Electrocatalysts for water electrolysis to produce green hydrogen
Toward greater efficiency
An electrocatalyst is a chemical entity used to lower the energy barrier of electrochemical reactions, such as water electrolysis that is the splitting of water into its elemental constituent (oxygen and hydrogen) by means of an electrical current.
This process requires an electrocatalyst to occur at lower voltages, making it commercially viable.
Therefore, the use of electrocatalysts is essential for improving the efficiency of electrolysis.
There are different types of electrocatalysts for water splitting.
Although the overall chemical reaction is displayed in the following equation as a simple chemical reaction, water splitting is a complicated chemical process (involving several reaction intermediates) and occurs on two separate sides of an electrochemical cell:
Additionally, depending on the pH, the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER) are different.
For example, when we refer to alkaline water electrolysis, the hydroxyl ion functions as a charge carrier and is the reagent for the OER (1) while it shows as a product in HER (2)
Challenges in developing electrocatalysts
The development of electrocatalysts faces several challenges. One of the primary issues is selectivity: the electrocatalyst must accelerate a specific chemical reaction while avoiding unwanted side reactions.
Additionally, considering the nature of an electrocatalyst for water electrolysis, which is usually a metal oxide, we need to consider its semiconducting properties. The composition and the particle size of the metal oxides are key for their conductivity and for unlocking performance levels comparable to their noble metal counterparts, making them a viable alternative for cost-effective and sustainable water electrolysis.
Finally, industrial scalability of the process is a crucial factor: the synthesis of an electrocatalyst must be lean and straightforward, and its costs competitive to allow large-scale production.
Future prospects and electrification
Despite the challenges, the future of electrocatalysts is promising.
As the world is moving towards electrification and more sustainable choices, the world of electrochemistry is following suit. The electrocatalyst arena for water electrolysis is trying to move beyond the precious metals and towards finding first-row transition metal oxide that are as performing.
Machine learning (ML) and artificial intelligence (AI) as well as high-throughput experimentation (HPE) can help in this sense. In fact, each with their own unique advantages can help develop better electrocatalysts for green hydrogen production.
For example, using AI and ML can simplify the way we optimize a catalyst by looking at several datapoints and make a virtual screening of electrocatalysts considering multiple features such as mechanisms of reactions, morphologies, pyrolysis screening etc.
Similarly, with HPE, we can speed up the synthesis of electrocatalysts and access thousands of different compositions, finding the most performing ones in a short period of time thus reducing labor and overall process costs.
De Nora’s contribution to research
De Nora’s scientists are actively participating in the race toward finding better electrocatalysts for water electrolysis to produce green hydrogen.
Their aim is lowering the costs of the current technologies, abandoning or minimizing the use of non-abundant and precious metals as well as finding better technological solutions to make electrochemical processes scalable, contributing to the decarbonization of the energy sector and achieving net-zero by 2050.