Tom Mackay

To meet the Net Zero targets pledged by the UK government by 2050, a transition from fossil fuels to renewable resources is imperative. However, renewable resources are intermittent; thus, energy storage solutions must be developed that store excess energy created by renewables for when production cannot meet demand. One sustainable energy carrier is hydrogen. Hydrogen stores a significant amount of energy and can be produced by electrically splitting water in an electrolyser. Nevertheless, global freshwater availability is location dependent. To overcome this challenge, highly abundant seawater can be used, but this introduces challenges due to the asymmetry and the plethora of contaminants.

It is of immense importance that electrolyser efficiency is maximised. Consequently, catalysts are used that minimise the energy requirements and maximise the amount of hydrogen produced. Traditionally, expensive noble metals have been used as catalysts, but to increase the commercialisation inexpensive earth abundant materials must be used instead.

The electrolyser is divided into the oxygen producing side- anode and the hydrogen producing side- cathode. Few cathodic catalysts have shown performances exceeding platinum in seawater and crucially fewer have shown stabilities worthy of industry. Many cathodic catalysts are susceptible to contaminant poisoning, particularly from Mg²⁺ and Ca²⁺ ions, which degrades the performance over time. A problem-solving and engineering approach is necessary to ensure the catalyst imparts a high efficiency, longevity and is sustainable. Molybdenum, nickel and sulphur-based materials have shown promise in freshwater electrolysis and by meticulously adjusting the structure the performance can be ameliorated, but insights in seawater are limited. My project will aim to study the performance of molybdenum/nickel sulphide cathodic catalysts in seawater and purposefully engineer strategies to endow a high activity and stability.