CAS: Investigations of Monometallic, Bimetallic and Dual-Anion Transition Metal X-ide Water Oxidation Electrocatalysts

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With the support of the Chemical Catalysis program in the Division of Chemistry, Professor Charles B. Mullins of the University of Texas-Austin will be studying materials to facilitate and increase the efficiency of the electrochemical decomposition of water molecules to make oxygen. This is the most important and limiting chemical reaction involved in electrochemical water-splitting to produce hydrogen. Currently hydrogen is heavily used in many industrially important chemical processes and it is anticipated to play a larger role in clean energy production in the future. The energy needs of the world will double over the next ~30 years as the global population increases and underdeveloped nations modernize. Electrochemical water-splitting will play a substantial role in clean energy production to serve this need. In addition to the important science to be uncovered, Mullins and his team will (i) create an animated video regarding energy for grade 8-12 students to assist in motivating these students to become more scientifically literate, (ii) involve researchers from underrepresented groups in this research to broaden participation, and (iii) communicate the results obtained to the broader scientific community and to the general public so that the work can have maximal impact. In this project, Professor Charles B. Mullins and his research group at the University of Texas-Austin will be studying the transformation of various types of metal X-ide (e.g., carbides, chalcogenides, pnictides, and borides) materials into highly active electrocatalysts (i.e., metal oxide/(oxy)hydroxide counterparts). In so doing, a key question will be how the in situ self-oxidation affects the oxygen evolution reaction (OER) performance-governing factors such as active surface area, electrical conductivity, incidental iron incorporation, and so forth. The team will also investigate the water oxidation electrocatalysis of X-ide catalysts which show no apparent self-oxidation during OER. Generally, these performance governing factors are complexly intertwined. To deconvolute the factor of interest from the measured OER activity, Mullins and coworkers will fabricate X-ide films with well-controlled shape, thickness, stoichiometry, and crystal structure via vapor deposition of target X-ide components under high vacuum conditions. The as-obtained films will be probed with many different ex situ characterization techniques as well as with an array of electrochemical methods. To more deeply understand model OER systems, Mullins and team will perform in situ measurements during OER testing, thoroughly undertake physicochemical characterization of post-OER X-ide materials, and perform computational studies as well. Through these systematic investigations, the investigators aspire to be able to provide some universal guidance for designing metal X-ide electrocatalysts, thereby putting forward protocols that could then potentially find broad application in the field of energy transduction.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.