Jiao Group

Recent News

2018-08-21: Carbon monoxide electrolysis at high current densities!

INFEWS

Carbon monoxide electrolysis has previously been reported to yield enhanced multi-carbon (C2+) Faradaic efficiencies of up to ~55%, but only at low reaction rates. This is due to the low solubility of CO in aqueous electrolytes and operation in batch-type reactors. Here, we present a high-performance CO flow electrolyser with a well controlled electrode–electrolyte interface that can reach total current densities of up to 1 A cm–2, together with improved C2+ selectivities. Computational transport modelling and isotopic C18O reduction experiments suggest that the enhanced activity is due to a higher surface pH under CO reduction conditions, which facilitates the production of acetate. At optimal operating conditions, we achieve a C2+ Faradaic efficiency of ~91% with a C2+ partial current density over 630 mA cm–2. Further investigations show that maintaining an efficient triple-phase boundary at the electrode–electrolyte interface is the most critical challenge in achieving a stable CO/CO2 electrolysis process at high rates. A news story regarding this project can be found here. And the Nature Catalysis paper can be viewed using this link.

2018-08-07: New NSF-NSFC joint project funded for innovations on the Nexus of Food, Energy, and Water systems

INFEWS

The Food-Energy-Water (FEW) Nexus is the compilation of the nitrogen, carbon, phosphorous, and water cycles interacting in equilibrium. Due to optimization of individual components of FEW systems in isolation, these cycles are quickly being pushed beyond the limit of their natural equilibria. One remedy to this challenge is to bring the four major cycles back into equilibrium by developing novel, renewable energy powered and efficient technologies. Through close collaboration with our research partners at Tianjin University, we (the Jiao and Xu Labs) at the University of Delaware will design a solar-driven catalysis system capable of producing liquid carbon fuels from carbon dioxide and water. A news story regarding this project can be found here.

2018-07-25: Mechanistic insights into CO2 reduction on Au and Ag

mechanism

Understanding reaction pathways and mechanisms for electrocatalytic transformation of small molecules, e.g., H2O, CO2, and N2, to value-added chemicals is critical to enabling the rational design of high-performing catalytic systems. Tafel analysis is widely used to gain mechanistic insights, and in some cases, has been used to determine the reaction mechanism. In a recent Perspective, we discussed the mechanistic insights that can be gained from Tafel analysis and its limitations using the simplest 2-electron CO2 reduction reaction to CO on Au and Ag surfaces as an example. By comparing and analyzing existing as well as additional kinetic data, we show that the Tafel slopes obtained on Au and Ag surfaces in the kinetically controlled region (low overpotential) are consistently ~59 mV dec-1, regardless of whether catalysts are polycrystalline or nanostructured in nature. The full discussion was published in ACS Catalysis.

2018-07-09: Generating oxygen from carbon dioxide

looping

Reclaiming oxygen (O2) efficiently from carbon dioxide (CO2), a major product of human metabolism, is a key technology to minimize the oxygen supply for challenging missions such as manned deep space exploration. Together with our partner at NASA Glenn Research Center, we developed an electro-thermochemical hybrid looping (ETHL) strategy to split CO2 into elemental carbon (C) and O2 under mild conditions with a 100% theoretical oxygen recovery efficiency, which cannot be accomplished using any existing electrochemical or thermochemical processes. Full details of this technology can be found in our recent publication in Energy & Environmental Science.

2018-04-11: Dr. Jiao testified before a senate committee!

Techno-Economic

Dr. Jiao was invited by U.S. Senator John Barrasso and Senator Tom Carper to testify before the Senate Committee on Environment and Public Works on April 11, 2018. The purpose of this hearing is to examine S. 2602, the Utilizing Significant Emissions with Innovative Technologies Act (or USE IT Act). The bill covers important research and investments on carbon capture and utilization technologies, including direct air capture, carbon utilization, and infrastructure. A full record of this hearing can be found at HERE. Link to the UDaily story.

2018-01-21: Cost analysis of CO2 electrolysis technologies!

The electrochemical reduction of carbon dioxide (CO2) has received significant attention in academic research, although the techno-economic prospects of the technology for the large-scale production of chemicals are unclear. In this work, we briefly reviewed the current state-of-the-art CO2 reduction figures of merit, and performed an economic analysis to calculate the end-of-life net present value (NPV) of a generalized CO2 electrolyzer system for the production of 100 tons/day of various CO2 reduction products. Under current techno-economic conditions, carbon monoxide and formic acid were the only economically viable products with NPVs of $13.5 million and $39.4 million, respectively. However, higher-order alcohols such as ethanol and n-propanol could be highly promising under future conditions if reasonable electrocatalytic performance benchmarks are achieved (e.g. 300mA/cm2 and 0.5V overpotential at 70% faradaic efficiency). Herein, we established performance targets such that if these targets are achieved, electrochemical CO2 reduction for fuels and chemicals production can become a profitable option as part of the growing renewable energy infrastructure. The results have been published in Industrial & Engineering Chemistry Research.

2017-10-10: Solar-powered CO2 electrolyzer!

A first-of-its-kind solar CO2 flow cell electrolyzer is reported here with a solar-to-fuel efficiency (SFE) of 6.5% at high operating currents (>1 A), orders of magnitude greater than those of other reported solar-driven devices that typically operate at currents of a few milliamperes. The approach of solar module-driven electrolysis, compared to monolithic photoelectrochemical cells, allows simpler manufacture, use of commercially available components, and optimization of the power transfer between the photovoltaic and the electrochemical systems. The results have been published in ACS Sustainable Chemistry & Engineering.

2017-08-07: Perspective Article in ACS Catalysis - Nanoporous Metals as Electrocatalysts: State-of-the-Art, Opportunities, and Challenges

Nanoporous metals with their distinct three-dimensional interconnected porous networks are promising materials as electrocatalysts for fundamental studies and practical applications because they have highly conductive self-supporting porous structures with large electrochemical surface areas. This Perspective provides an overview of the recent developments and state-of-the-art nanoporous metals as electrocatalysts for various important electrochemical systems. Potential strategies and opportunities for utilizing the unique characteristics of nanoporous metals to overcome typical problems faced in electrocatalysis are presented. Lastly, challenges regarding the synthesis of nanoporous metals with controlled porous structure and targeted surface catalytic sites are also discussed to stimulate new ideas and interests for nanoporous metallic electrocatalysts.

2017-05-06: Charles won the 2017 Chemical Engineering Industrial Sponsors Undergraduate Research Award!

Congratulations to Charles for winning the Chemical Engineering Industrial Sponsors Undergraduate Research Award to recognize his research achievement in renewable chemical productions. The award was presented at the 2017 College Recognition of Academic Honors & Achievements Ceremony on Saturday, May 6, 2017 at Mitchell Hall.

2017-04-11: Wesley wins the 2017 Bill N. Baron Fellowship Award!

Congratulations to Wesley for winning the 2017 Bill N. Baron Fellowship Award for his contribution to the solar energy field. The award will be the presented at 2017 College Recognition of Academic Honors & Achievements Ceremony on Saturday, May 6, 2017 at Mitchell Hall.

2017-04-10: Nanoporous catalysts for biomass conversion

Biomass

By finding new catalysts for selective and efficient conversion of biomass-derived products to industrially relevant chemicals and fuels, a transition from fossil fuel feedstocks may be achieved. Furfural is a platform chemical which may be converted to multiple heterocyclic and ring-opening products, but to date there have been few catalysts which enable selective hydrodeoxygenation to 2-methylfuran. In this work, we present a self-supported nanoporous Cu–Al–Co ternary alloy catalyst with high furfural hydrodeoxygenation activity toward 2-methylfuran, achieving up to 66.0% selectivity and 98.2% overall conversion at 513K with only 5% Co composition. The results have been published in Industrial & Engineering Chemistry Research.

2017-03-02: Wesley wins the Kokes Award!

Congratulations to Wesley for winning the 2017 Kokes Award for the 25th North American Catalysis Society (NACS) meeting in Denver, CO.

2017-02-24: Turning carbon dioxide into alcohols

Our group is receiving a grant from the US Department of Energy to develop a technology, which allows us to convert CO2 captured in the flue gas into high-value alcohols. So excited! A news story about this grant was just released by UDaily and the official DOE announcement can be found here.

2017-02-17: Spectroscopic study of electrochemical CO2 reduction on gold

FTIR

Molecular level understanding of the role of bicarbonate in increasing CO2 reduction rates is an important topic, while the lack of in-situ tools make it difficult to directly probe the electrochemical interface. Together with the Xu lab and other collaborators, we developed a protocol to observe normally invisible reaction intermediates with a surface enhanced spectroscopy by applying square-wave potential profiles. Further, we demonstrate that bicarbonate, through equilibrium exchange with dissolved CO2, rather than the supplied CO2, is the primary source of carbon in the CO formed at the Au electrode by a combination of in-situ spectroscopic, isotopic labeling, and mass spectroscopic investigations. We propose that bicarbonate enhances the rate of CO production on Au by increasing the effective concentration of dissolved CO2 near the electrode surface through rapid equilibrium between bicarbonate and dissolved CO2. The results have been published in JACS.

2017-02-17: Wesley wins the University Doctoral Fellowship Award

Congratuations to Wesley for winning the University Doctoral Fellowship Award! Well done!

2017-01-19: A bimetallic catalyst for electrochemical CO2 reduction to formate

AgSn

First-row transition metals are potential candidates as catalysts for electrochemical CO2 reduction; however, their high oxygen affinity makes them easy to be oxidized, which could, in turn, strongly affect the catalytic properties of metal-based catalysts. Together with collaborators at Northwestern University and Virginia Tech, we recently proposed a strategy to synthesize Ag-Sn electrocatalysts with a core-shell nanostructure that contains a bimetallic core responsible for high electronic conductivity and an ultra-thin partially oxidized shell for catalytic CO2 conversion. This concept was demonstrated by a series of Ag-Sn bimetallic electrocatalysts. At an optimal SnOx shell thickness of ~1.7 nm, the catalyst exhibited a high formate Faradaic efficiency of ~80% and a formate partial current density of ~16 mA cm-2 at -0.8 V vs. RHE, a remarkable performance in comparison to state-of-the-art formate-selective CO2 reduction catalysts. The results have been published in JACS.

2016-11-07: New Group Member: Emily Jeng

We are happy to announce that Emily Jeng is going to join us beginning in January 2017. Emily, welcome to the Jiao group!

2016-09-06: Photoelectrochemical carbon dioxide reduction using a nanoporous Ag cathode

PEC

Solar fuel production from abundant sources using photoelectrochemical (PEC) systems is an attractive approach to address the challenges associated with the intermittence of solar energy. In comparison to electrochemical systems, PEC cells directly utilize solar energy as the energy input, and if necessary, an additional external bias can be applied to drive the desired reaction. In our recent work, a PEC cell composing of a Ni-coated Si photoanode and a nanoporous Ag cathode was developed for CO2 conversion to CO. The thin Ni layer not only protected the Si wafer from photo-corrosion, but also served as the oxygen evolution catalyst. At an external bias of 2.0 V, the PEC cell delivered a current density of 10 mA cm-2 with a CO Faradaic efficiency of ~70%. More importantly, a stable performance up to 3 hours was achieved under photoelectrolysis conditions, which is among the best literature reported performances for PEC CO2 reduction cells. The photovoltage of the PEC cell was estimated to be ~0.4V, which corresponded to a 17% energy saving by solar energy utilization.

Link: News Archive