Exploring microstructures of metal-doped oxides via simulated Raman spectrum.

Solid solution of metal-doped oxide has been widely used in material industry and catalysis process. Its performance is highly correlated with the distribution of doped ions. Due to the complex distribution of doped ions in solid solution and its variation with temperatures, to obtain the microstructures of metal-doped ions in solid solution remains a substantial challenge. Taken Ce1-xZrxO2 as a model, the global structure searching, structures proportion with temperature determined by Boltzmann distribution, and the weighted simulation Raman spectra were integrated to explore the microstructures of metal-doped solid solution oxides. It was further verified by application into rutile and anatase TiO2 mixture, indicating that the present method is feasible to deduce the microstructure of metal composite oxides. We anticipate that it provides a powerful solution to explore microstructures of solid solution and complex metal oxides.

Research on the impact of regional integration policy on carbon emissions--Taking the Yangtze River Economic Belt as an example.

The Yangtze River Economic Belt serves as a paradigm of ecological integration and high-quality development within China. Under the constraints of the "Dual Carbon" goal, how does the integrative policy of the Yangtze River Economic Belt, aimed at reinforcing inter-regional industrial cooperation, impact carbon emissions across various provinces within the region? Leveraging panel data from 30 Chinese provinces spanning 2009-2019 and treating the 2016 promulgation of the "Yangtze River Economic Belt Development Planning Outline" as a quasi-natural experiment, this study employs a Difference-in-Differences (DID) model for discerning the effects of regional integration policies on carbon emissions, intensity, and efficiency in the 11 provinces of the Yangtze River Economic Belt. The research further delves into the underlying mechanisms through which policy interventions modulate provincial carbon emissions. Key findings include: (1) The policy's enactment has significantly attenuated provincial carbon emissions and intensity, albeit somewhat hampering the enhancement of carbon efficiency-conclusions robust to parallel trend and placebo tests; (2) Heterogeneity analyses reveal disparities in the policy's carbon emission effects, contingent on varying economic development levels and geographical loci; (3) Mechanistically, while the integration bolsters regional environmental governance and strengthens economic ties-thereby curtailing provincial emissions-it is evident that local governments have been somewhat inept in effectively channeling the influx of substantial short-term capital, hence stifling provincial carbon efficiency. In light of these insights, it is posited that local governments within the Yangtze River Economic Belt should ardently endeavor to refine and elevate regional industrial structures, champion the construction of an integrated regional market, intensify capital oversight and coordinated utilization, and enhance the efficiency of regional capital allocation, all in the quest to augment regional carbon emission reduction performance.

Tuning the Electronic Structures of Anchor Sites to Achieve Zero-Valence Single-Atom Catalysts for Advanced Hydrogenation.

Single-atom catalysts (SACs) have recently become highly attractive for selective hydrogenation reactions owing to their remarkably high selectivity. However, compared to their nanoparticle counterparts, atomically dispersed metal atoms in SACs often show inferior activity and are prone to aggregate under reaction conditions. Here, by theoretical calculations, we show that tuning the local electronic structures of metal anchor sites on g-C3N4 by doping B atoms (BCN) with relatively lower electronegativity allows achieving zero-valence Pd SACs with reinforced metal-support orbital hybridizations for high stability and upshifted Pd 4d orbitals for high activity in H2 activation. The precise synthesis of Pd SACs on BCN supports with varied B contents substantiated the theoretical prediction. A zero-valence Pd1/BCN SAC was achieved on a BCN support with a relatively low B content. It exhibited much higher stability in a H2 reducing environment, and more strikingly, a hydrogenation activity, approximately 10 and 34 times greater than those high-valence Pd1/g-C3N4 and Pd1/BCN with a high B content, respectively.

Large-scale interplant exchange of macromolecules between soybean and dodder under nutrient stresses.

Parasitic plants and their hosts communicate through haustorial connections. Nutrient deficiency is a common stress for plants, yet little is known about whether and how host plants and parasites communicate during adaptation to such nutrient stresses. In this study, we used transcriptomics and proteomics to analyze how soybean (Glycine max) and its parasitizing dodder (Cuscuta australis) respond to nitrate and phosphate deficiency (-N and -P). After -N and -P treatment, the soybean and dodder plants exhibited substantial changes of transcriptome and proteome, although soybean plants showed very few transcriptional responses to -P and dodder did not show any transcriptional changes to either -N or -P. Importantly, large-scale interplant transport of mRNAs and proteins was detected. Although the mobile mRNAs only comprised at most 0.2% of the transcriptomes, the foreign mobile proteins could reach 6.8% of the total proteins, suggesting that proteins may be the major forms of interplant communications. Furthermore, the interplant mobility of macromolecules was specifically affected by the nutrient regimes and the transport of these macromolecules was very likely independently regulated. This study provides new insight into the communication between host plants and parasites under stress conditions.

Directional and Orderly Arranged Ni0.9Mn0.1(OH)2 Enables the Synthesis of Single-Crystal Ni-Rich Co-Free LiNi0.9Mn0.1O2 with Enhanced Internal Structural Stability.

In this paper, the effect of the structure characteristics of the precursor on the electrochemical properties of a single-crystal cobalt-free high-nickel LiNi0.9Mn0.1O2 cathode is systematically studied. Precursors with different morphologies are synthesized by adjusting the coprecipitation reaction conditions. The results of SEM and XRD show that with the increase in the orderly stacking arrangement of internal primary nanosheets of Ni0.9Mn0.1(OH)2, the exposed active {010} planes at the surface increase. The prepared cathode materials finally inherit the structural features of the precursor, and the single-crystal Co-free Ni-rich LiNi0.9Mn0.1O2 cathode with highly exposed active {010} planes shows a well-ordered crystal structure and low Li+/Ni2+ cation mixing. The characterization results reveal that the high percentage of {010} planes will improve the Li+ transportation kinetics, decrease electrochemical impedance, and significantly alleviate the accumulation of rock-salt phases. Therefore, the material with this structure shows good electrochemical performance.

Balanophora genomes display massively convergent evolution with other extreme holoparasites and provide novel insights into parasite-host interactions.

Parasitic plants have evolved to be subtly or severely dependent on host plants to complete their life cycle. To provide new insights into the biology of parasitic plants in general, we assembled genomes for members of the sandalwood order Santalales, including a stem hemiparasite (Scurrula) and two highly modified root holoparasites (Balanophora) that possess chimaeric host-parasite tubers. Comprehensive genome comparisons reveal that hemiparasitic Scurrula has experienced a relatively minor degree of gene loss compared with autotrophic plants, consistent with its moderate degree of parasitism. Nonetheless, patterns of gene loss appear to be substantially divergent across distantly related lineages of hemiparasites. In contrast, Balanophora has experienced substantial gene loss for the same sets of genes as an independently evolved holoparasite lineage, the endoparasitic Sapria (Malpighiales), and the two holoparasite lineages experienced convergent contraction of large gene families through loss of paralogues. This unprecedented convergence supports the idea that despite their extreme and strikingly divergent life histories and morphology, the evolution of these and other holoparasitic lineages can be shaped by highly predictable modes of genome reduction. We observe substantial evidence of relaxed selection in retained genes for both hemi- and holoparasitic species. Transcriptome data also document unusual and novel interactions between Balanophora and host plants at the host-parasite tuber interface tissues, with evidence of mRNA exchange, substantial and active hormone exchange and immune responses in parasite and host.

Cellulose-Assisted Vertically Heterostructured PEO-Based Solid Electrolytes Mitigating Li-Succinonitrile Corrosion for Lithium Metal Batteries.

In the field of solid-state lithium metal batteries (SSLMBs), constructing vertically heterostructured poly(ethylene oxide) (PEO)-based solid electrolytes is an effective method to realize their tight contact with cathodes and Li anodes at the same time. Succinonitrile (SN) has been widely used in PEO-based solid electrolytes to improve the interface contact with cathodes, enhance the ionic conductivities, and obtain a high electrochemical stability window of PEO, but its application is still hindered by its intrinsic instability to Li anodes, which results in corrosion and side interactions with lithium metal. Herein, the cellulose membrane (CM) is introduced creatively into the vertically heterostructured PEO-based solid electrolytes to match the PEO-SN solid electrolytes at the cathode side. With the advantage of the interaction between -OH groups of CM and -C≡N groups in SN, the movement of free SN molecules from cathodes to Li anodes is limited effectively, resulting in a stable and durable SEI layer. In specific, the Li||LiFePO4 battery with the CM-assisted vertically heterostructured PEO-based solid electrolyte by in situ preparation delivers a discharge capacity of around 130 mAh g-1 after 300 cycles and capacity retention of 95% after 500 cycles at 0.5 C. Our work provides a solution to construct PEO-based solid electrolytes feasible to match cathodes and Li anodes effectively by intimate contact with electrodes.

Mixing planting with native tree species reshapes soil fungal community diversity and structure in multi-generational eucalypt plantations in southern China.

The continuous planting pattern of eucalypt plantations negatively affects soil quality. A mixed planting pattern using native species implanted in pure plantations has been considered a preferable measure for this problem. However, the impact of this approachon the structure and function of fungal communities is not clear. Here, harvesting sites that had undergone two generations of eucalypt plantations were selected to investigate soil fungal community structure and the co-occurrence network characteristics in response to two silvicultural patterns involving the third generation of eucalypt plantations (E) and mixed plantations of Eucalyptus. urograndis × Cinnamomum. camphora (EC) and E. urograndis × Castanopsis. hystrix (EH). Compared with the first generation of eucalypt plantations (CK), E markedly weakened enzyme activities associated with carbon-, nitrogen-. and phosphorus-cycling. Reduced soil fungal alpha diversity, and elevated the relative abundance of Basidiomycota while decreasing the abundance of Ascomycota. In contrast, EC and EH not only enhanced fungal alpha diversity, but also reshaped fungal composition. At the class level, E caused an enrichment of oligotrophic Agaricomycetes fungi, classified into symbiotroph guild, while EC markedly decreased the abundance of those fungi and increased the abundances of Sordariomycetes, Dothideomycetes, Eurotiomycetes, and Tremellomycetes fungi, which were classified into saprotroph or pathotroph guild. Moreover, fungal network complexity and robustness topological attributes were higher or significantly higher in mixed plantations soils compared with those of pure eucalypt plantation E. Furthermore, fungal diversity, structure, and functional taxa were significantly affected by soil organic matter, pH, total nitrogen, and nitrate nitrogen.

Between-Plant Signaling.

Parasitic plants use a special organ, the haustorium, to attach to and penetrate host tissues, forming phloem and/or xylem fusion with the host vascular systems. Across this haustorium-host interface, not only water and nutrients are extracted from the host by the parasitic plant, but also secondary metabolites, messenger RNAs, noncoding RNAs, proteins, and systemic signals are transported between the parasite and host and even among different hosts connected by a parasite. Furthermore, mycorrhizal fungi can form common mycelial networks (CMNs) that simultaneously interconnect multiple plants. Increasing lines of evidence suggest that CMNs can function as conduits, transferring stress-related systemic signals between plants. Between-plant signaling mediated by haustoria and CMNs likely has a profound impact on plant interactions with other organisms and adaptation to environmental factors. Here, we summarize the findings regarding between-plant transfer of biomolecules and systemic signals and the current understanding of the physiological and ecological implications of between-plant signaling.

ZmMYC2s play important roles in maize responses to simulated herbivory and jasmonate.

Both herbivory and jasmonic acid (JA) activate the biosynthesis of defensive metabolites in maize, but the mechanism underlying this remains unclear. We generated maize mutants in which ZmMYC2a and ZmMYC2b, two transcription factor genes important in JA signaling, were individually or both knocked out. Genetic and biochemical analyses were used to elucidate the functions of ZmMYC2 proteins in the maize response to simulated herbivory and JA. Compared with the wild-type (WT) maize, the double mutant myc2ab was highly susceptible to insects, and the levels of benzoxazinoids and volatile terpenes, and the levels of their biosynthesis gene transcripts, were much lower in the mutants than in the WT maize after simulated insect feeding or JA treatment. Moreover, ZmMYC2a and ZmMYC2b played a redundant role in maize resistance to insects and JA signaling. Transcriptome and Cleavage Under Targets and Tagmentation-Sequencing (CUT&Tag-Seq) analysis indicated that ZmMYC2s physically targeted 60% of the JA-responsive genes, even though only 33% of these genes were transcriptionally ZmMYC2-dependent. Importantly, CUT&Tag-Seq and dual luciferase assays revealed that ZmMYC2s transactivate the benzoxazinoid and volatile terpene biosynthesis genes IGPS1/3, BX10/11/12/14, and TPS10/2/3/4/5/8 by directly binding to their promoters. Furthermore, several transcription factors physically targeted by ZmMYC2s were identified, and these are likely to function in the regulation of benzoxazinoid biosynthesis. This work reveals the transcriptional regulatory landscapes of both JA signaling and ZmMYC2s in maize and provides comprehensive mechanistic insight into how JA signaling modulates defenses in maize responses to herbivory through ZmMYC2s.

Tuning the CO2 Hydrogenation Selectivity of Rhodium Single-Atom Catalysts on Zirconium Dioxide with Alkali Ions.

Tuning the coordination environments of metal single atoms (M1 ) in single-atom catalysts has shown large impacts on catalytic activity and stability but often barely on selectivity in thermocatalysis. Here, we report that simultaneously regulating both Rh1 atoms and ZrO2 support with alkali ions (e.g., Na) enables efficient switching of the reaction products from nearly 100 % CH4 to above 99 % CO in CO2 hydrogenation in a wide temperature range (240-440 °C) along with a record high activity of 9.4 molCO gRh -1 h-1 at 300 °C and long-term stability. In situ spectroscopic characterization and theoretical calculations unveil that alkali ions on ZrO2 change the surface intermediate from formate to carboxy species during CO2 activation, thus leading to exclusive CO formation. Meanwhile, alkali ions also reinforce the electronic Rh1 -support interactions, endowing the Rh1 atoms more electron deficient, which improves the stability against sintering and inhibits deep hydrogenation of CO to CH4 .

Comparative genomics of orobanchaceous species with different parasitic lifestyles reveals the origin and stepwise evolution of plant parasitism.

Orobanchaceae is the largest family of parasitic plants, containing autotrophic and parasitic plants with all degrees of parasitism. This makes it by far the best family for studying the origin and evolution of plant parasitism. Here we provide three high-quality genomes of orobanchaceous plants, the autotrophic Lindenbergia luchunensis and the holoparasitic plants Phelipanche aegyptiaca and Orobanche cumana. Phylogenomic analysis of these three genomes together with those previously published and the transcriptomes of other orobanchaceous species created a robust phylogenetic framework for Orobanchaceae. We found that an ancient whole-genome duplication (WGD; about 73.48 million years ago), which occurred earlier than the origin of Orobanchaceae, might have contributed to the emergence of parasitism. However, no WGD events occurred in any lineage of orobanchaceous parasites except for Striga after divergence from their autotrophic common ancestor, suggesting that, in contrast with previous speculations, WGD is not associated with the emergence of holoparasitism. We detected evident convergent gene loss in all parasites within Orobanchaceae and between Orobanchaceae and dodder Cuscuta australis. The gene families in the orobanchaceous parasites showed a clear pattern of recent gains and expansions. The expanded gene families are enriched in functions related to the development of the haustorium, suggesting that recent gene family expansions may have facilitated the adaptation of orobanchaceous parasites to different hosts. This study illustrates a stepwise pattern in the evolution of parasitism in the orobanchaceous parasites and will facilitate future studies on parasitism and the control of parasitic plants in agriculture.

Li-Deficient Materials-Decoration Restrains Oxygen Evolution Achieving Excellent Cycling Stability of Li-Rich Mn-Based Cathode.

With the increasing demand for high energy density and rapid charging performance, Li-rich materials have been the up and coming cathodes for next-generation lithium-ion batteries. However, because of oxygen evolution and structural instability, the commercialization of Li-rich materials is extremely retarded by their poor electrochemical performances. In this work, Li-deficient materials Li0.3NbO2 and (Nb0.62Li0.15)TiO3 are applied to functionalize the surface of Li1.2Mn0.54Ni0.13Co0.13O2, aiming to suppress oxygen evolution and increase structural stability in LIBs. In addition, a fast Li-ion transport channel is beneficial to enhance Li+ diffusion kinetics. The results demonstrate that the electrodes decorated with Li0.3NbO2 and (Nb0.62Li0.15)TiO3 materials exhibit more stable cycling stability after long-term cycling and outstanding rate capability.

Inter-species mRNA transfer among green peach aphids, dodder parasites, and cucumber host plants.

mRNAs are transported within a plant through phloem. Aphids are phloem feeders and dodders (Cuscuta spp.) are parasites which establish phloem connections with host plants. When aphids feed on dodders, whether there is trafficking of mRNAs among aphids, dodders, and host plants and if aphid feeding affects the mRNA transfer between dodders and hosts are unclear. We constructed a green peach aphid (GPA, Myzus persicae)-dodder (Cuscuta australis)-cucumber (Cucumis sativus) tritrophic system by infesting GPAs on C. australis, which parasitized cucumber hosts. We found that GPA feeding activated defense-related phytohormonal and transcriptomic responses in both C. australis and cucumbers and large numbers of mRNAs were found to be transferred between C. australis and cucumbers and between C. australis and GPAs; importantly, GPA feeding on C. australis greatly altered inter-species mobile mRNA profiles. Furthermore, three cucumber mRNAs and three GPA mRNAs could be respectively detected in GPAs and cucumbers. Moreover, our statistical analysis indicated that mRNAs with high abundances and long transcript lengths are likely to be mobile. This study reveals the existence of inter-species and even inter-kingdom mRNA movement among insects, parasitic plants, and parasite hosts, and suggests complex regulation of mRNA trafficking.

Study of the Off-Axis Fresnel Zone Plate of a Microscopic Tomographic Aberration.

A tomographic microscopy system can achieve instantaneous three-dimensional imaging, and this type of microscopy system has been widely used in the study of biological samples; however, existing chromatographic microscopes based on off-axis Fresnel zone plates have degraded image quality due to geometric aberrations such as spherical aberration, coma aberration, and image scattering. This issue hinders the further development of chromatographic microscopy systems. In this paper, we propose a method for the design of an off-axis Fresnel zone plate with the elimination of aberrations based on double exposure point holographic surface interference. The aberration coefficient model of the optical path function was used to solve the optimal recording parameters, and the principle of the aberration elimination tomography microscopic optical path was verified. The simulation and experimental verification were carried out utilizing a Seidel coefficient, average gradient, and signal-to-noise ratio. First, the aberration coefficient model of the optical path function was used to solve the optimal recording parameters. Then, the laminar mi-coroscopy optical system was constructed for the verification of the principle. Finally, the simulation calculation results and the experimental results were verified by comparing the Seidel coefficient, average gradient, and signal-to-noise ratio of the microscopic optical system before and after the aberration elimination. The results show that for the diffractive light at the orders 0 and ±1, the spherical aberration W040 decreases by 62-70%, the coma aberration W131 decreases by 96-98%, the image dispersion W222 decreases by 71-82%, and the field curvature W220 decreases by 96-96%, the average gradient increases by 2.8%, and the signal-to-noise ratio increases by 18%.

Adsorption of inorganic and organic phosphorus onto polypyrrole modified red mud: Evidence from batch and column experiments.

The ubiquitous presence of inorganic and organic phosphorus in wastewater and natural water bodies has deteriorated the water environment qualities and exerted significant influences on ecosystems. In this study, an effective polypyrrole modified red mud adsorbent (PRM) was optimized for the adsorptive removal of inorganic and organic phosphorus from aqueous solutions. The addition of ferric chloride and pyrrole was optimized for complete oxidation and modification of polypyrrole onto red mud. Kinetic studies illustrated that the adsorption progress was accomplished by physical and chemical adsorption. The experimental data of the optimized PRM were described well by Langmuir isotherm, and the equilibrium adsorption capacity was 32.9 and 54.7 mg/g for inorganic and organic phosphorus, respectively. The PRM showed commendable adsorption performance despite the pH conditions ranging from 3 to 11. From the effect of ion strength and X-ray photoelectron spectroscopy (XPS) tests, we found that ligand exchange is the main mechanism of orthophosphate adsorption onto PRM, while electrostatic attraction played an important role in organic phosphorus adsorption. The adsorption performance from column studies showed that the velocity of flow influenced the breakthrough time of the column but the initial concentration had minor impacts. This study would extend the potential application of polypyrrole modified red mud, acting as an efficient adsorbent for inorganic and organic phosphorus adsorption in water treatment.

A chromosome-scale Gastrodia elata genome and large-scale comparative genomic analysis indicate convergent evolution by gene loss in mycoheterotrophic and parasitic plants.

Mycoheterotrophic and parasitic plants are heterotrophic and parasitize on fungi and plants, respectively, to obtain nutrients. Large-scale comparative genomics analysis has not been conducted in mycoheterotrophic or parasitic plants or between these two groups of parasites. We assembled a chromosome-level genome of the fully mycoheterotrophic plant Gastrodia elata (Orchidaceae) and performed comparative genomic analyses on the genomes of G. elata and four orchids (initial mycoheterotrophs), three parasitic plants (Cuscuta australis, Striga asiatica, and Sapria himalayana), and 36 autotrophs from various angiosperm lineages. It was found that while in the hemiparasite S. asiatica and initial mycoheterotrophic orchids, approximately 4-5% of the conserved orthogroups were lost, the fully heterotrophic G. elata and C. australis both lost approximately 10% of the conserved orthogroups, indicating that increased heterotrophy is positively associated with gene loss. Importantly, many genes that are essential for autotrophs, including those involved in photosynthesis, the circadian clock, flowering time regulation, immunity, nutrient uptake, and root and leaf development, were convergently lost in both G. elata and C. australis. The high-quality genome of G. elata will facilitate future studies on the physiology, ecology, and evolution of mycoheterotrophic plants, and our findings highlight the critical role of gene loss in the evolution of plants with heterotrophic lifestyles.

Surface LiMn1.4Ni0.5Mo0.1O4 Coating and Bulk Mo Doping of Li-Rich Mn-Based Li1.2Mn0.54Ni0.13Co0.13O2 Cathode with Enhanced Electrochemical Performance for Lithium-Ion Batteries.

To improve the initial Coulombic efficiency, cycling stability, and rate performance of the Li-rich Mn-based Li1.2Mn0.54Ni0.13Co0.13O2 cathode, the combination of LiMn1.4Ni0.5Mo0.1O4 coating with Mo doping has been successfully carried out by the sol-gel method and subsequent dip-dry process. This strategy buffers the electrodes from the corrosion of electrolyte and enhances the lattice parameter, which could inhibit the oxygen release and maintain the structural stability, thus improving the cycle stability and rate capability. After LiMn1.4Ni0.5Mo0.1O4 modification, the initial discharge capacity reaches 272.4 mAh g-1 with a corresponding initial Coulombic efficiency (ICE) of 84.2% at 0.1C (1C = 250 mAh g-1), far higher than those (221.5 mAh g-1 and 68.9%) of the pristine sample. Besides, the capacity retention of the coated sample is enhanced by up to 66.8% after 200 cycles at 0.1C. Especially, the rate capability of the coated sample is 95.2 mAh g-1 at 5C. XRD, SEM, TEM, XPS, and Raman spectroscopy are adopted to characterize the morphologies and structures of the samples. This coating strategy has been demonstrated to be an effective approach to construct high-performance energy storage devices.

Herbivory-induced systemic signals are likely to be evolutionarily conserved in euphyllophytes.

Herbivory-induced systemic signaling has been demonstrated in monocots and dicots, and is essential for plant defense against insects. However, the nature and evolution of herbivory-induced systemic signals remain unclear. Grafting is widely used for studying systemic signaling; however, grafting between dicot plants from different families is difficult, and grafting is impossible for monocots. In this study, we took advantage of dodder's extraordinary capability of parasitizing various plant species. Field dodder (Cuscuta campestris) was employed to connect pairs of species that are phylogenetically very distant, ranging from fern to monocot and dicot plants, and so determine whether interplant signaling occurs after simulated herbivory. It was found that simulated herbivory-induced systemic signals can be transferred by dodder between a monocot and a dicot plant and even between a fern and a dicot plant, and the plants that received the systemic signals all exhibited elevated defenses. Thus, we inferred that the herbivory-induced systemic signals are likely to be evolutionarily well conserved among vascular plants. Importantly, we also demonstrate that the jasmonate pathway is probably an ancient regulator of the biosynthesis and/or transport of systemic signals in vascular plants. These findings provide new insight into the nature and evolution of systemic signaling.

Probing Interfacial Electronic Effects on Single-Molecule Adsorption Geometry and Electron Transport at Atomically Flat Surfaces.

Clarifying interfacial electronic effects on molecular adsorption is significant in many chemical and biochemical processes. Here, we used STM breaking junction and shell-isolated nanoparticle-enhanced Raman spectroscopy to probe electron transport and adsorption geometries of 4,4'-bipyridine (4,4'-BPY) at Au(111). Modifying the surface with 1-butyl-3-methylimidazolium cation-containing ionic liquids (ILs) decreases surface electron density and stabilizes a vertical orientation of pyridine through nitrogen atom σ-bond interactions, resulting in uniform adsorption configurations for forming molecular junctions. Modulation from vertical, tilted, to flat, is achieved on adding water to ILs, leading to a new peak ascribed to CC stretching of adsorbed pyridyl ring and 316 % modulation of single-molecule conductance. The dihedral angle between adsorbed pyridyl ring and surface decreases with increasing surface electronic density, enhancing electron donation from surface to pyridyl ring.