RSC Advances Blog

Functional porous materials underpin a vast range of critical chemical processes, with prominent examples including water purification, building material formulation, fuel storage, pollution abatement, and the energy-efficient production of useful materials from both natural and renewable resources. The underlying chemical and physical processes associated with such applications are a result of the interactions of these porous structures with fluids (gases or liquids), typically via their encapsulation, surface-adhesion, and/or chemical reaction. The efficacy of the materials employed within such applications (such as porous metal oxides, zeolites and metal-organic frameworks) is a direct consequence of their inherently large surface-to-volume ratios, which ensure that interfacial interactions dominate the behaviour of imbibed chemicals.

Despite the ubiquity and importance of porous media across the spectrum of chemical sciences, our understanding of many of the basic properties of fluids confined within these materials remains very limited. Indeed, characterising interfacial phenomena occurring at the highly inaccessible solid surfaces contained within porous structures is a significant analytical challenge, requiring state-of-the-art techniques with the ability to discriminate between molecules interacting with the interface of interest and the surrounding solid and fluid components. NMR relaxation methods have recently emerged as potential route to such information. Unlike NMR spectroscopy, which provides structure-dependent NMR frequency data, relaxation methods depend on the time-domain behaviour of the acquired NMR signal. This relaxation data is sensitive to molecular dynamics, and for fluids confined within porous structures has the potential to provide insight into a plethora of phenomena, including pore size distributions and surface chemistry. The key novelty of this approach lies in that fact that it is inherently non-invasive, and so has the potential to be performed under operando conditions.

Relaxation-based approaches are now regularly applied to characterise heterogeneous catalysts; for instance, we recently compared relaxation data acquired from a range of primary alcohols within a silica-based catalyst support material with DFT-based adsorption energy calculations, revealing the sensitivity of NMR relaxation phenomena to adsorption interactions occurring at the solid-liquid interface.[1] Similar approaches have been shown as a potential route for the assessment of metal nanoparticle deposition.[2,3] These measurements made use of the paramagnetic nature of the precursor materials used in nanoparticle deposition methods, the presence of which significantly alters the observed NMR relaxation characteristics of probe fluids within the pore network, highlighting the versatility of NMR relaxation-based analyses for porous media characterisation.

1) N. Robinson, C. Robertson, L. F. Gladden, S. J. Jenkins and C. D’Agostino, Direct correlation between adsorption energetics and nuclear spin relaxation in a liquid-saturated catalyst material, ChemPhysChem, 2018, 19, 2472–2479.
2) C. D’Agostino, P. Bräuer, P. Charoen-Rajapark, M. D. Crouch and L. F. Gladden, Effect of paramagnetic species on T₁, T₂ and T₁/T₂ NMR relaxation times of liquids in porous CuSO₄/Al₂O₃, RSC Adv., 2017, 7, 36163–36167.
3) C. D’Agostino and P. Bräuer, Exploiting enhanced paramagnetic NMR relaxation for monitoring catalyst preparation using T₁ – T₂ NMR correlation maps, React. Chem. Eng., 2019, 4, 268–272.

About the Web Writer:

Dr Neil Robinson is a postdoctoral Research Associate in the Fluid Science and Resources Research Group at the University of Western Australia. He previously undertook his MChem degree at Cardiff University, and obtained a PhD in Chemical Engineering from the University of Cambridge. His research focuses on the application of novel magnetic resonance methods for the study of gas and liquid dynamics within porous media of importance to the energy-environment nexus.

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Argentina, Bolivia and Chile make up the “Lithium Triangle”, where 70 % of the world’s lithium reserves are concentrated. These factors lead to the study in the development of lithium batteries being of great interest to my country and particularly to me, because I am beginning to research on this topic, so I am interested in reading articles on lithium batteries. During the last decades, numerous investigations have been carried out in the area of lithium batteries, in relation to their components such as electrodes, separators and electrolytes, to make them safer, environmentally friendly and economical.

A battery is made up of a set of electrochemical cells, which are made up of three main components: cathode, anode and electrolyte. In the case of the lithium battery, when charging battery, the lithium ions move from the positive electrode (cathode) towards the negative electrode (anode), and in opposite way during the discharge process. In this type of battery, the negative electrode is mainly composed of carbonaceous materials and the positive electrode of metal oxides. There is an urgent need for better lithium-ion batteries in order to create sustainable solutions based on relatively limited resources with a long-term perspective, and to apply the knowledge of mesoporous based cathode materials to an exciting field of lithium-ion battery research.

The article “Electrochemical performance of nano-sized LiFePO4-embedded 3D-cubic ordered mesoporous carbon and nitrogenous carbon composites” focuses on generic principles applicable to more advanced materials and systems for the development of highly electroactive olivine structured cathode materials for high performance lithium-ion batteries. This research findings would open potential avenues for fundamental on state-of-the-art mesoporous carbon-based materials for energy storage systems. Exploitation of novel porous cathode materials and a strengthening of fundamental understanding of their textural property and electrochemical performance relationships have played a major role in developing the lithium-ion battery research field.

One way to overcome the limitations of commercial lithium batteries is to modify the active material used in the negative electrode. Current devices use mainly carbonaceous material, which has the advantage of operating at low potentials. During the charging and discharging process, the carbonaceous material undergoes a reversible volumetric variation of approximately 10% and maintains its structure, giving stability to the battery for many cycles. Although the storage capacity of this material has allowed for the development of current portable electronic devices, it translates into a low energy density when considering its application in electric vehicles. Therefore, much of the lithium battery research is focused on the development of next generation batteries with high energy density (i.e. lighter batteries). However, enabling stable cycling and high-power output is also desirable for next generation batteries. Operation of lithium batteries at high power often leads to a decrease in the cycle life. Often a high-power output is required for a short duration, for example for rapid vehicle acceleration. The developed electrode material is cheap and easy to make, and is applicable to these high power applications.

The article “A stable TiO2–graphene nanocomposite anode with high rate capability for lithium-ion batteries” focuses on the development of new electrode materials for lithium batteries that offers stable cycle performance at high power density. Titanium dioxide is an abundant metal oxide that is widely used as a pigment in paint, sunscreen, and food coloring. Titanium dioxide can be used as a stable negative electrode material, enabling long life for the battery. However, it has low electrical conductivity, thus combining the titanium dioxide with a conducting additive has been found to enhance its performance. In this study, the high power stable cycling performance of a titanium dioxide/graphene composite, prepared by a simple synthesis method, was demonstrated. The new electrode material could be used in the next generation batteries, which will be much safer and with higher power density and longer cycle life than ever before. It should be noted that this work was performed with the collaboration between battery research groups at the Helmholtz Institute of Ulm, the University of Waterloo, and the University of Calgary.

I thank Dr. Parasuraman Selvam and Dr. Edward P. L. Roberts for their cordial responses.

Read the articles:

Electrochemical performance of nano-sized LiFePO4-embedded 3D-cubic ordered mesoporous carbon and nitrogenous carbon composites
Sourav Khan, Rayappan Pavul Raj, Talla Venkata Rama Mohan and Parasuraman Selvam
RSC Adv., 2020, 10, 30406–30414

A stable TiO2–graphene nanocomposite anode with high rate capability for lithium-ion batteries
Umer Farooq, Faheem Ahmed, Syed Atif Pervez, Sarish Rehman, Michael A. Pope, Maximilian Fichtner and Edward P. L. Roberts
RSC Adv., 2020,10, 29975-29982

About the Web Writer:

Cristian M. O. Lépori is Doctor in Chemical Sciences and currently has a postdoctoral position at the “Enrique Gaviola” Institute of Physics, CONICET, National University of Córdoba (Argentina). He works in the area of nuclear magnetic resonance studying hybrid materials formed with porous matrices and ionic liquids for use in lithium batteries. He likes to plan, organize and carry out science dissemination activities. You can find him on Twitter at @cristianlepo.

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Recalling my early days as a PhD student, our lab was just setting up equipment for tests, which involved a group of devices that could evaluate the efficiency of our electrodes for splitting water into hydrogen and oxygen using sunlight. For that, we needed a “sun” in the lab to give out consistent irradiation, which was a powerful Xe lamp (Fig. 1). Only when our sample electrodes were illuminated with this big bulb would they get excited, generate electric current and produce gas.

The more interesting part was, however, something called a monochromator. When I was doing physics module as an undergraduate and first came across this instrument in textbook, I mumbled, ‘What’s the big deal?’ But as different colours of light came out one after another in front of my eyes (with special safety goggles on, of course), it was like seeing some kind of magic unfolding. This was even cooler than ‘The Dark Side of The Moon’! But what the expensive monochromator really did was to allow us to evaluate how well our samples respond to each wavelength of light, technically called incident photon-to-current conversion efficiency (IPCE).

Another measurement we did was called intensity modulated photocurrent spectroscopy (IMPS), which has been gaining increasing popularity over the years. This test involved superimposing an AC signal on a DC signal and giving it as input to an LED so that the light intensity changed sinusoidally around a constant level. When the experiment started and you would see the light start to jiggle, at all sorts of frequencies from kHz to mHz, just like stage lights. Suddenly, we were like: It’s party time! Now back to business, we had to take recordings of the current generated by our electrodes and calculate a couple of rate constants to understand the kinetics of the water splitting reaction.

These fun experiments led our group to a number of publications (1, 2), including one in RSC Advances. Moving on to a different university as a postdoc, I’m planning to buy them again!

Fig 1. Lab setup at University of Bath (2017). Now at Imperial College London under group of Salvador Eslava.

References

1. J. Zhang et al., RSC Adv., 2017, 7, 35221
2. J. Zhang et al., Energy Environ. Sci., 2018, 11, 2972

About the Web Writer: 

Jifang Zhang completed his BEng at Beijing Institute of Technology, before moving to the UK for MSc at the University of Edinburgh and PhD at University of Bath. Now he is back in Beijing as a postdoc researcher at Tsinghua University.

Outside working hours, he is always juggling between karate, running, drumming and photography. You can find him on Instagram @jifang_zhang.

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In my recent blog post, I discussed the benefits of online conferences for inclusion and wide participation. Access to science without barriers like money and travel is always appreciated and fosters greater interest and collaboration within communities.

As a PhD student at the University of Kent in the UK, I am privileged because my institution has subscriptions to most of the journals needed to progress with my research and understanding. This level of access is quite normal in the UK and therefore it can be easy to forget that not everyone has this luxury. But it is important for this imbalance to be recognized and over the last few years it has been pleasant to see the increased use of open access publishing. I was pleased to publish my first paper as open access because I believe that the dissemination of research will be increasingly important as the world faces new problems.

Scientific innovation can take huge leaps forward when working to overcome challenges. We have seen evidence of this with COVID-19 and the incredible response from scientists all over the world. However, COVID-19 is not the only issue that the world faces. Each country has its own characteristics such as climate, agriculture and infrastructure which results in specific and unique challenges that may light the spark for scientific innovation. However, lack of access to key research can result in missed opportunities and ideas that would benefit the entire world. Issues such as climate change and antimicrobial resistance, pose serious threats to our way of life, with consequences worse than we have seen with the ongoing COVID-19 pandemic, which has shocked the world. Therefore, it is increasingly important that the global scientific community can work collaboratively and with fewer barriers through open access so that we can be better prepared for what the future holds.

It is also important to recognise that misinformation and misunderstanding surrounding science is becoming increasingly common, resulting in a disconnect with the public. With the adoption of open access, factual and reliable scientific information will be much easier to find by anyone if they so wish.

Unfortunately, publishing open access does not come without issues. It can be expensive, and the existence of predatory journals can result in published science that has not been through the same rigorous peer-review process that is used by reputable journals. But choosing to publish open access in trusted journals, providing funds are available, will help to advance the progress and inclusivity of science, which is important now more than ever.

About the Web Writer:

Lee Birchall has recently started his PhD under the supervision of Dr. Helena Shepherd at the University of Kent, where he also completed his MSc under the supervision of Dr. Stefano Biagini. He obtained a first class BSc at University College London. He enjoys music, languages and windsurfing and you can find him on Twitter at @LTBIRCH.

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Among different types of malignant diseases, breast cancer is the most prevalent one among women throughout the world. Breast cancer patients often face bone metastasis at middle and late stages of malignancies, causing various skeletal diseases (e.g. bone loss, extreme pain, hypercalcaemia, pathological fracture etc) as well as mortality. The conventional therapies for breast cancer metastasis to bone include surgery and chemotherapy, which involve several limitations. For instance, surgery is not suitable for eliminating poorly defined and small metastases. Then again, chemotherapy is associated with adverse toxicity, side effects, drug resistance, tumour recurrence, tumour targeting issue etc. Therefore, it is urgently required to develop some alternative approaches for the treatment of breast cancer and associated bone metastasis by solving the aforementioned limitations. In this context, nanomedicine might play a pivotal role, considering its potent biomedical applications in drug delivery, radiotherapy, gene therapy and photothermal therapy (PTT) to treat different types of cancers. Of late, near-infrared (NIR) laser light-based PTT involving biocompatible nanomaterials has been immense popular, due to the minimized invasiveness approach with enhanced safeguarding of adjacent tissues and potent anti-cancer efficiency, by producing high temperature in tumour tissues locally upon absorbance of light, ultimately leading to cancer cell death in a targeted manner. Even though, PTT has been widely studied for the treatment of superficial tumours, there is scarcity of reports related to its application for the therapy of deep tumors including bone metastasis of breast cancer.

In this scenario, Wang and co-workers have recently developed an NIR-triggered nanoplatform based on IR780 (NIR absorber)-encapsulated biocompatible poly-lactide-co-glycolide (PLGA) nanoparticles (IR780@PLGA NPs) and investigated its PTT potential for the treatment of bone metastasis of breast cancer. The researchers established a bone metastasis model of tumours in BALB/c mice by inoculating 4T1 cells (mice breast cancer cells) into right tibia of mice through intraosseous infusion. The intra-tumoural administration of IR780@PLGA NPs to the tumor containing mice in presence of NIR light exhibited better tumor growth inhibition than the PBS control group and IR780@PLGA NPs group without NIR radiation, suggesting that the nanoplatform could effectively suppress the breast cancer cell metastasis to bone through PTT. Additionally, histopathology study revealed that tumor containing legs administered with IR780@PLGA NPs and NIR light illustrated less damage of bone and more number of healthy tissues around it as compared to the control groups. Overall, the study provides the basis for potent clinical application of IR780@PLGA NPs-based PTT for the treatment of bone metastasis of breast cancer in near future.

Reference

Near-infrared-induced IR780-loaded PLGA nanoparticles for photothermal therapy to treat breast cancer metastasis in bones, Li et al., RSC Adv., 2019, 9, 35976-35983

About the Web Writer:

Dr. Ayan Kumar Barui received his Ph.D. degree from CSIR-Indian Institute of Chemical Technology (CSIR-IICT), India in 2017. Then he worked as a postdoctoral research associate in Ulsan National Institute of Science and Technology (UNIST), South Korea for more than two years. Currently, he is associated with an R&D institute based in India. His research focuses on the development of nano/bio-materials for pro- and anti-angiogenic therapy, targeted drug delivery, cancer therapy, vascular disease therapy, wound healing, and bio-imaging. He possesses 37 peer-reviewed international publications and several international conference awards. He is recognized as a member (MRSC) of the prestigious Royal Society of Chemistry (RSC), UK. He also serves as an invited reviewer for various international journals including Nanoscale, Biomaterials Science, Journal of Materials Chemistry B, Materials Science and Engineering C, RSC Advances, Food & Function etc.

You can find him on Twitter @AYANBARUI

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The continuous depletion of limited reserved fossil fuels and corresponding environmental concerns due to their combustion strictly demands the exploration of alternative energy resources for sustainability. Although solar and wind energies are harvested, the seasonal intermittence restricts their broad application. In this regard, the scientific community has developed the fuel cell using gaseous fuels like oxygen (at the cathode half-cell) and hydrogen (at the anode half-cell) that can produce electricity with better specific energies without compromising efficiency. The scalable production of these gaseous fuels (i.e. H₂ and O₂) has become a great challenge for energy researchers. Among the many processes and technologies developed, a green process for the production of these molecular fuels is the electrochemical splitting of water in an electrolyzer. The smooth running of the electrolyzer depends on both the cathodic and anodic half reactions. Whereas the cathodic half reaction (hydrogen evolution reaction; HER) is very straight forward, the multiproton-coupled electron transfer steps cause OER to face sluggish reaction kinetics demanding additional potential (overpotential) to overcome the reaction barrier. Hence, the HER is greatly hampered and thereby the overall electrolysis process. Since the efficiency of the half-cell strictly adheres on the catalytic efficacy of the electrocatalyst, researchers are focusing on the design of new catalyst materials. Among them, the transition metal based dichalcogenides (TMDs) and phosphides (TMPs) are the recent topics of study. Although these electrocatalysts catalyze OER efficiently, phase and composition changes during the course of reaction raises questions about the catalytically active centers of the electrocatalysts.

The in-depth characterization of post catalytic sample as well as in situ sample analysis clearly demonstrates the surface transformation of the TMDs and TMPs. In a particular study by Dutta and Samantara et al. have demonstrated the OER performances of Co₂P nano needles in alkaline electrolytic conditions (1). As per the report, a significant broad peroxidation peak was observed in the linear sweep voltammetry signifying the surface oxidation of Co₂P to corresponding oxides (CoO_x). The interface of Co₂P-CoO_x facilitate carrier transportation from the core Co₂P to oxides on the surface, thereby improving the electrocatalytic performances. Likewise, the core-shell Au@Co₂P nanostructures derived via the wet chemical synthesis method were found to act as precursor catalysts for OER. However, the surface oxidized forms, i.e. Co-phosphates and Co-oxides/hydroxides, act as the real active centers of the electrocatalysts in alkaline conditions. The surface transformations were monitored by the X-ray photoelectron study of the post OER sample (2).

P 2p of Au@Co2P after OER tests in comparison with those before OER tests.

Similar surface transformations have been noticed also in case of TMDs. During the course of the OER, the surfaces of metal sulphides and selenides transform to their corresponding oxides and oxy-hydroxides and perform as active electrocatalysts to catalyze the water oxidation. Moreover, these surface transformed oxidized functionalities are more catalytically active than the parent TMDs, TMPs and the respective oxides alone. It is therefore imperative to characterize and define the real active centers of the catalysts used for water oxidation, particularly in alkaline electrolytic conditions.

References

1. Anirban Dutta, Aneeya K. Samantara, Sumit K. Dutta, Bikash Kumar Jena, and Narayan Pradhan, ACS Energy Lett., 2016, 1, 1, 169–174.
2. Xiaofang Zhang, Aixian Shan, Sibin Duan, Haofei Zhao, Rongming Wang and Woon-Ming Lau, RSC Adv., 2019,9, 40811-40818.

About the Web Writer:

Dr. Aneeya K. Samantara is Doctor in Chemical Sciences and currently has a Postdoctoral position (NPDF) in the School of Chemical Sciences, National Institute of Science Education and Research, Bhubaneswar, Odisha, India. Recently he joined as Community Board Member of the “Materials Horizon” of Royal Society of Chemistry, London. He pursued his PhD at the CSIR-Institute of Minerals and Materials Technology, Odisha, India. Before joining the PhD program, he completed his master of philosophy in chemistry at Utkal University and master in science in advanced organic chemistry at Ravenshaw University, Cuttack, Odisha, India. Dr. Samantara’s research interests include the synthesis of transition metal based electrocatalysts and graphene composites for energy storage and conversion applications. You can find him on Twitter at @cmrjitu.

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