phosphorus (P) limitations. Two archetypal theories have been widely acknowledged in the literature to represent N and P limitations on ecosystem processes: Liebig's Law of the Minimum (LLM) and the Multiple Element Limitation (MEL) approach. LLM states that the more limiting nutrient controls plant growth, and commonly leads to predictions of dramatically dampened ecosystem carbon accumulation over the 21st century. Conversely, the MEL approach recognizes that plants possess multiple pathways to coordinate N and P availability and invest resources to alleviate N or P limitation. We implemented these two contrasting approaches in the E3SM model, and compiled 98 in situ forest N or P fertilization experiments to evaluate how terrestrial ecosystems will respond to N and P limitations. We find that MEL better captured the observed plant responses to nutrient perturbations globally, compared with LLM. Furthermore, LLM and MEL diverged dramatically in responses to elevated CO2 concentrations, leading to a two-fold difference in CO2 fertilization effects on Net Primary Productivity by the end of the 21st century. The larger CO2 fertilization effects indicated by MEL mainly resulted from plant mediation on N and P resource supplies through N2 fixation and phosphatase activities. This analysis provides quantitative evidence of how different N and P limitation strategies can diversely affect future carbon and nutrient dynamics.

Status quo of fertilization strategies and nutrient farm gate budgets on stockless organic vegetable farms in Germany

Fertilizer management in stockless organic vegetable production is strongly affected by external nutrient purchases due to the high nitrogen (N) and potassium (K) requirements of vegetables. However, the database on nutrient flows and budgets in organic vegetable farming in Europe is very limited. Therefore, a survey based on semi-structured interviews was carried out comprising 12 organic horticultural farms in Germany. The results show that three different main fertilizer categories are used as inputs in different ratios by the inventoried farms: (1) base fertilizers (e.g., composts, solid farmyard manures), (2) commercial organic N fertilizers (e.g., keratins or plant products from food production or fermentation processes), and (3) commercial mineral fertilizers (e.g., potassium sulfate), all of which are approved for organic production. Ninety percent of the total nutrient inputs to the farms came from these fertilizers and biological N2 fixation, with the remaining 10% coming from other inputs, such as seeds or growing media. The estimated yearly average total farm budgets were nearly balanced across all farms with moderate surpluses (67.5 kg N ha−1, 2.06 kg P ha−1, and 0.26 kg K ha−1). However, large imbalances were found for most of the individual farms. These imbalances indicate the risk of nutrient accumulation or nutrient depletion in the soil, depending on the fertilization strategy and productivity of the farm. More specifically, increasing N share from base fertilizers led to increased P and K budgets, while strategies based on the use of large amounts of keratins led to the opposite—K and P depletion. We concluded that balanced nutrient management in organic vegetable production systems requires a thorough calculation and should combine the use of base fertilizers, commercial fertilizers with low P content, and increased N supply via BNF.

Bimetallic NH2-MIL-101(Fe, Co) as highly efficient photocatalyst for nitrogen fixation

Developing effective catalysts for N2 photofixation at ambient conditions is highly desirable but still challenging. Herein, we reported a novel Co-doped NH2-MIL-101(Fe) (NM-Fe) bimetallic organic framework (BMOF) for visible-light-driven catalytic N2 fixation. It was found that the doping of Co ions could effectively enhance light-harvesting, reduce the conduction band potential, suppress the recombination of photogenerated carriers, and promote the activation of N2. Consequently, the photocatalytic N2 reduction efficiency of bimetallic NH2-MIL-101(Fe, Co) (NM-Fe-Co) was obviously boosted. The sample with the optical Co/Fe molar ratio of 0.15, namely NM-Fe-0.15Co, enabled an ammonia evolution rate up to 335.7 µmol g−1 h−1 without the aid of any sacrificial agents, a 4.4-fold increase over the monometallic NM-Fe baseline. Additionally, the bimetallic NM-Fe-Co displayed excellent stability. The possible reaction mechanism of nitrogen fixation over NM-Fe-Co was proposed based on in-situ infrared analysis. Our study demonstrates a promising strategy for designing potent MOF-based catalysts for N2 photofixation.

Sustainability Analysis of Nitrogen Use Efficiency in Soybean-Corn Succession Crops of Midwest Brazil

Nitrogen (N) is abundant in the atmosphere as N2, which is converted into reactive forms (Nr) for plant assimilation. In pre-industrial times, atmospheric N2 conversion to Nr balanced Nr reconversion to N2, but 20th-century human activity intensified this conversion via synthetic fertilizers, biological N2 fixation, and fossil fuel burning. The surplus of Nr detrimentally impacts ecosystems and human well-being. This study aimed to assess the N use efficiency in the soil–plant system of the soybean-corn succession (SPSS,C) in Mato Grosso and Mato Grosso do Sul, Brazil’s midwest. We estimated N macrofluxes in SPSS,C and identified key agro-environmental indicators. Between 2008 and 2020, the yearly sowed area for the SPSS,C increased by 3.3-fold (currently 7.3 million ha). The average annual input of net anthropogenic Nr, average annual N balance, and N loss in SPSS,C was estimated to be ~204 kg [N] ha−1, 57 kg [N] ha−1, and 30 kg [N] ha−1, respectively, indicating persistent N accumulation and loss. The average results of the agronomic efficiency and N retention indicator in the SPSS,C was 0.71 and 0.90, respectively. Modest N use efficiency results reflect N loss effects. Despite these limitations, there are opportunities in SPSS,C for management strategies to reduce N loss and enhance efficiency.

Defect modulation of MIL-68(Fe) MOFs by Cu doping for boosting photocatalytic N2 fixation

Photocatalytic N2 fixation is a green process for ammonia synthesis by converting N2 and H2O to NH3 and O2 directly using solar energy. Its efficiency is largely limited by the chemisorption and activation of N2. This work adopts defect engineering strategy to develop a series of MIL-68(Fe) MOFs with varying concentrations of defects by doping Cu2+ on the metal nodes of MOFs. Upon Cu2+ doping, a larger number of oxygen vacancy defects are created due to the induced crystal distortion to form coordinatively unsaturated Fe2+ sites, which can serve as the active sites for promoting the chemisorption and activation of N2. The photogenerated holes oxidize H2O to O2 and H+, and the photogenerated electrons combine with formed H+ to reduce the activated N2 to NH3. It was found that the sample with 10 mol% Cu2+ doping shows the highest NH3 production rate (21.0 μmol·g−1·h−1), which is 8.4 times higher than that (2.50 μmol·g−1·h−1) of the pristine MIL-68(Fe). The excellent performance is ascribed to the adequate Fe2+ active sites to chemisorb and activate N2 and the optimal mobility of photogenerated charges. Finally, a mechanism is proposed to illustrate how the number of defects affects the photocatalytic N2 fixation performance at the molecular level.

Highly efficient nitrogen fixation over S-scheme heterojunction photocatalysts with enhanced active hydrogen supply.

Photocatalytic N2 fixation is a promising strategy for ammonia (NH3) synthesis; however, it suffers from relatively low ammonia yield due to the difficulty in the design of photocatalysts with both high charge transfer efficiency and desirable N2 adsorption/activation capability. Herein, an S-scheme CoSx/ZnS heterojunction with dual active sites is designed as an efficient N2 fixation photocatalyst. The CoSx/ZnS heterojunction exhibits a unique pocket-like nanostructure with small ZnS nanocrystals adhered on a single-hole CoSx hollow dodecahedron. Within the heterojunction, the electronic interaction between ZnS and CoSx creates electron-deficient Zn sites with enhanced N2 chemisorption and electron-sufficient Co sites with active hydrogen supply for N2 hydrogenation, cooperatively reducing the energy barrier for N2 activation. In combination with the promoted photogenerated electron-hole separation of the S-scheme heterojunction and facilitated mass transfer by the pocket-like nanostructure, an excellent N2 fixation performance with a high NH3 yield of 1175.37 μmol g-1 h-1 is achieved. This study provides new insights into the design of heterojunction photocatalysts for N2 fixation.

Emerging nitrogen-fixing cyanobacteria for sustainable cotton cultivation

Amid growing environmental concerns and the imperative for sustainable agricultural practices, this study examines the potential of nitrogen-fixing cyanobacteria as biofertilizers, particularly in cotton cultivation. The reliance on synthetic nitrogen fertilizers (SNFs), prevalent in modern agriculture, poses significant environmental challenges, including greenhouse gas emissions and water system contamination. This research aims to shift this paradigm by exploring the capacity of cyanobacteria as a natural and sustainable alternative. Utilizing advanced metabarcoding methods to analyze the 16S rRNA gene, we conducted a comprehensive assessment of soil bacterial communities within cotton fields. This study focused on evaluating the diversity, structure, taxonomic composition, and potential functional characteristics of these communities. Emphasis was placed on the isolation of native N2-fixing cyanobacteria strains rom cotton soils, and their subsequent effects on cotton growth. Results from our study demonstrate significant plant growth-promoting (PGP) activities, measured as N2 fixation, production of Phytohormones, Fe solubilization and biofertilization potential of five isolated cyanobacterial strains, underscoring their efficacy in cotton. These findings suggest a viable pathway for replacing chemical-synthetic nitrogen fertilizers with natural, organic alternatives. The reintegration of these beneficial species into agricultural ecosystems can enhance crop growth while fostering a balanced microbial environment, thus contributing to the broader goals of global sustainable agriculture.

Construction of Gold/Rhodium Freestanding Superstructures as Antenna-Reactor Photocatalysts for Plasmon-Driven Nitrogen Fixation.

Precisely controlling the architecture and spatial arrangement of plasmonic heterostructures offers unique opportunities to tailor the catalytic property, whereas the lack of a wet-chemistry synthetic approach to fabricating nanostructures with high-index facets limits their practical applications. Herein, we describe a universal synthetic strategy to construct Au/Rh freestanding superstructures (SSs) through the selective growth of ordered Rh nanoarrays on high-index-faceted Au nanobipyramids (NBPs). This synthetic strategy works on various metal nanocrystal substrates and can yield diverse Au/Rh and Pd/Rh SSs. Especially, the obtained Au NBP/Rh SSs exhibit high photocatalytic activity toward N2 fixation as a result of the spatially separated architecture, local electric field enhancement, and the antenna-reactor mechanism. Both theoretical and experimental results reveal that the Au NBPs can function as nanoantennas for light-harvesting to generate hot charge carriers for driving N2 fixation, while the Rh nanoarrays can serve as the active sites for N2 adsorption and activation to synergistically promote the overall catalytic activity in the Au NBP/Rh SSs. This work offers new avenues to rationally designing and constructing spatially separated plasmonic photocatalysts for high-efficiency catalytic applications.

Enhanced photocatalytic nitrogen fixation performance via in situ constructing BiO2–x/NaNbO3 heterojunction

The fabrication of heterojunction catalysts is an effective strategy to enhance charge separation efficiency, thereby boosting the performance of photocatalysts. In this study, BiO2–x nanosheets were synthesized through a hydrothermal process and loaded onto NaNbO3 microcube to construct a series of BiO2–x/NaNbO3 heterojunctions for photocatalytic N2 fixation. Results indicated that 2.5% BiO2–x/NaNbO3 had the highest photocatalytic performance. The NH3 production rate under simulated solar light reached 406.4 μmol·L−1·g−1·h−1, which reaches 2.6 and 3.8 times that of NaNbO3 and BiO2–x, respectively. BiO2–x nanosheets primarily act as electron trappers to enhance the separation efficiency of charge carriers. The strong interaction between BiO2–x and NaNbO3 facilitate the electron migration between them. Meanwhile, the abundant oxygen vacancies in BiO2–x nanosheets may facilitate the adsorption and activation of N2, which may be another possible reason of the high photocatalytic activity of the BiO2–x/NaNbO3. This study may offer new insights for the development of semiconductor materials in photocatalytic nitrogen fixation.

Dissolved organic matter offsets the detrimental effects of climate change in the nitrogen‐fixing cyanobacterium Crocosphaera

AbstractDiazotrophs provide a significant reactive nitrogen source in the ocean. Increased warming and stratification may decrease nutrient availability in the future, forcing microbial communities toward using dissolved organic matter (DOM). Not depending on reactive nitrogen availability, diazotrophs may be “winners” in a nutrient‐depleted ocean. However, their ability to exploit DOM may influence this success. We exposed cultures of the widespread Crocosphaera to low (26°C, pH 8.1), moderate (28°C, pH 8.0), and extreme (30°C, pH 7.9) climate change scenarios, under control or DOM‐amended conditions. Growth was suboptimal in the low and extreme treatments and favored in the moderate treatment. DOM was preferred as a carbon source regardless of the treatment and promoted N2 fixation in extreme conditions. This was reflected in the increased expression of photosynthesis genes to obtain energy. DOM provides Crocosphaera with a key ecological advantage, possibly dictating diazotroph‐derived nitrogen inputs in the future ocean.

Promoted photocatalytic N2 fixation to ammonia over floatable TiO2/Bi/Carbon cloth through relay pathway

The floatable photocatalyst at N2-water interface allows the adequate supply of N2 reactant and the utilization of photothermal energy for photocatalytic N2 fixation, however, the presence of non-volatile NO3− product poses a challenge to the stability as it easily covers the catalytic active sites. Herein, a floatable TiO2/Bi/CC (Carbon cloth) photocatalyst was designed, in which the non-volatile NO3− can be transformed to the volatile NH3 via the newly synergistic relay photocatalysis pathway (N2 → NO3− → NH3) between TiO2 (N2 → NO3−) and Bi (NO3− → NH3). Attractively, the spontaneous NO3− → NO2− step occurs on Bi component to promote the relay pathway performing. Therefore, TiO2/Bi/CC system displays better long-term stability than TiO2/CC, and moreover, it achieves a higher NH3 yield of 8.28 mmol L−1 h−1 g−1 (i.e. 4.14 mmol h−1 m−2) than that 1.46 mmol L−1 h−1 g−1 for TiO2/Bi powder. Importantly, the N2 fixation products by TiO2/Bi/CC effectively promote lettuce growth and enhance lettuce nutrient contents, which further validates the feasibility of this system in large-scale application of crop cultivation.

Absorption and Transport of Phosphorus in Nodulated Soybean Plants and Diagnosis of Phosphorus Status Using Xylem Sap Analysis

Phosphorus (P) is an essential major element for plants. The absorption and transport of P are important for soybean growth and yield, including nodule growth and N2 fixation. Through an analysis of xylem sap, we investigated how nodulated soybean plants absorb PO4 via the roots and transport it to the shoot. The nodulated soybean plants were treated with 0, 50, and 250 μM PO4 concentrations for 1, 3, 7, and 15 days. The PO4 concentration in the xylem sap significantly decreased after 1 day of P deprivation, and then it gradually decreased for 15 days. The high-concentration (250 μM PO4) treatment increased the PO4 concentrations in the xylem sap at 7- and 15-day timepoints but not at the 1- or 3-day timepoints. The soybean plants were treated with 0, 25, 50, 100, 150, 250, and 500 μM PO4 for 3 days. The PO4 absorption rate increased consistently in conjunction with the increase in the PO4 concentration; however, the PO4 concentrations in the xylem sap increased only from 0 to 50 μM PO4 but were constant under higher P concentrations. The soybean plants accumulated extra PO4 in the roots. The PO4 concentration in the xylem sap immediately reflected the P deficiency conditions; thus, this index may be used as an indicator for the diagnosis of P deficiency.

The Feather Moss Hylocomium splendens Affects the Transcriptional Profile of a Symbiotic Cyanobacterium in Relation to Acquisition and Turnover of Key Nutrients

Moss-cyanobacteria symbioses were proposed to be based on nutrient exchange, with hosts providing C and S while bacteria provide N, but we still lack understanding of the underlying molecular mechanisms of their interactions. We investigated how contact between the ubiquitous moss Hylocomium splendens and its cyanobiont affects nutrient-related gene expression of both partners. We isolated a cyanobacterium from H. splendens and co-incubated it with washed H. splendens shoots. Cyanobacterium and moss were also incubated separately. After 1 week, we performed acetylene reduction assays to estimate N2 fixation and RNAseq to evaluate metatranscriptomes. Genes related to N2 fixation and the biosynthesis of several amino acids were up-regulated in the cyanobiont when hosted by the moss. However, S-uptake and the biosynthesis of the S-containing amino acids methionine and cysteine were down-regulated in the cyanobiont while the degradation of selenocysteine was up-regulated. In contrast, the number of differentially expressed genes in the moss was much lower, and almost no transcripts related to nutrient metabolism were affected. It is possible that, at least during the early stage of this symbiosis, the cyanobiont receives few if any nutrients from the host in return for N, suggesting that moss–cyanobacteria symbioses encompass relationships that are more plastic than a constant mutualist flow of nutrients.

Multi-functional energy conversion by strongly coupled Ag3PO4/ZIF-67 heterostructures

The present study demonstrates a multi-functional photocatalytic energy conversion through the synergistic integration of Ag3PO4 nanoparticles with ZIF-67. Unique structures were engineered by incorporating Ag3PO4 particles into ZIF-67, resulting in Ag3PO4@ZIF-67 core-shell nanocomposites, and by decorating Ag3PO4 on ZIF-67 outer surfaces, forming Ag3PO4/ZIF-67 structures. The hydrothermal synthesis was combined with comprehensive structural, optical, and electrochemical analyses. These engineered nanocomposites were systematically investigated as photocatalysts for water splitting, CO2 reduction and N2 fixation, exhibiting remarkable performance in the diverse energy conversion reactions. Notably, Ag3PO4/ZIF-67 structures displayed the highest photocatalytic activities attributed to the large surface area, high accessibility of reactants, and the direct Z-scheme mechanism of interfacial electron-hole recombination, outperforming individual Ag3PO4 nanoparticles and ZIF-67. The Ag3PO4/ZIF-67 photocatalyst represents a significant advancement in the field and holds great promise for practical applications.