Mechanistic Insights into Electrodeposition in Seawater at Variable Electrochemical Potentials

The classical approach to manufacturing cement and concrete involves considerable and energy-intensive exploitation of minerals from the environment, calling for alternative and sustainable methods to obtain such resources. Electrodeposition resulting from local pH changes near an oxygen or water reduction electrode can be used to grow valuable minerals in seawater for use in the cement and concrete industries, with the potential to use clean electricity without relying on the mining of resources. Limited knowledge is available about the electrochemical reaction networks that yield mineral precipitates via electrodeposition in seawater, hindering a complete assessment of the promise of such an approach to serving the construction industry. This work presents an investigation of the electrodeposition in seawater as a function of the applied potential. The work identifies multiple electrochemical potential regimes that yield distinct polymorphs, quantities, and production rates of calcium and magnesium-based minerals due to the varying rates of oxygen reduction and water-splitting reactions. The quality of the produced minerals is comparable to that of traditionally mined aggregates in terms of morphology and composition, supporting that seawater represents a vast source of raw materials for use in the construction industry upon an enhancement in the efficiency of hydroxide-producing reactions and the reactor design.