Dramatically Enhanced Stability of Silver Passivated Dicalcium Nitride Electride: Ag-Ca2N

Abstract

Electrides have received considerable attention due to their exotic properties. However, the high reactivity with oxygen and moisture immediately decomposed electrides in an ambient air environment. Here we passivated dicalcium nitride electride (Ca2N:e–) with silver via a wet chemical approach (Ag-Ca2N), significantly enhancing stability up to 17 min at room temperature in an ambient air environment. The Ca2N:e– was employed as a reducing agent due to the low work function (2.6 eV), high mobility, and high electron concentration facilitating electron transfer to Ag+ ion in an aprotic cosolvent. Moreover, the noble metal surface passivation (thickness: 55 nm) was achieved with negligible increase in work function of Ag-Ca2N (2.78 eV). The optimized molar ratio of AgNO3/Ca2N:e– was 0.5. The enhanced stability of Ag-Ca2N in organic reaction medium enabled successful aldol condensation reaction outside the glovebox, with a high α,β-unsaturated ketone yield of 75.4%, without involving environmentally harmful strong acid or base. The enhanced stability and low work function may realize practical economic applications of Ag-Ca2N.