Coordinatively Unsaturated Selenides over CuFeSe 2 toward Highly Efficient Mercury Immobilization.

Metal selenides have been demonstrated as promising Hg 0 remediators, while their inadequate adsorption rate primarily impedes their application feasibility. Based on the critical role of coordinatively unsaturated selenide ligands in immobilizing Hg 0 , this work proposed a novel strategy to enhance the Hg 0 adsorption rate of metal selenides by magnitudes by purposefully adjusting the selenide saturation. Copper iron diselenide (CuFeSe 2 ), in which the surface reconstruction tended to occur at ambient temperature, was adopted as the concentrator of unsaturated selenides. The adsorption rate of CuFeSe 2 reached as high as 900.71 μg·g -1 ·min -1 , far exceeding those of the previously reported metal selenides by at least 1 magnitude. The excellent resistance of CuFeSe 2 to flue gas interference and temperature fluctuation warrants its applicability in real-world conditions. The theoretical investigations and mechanistic interpretations based on density functional theory (DFT) calculation further confirmed the indispensable role of unsaturated selenides in Hg 0 adsorption. This work aims not only to develop a Hg 0 remediator with extensive applicability in coal combustion flue gas but also to take a step toward the rational design of selenide-based sorbents for diverse environmental remediation by the facile surface functionalization of coordinatively adjustable ligands.