In Situ TEM Gas & Heating
The Climate Is Everyone’s Responsibility
And we’re looking to the scientific community for answers!
As global warming continues to increase towards the dangerous 2°C above pre-industrial level, the demand is now on the scientific community to bridge the gap between production and sustainability. It’s widely accepted that nanotechnology is needed to help solve the challenges facing human society today, including the energy crisis and environmental protection. The Paris Agreement in 2015 showed that we can as a global community reach a consensus on climate action. We as the scientific community need to turn this agreement into reality, and an understanding of the nano-world is required to assist in providing solutions to these global challenges. The Climate system enables the nano-world to be investigated in the real-world 1 bar pressure, gas and heating environment.
Climate Application Fields
Observe & Control chemical reactions at the nano-scale
The Climate In Situ TEM Gas & Heating System enables atomic resolution imaging of gas-solid interactions and sample dynamics in research areas such as catalysis, nanomaterials growth and corrosion studies. The Nano-Reactor is the ‘lab on chip’ MEMS based technology enabling the 1 Bar pressure & elevated temperature environment for in situ TEM. The Climate system converts high-vacuum (S)TEMs from a static imaging tool into a dynamic in situ chemical laboratory, enabling real-time observation and analysis of materials!
The 8 in 1 solution
The Climate system brings an ‘integrated’ approach to TEM characterisation of catalysts. Previously only possible with a number of separate techniques, Climate in conjunction with the TEM combines the following 6 separate techniques into one seamless platform.
- 1. Size
- 2. Shape
- 3. Crystal structure
- 4. Atomic Structure
- 5. Chemical Bonding
- 6. Calorimetry
- 7. Gas Analysis
- 8. Chemistry
Real-time imaging of catalyst activity
Experiment: Ni exposed to 500 mBar He:H2:O2 at 730 °C In this in situ TEM video using the Climate system, a heterogeneous catalyst, Ni oxide, was first reduced before a gas flow of Helium + Hydrogen + Oxygen was introduced to the Nano-Reactor at 730 °C. This video clearly shows certain regions of active particles and others that are inactive. This highlights which catalyst particles really contribute to the reaction, thus, enabling a way to investigate, understand and improve the activity on the single particle level. Interestingly, seen in the top right of this video, one particle shows very unusual shape dynamics for a metal catalyst and provides insight into catalytic reaction mechanics and performance. Click the next tab to view the shape dynamics of this particle at higher resolution.
Metal catalyst dynamics revealed by In Situ TEM
Experiment: Ni exposed to 500 mBar He:H2:O2 at 730 °C This in situ TEM video clearly visualises the structure dynamics of the Ni catalyst particle oscillating through three stages of the catalytic reaction process – (1) activation, (2) the working state under reaction conditions and (3) recovery from the working state to its initial state. The drastic morphological change suggests that the cycle variation may not only be limited to the surface structure, however, takes place throughout the entire particle. Although little modelling has been identified which support such dynamics in metal catalysts, it highlights that using in situ TEM techniques for catalyst research can reveal unexpected and exciting scientific phenomenon.
Single particle electron diffraction
Experiment: Ni exposed to 500 mBar He:H2:O2 at 730 °C The investigation and understanding of catalyst mechanics requires observation of the crystal structure evolution. Commonly, the in situ X-Ray Diffraction based on a synchrotron source is used for obtaining such information, however, averages the information over a large amount of particles. In situ TEM selected area electron diffraction (SAED) opens a door to closely investigate the dynamic crystalline evolution of a single particle and can be carried out on every TEM.
Experiment data from Dr. Marc Willinger & Dr. Ramzi Farra, Fritz-Haber-Institute fur der Max-Planck-Gesellschaft, Germany.
Atomic resolution surface dynamics
Experiment: Cu exposed to 500 mBar H2:N2:O2 at 350 °C This in situ movie was recorded showing the real-time structure dynamics of Cu nanoparticles in a reaction environment at atomic resolution. The images indicate that the surface with a certain orientation shows oscillatory behaviour while other surfaces are not active. With this knowledge, the design and synthesis of catalysts can be optimised to achieve higher reactive productivity.
Experiment data from Dr. Marc Willinger & Dr. Ramzi Farra, Fritz-Haber-Institute fur der Max-Planck-Gesellschaft, Germany & Dr. Qiang Xu, DENSsolutions, The Netherlands.
Measuring chemical bonding evolution using EELS
Experiment: CuO exposed to 500 mBar H2:N2:O2 at 350 °C The chemical bonding evolution of catalysts in the real-working environment is challenging to obtain. Commonly, only the averaged bonding state of an amount of particles is possible to be acquired using in situ XPS on few sites with synchrotron sources. In situ TEM-EELS makes the similar study available for every FEG TEM and even the chemical state of a single particle can be monitored. HRTEM images (below left) were taken at 300 °C with a resolution better than 1 Å (see FFT – below right) after the sample was reduced from CuO in 1 bar pressure of H2 + 4N2. EELS measurements were taken at 50 °C increments, showing that the reduction of CuO to metallic Cu is achieved at 250 °C.
Experiment data from Dr. Qiang Xu, DENSsolutions, The Netherlands.
Calorimetric analysis of CuO particle dynamics
Experiment: CuO exposed to 110 mBar MeOH at 500 °C The amount of heat absorbed or dissipated by the specimen during endo- or exo-thermic reactions can be determined with the highest accuracy using the Climate Nano-Reactor’s 4-point-probe micro-heater. A catalytic process usually contains several steps of reactions that generate or consume heat. Using constant temperature mode, the heat exchange within the Nano-Reactor can be measured for small but perceptible changes in the input power of the micro-heater. This exothermic behaviour was observed in the CuO redox experiment shown below where in situ TEM was used to observed the continuous phase transformations between Cu and Cu2O. The temperature set at 500 °C between 13:02 and 15:33 showed the reaction conditions as steady. As shown on the data sets below before 15:33, the temperature was oscillating around its mean value but power consumption was stable. However, just before 15:40 (shown below) no more oscillation of the temperature was observed and the power consumption of the Nano-Reactor suddenly decreases. Thereafter, the power signal shows irregular fluctuations with a decreasing trend over time. Although this phenomenon is not fully understood, it’s clear that there are exothermic reactions happening with no indication of change in relevant other parameters that would impact the power consumption of the heating spiral. Experiment data from Dr. Marc Willinger & Dr. Ramzi Farra, Fritz-Haber-Institute fur der Max-Planck-Gesellschaft, Germany.
In situ Gas Analyzer
DENSsolutions introduces a new Gas Analyzer specifically designed to work seamlessly with the Climate in situ Gas&Heating solution. By enabling analysis of reaction products, it transforms the Climate into the only platform in the market able to combine TEM-based data with information about the kinetics of the reaction under examination.
Climate EDS compatible nano-reactor
The smallest known chemical reactor
Based on MEMS technology, the Nano-Reactor is a functional sample carrier that enables the controlled and clean reactive environment for imaging chemical reactions at the nano-scale. Integrated into the Nano-Reactor is the 4-contact micro-heater and micro-sensor for locally controlling the temperature environment from RT to 1,000 °C. As a consumable, the Nano-Reactor ensures a clean experiment and keeps your research at the forefront of technology!
Modular Sample Holder
Removable tip & tubing for clean experiments
A clean environment is essential to in situ microscopy and the modularity of the Sample Holder allows for all components that come into contact with the reaction gases to be replaced or cleaned on-site by the user. This includes the gas tubing, metal tip & lid, O-rings and consumable Nano-Reactor. The holder meets the X-Rays safety requirements of all TEM manufacturers.
Gas Supply Systems
Precise and fast control of your gas experiment
The Gas Supply System is a game changer for TEM catalyst research that integrates all gas control functions into one smooth platform. Optimised for gas flow through the Nano-Reactor, the Gas Supply System Light (Climate G) controls the pressure and flow while the full Gas Supply System (Climate G+) adds dynamic mixing with precise control of gas composition at the sample. The Gas Supply Systems allow for imaging and analysis of catalyst particles reactions at the atomic scale.
Total control of your gas environment
Stratus provides direct digital control over all values, regulators and features of the Gas Supply System. With programmable workflows and automation settings, Stratus makes the operation of the Gas Supply System simple with detailed graphs displaying in real-time the pressure / flow rates vs time data. The choice of Direct Control or Advanced Flowsheet mode makes running basic or complex experiments simple with total control of the gas parameters in the Nano-Reactor.
Accurate analysis of reaction products
Designed to work flawlessly with the Climate Gas&Heating solution, the DENSsolutions Gas Analyzer enables accurate analysis of gasses produced during chemical reactions within the Nano-Reactor, even in very small amounts.
Static & flow modes
Frequently Asked Questions
Is the Climate compatible with EDS and EELS?
Yes, EELS has proven to produce very good spectra even at pressures as high as 1 Bar. The primary electron beam from a TEM will have minimal interaction with the Nano-Reactor windows or the small quantity of gas inside. Moreover, the newly introduced tip and Nanoreactor allow collection of high quality EDS spectra and maps at tilt angles up to 30 degrees (for S-TWIN lens)
What is the preparation time for a typical experiment?
Preparing the system to run an experiment would typically take less than 30 minutes:
- 5 minutes to load the sample on the Nano-Reactor (e.g. drop casting method and let the ethanol drop evaporate)
- 10 minutes to assemble the tip: placing the Nano-Reactor and closing off the lid
- 3 minutes to align the top chip membrane around the heater spiral on the bottom chip
- 10 minutes to do the electrical connection and leak test (pump down time taking most this time)
This time does not include sample preparation as this can vary from sample to sample.
What type of samples can be used inside the Climate Nano-Reactor?
The typical samples used are nanoparticles for catalyst research which can be drop cast using a small (<2 μL) pipette to deposit directly onto the electron transparent window. Nanowires and thin lamellas can be loaded onto the Nano-Reactor using tweezers and/or micro-manipulators. In general, any sample that is less than 6 um (viewing area, the area heated at maximum temperature is about 100 um) in diameter and less than 5 um in height can be loaded into the Nano-Reactor for TEM imaging.
What gases can be used in the Climate system?
The list of permitted gases is determined based on if that particular gas will interact with the materials used in the Nano-Reactor, Sample Holder and Gas Supply System. The materials in which the gas will be in contact with include:
- Silicon Nitride – Nano-Reactor’s window material
- Stainless Steel – Gas inlet lines, mass flow controllers, pressure gauges, control and mixing valves, pumps
- PEEK tubing – Fine tubing between Flow Control Unit and Sample Holder
- Fused Silica – Components in the Sample Holder
- Titanium – Sample Holder tip and lid
- Viton – Valve and controller seals in the Gas Supply System and O-rings sealing the Nano-Reactor
Any gases that can react with the above materials at room temperature (or at elevated temperatures for Silicon Nitride) should be avoided. If these gases are critical to your experiment, it is possible to dilute them to a safe level, however, this should be in consultation with DENSsolutions. Alternative materials for some components are possible, please contact DENSsolutions to discuss – e.g. Viton can be replaced by Kalrez. The mass flow controllers at the gas input lines of the Gas Supply System are calibrated for CxHy, O2, H2, N2, He, Ar, CO, CO2, Air. To know the exact gases that can be used, please refer to the chemical resistance sheet. For toxic gases the user will need to install additional safety features to monitor the concentration of that gas inside the lab room.
Is it necessary to use the Climate Gas-flow Supply System?
DENSsolutions strongly recommends the use of the Climate Gas Supply System that require gas mixing and/or flow. The Climate Gas Supply System has been built specifically for the Nano-Reactor, which ensure the utmost in safety and performance. The Climate G and G+ comes standard with a Gas Supply System. If only static gas experiments where a gas flow is not needed, the Climate AIR system allows the Climate to work in atmospheric conditions, enabling the study of corrosion under real conditions. In all the versions, manual valves ensure the holder can be moved and kept at desired conditions without being connected to the GSS. It is possible to connect your own gas supply system to the Climate Sample Holder, however, DENSsolutions cannot take responsibility for the safe operation of the Climate system.
How long would it take to replace the gas tubing?
Can I safely use the Climate holder in my TEM?
Yes. The Climate system workflow dictates that after assembly of the holder tip but before insertion into the TEM goniometer, the Climate holder is tested for vacuum leaks. Only after this test is passed successfully, the user can continue to the next step (TEM insertion). The Climate holder dimensions are designed within the specifications for the applicable Objective Lens pole piece as provided by the TEM manufacturer (Thermo Fisher Scientific or JEOL). As long as the holder is also used within the Z- and T-axis range as specified in the user manual there will be no danger of a collision between holder and pole piece.
Will the use of the Nano-Reactor have an impact on the analytical results?
The largest effect will be from the heater Nano-Chip, that will produce mainly Si peaks in the EDS or EELS spectrum, in particular when the electron beam is close to the edge of a transparent window (6 µm diameter). Acquiring a background spectrum by using the Nano-Reactor with gas but without a sample can help in highlighting the specific sample related results in your spectra and maps. In theory some scattering will occur on the electrons passing through the Nano-Reactor. Given the energy of the primary beam (usually 200 or 300 keV) and the low density of the gas and the window there will only be a minor effect.
What is the tilt range?
Currently, thanks to the newly designed tip and chips, it is possible to tilt up to ±30 degrees (for FEI/TF with an S-TWIN objective lens and +/- 25 degrees for JEOL with an WGP objective lens), depending on microscope setup.
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