Direct Electrolytic Splitting of Seawater: Opportunities and Challenges

Hot, coastal, hyper-arid regions with intense solar irradiation and strong on- and off-shore wind patterns are ideal locations for the production of renewable electricity using wind turbines or photovoltaics. Given ample access to seawater and scarce freshwater resources, such regions make the direct and selective electrolytic splitting of seawater into molecular hydrogen and oxygen a potentially attractive technology. The key catalytic challenge consists of the competition between anodic chlorine chemistry and the oxygen evolution reaction (OER). This Perspective addresses some aspects related to direct seawater electrolyzers equipped with selective OER and hydrogen evolution reaction (HER) electrocatalysts. Starting from a historical background to the most recent achievements, it will provide insights into the current state and future perspectives of the topic. This Perspective also addresses prospects of the combination of direct seawater electrolysis with hydrogen fuel cell technology (reversible seawater electrolysis) and discusses its suitability as combined energy conversion–freshwater production technology.