A low-cost calcium silicate hydrate with an exceptionally large sequestration capacity for aqueous divalent nickel

Nickel (Ni) is a high-value resource in industrial economies with essential uses in ferrous and non-ferrous alloys, electric-vehicle batteries, magnets, and catalysts, but has acute supply-chain risks and is classified as a critical material (or mineral). Here we show that large-scale spontaneous sequestration of nickel occurs in a low-cost calcium silicate hydrate material (CS) under mild conditions. CS takes up Ni[Formula: see text] ions rapidly from aqueous solution to achieve loadings as high as 440 kg Ni per tonne CS. This chemistry brings new opportunities in nickel recycling, recovery and environmental clean-up. The Ni sequestration reaction of CS is similar to that previously described (A Hamilton et al., Scientific Reports (2024) 14:7052) for cobalt, although it is about four times faster. Full kinetic and reaction product data are reported. The reaction provides an easy synthesis route to a new Ni-phyllosilicate with a high metal loading, one of a class of materials in active development as catalysts for process-scale water-splitting and reforming reactions.