Chemical solution-based synthesis of earth-abundant electrocatalysts for PEM water electrolysis

Abstract

CLEANH2: Chemical solution-based synthesis of earth-abundant electrocatalysts for PEM water electrolysis Naomi Billiet, Dries De Sloovere, Mohammadhosein Safari, Marlies K. Van Bael, An Hardy UHasselt, Institute for Materials Research (IMO-Imomec) and Imec division Imomec, DESINe, Agoralaan, building D, 3590 Diepenbeek, Belgium. EnergyVille, Thor Park 8320, 3600 Genk, Belgium In the effort to combat global warming, there is an urgent need for clean energy production. Herein, hydrogen gas (H2) plays an important role as it can function as energy storage chemical and clean fuel. Hydrogen gas has a high specific energy density, it has carbon dioxide (CO2) free combustion and functions as a feedstock chemical for several relevant chemicals such as ammonia and methanol. A promising production method for H2 is water electrolysis making use of renewable energy sources. Water electrolysis produces H2 and O2 via the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). This method does not release CO2 or other volatile by-products in contrast to steam methane reforming, coal gasification and oxidation of hydrocarbons.1 Commercial water electrolysis methods are alkaline electrolysis and PEM (proton exchange membrane) electrolysis. The advantages of PEM electrolysis compared to alkaline electrolysis are the higher energy efficiency, quick response, scalability and the possibility to work at elevated pressures.2 Unfortunately, PEM electrolysis still has some challenges, such as the high price and low abundancy of the electrocatalysts. In the CLEANH2 project, we tackle these challenges. Our aim is to select, synthesize, characterize and evaluate earth-abundant electrocatalysts for both HER and OER. The focus will be placed on metal sulfides for HER and metal oxides for OER.3-6 These materials will be synthesized by solution-based synthesis methods, such as hydrothermal synthesis and sol-gel synthesis. The synthesis parameters will be varied to optimize the materials properties and morphology for PEM electrolysis. These will be linked to the catalytic activity for water electrolysis and the stability of the material. 1. Acar, C. et al. Comparative assessment of hydrogen production methods from renewable and non-renewable sources. International journal of hydrogen energy. 39, p1-12 (2014). 2. Guo, Y. et al. Comparison between hydrogen production by alkaline water electrolysis and hydrogen production by PEM electrolysis. IOP Conference series: Earth and Environmental Science. 371, p42022 (2019). 3. Sun, X. et al. Earth-abundant electrocatalysts in proton exchange membrane electrolyzers. Catalysts, 8/12, p657 (2018). 4. Guo, Y. et al. Nanoarchitectonics for Transition-Metal-Sulfide-Based Electrocatalysts for Water Splitting. Advanced Materials, 31/17, p1807134 (2019). 5. Gu, X. et al. Oxygen evolution electrocatalysis using mixed metal oxides under acidic conditions: Challenges and opportunities. Journal of Catalysis. 388, p130-140 (2020). 6. Gao, J. et al. Progress of Nonprecious-Metal-Based Electrocatalysts for Oxygen Evolution in Acidic Media. Advanced Materials. 33/31, p2003786 (2021).