SISCA

SISCA in Review: 2012 to 2017

Caltech's Sustainability Innovation Student Challenge Award (SISCA) prize program was established by Dow to recognize and reward students for their innovation and research aimed at finding sustainable solutions to the world's most pressing social, economic and environmental problems.

The program started at Caltech in 2012, and ran through 2017. While active, SISCA was open to currently enrolled Caltech graduate students and teams with at least one Caltech graduate student team member.

SISCA applicants had to explain what global challenge their project or research aimed to solve sustainably and how it related to the selection criteria, inclusive of how it tied into advancing Dow's Sustainability Goals. Entrants went on to participate in a celebratory poster session, where the winners were announced.

Winning projects and research featured analysis from multiple disciplines and reflected a commitment to deliver breakthrough solutions for global challenges such as food (security, waste reduction, nutrition access), energy (efficiency and conservation), water (security, conservation, efficiency), climate change, nature and social issues.

Selection Criteria

• Potential for solving world challenges in alignment with the spirit of Dow's 2025 Sustainability Goals
• Interdisciplinary nature of work: An ideal SISCA winning project features interdisciplinary work with implications of the work extending beyond the student's primary discipline or area of study.
• Innovative thinking and excellence in research or project implementation

Wen-Hui Cheng is a PhD student in Materials Science. She is member of Professor Harry Atwater's research group and part of the Joint Center of Artificial Photosynthesis (JCAP). Matthias Richter is a postdoctoral scholar in Professor Nate Lewis' group, also working with JCAP. Their winning innovation is a breakthrough device for splitting water with sunlight to make hydrogen fuel with remarkable efficiency!

The team's promising design brings us closer to meeting the US Department of Energy's target of $2/kg hydrogen and paves the way for high performance to become the new norm. By carefully managing the electronic properties of the semiconductor/protection layer/catalyst combination, the anti-reflection properties of the protection layer, and optical properties of the high performance catalyst used for hydrogen production, their device works with record solar-to-hydrogen efficiency of 18.5%.

Using a tandem III-V photovoltaic structure in conjunction with optimized electrocatalysts that are deposited by methods they developed, their device maximizes the efficiency, while minimizing parasitic optical absorption and reflection losses. Operating at approximately 80% of the theoretical maximum for the light absorbers used, their results signify that catalyst overpotentials are minimized, resistive losses through the device are lessened, and optical losses are largely reduced.

The team's future work will begin to explore the advantages of having a device that works well at neutral pH. Chief among these is the electrochemical reduction CO₂ to potential carbon-based fuels or fuel precursors, as this process is generally best accomplished at neutral pH. Transforming waste CO₂ by direct photoelectrochemical CO₂ reduction into a valuable raw material is an important first step towards a circular CO₂ economy and CO₂ footprint mitigation.

Our Runner Up team includes chemistry graduate students Anthony Chen and David Schuman, and postdoctoral scholars Julian West and Bryan Hunter. Working in the labs of Professors Harry Gray and Brian Stoltz, this team has combined their expertise in inorganic synthesis, electrochemistry, catalysis, and organic synthesis towards development of a C–H oxidation process that is sustainable by design.

C-H oxidation is an important chemical reaction that is essential in both industrial and natural processes. In industry, current C–H oxidation methods typically use toxic metals (e.g. chromium) and/or dangerous oxidizing reagents (e.g. hydrogen peroxide), both of which can be hazards to the environment and workers.

In contrast, the team is refining a breakthrough highly-active water oxidation electrocatalyst made from earth abundant elements (iron and nickel) that is able to readily oxidize C–H bonds. Preliminary data also shows that the selectivity of the catalyst may be tuned by simply modulating the applied potential. This hitherto-unknown means of control has the capability to vastly simplify synthetic schemes for making pharmaceuticals, advanced materials, and low-carbon fuels.

The team is hopeful that their approach will increase confidence in chemical technology by demonstrating how it eliminates toxic and environmentally-hazardous components necessary for previous technologies. Their ongoing research aims to further increase the efficiency of the system while simplifying reaction set-up.

Our winning team is comprised of Russell (Rusty) Lewis, a graduate student in bioengineering, Kai Chen, a graduate student in chemistry, and Jenny Kan PhD a postdoctoral scholar in chemistry & chemical engineering–All members of Frances Arnold's diverse and highly collaborative research group.

Drawing on their expertise in chemistry, biology and engineering, the team developed a biocatalyst capable of carbon-silicon bond formation. Specifically, they discovered that heme proteins could produce organosilicons via carbene insertion into silicon-hydrogen bonds, a transformation that has no precedent in natural biological systems.

Conventional methods for the synthesis of organosilicon compounds are limited in their efficiency, selectivity, and sustainability. As these materials have wide use in pharmaceuticals, agrochemicals, medical diagnostics, coatings and paints, organic LEDS, and more, this new biocatalytic approach to organosilicon chemistry offers powerful new solutions to the global challenge of sustainable chemistry.

The team's iron-based biocatalyst is renewable, biodegradable and non-toxic. It can also be produced very cheaply by fermentation using well-established recombinant protein expression technology. It functions in water, at ambient temperature and at neutral pH, both in vitro and in whole E. coli cells, making it the first biocatalyst capable of carbon-silicon bond formation and the first iron-based catalyst ever reported for this transformation.

Furthermore, the biocatalyst outcompetes the best synthetic catalysts known for this class of reaction in terms of cost, operational ease, catalyst efficiency and environmental impact. And, since the engineered enzymes are fully genetically-encoded, assemble and function in cells, the new chemistry can be integrated with metabolic pathways to utilize renewable resources such as biomass for creating new organosilicon products.

To learn more see Caltech's news feature "Bringing Silicon to Life".
This innovation has also gone on to be featured by C&EN as one of 2016's top research highlights -scroll down to biocatalysis.

Jinglin Huang is a graduate student in medical engineering and Cong Wang is a graduate student in aerospace engineering. Both work in Dr. Gharib's lab and together they have been developing enhanced superhydrophobic materials made from Carbon Nanotubes (CNT) for applications in solar seawater desalinization systems.

Solar-driven seawater desalination or solar distillation is a promising water treatment technology that is currently prohibitively expensive. During this process, seawater flows through a series of channels and is evaporated, captured and condensed into fresh water. Over time, salts build up in the channels requiring that the system be shut down and the channels flushed out using expensive energy and clean water inputs.

Huang & Wang's custom CNT superhydrophobic materials aim to eliminate the salt build up altogether, which would allow for continuous and cost-effective distillation. CNT also has fantastic light and heat-absorbing properties that can assist the distillation process and improve water evaporation efficiency. The materials repel salt and prevent corrosion by creating a layer of air between the surface and flow. By modifying the material's surface geometry, the team has improved the surface performance and stability of the critical air layer.

Trevor Del Castillo and Niklas Thompson are graduate students in chemistry advised by Professor Jonas C. Peters. Their research focuses on the mechanism of the fixation of dinitrogen (N₂) to ammonia (NH₃) catalyzed by iron (Fe) complexes.

Although N₂ constitutes 80% of the Earth's atmosphere, this inert gas must be reduced –or "fixed" –into reactive forms such as NH₃ before the element can be incorporated into fertilizers and commodity chemicals. Currently, the industrial synthesis of NH₃ comes from N₂ and H₂ via the energy-intensive Haber-Bosch process.

Haber-Bosch is performed on a staggering scale –annually consuming ~2% of the global energy supply and ~4% of the global natural gas supply in order to produce over 120 million metric tons of reduced nitrogen. Unfortunately, due to the intense reaction conditions and high associated overhead cost, this process is not practiced in a fashion that can be sustained moving forward. Understanding how to catalyze this reaction under mild conditions with earth-abundant materials is an important step in developing a sustainable method for the synthesis of NH₃.

Inspired by the nitrogenase family of enzymes that perform biological nitrogen fixation at ambient pressures and temperature, Del Castillo and Thompson's research group previously discovered that certain phosphine-supported iron compounds can catalyze the reduction of N₂ to NH₃ at low temperature and ambient pressure using proton and electron equivalents.

Del Castillo and Thompson have since demonstrated that their most active iron based catalyst is among the most robust molecular N₂ to NH₃ conversion catalyst known. Looking forward, the team envisions the development of a process coupling artificial photosynthesis to the reduction of N₂ to NH₃, opening the door for modular, affordable, onsite fertilizer production.

Cody Finke is a PhD student in environmental science and engineering in Professor Michael Hoffmann's research group. Justin Jasper is a Resnick Sustainability Institute Postdoctoral Scholar also working with the Hoffman team. Together they've been enhancing a modular, solar powered, electrochemical, on-site wastewater treatment system created by their group for toilets in the developing and developed world.

The duo incorporated a low-pressure (germicidal) UV lamp that converts free chlorine to the powerful oxidant hydroxyl radical (OH) into the technology. By applying UV irradiation during electrochemical treatment of toilet wastewater, treated water quality is enhanced as compared to electrochemical treatment alone.

With UV added to the electrochemical wastewater treatment process, additional removal of organic carbon and pharmaceuticals, combined with nitrogen and phosphate removal, results in water suitable for agriculture and ecosystem services. Further, a lower formation rate of carcinogenic disinfection by-products provides water that is safe for reuse as flushing and hand-washing water, and potentially as drinking water.

With an operating cost of less than 5 US cents per day, this wastewater treatment technology meets benchmarks for affordability in the developing world. This system has the potential to protect human health and ecosystem well-being in communities most at risk to disease and resource-loss through environmental pollution.

Anton is a PhD candidate in chemistry advised by Professor Robert H. Grubbs. His work responds to the challenge of finding alternatives to precious metal catalysts. This is important because currently precious metal catalysts are routinely used on very large scales in the chemical industry to produce everyday items such as medicines, crop protection agents, cosmetics, plastics and electronics. The problem with precious metals is that they are extremely expensive, steadily rarefying and non-renewable. They are also toxic to humans and poisonous to the environment.

Anton's research led to the discovery that a catalyst based on potassium –potassium tert-butoxide is able promote a fundamental chemical reaction: bond formation between carbon and silicon atoms. Not only does it successfully replace precious metals, but it appears to be a superior catalyst: as bond formation proceeds at ambient temperature; with higher turnover; without solvent, or water; and producing H₂ as the only byproduct. Further, the reaction uses commodity chemicals and inexpensive silicon sources as starting materials. The discovered potassium catalyst is orders of magnitude less expensive than the state-of-the-art precious metal catalysts.

The catalyst itself can be simply prepared in a single chemical step from renewable materials: tert-butanol is obtained from lignocellulose and the potassium is obtained from plant matter (potash; produced worldwide at amounts exceeding 30 million tonnes per year for use in fertilizers). This method has been demonstrated to produce hundreds of grams (and appears "indefinitely scalable" without loss of activity) of academically- and industrially useful chemical building blocks at very low cost. The reaction produces no toxic waste streams (heavy metal or otherwise). The reagents and catalyst safely decompose in the environment into benign materials: silicates, and t-BuOH, KOH, and K₂CO₃ respectively. This discovery has thus far prompted collaborations spanning multiple fields including drug discovery, semiconductor synthesis, and nuclear medicine.

Prineha Narang is a PhD candidate in applied physics, co-advised by Professors Nathan S. Lewis and Harry A. Atwater. Pri's research is aimed at discovery and integration of new components for a prototype solar fuels generator built by the Joint Center for Artificial Photosynthesis (JCAP), where she's been a researcher since her arrival at Caltech.

A solar fuels generator requires semiconducting materials for light absorption and Pri's research has revealed a new class of nitride materials, the Zinc-IV-nitrides, with tunable light absorption properties that make them promising candidates for this role. Further, since the materials are abundant, such devices are more likely to be scalable to cost-effective mass production.

In tandem to her semiconductor experiments, Pri has engaged in theoretical work exploring using plasmonic hot carriers to drive photocatalysis in a solar fuels device. Plasmons are collective electron oscillations in a conductive material, with the unique ability to absorb and scatter light at specific wavelengths across a wide region of the electromagnetic spectrum. Plasmon-driven chemistry is a significant departure from traditional catalysis efforts and could couple light energy into chemical reactions in a manner that would greatly reduce the energy input requirements of chemical reactions.

Nicole Peck is a PhD student in bioengineering in Frances Arnold's research group and Dr. Zhan Wang is a postdoctoral fellow also working with the group. The two scientists have engineered biocatalysts to develop enzymatic alternatives to traditional transition metal catalysis. Specifically, the team engineered cytochrome P450 enzymes to perform carbene transfer, the carbon analogue of P450's native monooxygenation chemistry. This transformation has never been seen in nature, and can be used to construct important carbon-carbon bonds.

Their biocatalysis method will save energy and lessen the impact on the environment because enzyme reactions take place in water, at room temperature and without toxic organic solvents or difficult purification steps. By expanding the reactions available through biosynthesis the team has opened a pathway for several key pharmaceuticals and agrochemicals to be produced with sustainable synthesis, which will lessen the environmental impact of the chemical industry. The potential applications of this new method are being further developed at Caltech in collaboration with Provivi, a startup formed by recent Caltech graduates.

Raymond is a fourth year graduate student in chemistry. His SISCA project outlines a method for recycling ruthenium-based catalysts that are used in olefin metathesis—an organic reaction routinely used in the synthesis of pharmaceuticals, advanced materials and fine chemicals. In the process of experimenting with making photoresists, Raymond discovered that the supposedly dead catalyst "waste" from these reactions can be reactivated by ultraviolet light. Through experimentation, he developed a waste-free synthesis of a new kind of photoresist with immediate applications in green microfabrication, and also identified how this discovery could be used to close the catalyst waste cycle in olefin metathesis chemistry.

Weitekamp has termed the patterning process PhotoLithographic Olefin Metathesis Polymerization (PLOMP). PLOMP resists can be prepared without generating any waste, at ambient temperature. Raymond hopes this invention will improve the energy efficiency of high-tech device manufacture, including integrated circuits, medical devices and MEMs.

Prakhar Mehrotra is a PhD student in aeronautics. His team's winning idea "Micro-Cold Storage" was aimed at addressing agricultural supply chain inefficiencies in developing nations. The team's concept creates a network of low-cost, small-scale cold storage units to mitigate the lack of cold storage infrastructure that in India alone wastes about 30% of all foods.The product they developed is a portable, high efficiency cold storage unit with photovoltaic panels scaled to fit on a standard size U-Haul truck. The PV panels power the cooling system, which is based on an efficient vapor compression cycle. The team has developed thermal storage technology to back up the system and a special control system to keep stored items fresh while reducing the cooling load by 15%. Winning SISCA has motivated the team to accelerate development of the product and has reinforced their vision of creating a clean and sustainable infrastructure for food storage.

Team members included Devendra Gupta, Prakeek Singhal and Vivek Pandy, students from the Indian Institute of Technology Kharagpur.

Kangwoo is a PhD student in environmental ecience and engineering. His SISCA project showcases technology aimed at creating a technically feasible and economically viable means of sustainably treating human waste. Powered by solar panels, the electrolysis cell uses wastewater as an electrolyte and inexpensive, highly reactive electrodes from bismuth oxide doped titanium dioxide. When activated, chloride in the wastewater is oxidized to the reactive chlorine species, which can degrade environmental pollutants including fine particles, dissolved organics and other aqueous pollutants. Additionally, oxygen and hydrogen are produced making this not only an infrastructure-free approach to sanitation, but also one that can be an energy source, through proper energy conversion practices. The chemistry presented in Kangwoo's SISCA project is a continuation of research being done by his Caltech research group (the Hoffmann Group) that won the grand prize at the Reinvent the Toilet Challenge sponsored by the Bill and Melinda Gates Foundation.

This project is being contributed to by members of Professor Michael Hoffmann's Group including Yan Qu, Hao Zhang, Daejung Kwon, Clement Cid and Asghar Aryanfa.