Title : Fe–M (M = Co, Ni) dual-atom metal-doped carbon nitride for catalytic reduction of HgCl2
Abstract:
Although low-temperature catalytic reduction can effectively reduce HgCl2 to Hg0, its practical application is hindered by the low reduction efficiency and deactivation of active sites caused by the reaction of acidic gases with the catalyst. In this study, a bimetallic organic framework is assembled by Fe–Ni that is used to provide single metal atom pairs. In addition, two novel dual-atom catalyst (Fe1Ni1CN and Fe1Co1CN) are precisely synthesised via calcination, in which adjacent Fe/Ni and Fe/Co single atom pairs are decorated on a g-C3N4 substrate. Owing to the synergistic effect between the atom pairs, the d-band electronic activity of catalysts are finely modulated and aligns well with the Sabatier principle. Accordingly, the Fe1Ni1CN and Fe1Co1CN exhibits boosted performance of low-temperature HgCl2 reduction, far exceeding the performances of Fe1CN Co1CN and Ni1CN counterparties with separate Fe, Co or Ni single-atom sites. The dual-atom catalyst presents outstanding acidic gas resistance to SO2, HCl, NO and CO2 and exhibits excellent durability and great recyclability under simulated flue gas conditions at 250oC. Theoretical simulations reveal that Fe1Ni1CN catalyst shows a low reaction energy for dissociative adsorption and reduction of the reactants, with the optimal chemical kinetic rate at the peak of the volcano plot, thereby theoretically validating the high efficiency of the dual-atom catalyst. This study presents an innovative strategy for designing efficient dual-atom catalysts via the synergistic effect of neighbouring metal sites and reveals the critical role of d-band electronic activity regulation towards enhanced low-temperature HgCl2 catalysis.
