Rumbles

Missing Excitons: How Energy Transfer Competes with Free Charge Generation in Dilute-Donor/Acceptor Systems

Anonymous — Thu, 08 Feb 2024 07:00:00 +0000

Missing Excitons: How Energy Transfer Competes with Free Charge Generation in Dilute-Donor/Acceptor Systems Anonymous (not verified) Thu, 02/08/2024 - 00:00

ACS ENERGY LETTERS, 2024, 896-907

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Beyond n-dopants for organic semiconductors: use of bibenzo[d]imidazoles in UV-promoted dehalogenation reactions of organic halides

Anonymous — Thu, 14 Dec 2023 07:00:00 +0000

Beyond n-dopants for organic semiconductors: use of bibenzo[d]imidazoles in UV-promoted dehalogenation reactions of organic halides Anonymous (not verified) Thu, 12/14/2023 - 00:00

BEILSTEIN JOURNAL OF ORGANIC CHEMISTRY, 2023, 19, 1912-1922

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Profile: Garry Rumbles

Anonymous — Sat, 03 Jun 2023 06:00:00 +0000

Profile: Garry Rumbles Anonymous (not verified) Sat, 06/03/2023 - 00:00

Daniel Morton

Dr. Garry Rumbles, who holds a joint appointment as a senior research fellow at the National Renewable Energy Laboratory (NREL) and an Adjoint Professor of Chemistry at CU Boulder recently stepped down as the Associate Director of RASEI. Among a host of other awards and recognition, Garry was recently elected to the 2022 class of AAAS Fellows.

Garry joined NREL in 2000 and has been a RASEI Fellow since the Institute’s inception in 2009. We sit down to find out a little more about Garry, how he came to be part of RASEI and looking forward.

Where are you from?

Essex, in the south of England. I grew up on a market garden and cereal farm that was far away from the middle of nowhere.

Tell us something from your childhood.

Working on the farm and with my family took up a lot of time. Football and family. I took up sailing when I was 17 and spent a lot of time on the rivers Blackwater and Crouch, both of which offer fantastic sailing! I met my wife, Lee, windsurfing in California, so the sport served me very well.

What did you want to be when you were growing up?

Pilot in the Royal Air Force

What do you enjoy doing outside of work?

Spending time with family, sailing, running, watching football. Skiing. I am a telemark skier, which Art Nozik got me into – it is great because everyone looks at you as though you are amazing, even if you are not!

Who have been some strong influences in your life?

George Porter. Art Nozik. My high school teachers. Where I grew up there were very few people who went on to higher education and university. In my class 6 people went to university, which doubled the number of people from that school who went on to higher education (the school opened in 1958). There was not a good structure or support for getting into university and my high school teachers took someone who had few academic aspirations and ignited a curiosity in chemistry and electronics.

How did you choose your area of research?

When I finished my undergraduate, I was fascinated by lasers, and that is what really hooked me. I went to work with Prof. David Phillips at the Royal Institution in London. I got to work on lasers and live in London! It was a great research environment and where I first connected with (Professor Sir) George Porter. He was a fantastic scientist who was endlessly curious. I remember being on a call with him on a Sunday evening where we spent an hour discussing whether a mole of yellow or red photons had more entropy. A Nobel Prize winner talking to me about this! I received a copy of his paper on the thermodynamics through the internal mail the next day.

What would you say to folks considering a similar research path?

Seek quality mentors. Don’t be modest, but don’t be arrogant – be confident. Talk to lots of people in research. Get advice, don’t try and do it all yourself. You need to know what you don’t know, and how to be successful. Learn the basics and make sure that you have a really strong foundation, not just in the sciences. You need to be able to communicate, present, and write effectively.

What is an important lesson you have taken from your work in research?

You need to know your “So what?” and “what is the impact?”. You need to be able to tell people why what you are doing is significant. One of the most important things, whether for putting together proposals, presenting your work, writing a paper, or talking to sponsors, is being able to concisely provide and articulate the conclusion. Give me the why – impress me!

Describe some of your philosophies toward approaching scientific challenges.

Connect with great scientists interested in collaboration. While I was at Imperial collaboration was not a big focus, things were rather siloed. I did get one chance to work on a collaboration with a team at the University of Cambridge, but I was not central, I was more of a satellite player. It was one of the things that was so attractive at NREL – you are integrated and work as part of ‘real’ team. NREL, with folks like Art Nozik, fosters an environment where you can be an intellectual leader, not just an ancillary participant, and this team atmosphere was something I really enjoyed. RASEI brings together the academic and National lab approaches, which is one of the things that makes it an exciting space to operate.

Value the human aspects of research-based teamwork. Being part of a team provides such a great opportunity for learning and discovering new approaches. It also gives you a chance to learn more about people and appreciate the balance and recognition of the different things people bring to projects. I have worked with some extremely talented people who go on to do things outside of research – which is fantastic. Everyone’s path is different, and everyone has different responsibilities and drives. Working as part of close-knit teams has given me a chance to appreciate this.

Tell us a bit about the impacts you see RASEI having in the future.

Institutes provide the opportunity for agility and being able to address large, cross-disciplinary challenges – something that Departments are not always able to do. Departments in the system provide the foundation for the research endeavor that enable Institutes to operate. Institutes exist in this space where folks can come together and interact, be more dynamic than otherwise possible. For RASEI the partnership with NREL really advances this idea.

Institutes act to bridge gaps between Departments, and to fill in gaps that are perhaps not normally covered, and this is where things can be exciting, where new ideas can come about.

I am looking forward to watching RASEI grow and have a reputation that demonstrates how much of a strength the partnership between CU Boulder and NREL is. This kind of organizational research collaboration is extremely powerful and needs to be lauded. A partnership like this, that has agility and the ability to pivot, is not only a great place to perform research, but is also going to be essential in how we attack new challenges.

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Metal–Carbodithioate-Based 3D Semiconducting Metal–Organic Framework: Porous Optoelectronic Material for Energy Conversion

Anonymous — Wed, 31 May 2023 06:00:00 +0000

Metal–Carbodithioate-Based 3D Semiconducting Metal–Organic Framework: Porous Optoelectronic Material for Energy Conversion Anonymous (not verified) Wed, 05/31/2023 - 00:00

ACS APPLIED MATERIALS & INTERFACES, 2023, 15, 23, 28228-28239

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2023 NREL Solar Photochemistry Retreat

Anonymous — Mon, 10 Apr 2023 06:00:00 +0000

2023 NREL Solar Photochemistry Retreat Anonymous (not verified) Mon, 04/10/2023 - 00:00

In April of 2023 RASEI hosted the NREL Solar Photochemistry retreat. The aim of these retreat meetings is to provide an opportunity for the team to catch up on recent progress, create time and opportunities to connect over research collaborations and outline a path forward for future research directions.

NREL Solar Photochemistry

04/2023

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Charge Concentration Limits the Hydrogen Evolution Rate in Organic Nanoparticle Photocatalysts

Anonymous — Mon, 27 Mar 2023 06:00:00 +0000

Charge Concentration Limits the Hydrogen Evolution Rate in Organic Nanoparticle Photocatalysts Anonymous (not verified) Mon, 03/27/2023 - 00:00

ADVANCED MATERIALS, 2023, 2210481

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RASEI Fellows elected to the 2022 Class of AAAS Fellows

Anonymous — Wed, 01 Feb 2023 07:00:00 +0000

RASEI Fellows elected to the 2022 Class of AAAS Fellows Anonymous (not verified) Wed, 02/01/2023 - 00:00

Find out about the AAAS Fellows

Check out the full 2022 Class

AAAS Fellows are a distinguished cadre of scientists, engineers, and innovators who have been recognized for their acheivements across disciplines, from research, teaching, and technology, to administration in academia, industry and government, to excellence in communicating and interpreting science to a range of audiences.

RASEI Fellows Garry Rumbles and Matthew Beard were selected as part of the Section on Chemistry 2022 Class of AAAS Fellows. Joining of cohort comprising of just 505 members for the 2022 class, election as a AAAS Fellow honors members whose efforts on behalf of the advancement of science, or its application in service to society, have ditinguished them among their peers and colleagues.

Congratulations Garry and Matt!

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RASEI Secures Funding to Pursue Collaborative Team Science Programs to Address Climate Change Challenges

Anonymous — Sat, 27 Aug 2022 06:00:00 +0000

RASEI Secures Funding to Pursue Collaborative Team Science Programs to Address Climate Change Challenges Anonymous (not verified) Sat, 08/27/2022 - 00:00

Daniel Morton

Thirteen members of RASEI secured funding from the Department of Energy to participate in inter-disciplinary team science to address a range of challenges associated with combating climate change.

EFRC Funding Announcement

DOE EFRC Homepage

CU Boulder Announcement

In recent decades the scientific endeavor has expanded our knowledge and deepened our understanding of many of the imposing problems that face society. With this improved insight comes an appreciation that many of these issues are multi-faceted, far-reaching, and complex. The climate crisis is the toughest challenge for this generation and is an exceptionally intricate, systematic and multi-layered puzzle. In order to address this challenge in a holistic fashion we need teams of innovative scientists, from across a broad range of scientific and engineering fields, to work together in an inter-disciplinary fashion.

The Renewable and Sustainable Energy Institute (RASEI), a joint institute between CU Boulder and the National Renewable Energy Laboratory (NREL), has prioritized becoming a hub for multi-disciplinary teams focused on climate solutions to work together. Development of this ecosystem anable teams to expand their collaboration across the entire RASEI community, extending to engagement with other academic, national labs and industrial partners along the Front Range. Through fostering a team environment, developing a culture of sharing and integration, RASEI aims to accelerate fundamental discoveries and their translation to applications and solutions that can be deployed to all communities in need.

In August of 2022 the Department of Energy (DOE) released $540 million of funding for research into clean energy technologies and low-carbon manufacturing, $400 million of which is to establish and continue multi-disciplinary team science at Energy Frontier Research Centers (EFRCs). Across the nation 43 EFRCs were funded, with 13 RASEI members involved in six of these Centers.

The EFRC program was established by the DOE Office of Basic Energy Sciences (BES) in 2009 to address the fact that global demand for energy is rapidly expanding, and the way in which energy is collected, stored and used needs to change. The goal of an EFRC is to bring together creative, multi-disciplinary scientific teams to tackle the toughest scientific challenges preventing advances in energy technologies. At the core of an EFRC's mission is to train the next generation of the scientific workforce, both in advanced technical techniques, and also in team science and developing the skills needed to work together to tackle large-scale problems. These Centers are initially funded for four years at about $4 million per year. If the Centers are successful, they can apply for renewed funding at the end of the first four years. Centers can only be renewed once.

For the 2022 funding announcement, two of the RASEI-infused EFRCs, one of which is based at NREL, were renewals of existing Centers, and the other four awards were to establish new research teams. You can find out more details about the different Centers in the summary boxes below.

The RASEI community is energized to be involved in these exciting collaborative opportunities, and the chance to work together across these teams as part of the RASEI community. Colorado’s U.S. Representative Ed Perlmutter captured this enthusiasm in his quote as part of the funding announcement:

“NREL and CU Boulder, among others, continue to lead our nation in their cutting-edge research and development of a variety of clean energy technologies and low-carbon manufacturing. Their work is essential in the fight to combat climate change and achieve important climate and clean energy goals in the future”

If you would like to keep up with the progress these teams make, check out the RASEI website or signup to our monthly newsletter.

Thirteen members of RASEI secured funding from the Department of Energy to participate in inter-disciplinary team science to address a range of challenges associated with combating climate change.

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A handle on charge reorganization

Anonymous — Fri, 01 Jul 2022 06:00:00 +0000

A handle on charge reorganization Anonymous (not verified) Fri, 07/01/2022 - 00:00

Nature Chemistry, 2022, 14, 720-722

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Resurrected microwave tool illuminates cutting-edge light-driven chemistry

Anonymous — Thu, 16 Jun 2022 06:00:00 +0000

Resurrected microwave tool illuminates cutting-edge light-driven chemistry Anonymous (not verified) Thu, 06/16/2022 - 00:00

Daniel Morton

Research Article

News and Views Highlight

Cell Chem Highlight

A century old technique has been revitalized to provide valuable insights for catalyzing chemical reactions.

Using advanced computer-aided design and coding tools, a long-overlooked microwave analysis technique uncovered new insights into cutting-edge, light-driven chemistry. The technique revealed that a component of the catalyst often considered inconsequential is actually responsible for a four-fold change in chemistry.

Organic chemistry underlies many of today’s manufacturing processes from pharmaceuticals to plastics, but these processes can often generate hazardous byproducts. Catalysts are a critical tool in for transitioning organic chemistry to a greener, more sustainable future. By accelerating the rate of a chemical reaction without itself being consumed, a catalyst molecule more efficiently uses raw materials, eliminates waste, and can avoid the use of toxic and hazardous substances. New research from a team of scientists at the Princeton University and the Renewable and Sustainable Energy Institute (RASEI; a joint institute between the National Renewable Energy Laboratory (NREL) and University of Colorado Boulder (CU Boulder)) reveals key insights into how an important class of catalysts operate and offers a path to improving their performance.

Photoredox catalysts, that harness the energy from light (photo-) to transfer electrons to, or from, other molecules (what chemists refer to as reduction and oxidation respectively (hence ‘redox’)), takes the sustainability of catalysts to a higher level, by enabling reactions driven by light. Today, many researchers are seeking to understand how these photoredox catalysts systems work and to use this understanding to improve the efficiency of the redox reaction so it can be used at industrial scales. Many different variables can be modified to tune the reaction, such as the structure of the catalyst and the conditions of the reaction. A new discovery, published in Nature Chemistry in April 2022, revitalizes an long-overlooked analytical technique that has revealed the importance of a variable previously thought to be insignificant and uncover a new approach for improving these processes.

The breakthrough results from a collaboration between researchers from NREL and Princeton University. Light-driven catalysis has undergone a renaissance in recent years, and the Knowles group at Princeton have been one of the pioneers. Not only do these systems provide more sustainable alternatives to existing chemical transformations, but the gentler, more selective conditions under which they operate, (using light, instead of heat, or harsh chemicals), makes possible new and societally impactful chemistry.

However, to use these new reactions at manufacturing scale, a detailed understanding of how the reaction works is required. While organic chemists are fantastic at discovering and developing new reactions, they typically don’t have the tools to probe the details of a reaction. Enter the Rumbles-Reid group at RASEI—a team of physical inorganic chemists who specialize in investigating the “how” of reactions. By reviving an overlooked characterization technique, the RASEI team revealed unexpected details about how these catalysts work. This collaboration was made possible by an Energy Frontier Research Center (EFRC) funded by the U.S. Department of Energy, a collaborative project that brings together expertise from across a range of scientific disciplines. The Bioinspired Light-Escalated Chemistry (BioLEC) EFRC mission has a strong overlap with the RASEI sustainability goals. The team, led by Gary Rumbles and Obadiah Reid, used computational methods to modernize a technique that, despite being over 100 years old (it was first reported in 1915), has found little application in main-stream chemistry.

The photoredox catalyst exists as a pair of molecules, called an ionic pair, so named because each half carries an electronic charge. One half, that contains the metal iridium and is the molecule that interacts with light, is the cation (it has a positive (+) charge because it is ‘missing’ an electron), and the other half is called the anion (it has a negative (–) charge because it has an ‘extra’ electron). Consider the situation when you have two magnets, the opposite poles, or charges, attract, and in the solid form the anion (–) and cation (+) of the catalyst are tightly paired. When the ionic pair is placed in solution to perform the reaction it interacts with the molecules of the solvent, and the attraction between the pair is reduced. When you separate a pair of magnets there is still attraction, albeit weaker, and this is the same for the ionic pair. Common thinking is that during the reaction, while the iridium containing cation is being excited by the light energy, the anion is merely a bystander, close by, but insignificant. This investigation shows that is not the case.

In this approach, with the technical name of Flash-photolysis time-resolved dielectric-loss spectroscopy (fp-TRDL), the reaction sample is irradiated with microwave radiation and by measuring how the microwave changes over time as it passes through the solution the team can quantity how the electrons are shared across the ionic pair. Measurements are taken on the nanosecond scale; one nanosecond is one billionth of a second. Ionic pairs that are strongly bound in solution (two magnets stuck together), produce a strong signal, while an ionic pair that is only weakly bound (two magnets that are separated, but still have some attraction), produce a much weaker signal.

To modernize this technique the RASEI team addressed two critical components. Computer-aided design and simulations were used to fabricate a sample vessel capable of measuring these light-driven reactions, taking measurements in both the ground state (when no light is shining) and in the excited state (when light is being shone on the reaction). And computer code was written capable of analyzing and interpreting the ultra-fast readings taken. This was a great opportunity to showcase the value of this approach, says Garry Rumbles, RASEI Associate Director, and leader of a research thrust in BioLEC.

“Many previous studies with this technique were on fundamental systems, chosen to show how it worked, the chance to work on a catalyst of such current importance was really exciting”.

This revitalized approach provided unprecedented insights into how the catalyst ionic pair behaves in the reaction. Two catalyst systems were investigated, one where the ‘bystander’ anion was small, and the other where the anion was relatively large. When the anion is small, the ionic pair remains tightly bound in the reaction, but when the anion is large, the pair are separated in solution.

What does this mean for the reaction? When the reaction is exposed to light, two different things happen depending on the configuration of the catalyst pair:

Small anion: With a tightly bound ionic pair, the small anion is an active participant in the transformation. When the catalyst is excited by light the ionic pair reorganizes, stabilizing the excited state. This makes the catalyst effective at donating an electron to other chemicals in the reaction—a reduction transformation.
Large anion: With a weakly bound ionic pair, the large anion is not available to reorganize in concert with the excited state, so no stabilization is possible, and the catalyst now favors accepting an electron from other chemicals in the reaction—an oxidation transformation.

The measurements show that there is a four-fold difference in selectivity between these oxidation and reduction. Catalysts with a small anion proceed via a reduction pathway and those with a large anion through an oxidation pathway. Being able to control which path a reaction takes is important, not only to make the required products, but also to reduce impurities and waste.

This collaboration, operating at the intersection of cutting-edge light driven catalysis and reinvention of a century-old technique, reveals that molecules which were previously considered inconsequential bystanders can effectively switch the path of a reaction. Before this, organic chemists may have observed that the choice of anion made a difference to their reaction, but with no tools to better understand this, it remained an unexplored observation. This technique provides a valuable tool to investigate these kinds of reactions, and with better understanding comes improved results.

“This is already changing how we think about photoredox reactions in BioLEC” says Rumbles. “The vast promise of light-driven catalysis means that these kinds of detailed insights could pave the way to a greener and more sustainable way of building organic molecules.”

This collaborative report provides new insight into how reactive species interact.

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