Chemical Sciences (2) Electrochemistry: Earth Abundant Electrocatalytic Materials for Converting CO2 to Value-Added Products
Abstract
The search for Earth-abundant electrocatalysts is critical to understanding how structure relates to function (activity, selectivity, and durability) as well as identifying materials that meet important military needs. The challenge is daunting given the sheer number of possible elemental combinations and the fact that a material at a fixed composition, on the nanoscale, has different properties depending upon its size, shape, and phase structure. Considering all possible material candidates that exist (conservatively speaking, >1020 possible combinations), the traditional serial approach to catalyst discovery based on trial-anderror, will not suffice; the current materials discovery process largely relies on intuitive but subjective, and sometimes serendipitous discoveries. To accelerate this process, we propose the development of an ultrahigh-throughput megalibrary approach to synthesize and screen Earth-abundant electrocatalyst candidates at an unprecedented rate (up to 109 per h). We will develop new synthesis techniques to expand the accessible materials design space, and we will establish advanced electroanalytical and spectroscopic screening strategies that can efficiently evaluate the performance of a huge number of synthesized electrocatalysts. Initial targets will be CO2 reduction electrocatalysts that can be used to synthesize value-added products of importance to the US Army (e.g., methanol, ethanol, ethylene, formate, formaldehyde). Successful execution of this work will expedite the discovery of next-generation catalyst materials of interest to the US Army and enumerate the relationships between nanoscale structure and catalyst function. The fundamental lessons learned from this effort will lay the foundation more broadly for a new and powerful form of materials discovery for reactions of military interest. In the context of the megalibrary platform, scanning probe lithography is used to create hundreds-of-millions of nanoreactors at precise positions on surfaces. This nanolithography process is highly controllable so that each spatially encoded nanoreactor formed on a chip contains precise amounts of chemical precursors in specific combinations and concentrations. Subsequent thermal annealing results in a single well-defined material being formed within each individual nanoreactor, yielding more than 109 unique materials per experiment within hours. To date, these newly synthesized megalibraries have allowed us to discover novel nanostructures that have permitted key insights into catalysis, small-molecule activation, and analyte sensing. These successes uniquely position us to execute a comprehensive one-year investigation into nanomaterial catalysts for electrochemical CO2 reduction specifically. By combining massively parallel materials synthesis with ultrafast electrocatalyst characterization, we will generate a data factory that uncovers design rules that facilitate the rational synthesis of catalysts with desired activities and selectivities. The results will promote the fundamental understanding of key catalyst parameters that determine surface-mediated bond activation and reactant and intermediate formation. We will use fluorescence-based optical techniques and scanning droplet electrochemical cell measurements to achieve rapid CO2 reduction catalyst discovery with Earth-abundant materials. These methods will be used to rapidly characterize catalyst performance by measuring sections of a megalibrary serially or in parallel. The relative catalyst product selectivity and turnover frequency will be determined among the 109 materials by measuring site-specific current densities or product generation, providing a readout in only minutes to an hour. These massive materials synthesis and rapid characterization techniques will allow us to learn about catalyst design at an unprecedented speed.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jul 28, 2023
- Source ID
- W911NF2310141
Entities
People
- Chad Mirkin
Organizations
- Army Contracting Command
- Northwestern University
- United States Army