Carbon Lattice Research Articles

Effect of CO2 on the characteristics of soot derived from coal rapid pyrolysis

The present work aims to investigate the effects of a CO2-rich atmosphere on the characteristics of coal-derived soot. The rapid pyrolysis of Shenfu bituminous coal was conducted in a Drop tube furnace (DTF) in N2 and CO2 atmospheres with a wall temperature of 1073–1473 K and residence time below 700 ms. The yields and microstructure characteristics of N2-soot and CO2-soot were analysed by using a series of techniques (elemental analysis, HRTEM, Raman, XRD, FT-IR and thermogravimetry techniques). CO2 enhanced the soot formation and proceeded the dehydrogenation. CO2 improved the order of internal carbon lattices, enhanced the lateral extension of carbon nanostructures, decreased the interplanar spacing of the graphene layers and also promoted the stack of polyaromatic layers. The variations of the SOLO, DUO, TRIO and QUARTO structures were also analysed, and the contribution of CO2 was found to reduce the defects of the basic structure units (BSU). The defects of soot were an important indication of the initial gasification reactivity. Overall, CO2-soot was more mature and low active than N2-soot.

Sensing ion channel in neuron networks with graphene field effect transistors

Graphene, the atomically-thin honeycomb carbon lattice, is a highly conducting 2D material whose exposed electronic structure offers an ideal platform for chemical and biological sensing. Its biocompatible, flexible and chemically inert nature associated with the lack of dangling bonds, offers novel perspectives for direct interfacing with biological molecules. Combined with its exceptional electronic and optical properties, this promotes graphene as a unique platform for bioelectronics. Among the successful bio-integrations of graphene, the detection of action potentials in numerous electrogenic cells including neurons has paved the road for the high spatio-temporal and wide-field mapping of neuronal activity. Ultimate resolution of sensing ion channel activity can be achieved with neural interfaces, and it was shown that macroscale electrodes can record extracellular current of individual ion channels in model systems, by charging the quantum capacitance of large graphene monolayer (mm2). Here, we show the field effect detection of ion channel activity within neuron networks, cultured during several weeks above graphene transistor arrays. Dependences upon drugs, reference potential gating and device geometry confirm the field effect detection of individual ion channel and suggest a significant contribution of grain boundaries, which provide highly sensitive nanoscale-sized sensing sites. Our theoretical analysis and simulations demonstrate that the ion gating of a single grain boundary in liquid affects the electronic transmission of the whole transistor channel, resulting in significant conductance variations. Monitoring the ion channels activity is of great interest as most of neurodegenerative diseases relied on channelopathies, which rely on ion channel abnormal activity. Thus, such highly sensitive and biocompatible neuro-electronics which open the way to FET detection at the sub-cell precision should be useful for a wide range of fundamental and applied research areas, including brain-on-chip, pharmacology, and in vivo monitoring or diagnosis.

High Chromium Steel Modification by the Intense Discrete Electron Beam: Structure and Properties

The Fe-Cr-C system thermodynamic analysis has been made. It has been demonstrated that the Fe-Cr alloys carbon alloy addition results in the significant structural-phase state change in them and exerts determinant influence on the M23С6, M7С3, M3С2and M3С carbides existence domain by the α-and γ-phases. The temperature field numerical calculations, forming in the steel superficial layer in the case of the electron beam irradiation, have been carried out. It has been demonstrated that the peak temperature, being achieved on the sample surface towards the end of the impulse effect, is below steel melting temperature at electrons beam energy density 10 J/cm2regardless of the electrons beam pulse duration (50-200 ms). The peak temperature on the irradiation surface is equal to the steel boiling temperature at electrons beam energy density (20-30) J/cm2and at pulse duration 50 μs. The peak temperature on the irradiation surface achieves and increases the steel melting temperature at pulse duration 200 μs. The AISI 321 and AISI 420 steel surface irradiation has been carried out by the intense pulse electron beam. The studies have been made and the nanostructured polyphaser superficial layers formation laws analysis have been done. It has been established that the steel electronic-beam treatment is accompanied by the М23С6((Cr, Fe,)23C6) composition initial carbide phase particles solution, by the carbon and chromium atoms superficial layer crystal lattice saturation, by the submicron sizes and dendritic crystallization cells formation, by the titanium carbide and chromium carbide nanosized particles abstraction. The mechanical and tribological tests of the AISI 321 and AISI 420 steel samples, irradiated by the intense pulse electron beam, have been done. It has been detected that the superficial layer hardness increases in 1.5 times and the superficial layer wear resistance increases in 1.5 times. The friction coefficient decreases in 1.6 times. The microhardness increases in 1.5 times. The wear resistance increases in 3.2 times. The friction coefficient reduces in 2.3 times

Disclination ensembles in graphene

We consider graphene disclination networks (DNs) — periodic distributions of disclination defects. Disclinations manifest themselves as 4-, 5-, 7- or 8-member carbon rings in otherwise 6-member ring ideal 2D graphene crystal lattice. Limiting cases of graphene-like 2D carbon lattices without 6-member motives, i.e., pseudographenes, are also studied. The geometry and energy of disclinated 2D carbon configurations are analyzed with the help of molecular dynamics (MD) simulation technique. A comparison of the obtained MD results with analytical calculations within the framework of the theory of defects of elastic continuum is presented.

Cobalt/Carbon Nanocomposite as Oxygen Evolution Reaction Electrocatalyst

AbstractElectrocatalysts based on cobalt are promising catalytic materials for water electrolysis. In this work, We reported a catalyst composed of cobalt nanoparticles embeded in a carbon lattice through synthesis with a cationic polymer (PEI) and carbonization process at three temperatures (800, 900 and 1000 °C). The material obtained at 1000 °C showed the highest activity towards the oxygen evolution reaction (OER) in an alkaline medium (1 M KOH). Moreover, the OER overpotential required to reach 10 mA cm−2 of 296 mV, was lower than for the commercial RuO2 catalyst. Further, the material also exhibited very good stability in a long‐term stability test at 10 mA cm−2.

Facile synthesis of boron-doped porous carbon as anode for lithium–ion batteries with excellent electrochemical performance

A novel boron-doped porous carbon (BC) was prepared through a facile one step pyrolysis process by using citric acid monohydrate, boron acid, and sodium chloride hybrid as precursor. Based on the analysis of X-ray photoemission spectroscopy and Raman spectroscopy, three boron-doping species (BC3, BC2O, and BCO2) were doped in the carbon lattice. The BC2O and BCO2 can generate abundant extrinsic defects and active sites in the carbon matrix. The electron-deficient boron atom in BC3 improves the electric conductivity by adding more positive charged holes. As anode for lithium–ion batteries, the BC exhibits a stable reversible capacity above 600 mAh g−1 after 800 cycles under a current density of 1 A g−1 and preferable rate performance. Hence, this work provides a facile and effective strategy to fabricate a promising anode material for the high-performance lithium–ion batteries.

A Heterogeneous Metal‐Free Catalyst for Hydrogenation: Lewis Acid–Base Pairs Integrated into a Carbon Lattice

A Heterogeneous Metal‐Free Catalyst for Hydrogenation: Lewis Acid–Base Pairs Integrated into a Carbon Lattice

A Heterogeneous Metal-Free Catalyst for Hydrogenation: Lewis Acid-Base Pairs Integrated into a Carbon Lattice.

Designing heterogeneous metal-free catalysts for hydrogenation is a long-standing challenge in catalysis. Nanodiamond-based carbon materials were prepared that are surface-doped with electron-rich nitrogen and electron-deficient boron. The two heteroatoms are directly bonded to each other to form unquenched Lewis pairs with infinite π-electron donation from the surrounding graphitic structure. Remarkably, these Lewis pairs can split H2 to form H+ /H- pairs, which subsequently serve as the active species for hydrogenation of different substrates. This unprecedented finding sheds light on the uptake of H2 across carbon-based materials and suggests that dual Lewis acidity-basicity on the carbon surface may be used to heterogeneously activate a variety of small molecules.

Graphitization of diamond by laser-accelerated proton beams

In this work, we investigate the interaction between fast energetic proton beams generated by laser-plasma based accelerators with carbon lattices of graphite and diamond. Theoretical and experimental results indicate that these proton beams cause both, a low sputtering of carbon atoms from lattices (estimated to be in the order of 3 × 10−8 displacements per atom for each single shot), and a heating (inside the target and within a depth of about 10 μm below the surface) at a temperature close to the sp3/sp2 transition. The defects generated inside the lattices by the atom displacements cause the random formation of amorphous carbon islands, while the higher temperature causes the start of diamond partial graphitization. All the results suggest the impossibility to use diamond as detector in laser-driven accelerators when placed close to the source, while they confirm that proton beams can be used as alternative to classical laser or ion beam methods to graphitize diamond in specific optoelectronic applications.

Designing Boron Nitride Islands in Carbon Materials for Efficient Electrochemical Synthesis of Hydrogen Peroxide.

Heteroatom-doped carbons have drawn increasing research interest as catalysts for various electrochemical reactions due to their unique electronic and surface structures. In particular, co-doping of carbon with boron and nitrogen has been shown to provide significant catalytic activity for oxygen reduction reaction (ORR). However, limited experimental work has been done to systematically study these materials, and much remains to be understood about the nature of the active site(s), particularly with regards to the factors underlying the activity enhancements of these boron-carbon-nitrogen (BCN) materials. Herein, we prepare several BCN materials experimentally with a facile and controlled synthesis method, and systematically study their electrochemical performance. We demonstrate the existence of h-BN domains embedded in the graphitic structures of these materials using X-ray spectroscopy. These synthesized structures yield higher activity and selectivity toward the 2e- ORR to H2O2 than structures with individual B or N doping. We further employ density functional theory calculations to understand the role of a variety of h-BN domains within the carbon lattice for the ORR and find that the interface between h-BN domains and graphene exhibits unique catalytic behavior that can preferentially drive the production of H2O2. To the best of our knowledge, this is the first example of h-BN domains in carbon identified as a novel system for the electrochemical production of H2O2.

Strength loss of carbon nanotube fibers explained in a three-level hierarchical model

Although the tensile strength of carbon nanotubes inherited from the sp2 hexagonal carbon lattice is as high as 120 GPa, the state-of-the-art mechanical resistance of carbon nanotube fibers is below 10 GPa. Material imperfections embedded in the complex microstructures are responsible for this remarkable reduction across multiple length scales. In this study, we rationalize this multi-scale degradation of mechanical performance through theoretical analysis of the processing-microstructure-performance relationship for carbon nanotube fibers based on the experiment data, offering a simplified model that not only quantifies the breakdown of material strength at the nanotube, bundle, and fiber levels, respectively, but also provides practical advices to optimize the manufacturing processes for elevated mechanical performance.

Biotransformation and Biological Interaction of Graphene and Graphene Oxide during Simulated Oral Ingestion.

The biotransformation and biological impact of few layer graphene (FLG) and graphene oxide (GO) are studied, following ingestion as exposure route. An in vitro digestion assay based on a standardized operating procedure (SOP) is exploited. The assay simulates the human ingestion of nanomaterials during their dynamic passage through the different environments of the gastrointestinal tract (salivary, gastric, intestinal). Physical-chemical changes of FLG and GO during digestion are assessed by Raman spectroscopy. Moreover, the effect of chronic exposure to digested nanomaterials on integrity and functionality of an in vitro model of intestinal barrier is also determined according to a second SOP. These results show a modulation of the aggregation state of FLG and GO nanoflakes after experiencing the complex environments of the different digestive compartments. In particular, chemical doping effects are observed due to FLG and GO interaction with digestive juice components. No structural changes/degradation of the nanomaterials are detected, suggesting that they are biopersistent when administered by oral route. Chronic exposure to digested graphene does not affect intestinal barrier integrity and is not associated with inflammation and cytotoxicity, though possible long-term adverse effects cannot be ruled out.

N-doped carbon quantum dots as fluorescent probes for highly selective and sensitive detection of Fe3+ ions

To investigate the effect of nitrogen on the photoluminescence properties of carbon quantum dots (CQDs), N-doped carbon quantum dots (N-CQDs) were synthesized by one-step hydrothermal treatment using biomass tar as the carbon precursor. As an inevitable organic pollutant, the unsaturated bonds in biomass tar, such as carboxylic acids, aldehydes, and aromatics, are favorable for formation of the graphitic carbon lattice. The obtained N-CQDs are spherical with an average particle size of 2.64nm and the crystal lattice spacing is 0.25nm, corresponding to the (100) facet of graphitic carbon. The N-CQDs emit bright blue photoluminescence under 365nm ultraviolet light, and they have excellent water solubility and stability with a high quantum yield of 26.1%. Coordination between the functional groups on the N-CQD surface and Fe3+ ions is promoted because of the improved electronic properties and surface chemical reactivity caused by N atoms, leading to a significant fluorescence quenching effect of the N-CQDs in the presence of Fe3+ ions with high selectivity and sensitivity. There is a linear relationship between ln (F0/F) and the Fe3+ concentration in the N-CQD concentration range 0.06–1400μmol/L with a detection limit of 60nmol/L, showing that the N-CQDs have great potential as a fluorescent probe for Fe3+ detection.

Structural origins of mechanical strengthening in poly(phenylene sulfide)/multiwalled carbon nanotube nanocomposites obtained via hot‐stretching

This study demonstrates that solid‐state hot‐stretching is an efficacious pathway via which to achieve interfacial enhancement between poly(p‐phenylene sulfide) (PPS) and multiwalled carbon nanotubes (MWCNTs). Samples of PPS/MWCNT composite were fabricated via a two‐fold procedure involving compression molding followed by hot‐stretching, and significant mechanical reinforcement was realized in the prepared nanocomposites. The interfacial shear strength obtained under 200% stretching strain was about eight times of that obtained in the unstretched (isotropic) counterpart. Large stretching strains, such as 200%, even could induce epitaxial crystallization of PPS lamellae on the surface of MWCNT monofilaments. Moreover, strong π–π interactions between the benzene rings on the backbones of PPS and the sp2 carbon lattice surface of MWCNTs appeared for highly oriented PPS chains and MWCNT monofilaments. A comprehensive structural analysis suggested that in addition to the orientation of both the PPS crystals and MWCNTs, the change in PPS crystallinity and the confinement effect of the amorphous PPS chains, strong π–π interactions and epitaxial crystallization induced via hot‐stretching orientation are mainly responsible for the prominent mechanical reinforcement observed. POLYM. COMPOS., 40:E589–E598, 2019. © 2018 Society of Plastics Engineers

Graphene Microelectrode Arrays for Electrical and Optical Measurements of Human Stem Cell-Derived Cardiomyocytes.

Cell-cell communication plays a pivotal role in biological systems' coordination and function. Electrical properties have been linked to specification and differentiation of stem cells into targeted progeny, such as neurons and cardiomyocytes. Currently, there is a critical need in developing new ways to complement fluorescent indicators, such as Ca2+-sensitive dyes, for direct electrophysiological measurements of cells and tissue. Here, we report a unique transparent and biocompatible graphene-based electrical platform that enables electrical and optical investigation of human embryonic stem cell-derived cardiomyocytes' (hESC-CMs) intracellular processes and intercellular communication. Graphene, a honeycomb sp2 hybridized two-dimensional carbon lattice, was synthesized using low pressure chemical vapor deposition system, and was tested for biocompatibility. Au and graphene microelectrode arrays (MEAs) were fabricated using well-established microfabrication methods. Au and graphene MEAs were interfaced with hESC-CMs to perform both optical and electrical recordings. Optical imaging and Raman spectroscopy confirmed the presence of monolayer graphene. Viability assay showed biocompatibility of graphene. Electrochemical characterization proved graphene's functional activity. Nitric acid treatment further enhanced the electrochemical properties of graphene. Graphene electrodes' transparency enabled both optical and electrical recordings from hESC-CMs. Graphene MEA detected changes in beating frequency and field potential duration upon β-adrenergic receptor agonist treatment. The transparent graphene platform enables the investigation of both intracellular and intercellular communication processes and will create new avenues for bidirectional communication (sensing and stimulation) with electrically active tissues and will set the ground for investigations reported diseases such as Alzheimer, Parkinson's disease and arrhythmias.

(Invited) Transparent Bioelectronics for Electrical and Optical Measurements of Embryonic Stem Cell Derived Cardiomyocytes

Understanding cellular electrical communication is of growing interest in stem cell biology. Electrical properties have been linked to specification and differentiation of stem cells into targeted progeny such as neurons and cardiomyocytes. Basic research at the tissue level of the heart and brain electrical activity has led to the development of tools to treat various ailments, such as pacemaker and deep brain stimulation electrodes for the treatment of cardiac arrhythmias and Parkinson’s disease respectively. Currently, there is a critical need and tremendous interest in developing new ways to complement fluorescent indicators such as voltage and Ca2+-sensitive dyes, for direct electrophysiological measurements of cells and tissue. Graphene, a honeycomb sp2 hybridized two-dimensional (2D) carbon lattice is a promising bioelectronic building block due to its outstanding electrical conductivity (charge carrier mobility up-to 200,000 cm2 V-1 s-1), mechanical flexibility, and optical properties (optical transmittance of ~97.7%). Here we report a unique transparent graphene-based electrical platform that enables concurrent electrical and optical investigation of ES-derived cardiomyocytes’ intracellular processes and intercellular communication. The graphene-based bioelectronics platform is also shown to be biocompatible in terms of adhesion, viability and cell stress. Our presented approach will greatly impact our basic understanding of signal transduction in complex cellular assemblies, and create new avenues for bidirectional communication (sensing and stimulation) with electrically active tissues. The developed nanomaterials-based measurement platform will set the ground for further investigations of the relationship between electrical signals and reported diseases such as Alzheimer, Parkinson’s disease and Arrhythmias.

Nanowire-Templated Three-Dimensional Out-of-Plane Fuzzy Graphene as an Oxygen Reduction Reaction Catalyst

Rate-limiting oxygen reduction reactions (ORR) and high-cost platinum at fuel cell cathodes are substantial barriers to commercial fuel cell viability. Carbon-based, metal-free ORR catalysts have high catalytic stability and can potentially dramatically reduce cost and increase efficiency of fuel cells. For increased ORR efficiency, nitrogen doping of graphene sp2-hybridized carbon lattice is utilized, to induce a net positive charge on adjacent C atoms to alter the O2 chemisorption mode and attract electrons from the ­electrode. We have recently reported synthesis of a novel graphene-based hybrid-nanomaterial composed of three-dimensional (3D) out-of-plane fuzzy graphene (3DFG) on 3D Si nanowire mesh template (NT-3DFG). Leveraging graphene’s outstanding surface-to-volume ratio and electrical conductivity, we attained exceptional electrochemically active surface area of ca. 1017 m2 g-1 (with high density of exposed, active graphene edges) and electrical conductivity of ca. 2400 S m-1. Here we report fine control over 3DFG flake size and edge density by varying the partial pressure of CH4 precursor as well as the plasma enhanced chemical vapor deposition (PECVD) process time and temperature (Figure 1.A-B). XPS analysis of C1s confirms the presence of graphite via the sp2 hybridized C bonds in 3DFG structures (Figure 1.C.I and III). We also show both in-situ and post synthesis N-doping of NT-3DFG through either incorporation of N2 during the PECVD process or post-synthesis N2-plasma treatment. XPS analysis of N1s confirms the presence of pyridinic-, pyrrolic-, and graphitic-N doping in the NT-3DFG structure (Figure 1.C.II and IV). In-situ N-doping of NT-3DFG resulted in ca. 87% pyridinic-N doping compared to ca. 52% through post-synthesis N2-plasma treatment. This pyridinic-N stabilizes the active site responsible for the chemical disproportionation of peroxide ions during ORR. Through cyclic voltammetry under acidic conditions, we demonstrate the functionality and properties of N-doped NT-3DFG as an ORR catalyst. With pyridinic-N doping and a high density of graphene edges, N-doped NT-3DFG demonstrates greater ORR efficiency than existing graphene-based hybrid nanomaterials. Figure 1. Characterization of N-doped NT3DFG. (A) SEM image of NT-3DFG synthesized with increasing partial pressure of CH4 and increasing PECVD process time. (B) Effect of increasing PECVD process temperature on NT-3DFG synthesized under 25 mTorr partial pressure of CH4 for 10 min. (C) X-ray photoelectron (XPS) spectra of (I) C1s and (II) N1s of in-situ N-doped NT-3DFG synthesized under 25 mTorr partial pressure of CH4 and 400 mTorr partial pressure of N2 for 30 min at 800˚C; and (III) C1s and (IV) N1s of NT-3DFG synthesized under 25 mTorr partial pressure of CH4 for 30 min at 800˚C doped with N post-synthesis under 300 mTorr partial pressure of N2 for 5 min at 300˚C. Cyan, purple, pink, red, green and blue represent C sp2, C sp3, C=O, Pyridinic N, Pyrrolic N and Graphitic N XPS spectra, respectively. Figure 1

(Invited) Graphitic Intercalation Compounds: A Versatile Nano-Template for the Synthesis of Multi-Functional Electrocatalysts

Bifunctional catalysts, which can perform both oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) at low overpotentials with high turnover efficiency (TON) and frequency (TOF), are highly sought after. Platinum group metals are among the best catalysts for both OER and ORR but their scarcity and high cost calls for alternatives. In this context non-precious transition metal and metal oxide are promising options despite their lower intrinsic catalytic activity and chemical stability.1 Carbon nano materials are promising materials for electro catalytic application thanks to their high surface areas, electrical conductivity and stability in acidic or basic aqueous solutions.2 Graphite can be intercalated by potassium forming a graphite intercalation compound (GIC) of defined stages. GICs can be readily exfoliated to monolayer graphene in organic solvents solely by stirring. These graphenide solutions are composed of charged graphene layers and are thermodynamically stable.3,4 In analogy to large flake size graphite, graphitic nano carbons with lateral sizes bellow 50 nm can also be intercalated successfully and can be dissolved in absolute organic solvents. Graphenide solutions have been used in a variety of different applications e.g. to generate transparent conductive films, quantum dots, and surfactant-free graphene in water.5 Additionally, their reducing character has been used to graft functional moieties covalently to the carbon framework.6 In this talk, the exploitation of the reduction potential of graphenide solutions for earth abundant metal nanoparticle generation will be discussed. The advantages of using graphenides as reduction reagent in nanoparticle synthesis are : i) graphenide solutions are strong reducing agents and no additional reducing agent is needed, ii) the redox reaction takes place in close proximity of the carbon lattice and the decoration of the carbon framework thus proceeds efficiently, iii) the amount of reduction agent can be controlled by the concentration of the respective graphenide solution used, iv) the by-product of the reaction is only the respective potassium salt, which can be removed easily. The resulting composite materials are interesting and promising earth abundant electrocatalysts, due to their structure, small size, morphology and conductive framework. These nanocarbon / metal nanoparticle composite materials exhibit high bifunctional electro catalytic activity towards ORR and OER as well as long term stability.7 Xia, W., et al., (2016) Angew. Chem. Int. Ed. 55, (8) 2650-2676.Mazzaro, R., et al., (2015) ChemistryOpen 4, (3), 268-273.Pénicaud, A., et al.,. (2013). Acc. Chem. Res. 46, (1), 129–137.Vallés, C., et al.. (2008) J. Am. Chem. Soc. 130, 15802–15804.Bepete, G., et al., (2016) Nat. Chem. 9, 347–352.Hof, F., et al., (2014) Chem. - A Eur. J. 20, 16644–16651.Hof, F., et al., (2017) Chem. - A Eur. J. 23, 15283–15288.

Morphology of MWCNT in dependence on N-doping, synthesized using a sublimation-based CVD method at 750 °C

The investigation of the morphology of N-doped multi-walled carbon nanotubes (N-MWCNT) is still a crucial issue. Considering different nitrogen precursors we synthesized N-MWCNT at 750 °C using a sublimation-based chemical vapor deposition (SCVD) method. Compared to undoped multi-walled carbon nanotubes (MWCNT), nitrogen incorporation into the carbon lattice leads to a straighter CNT morphology in which the catalyst particles are mostly consist of iron carbide and not of metallic iron. An important finding is that not only the presence and concentration of nitrogen and the formation of iron carbide have a strong influence on the CNT straightness, but also the concentration of the sublimated catalyst precursor ferrocene in the gas phase. The lower its concentration the longer and larger the catalyst particle, resulting in a high CNT straightness.

Directed nucleation and growth by balancing local supersaturation and substrate/nucleus lattice mismatch

Controlling nucleation and growth is crucial in biological and artificial mineralization and self-assembly processes. The nucleation barrier is determined by the chemistry of the interfaces at which crystallization occurs and local supersaturation. Although chemically tailored substrates and lattice mismatches are routinely used to modify energy landscape at the substrate/nucleus interface and thereby steer heterogeneous nucleation, strategies to combine this with control over local supersaturations have remained virtually unexplored. Here we demonstrate simultaneous control over both parameters to direct the positioning and growth direction of mineralizing compounds on preselected polymorphic substrates. We exploit the polymorphic nature of calcium carbonate (CaCO3) to locally manipulate the carbonate concentration and lattice mismatch between the nucleus and substrate, such that barium carbonate (BaCO3) and strontium carbonate (SrCO3) nucleate only on specific CaCO3 polymorphs. Based on this approach we position different materials and shapes on predetermined CaCO3 polymorphs in sequential steps, and guide the growth direction using locally created supersaturations. These results shed light on nature's remarkable mineralization capabilities and outline fabrication strategies for advanced materials, such as ceramics, photonic structures, and semiconductors.