Under-Coordinated Selenide Enriched Amorphous Cobalt Selenide Prepared under Ambient Conditions for Highly Efficient Immobilization of Gaseous Elemental Mercury

The limited adsorption capacity of commercialized sorbents towards elemental mercury (Hg-0) remains a major challenge facing their extensive applications under the regulation of the Minamata Convention. Metal selenides were recently found to be promising alternatives to commercialized sorbents for capturing Hg-0 from industrial flue gas due to the high affinity between Hg-0 and selenide. In metal selenides, under-coordinated selenide sites play critical roles in oxidation and subsequent immobilization of Hg-0, while there is still no simple way to increase the abundance of under-coordinated selenide in metal selenides under ambient conditions. In this work, an effective and facile precipitation pathway was proposed to prepare amorphous cobalt selenide (a-CoSe2) with under-coordinated selenide enriched surface under ambient conditions. The a-CoSe2 as synthesized achieved outstanding Hg-0 uptake capacity and adsorption rate (534.2 mg g(-1) and 483.1 mu g g(-1) min(-1)), far surpassing those of crystalline cobalt selenide (c-CoSe2) by magnitudes. The characteristic results demonstrated that the under-coordinated selenide enriched nature of a-CoSe2 is the principal reason causing the significant performance improvement, which is fully in line with our hypothesis and purpose. This work not only proposes a potential sorbent for efficient Hg-0 sequestration from industrial flue gas but also inspires the further development of synthesis strategies for amorphous materials.