The escalating global climate crisis has led researchers at Northwestern University to develop carbon-negative building materials. By harnessing seawater, electricity, and CO2, scientists have created a method to trap greenhouse gases in solid minerals, inspired by natural processes like shell formation in marine organisms. This innovative approach involves splitting seawater using electricity to generate hydrogen and hydroxide ions, which, when combined with CO2, lead to the formation of minerals like calcium carbonate and magnesium hydroxide that effectively capture and store CO2. These mineral materials, which can be controlled in texture and density, have the potential to replace sand and gravel in concrete, as well as serve as the foundation for other construction materials like cement, plaster, and paint. The process not only offers a sustainable alternative to traditional sourcing of sand but also demonstrates the ability to store over half of their weight in CO2, depending on the mineral composition. This method not only mimics nature's long-term carbon storage solutions but also produces clean hydrogen gas that can be used as a clean fuel for various applications. The study envisions a circular approach where CO2 is sequestered right at the source, with the possibility of localized production of materials for the construction industry using clean electricity. The findings highlight the potential to transform the construction sector by reducing carbon emissions and creating carbon sinks through innovative material production.