Sustainable materials are key to solving global environmental problems | Imperial News





Researchers have mapped how we can grow the crucial materials we need for everyday life in a more sustainable way.

From wind turbines and solar cells to packaging and textiles, materials are the key components of some of the fundamental objects we need every day.

Our ability to produce and process engineered materials over the past 150 years is responsible for our high standard of living today. However, the way we currently manufacture and use materials is having adverse effects on the planet, creating many serious environmental issues.

In a roadmap developed by key researchers in the field of sustainable materials, including Professor Magda Titirici, Dr Hui Luo, Dr Heather Au and Dr Maria Crespo Ribadeneyra from Imperial’s Department of Chemical Engineering, the scientists highlighted outstanding challenges and ways to resolve them.

Material science knowledge

Materials science is a highly interdisciplinary field of chemical engineering, spanning the design, discovery and application of new materials and is key to solving many sustainability challenges. This mainly involves creating more sustainable material alternatives by using natural raw materials while ensuring that you don’t deplete important resources.

“I am very happy to see this Sustainable Materials Roadmap published. It encompasses important contributions from the scientific community working in this important area of ​​research across various themes.” Professor Magda Titirici Department of Chemical Engineering

Critical materials represent a class of substances that constitute the central components of sustainable energy systems because they are the most efficient. Examples include permanent magnets made from rare earth metals used in wind turbines such as dysprosium, neodymium and praseodymium, lithium and cobalt in lithium-ion batteries, platinum in fuel cells and electrolyzers and silicon in solar cells.

The roadmap assesses how we can produce important substances like these critical materials for a more sustainable future. Lead author Professor Magda Titirici said: “I am very happy to see this Sustainable Materials Roadmap published. It encompasses significant contributions from the scientific community working in this important area of ​​research on various topics ranging from raw sustainable precursors to naturally inspired materials manufacturing, different classes of materials, their applications, sustainability assessment and the recycling.

She added, “I would like to thank all the authors for their outstanding efforts contributing to this critically important topic to reduce our dependence on fossil fuels and critical materials, an essential prerequisite for transitioning to a green economy.”

Sustainable quantum dots

Quantum dots (QDs) have tunable, strong, and robust fluorescence properties that have the potential for applications in solar cells, light-emitting diodes, sensing, and bio-imaging. However, most semiconductor QDs contain metals which have high toxicity and significant environmental impact.

“Carbon dots have the potential to serve as a sustainable alternative to conventional quantum dots in applications such as solar cells, LEDs, sensing and bio-imaging.” Dr. Hui Luo Department of Chemical Engineering

The discovery of carbon-based fluorescent dots in 2004 drew people’s attention to this new zero-dimensional carbon material as a potential sustainable alternative to existing quantum dots. These carbon dots typically have an average particle size of less than 10 nanometers and they can be produced either by top-down methods involving cutting large carbonaceous materials such as graphite into smaller fragments, or by bottom-up approaches by growing small precursor molecules such as glucose to larger carbon. polymers.

Producing carbon points using this bottom-up approach is considered more sustainable and environmentally friendly. However, the inhomogeneity of the structure of the carbon points makes it difficult to acquire precise information on their chemical structure. Similarly, the carbon point yields in current synthesis approaches are too low to achieve a sustainable workflow and therefore their use is currently limited.

According to co-author and research associate, Dr. Hui Luo: “Carbon dots have the potential to serve as a sustainable alternative to conventional quantum dots in applications such as solar cells, LEDs, sensing and bio -imagery. However, challenges remain to precisely control their chemical and optical structures and increase production yield.

“Progress has been made in research to address these challenges by studying the fundamentals and developing high throughput systems, which will unlock the vast potential of carbon points in future society.”

Create sustainable materials for batteries

To achieve the objective of carbon neutrality by 2050, a reorientation of energy production towards renewable sources is imperative. Sustainable batteries will play a leading role in this energy transition.

“Emerging energy storage technologies have the potential to achieve full-spectrum sustainability alongside technological advancements by learning from the shortcomings of current lithium-ion batteries (LIBs).” Dr. Heather Au Department of Chemical Engineering

Lithium-ion batteries currently dominate the market but have significant environmental impacts due to their reliance on graphite and transition metal oxides. Natural graphite is in limited supply and although synthetic graphite offers a possible alternative, it is expensive to produce and derived from petroleum, a fossil fuel. Apart from this, the transition oxides used to make the cathode contain cobalt which is considered an endangered resource dependent on heavy mining in the Democratic Republic of Congo.

Future energy systems will require greater demand for energy storage, presenting batteries as a critical area of ​​research in the years to come. According to researcher Dr. Heather Au: “Emerging energy storage technologies have the potential to achieve full-spectrum sustainability alongside technological advances by learning from the shortcomings of current lithium-ion batteries (LIBs).”

Dr Maria Crespo Ribadeneyra, Research Associate, added: “Critical examination of the entire battery lifecycle will help achieve environmental balance and safety by targeting high performance materials based on abundant elements and not geopolitically compromised, while keeping a circular economy mindset”.

“While significant progress has been made in alternative battery chemistries, there is still much to be done to develop innovations in synthesizing greener materials, manufacturing less energy-consuming cells, improving battery life and battery safety and design for end of life.”

The key to a sustainable future

By compiling the roadmap, the team hoped to demonstrate how a transition to using sustainable materials is possible for a greener future.

Dr. Titirici concluded: “We hope to contribute to the development of the wider sustainable materials research community, providing a guide for universities, industry, government and funding agencies in this research space of critically important and rapidly developing, which is the key to future sustainability.

‘The Sustainable Materials Roadmap’ by Titirici et al., published January 25, 2022 in JPhys Materials

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