Introducing Infinity: DENSsolutions’ pioneering 8-contact environmental in situ solution

by Lama Elboreini | Jul 27, 2024 | Climate, Interview, Stream

An interview with DENSsolutions’ Senior Mechanical Engineer about our latest innovation, Infinity – featuring an environmental holder with combined heating and biasing capabilities in both gas and liquid environments.

In this article, we delve into DENSsolutions’ cutting-edge Infinity solution through an exclusive interview with lead developer and Senior Mechanical Engineer, Christian Deen-van Rossum. Here, Christian takes us through the key features of this innovation, highlighting its benefits, diverse applications, and offering an inside look into the development journey of this advanced solution.

1) What are the main benefits of the Infinity solution for users?

“Climate Infinity and Stream Infinity bring forth numerous advantages for your in situ experiments:

1) Apply simultaneous heating and biasing stimuli: The new Climate/Stream Infinity holder features eight electrical contacts that enable simultaneous application of electrical and thermal stimuli in a gas or liquid environment. The contacts can be used for various electrically driven MEMS-based sensors and actuators, essentially transforming the Infinity system into a vast research playground. Importantly, for liquid studies, this opens the door to performing electrochemistry as a function of temperature.

2) Securely transfer your sample from one microscope to the other: The assembled tip of the Infinity holder containing a Nano-Reactor/Cell works as a cartridge, enabling complementary studies of the same sample using different TEM vendors, namely JEOL or Thermo Fisher Scientific (TFS). These microscopes can either be located in the same TEM lab, user facility or even in different universities/institutes. Remarkably, this removable tip also facilitates multi-modal characterization for SEM and beamline setups. Furthermore, the chips being used are universal, meaning that you can directly correlate experimental results obtained from JEOL and TFS microscopes, with improved Nano-Chip logistics.

3) Easily switch between STEM and TEM mode: By flipping the tip 180 degrees, you can directly change the sample position to be either on the top or bottom without a need to disassemble the tip. This grants you the freedom to flawlessly switch between STEM or TEM mode, respectively, depending on your experimental needs, while maintaining the best resolution performance. Importantly, you can switch between both imaging modes within a matter of seconds.

4) Perform gas and liquid studies with the same holder: The new environmental Infinity holder is your all-in-one solution for both gas and liquid experiments. Simply choose the appropriate function for the chips and connect the necessary gas or liquid supply system. Our extensive range of chip types includes gas-heating (GH), liquid-heating (LH), gas-heating-biasing (GHB), and liquid-heating-biasing (LHB), offering unparalleled versatility for your experimental needs. New MEMS chip designs will further expand the application space of the Infinity system.

5) Ease of use: We understand that a great product should be easy to use without a steep learning curve. Therefore, our design process focused on making sure the holder can be effortlessly utilized from the start. By prioritizing user-friendly design and continuously testing with real users, we ensured our product is not only powerful and effective but also simple and enjoyable to use. Because of this, the Infinity holder significantly reduces the time-to-experiment, allowing you to spend your time leveraging its capabilities to drive innovation and productivity. One highlight of the Infinity holder is the removal of all assembly tools and the introduction of self-aligning windows. When you place our chips in the tip of the holder, the membranes automatically align to provide a consistently clear field of view. Designed for a perfect fit, the Infinity holder ensures precise alignment without manual adjustments. This simplifies installation, reduces the risk of leaks, and allows you to focus more on your research and less on setup.

2) What inspired the development of Infinity, and what challenges did you encounter during the process?

“We wanted to bring a better, future-proof and more user-friendly holder to the market that truly meets the needs of our customers. For that reason we developed a holder from a customer-centric approach, driven by extensive customer input and thorough market research, rather than simply pushing the latest technology. We engaged with our customers to understand their challenges and desires and gathered invaluable feedback that helped shape every aspect of our product. By doing this we made sure that we were addressing real pain points and delivering solutions that would help improve the customer experience and reduce time to experiment. This customer-focused approach means that our product is not just a collection of the latest technological advancements, but a thoughtfully designed solution that reflects the actual needs and desires of our users.”

3) What are the main application fields that will benefit from Climate Infinity and Stream Infinity?

“The Infinity system can be used for broad applications ranging from materials science to energy and life science. In materials science, the Infinity system enables the study of nucleation, growth, assembly and corrosion under well-defined chemical environments (gas, vapor and liquid) and external stimuli (heating, biasing or both). The information obtained not only provides insights into the dynamic processes of material formation but also offers guidelines for the controllable synthesis of materials with improved performance. In energy studies, the Infinity system can mimic the real working conditions of various functional devices (such as batteries, supercapacitors, fuel cells, memristors, resistive random access memory, etc.). This allows the direct monitoring of the evolution and degradation of key materials, including rechargeable battery electrodes, thermo-, electro- and thermoelectro-catalysts and phase-change materials, at the nano- or even atomic scale. For life science, it is possible to image whole cells and resolve fine structures of biomaterials and proteins in their native state, and study various dynamics of biological samples in an environment close to a real organism. Moreover, the Infinity system provides a unique platform for correlative studies across different detection sources, such as electron, X-ray, neutron and visible light.”

4) Has Infinity already been installed?

“Yes, the system has been installed at numerous sites already, including EMAT (Antwerpen, Belgium), FAU Erlangen-Nurnberg (Erlangen, Germany) and UC Irvine (Irvine, USA).”

Dr. Mingjian Wu from FAU Erlangen-Nürnberg

From left to right: Dr. Alexander Zintler from EMAT and Christian Deen van Rossum from DENSsolutions

From left to right: Dr. Hongkui Zheng and Dr. Hongyu Sun from DENssolutions, as well as Pushp Raj Prasad, Prof. Joe Patterson, Zhaoxu Li and Elmira Baghdadi from UC Irvine

Dr. Mingjian Wu from FAU Erlangen-Nürnberg

From left to right: Dr. Alexander Zintler from EMAT and Christian Deen van Rossum from DENSsolutions

From left to right: Dr. Hongkui Zheng and Dr. Hongyu Sun from DENssolutions, as well as Pushp Raj Prasad, Prof. Joe Patterson, Zhaoxu Li and Elmira Baghdadi from UC Irvine

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In situ LPEM: Illuminating the electrochemical nanoscale dynamics of active materials

by Lama Elboreini | Jun 11, 2024 | Electrochemistry, Materials science, Stream

Using the DENSsolutions Stream system, researchers take a magnified look at the nanoscale processes governing electrochemical activity in active molecular materials.

Original article by Gibson et al.

Active materials’ ability to interact with their environment in dynamic ways makes them invaluable across numerous fields, enhancing the functionality, efficiency and sustainability of various products and technologies that we use daily. This includes bio-sensors, flexible electronics, water purification and solar cells. Indeed, a thorough comprehension of the behavior of active materials under electrochemical conditions is crucial for their development. While substantial efforts have been made to understand the self-assembly mechanisms of biologically active materials, there is currently a large knowledge gap on how synthetic active materials behave. Traditional microscopy techniques often fall short in capturing the real-time dynamics of materials immersed in liquid environments. This is where liquid phase electron microscopy (LPEM) comes into play, offering a powerful solution to bridge this gap.

In a recent study published in the renowned journal of ACS Nano, a team of researchers from the University of California (UC) Irvine and the University of Massachusetts Boston employed the DENSsolutions Stream system to investigate the dynamics of electrochemically driven active materials. Impressively, they were able to capture single fiber dynamics at subsecond temporal resolution, as well as larger transitory fiber foci structures with nanoscale resolution. This research, involving our dear user at UC Irvine, Prof. Dr. Joe Patterson, is a major step forward in using electrochemical liquid EM to understand the dissipative self-assembly processes that generate active materials – a research space that remains largely unexplored. Notably, our Stream system played a vital role in enabling the visualization of these intricate electrochemical processes, providing key insights into the relationship between chemical kinetics and material dynamics.

Hierarchical evolution of fiber dynamics

The nanoscale self-assembly processes observed in this study involve the electrochemical oxidation of a free cysteine thiol precursor (CSH) molecule to its disulfide gelator form (CSSC) using the ferricyanide/ferrocyanide redox couple as a electrochemical catalyst. For the experiments, Wyeth Gibson and his fellow collaborators utilized the Stream Nano-Cell’s working electrode as the anode, which provided the driving force for the oxidation of ferrocyanide to ferricyanide and the follow-up oxidation of CSH to CSSC.

After capturing the dynamics of individual fibers under electrochemical stimulation near the electrode, the researchers were then able to capture the micrometer-scale hierarchical evolution of fiber clusters. As shown in the movie below, the fiber foci experience a maximum growth at 87 s and disassembly at 167 s. Evidently, the overall growth and shrinking of the fiber foci seem to loosely correspond with application and removal of electrochemical stimulus.

Movie 1: LPEM movie depicting the fiber foci growth and disassembly

Capturing fiber foci modification

The next step for the researchers was to study the active material’s dynamics in response to further electrochemical stimulus. They applied a current to the structures and activated the electron beam, which was maintained at a constant throughout the experiment. As shown in Movie 2 below, for the first 100 seconds, the fiber foci remained stable. At 100 s, a self-assembly growth front moved from left to right, causing the structures to grow and increase in contrast. At 200 s, a second growth front emerged as the first front reached the electrode boundary, spreading outward from the electrode in all directions. Between 400 and 600 seconds, the structures began to break down, shrink and decrease in contrast across the viewing window.

Movie 2: LPEM movie depicting the electrochemically driven fiber foci modification

Movie 3: LPEM movie depicting the fiber foci modification

It is evident that the distance from the electrode affects the maximum structural density in a sequential manner. Notably, Dr. Gibson and his collaborators effectively demonstrate that the active material can be dynamically manipulated to form multiple growth fronts influenced by electrodes at different spatial locations.

Next, a regional segmentation analysis was performed in order to quantify the observed wave-like propagation of these self-assembly fronts. This is depicted in Movie 3, whereby the middle panel shows the segmented particles corresponding to the LPEM movie shown in the left panel. The graph in the video depicts the normalized change in segmented particle area over time for each region, with the segmented regions represented by blue (closest to the electrode), purple, red, and yellow (farthest from the electrode). It is evident that the distance from the electrode affects the maximum structural density in a sequential manner. Notably, Dr. Gibson and his collaborators effectively demonstrate that the active material can be dynamically manipulated to form multiple growth fronts influenced by electrodes at different spatial locations.

Movie 3: LPEM movie depicting the fiber foci modification

Integrating observations with simulations

To gain a clearer understanding and measure the structural transformation within the liquid cell, the researchers utilized structural dissimilarity (DSSIM) analysis on the electrochemical LPEM video. DSSIM analysis is a video processing technique that spatially and temporally quantifies structural changes occurring in a video. Importantly, by combining the LPEM data with kinetic simulations, they discovered that the formation of an active material can foster a local environment that boosts the pace of the self-assembly process, exhibiting an autocatalytic behavior.

Movie 4: DSSIM visualization and quantification of fiber foci dynamics

A pioneering electrochemistry study

Conclusively Prof. Dr. Joe Patterson and his fellow researchers performed a cutting-edge study, employing a combination of techniques including LPEM, electrochemical analysis, quantitative video analysis and kinetic simulations to explore a widely untapped research space – the self-assembly mechanisms in electrochemically fueled active materials. This innovative research highlights the crucial role of liquid electron microscopy in studying active materials, offering vital insights into the interplay between chemical kinetics and material behavior. We are certainly proud of the key role that our Stream system has played in bringing this research to fruition, and we look forward to the pioneering academic contributions that the Patterson Lab will continue to deliver.

“These were the most challenging liquid electron microscopy experiments I have ever performed, and the DENSsolutions Stream system was essential for getting them to work.”

Prof. Dr. Joe Patterson Professor | University of California Irvine

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Radboudumc expands its bio-research capabilities with newly installed DENSsolutions Stream system

by Lama Elboreini | Dec 5, 2023 | Interview, Stream

We are excited to announce that DENSsolutions has installed a Stream system at the renowned Radboud University Medical Center (Radboudumc) in Nijmegen, the Netherlands. In this article, we interview Luco Rutten, PhD Candidate at Radboudumc, to learn more about the institute’s electron microscopy center, the team’s research direction and the pivotal role our Stream system will play in advancing their bio-research initiatives.

What is the Radboudumc Electron Microscopy Center known for?

“The Radboudumc Electron Microscopy (EM) Center, established in 2019 under the leadership of Dr. Anat Akiva and Prof. Dr. Nico Sommerdijk, operates as part of the RTC Microscopy within Radboud University Medical Center in Nijmegen, The Netherlands. Specializing in cutting-edge imaging and analysis techniques, including cryo-correlative light electron microscopy (cryo-CLEM), the EM Center serves users from both academia and industry. Notably, the center is equipped with a recently installed 200 kV Thermo Fisher Scientific TALOS F200C-G2 transmission electron microscope, featuring a Falcon 4i Direct Electron Detector, segmented STEM detector and EDS detector.”

What type of applications are the EM Center’s users interested in using Stream for?

“Since the Electron Microscopy Center is part of the University Medical Center, we are especially interested in using Stream to study biological and biomimetic processes under relevant conditions. For instance, the aggregation of protein-calcium complex and the biomineralization of organic scaffolds such as collagen mimicking health and disease. By adding the dynamic information from liquid phase EM to our cryo-CLEM workflow, we can unravel the mechanisms at the nanoscale of life.”

What particular features of Stream stood out to you?

“With our aim to study biological processes, the ability of the Stream system to seamlessly approach physiological conditions is of great importance. Since life occurs at 37 °C, precise control over the temperature is critical. Moreover, with Stream we are able to control liquid flow, enabling us to work with concentrations very close to physiological conditions. Additionally, we often deal with hybrid systems composed of both organic and inorganic materials, which can limit the contrast. By controlling the bulging of the windows through adjusting the front and back pressure, we’re able to reduce the liquid thickness as much as possible.“

Could you tell us a bit more about the funding granted to acquire the systems?

“Prof. Dr. Nico Sommerdijk, the lead PI of the project titled ‘In Situ Imaging of Biological Materials with Nanoscale Resolution using Liquid Phase Electron Microscopy’, was awarded the NWO-groot grant of 1.5 million euros by the Dutch Scientific Organization to acquire state-of-the-art equipment for liquid phase electron microscopy to study biological processes. Part of this grant was used to acquire the Stream system. The aim of the program is to establish a globally unique facility dedicated to liquid phase electron microscopy on biological materials. The integration of the latest developments in software, hardware and sample preparation techniques will broaden the range of biological materials that can be investigated.”

In your experience so far, how have you found working with Stream?

“Operating the Stream system becomes quite routine after working with it a couple of times. The recent workshop organized by DENSsolutions for Stream users (see image below) provided a valuable opportunity to learn from experts like Dr. Hongyu Sun, DENSsolutions Senior App Scientist, and exchange experiences in working with the holder with other participants.“

From left to right: Dr. Hongyu Sun (DENSsolutions), Luco Rutten (Radboudumc), Yannick Rutsch (FZ Jülich) and Rebecka Rilemark (Chalmers University of Technology)

Luco Rutten
PhD Candidate | Electron Microscopy Center, Radboudumc

Luco Rutten received his Master’s degree in Chemistry and Chemical Engineering from the Eindhoven University of Technology. He is in his last year of his PhD at \Radboudumc under the supervision of Dr. Elena Macías-Sánchez and Prof. Dr. Nico Sommerdijk. As part of the Biomineralized Tissues group and the Electron Microscopy Center, he is using advanced electron microscopy to study bone mineralization mechanisms.

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DENSsolutions successfully installs both a Stream and Climate system at Cardiff University

by Lama Elboreini | Jun 14, 2023 | Climate, Interview, Stream

From left to right: Oliver Mchugh and Dr. Thomas Slater from Cardiff University, Dr. Lars van der Wal and Alex Rozene from DENSsolutions

We are excited to announce that DENSsolutions has installed both a Stream and Climate system at the renowned Cardiff University in Wales, the United Kingdom. In this article, we interview Dr. Thomas Slater, Lecturer at Cardiff University, to learn more about the Cardiff Catalysis Institute Electron Microscope Facility, the team’s research direction and the pivotal role our Stream and Climate systems will play in advancing their research initiatives.

Can you tell me about the Cardiff Catalysis Institute Electron Microscope Facility?

“The Cardiff Catalysis Institute Electron Microscope Facility (CCI-EMF) is based at Cardiff University, one of Britain’s leading research Universities. The CCI-EMF is a new, world-class electron microscopy facility located in the University’s Translational Research Hub on its Innovation Campus. It houses an array of state-of-the-art imaging and analytical instruments designed around the study of heterogeneous catalysts and nano materials. The mission of the facility is to provide researchers in academia and industry with cutting-edge microscopy equipment, creating a Welsh hub for electron microscopy expertise and skills development.

In October 2022, we installed a 200 kV Thermo Fisher Scientific Cold-FEG Spectra 200. This aberration-corrected scanning transmission electron microscope (AC-STEM) is the first of its type in Wales. It is optimised for the study and analysis of heterogeneous catalysts and nanoparticles and is fitted with the Super-X EDS detector, Panther STEM detection system for HAADF/BF and iDPC imaging, Gatan’s Continuum ER EELS and Quantum Detectors Merlin detector. The facility also hosts a JEM-2100 LaB₆ transmission electron microscope with a high-resolution Gatan digital camera and Oxford X-max EDS detector and a Tescan MAIA-3 field emission gun scanning electron microscope (FEG-SEM), which enables secondary electron (SE), in-beam SE, low-kV backscattered electron (BSE), in-beam BSE and scanning transmission electron microscopy (STEM) imaging capabilities.”

What type of applications are the users at CCI-EMF interested in using the Stream and Climate systems for?

“The Stream In Situ TEM Liquid + Biasing or Heating system will enable us to study liquid-phase reactions and follow the mechanisms of nanoparticle synthesis in solution. Nanoparticle growth and crystallization on the surface of metal oxide supports is of particular interest to us, along with catalyst stability in solution and the mechanisms of deactivation through leaching and particle migration.

The Climate In Situ TEM Gas + Heating system will allow the CCI researchers to conduct operando STEM, TEM and chemical imaging of heterogeneous catalysts under reaction conditions. We aim to develop an improved understanding of structure-activity relationships, oxidation and reduction processes, catalysts synthesis, catalyst stability and deactivation mechanisms. Crucially, we will be able to study changes in the structure and chemistry as a function of temperature, pressure and composition, improving our understanding of catalysed processes at or near real reaction conditions.”

What particular features of the DENSsolutions systems stood out to you?

“For us it was critical to have excellent thermal stability, a uniform heated zone and fast gas mixing at the cell to ensure reproducibility and correlation with our larger scale benchtop micro- reactors. Chemical compatibility with a wide range of reaction gases and catalyst materials was also important as we support a vast number of researchers across multiple research projects with very different experimental requirements.”

Could you tell us a bit more about the funding granted to acquire the systems?

“The system was purchased with European Regional Development Funding (ERDF) through the Welsh European Funding office (WEFO) and part-funded by The Wolfson Foundation. The funding enabled the CCI to establish its own EM facility through the purchase of advanced microscopes and equipment such as the DENSsolutions Stream and Climate systems. This capability enhances and strengthens the already outstanding catalyst research facilities of the CCI and our aim is to use this new capability to support the research needs of the University, our existing partners, local industry as well as develop new research strands.”

In your experience so far, how have you found working with Stream and Climate?

“The installation went very smoothly and was completed in a couple of weeks, including the 3 days of training. The hardware is robust, and the chip assembly relatively intuitive. We are able to have chips prepared, assembled, leak-checked and in the microscope within the space of a couple of hours which leaves the rest of the days free for experiments. The parameter control is made easy through the Impulse software workflow which guides you from start to finish. In fact, we were running experiments ourselves and generating data within a week of installation.”

Dr. Tom Slater
Lecturer | Electron Microscopy of Catalytic Materials, Cardiff University

Dr. Tom Slater received his Ph.D. in Nanoscience from the University of Manchester, where he also did postdoctoral work in the Henry Moseley X-ray Imaging Facility. He then joined the electron Physical Sciences Imaging Centre (ePSIC) as an electron microscopy scientist. He was appointed as a Lecturer in Electron Microscopy of Catalytic Materials at Cardiff University in 2022, where his research focuses on imaging of heterogeneous catalysts.

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Liquid flow control: Unlock untapped research capabilities within in situ LPEM

by Lama Elboreini | Nov 7, 2022 | Electrochemistry, LPTEM, Stream

Via the unique on-chip microfluidic channel of the DENSsolutions Stream system, researchers were able to create a highly controlled chemical environment for visualizing the nanoscale metallic electrodeposition of copper crystals.

Original article by Cheng et al.

Liquid phase transmission electron microscopy (LPTEM) enables the observation of time-resolved dynamics in liquid state at high spatial resolution. The technique has gained exponential popularity over the last decade, and has contributed greatly to a wide range of fields, including materials science, chemistry and life science. With LPEM, researchers can explore the dynamical evolution of key materials and uncover fundamental insights into nucleation and growth. Only in recent years have researchers been able to control the chemical environment within an in situ LPEM experiment, owing to the award-winning innovation that is the DENSsolutions Stream system. In a recent publication, researchers including Dr. Ningyan Cheng from Anhui University utilized the Stream system to visualize the metallic electrodeposition of copper crystals in a highly controlled chemical environment. This was made possible due to the unique on-chip flow channel of Stream, which enables numerous advantages such as the ability to flush away beam-induced species, explore flow-dependent liquid dynamics and easily change electrolyte composition.

On-chip microfluidic channel

The core of the DENSsolutions Stream system is our patented Nano-Cell, which consists of a top and bottom chip, together forming a sealed compartment that enables users to safely perform liquid experiments inside the TEM. The bottom chip contains spacers, an integrated liquid inlet, flow channel and an outlet. Via pressure-based pumps, a liquid sample can be driven from the inlet through the field of view and then through the outlet. This process is demonstrated in the video below. Importantly, users can independently control the pressure at the inlet and outlet of the Nano-Cell, and therefore the absolute pressure in the microfluidic channel. This then enables full control over the liquid flow rate within the cell.

Movie 1: Animation depicting the microfluidic channel of the Stream Nano-Cell

Efficient liquid flow

Before observing any liquid phenomena in the TEM, Dr. Cheng and her fellow collaborators first had to ensure that the flow was efficient and well-controlled. To do this, the researchers first assembled a dry Nano-Cell. The flow was then initiated by turning on the pressure-based pump, while keeping all imaging parameters constant. After 30 seconds, the imaging contrast changed abruptly, implying that the liquid had definitely flowed into the Nano-Cell. This process is shown in the video below. The time taken to completely fill the Nano-Cell ranges anywhere from tens of seconds to just 3 minutes when a flow rate of 8 μl/min is applied.

Movie 2: In situ TEM movie showing the liquid flow into the Nano-Cell in just 30 seconds

Removal of beam-induced species

A key benefit of controlling the liquid flow within an LPEM experiment is the ability to remove beam-induced particles. The researchers first generated particles by increasing the electron flux on purpose through changing the spot size from 5 to 1. The process of removing the beam-induced species in this experiment is detailed in the video below, with the direction of the flow going from top to bottom. As soon as the flow was cut off at 6.4s, the particles started to form and grow on the membrane. The flow was then switched on again at 11.7 seconds, which is when the particles that were stuck to the membrane started to peel off and move from the top to the bottom area in the field of view. It took just 2 minutes to fully flush away the particles, which is a reproducible process. The direction of the particles’ movement is the same as the direction of the flow (top to bottom), confirming the effectiveness and power of the liquid flow control.

Movie 3: Removal of beam-induced species via liquid flow control

Capturing flow-dependent liquid dynamics

The next step for the researchers was to explore the effect of the flow rate on the electrochemical copper crystallization and dissolution processes in real time. They first observed the effect of using a higher flow rate of 1.4 μl/min on the Cu deposition and dissolution processes, which showed to be reversible. The protocol included the initial electrode cleaning, deposition (−0.9 V, 10 s), dissolution (+0.4 V, 15 s) and repeating the process for 4 cycles. As demonstrated in the video below, the researchers found that uniform copper deposition can be obtained at a higher liquid flow rate (~1.4 μl/min), whereas at a lower liquid flow rate (0.1 μl/min), the growth of copper dendrites was observed.

Movie 4: Copper electrodeposition at a flow rate of 1.4 μl/min (left) and 0.1 μl/min (right)

Changing electrolyte composition

Besides exploring the effects of altering the flow rate, a major point of interest in this study was observing the effect of adding foreign ions, such as phosphates, on the electrodeposition. Such additives can affect the electrochemically deposited crystals by, for example, changing the nuclei structures. The researchers first studied the electrodeposition of copper from a pure CuSO₄ aqueous solution. In this case, no obvious dendritic morphology was observed and instead only granules were formed (see below Figure 1, Left).

After the experiment, the electrolyte in the sample source was replaced by a mixture of CuSO₄ and KH₂PO₄ solution. The liquid was kept flowing with a flow rate of 3 μl/min for 15 min, which enabled the researchers to directly study the electrolyte effect on the depositions in the same liquid cell by excluding all the uncertainties during different cell assembly. Contrastingly in this case, copper dendrites were observed to grow and the addition of H₂PO₄− ions in the electrolyte led to the formation of Cu-phosphate complexes (see Figure 1, Right). These results further confirm the importance of being able to modulate the electrolyte composition, and demonstrate the effectiveness of the environment control that Stream enables.

Figure 1: The effect of phosphate addition on Cu electrodeposition

Exploiting electrode design to alter the chemical environment

When studying Cu electrodeposition in the previous experiment, the researchers saw that dendrite formation can be further promoted by the in situ addition of foreign ions, such as phosphates. In order to confirm the generality of this technique, they also took a look at Zn electrodeposition in an aqueous solution of ZnSO₄. The figure below shows the total growth of the zinc layer at b) a lower potential of −0.9 V (versus Pt) in the first 10 seconds, and c) a higher potential of −1.1 V (versus Pt) in the next 10 seconds. In d) the total growth of the Zn depositions in the first 20 seconds is shown. The researchers observed in the first 10 seconds (−0.9 V) that the deposition on the inner edge is rougher compared to the outer edge. In the following growth at −1.1 V, dendritic depositions are nucleated and grown on the previous outer edge, while no further growth can be observed in the inner edge. This experiment demonstrates that the special electrode design of Stream enables the exploration of rich liquid dynamics within different chemical environments.

Figure 2: Zinc electrodeposition in b) the first 10 seconds with a potential of −0.9 V and c) in the next 10 seconds with a potential of −1.1 V. d) shows the total Zn growth in the 20 seconds.

Conclusion

Through this study, it is shown that Stream’s distinctive ability to enable liquid flow control opens the doors for researchers to truly alter the chemical environment within the liquid cell. By controlling the liquid flow, a user can flush away beam-induced species, explore flow-dependent liquid dynamics and easily change electrolyte composition. Moreover, the unique design of the electrodes in the Stream system allows researchers to explore complex liquid dynamics within different chemical environments within the same liquid cell. Importantly, the direct observations made by Cheng et al. not only provide new insights into understanding the nucleation and growth, but also give guidelines for the design and synthesis of desired nanostructures for specific applications, such as high performance electrocatalysis for energy conversion and electrodes for secondary batteries.

Image of Dr. Ningyan Cheng from Max-Planck-Institut für Eisenforschung GmbH

“The DENSsolutions Stream System not only provides a useful means to study a wide range of dynamics in solution, but also enables systematic studies of the effect of the chemical environment on the corresponding reactions through precise control of the flow rate, liquid composition and other significant parameters.”

Prof. Dr. Ningyan Cheng Associate Professor | Anhui University