Photocatalytic CO2 reduction and environmental remediation using mineralization of toxic metal cations products

Exploring a sustainable route for the efficient treating/recycling of heavy metal (like Ni²⁺, Cd²⁺, Cu²⁺) contamination of water is highly desirable both from the environment and resource view. Herein, we reported the scale-up synthesis of monolayer magnesium-aluminium layered double hydroxide (m-MgAl-LDH) nanosheets, which showed exceptional ability to mineralize Ni²⁺, Cd²⁺ and Cu²⁺ rapidly and efficiently. Furthermore, m-MgAl-LDH can purify 1 ppm Cu²⁺, Ni²⁺ and Cd²⁺ to safe levels. The sorption sites of heavy metal ions were revealed. Ni²⁺ and Cd²⁺ substitute for the Mg²⁺ sites within the MgAl-LDH layers, while Cu²⁺ ions anchor on the surface of MgAl-LDH with high dispersion. The mineralized products from Ni²⁺ and Cu²⁺ cations further showed excellent performance in visible-light-induced photocatalytic reduction of CO₂ and removal of anions (like PO₄^3- and toxic AsO₂^- ions) efficiently, providing an alternative for the mitigation of energy and resource crisis.