2020 Virtual AIChE Annual Meeting

(513bi) Earth Abundant Transition Metal Phosphide Catalysts for Highly Efficient Oxygen Evolution Reaction in Electrochemical Devices

Authors

Kondori, A. - Presenter, Illinois Institute of Technology
Esmaeilirad, M., Illinois Institute of Technology
Asadi, M., Illinois Institute of Technology
The path toward sustainable energy supplies for our future energy needs opens a new paradigm in development of efficient and cost-effective renewable energy conversion devices. In this regard, improving the efficiency of oxygen evolution reaction (OER) is challenging for many emerging systems, i.e. water-electrolysis, metal-air batteries and fuel cells. Particularly, an efficient OER for water electrolysis offers a promising approach to effectively generate hydrogen, as the main product, to store the intermittent renewable energy in chemical bonds. This reaction is thermodynamically uphill and kinetically slow that requires high overpotentials to achieve suitable rates, calling a need for development of high-performance, earth-abundant catalysts that outperform state-of-the-art precious catalysts (Iridium oxide and ruthenium oxide) to make the application of OER feasible.

Here, we are presenting a study of stable transition metal phosphide (TMP) based catalyst as an earth-abundant candidate with outstanding catalytic properties at active sites for OER in protic media. Activity and stability of our catalyst was tested and compared with state-of-the-art catalysts using cyclic voltammetry and chronopotentiometry experiments in 1M KOH electrolyte. The OER onset potential for our TMP-based catalyst is 1.40 V RHE (η=170 mV), that is ~100 mV lower than IrO2 nanoparticles under identical experimental conditions. A current density of 10 mA/cm2 for this catalyst is achieved at η=270 mV that is 1.3 times lower than IrO2 nanoparticles (η=343 mV), suggesting a 30% higher energy efficiency electrocatalysis using this catalyst. Our measurements indicate a low Tafel slope of 56 mV/dec that is 1.4 times lower than IrO2 (80 mV/dec), suggesting a faster OER kinetics on active sites of the TMP-based catalyst. The cost-effective and high-performance catalyst developed in this study paves the way toward an efficient energy conversion device that can work with renewable energies such as solar/wind energy to address ever-increasing energy demands in a sustainable pathway.