D-d Orbital coupling induced by crystal-phase engineering assists acetonitrile electroreduction to ethylamine

Abstract

The d-d orbital coupling induced by crystal-phase engineering can effectively adjust the electronic structure of electrocatalysts, thus showing significant catalytic performance, while it has been rarely explored in electrochemical acetonitrile reduction reaction (ARR) to date. Herein, we successfully realize the structural transformation of PdCu metallic aerogels (MAs) from face-centered cubic (FCC) to body-centered cubic (BCC) through annealing treatment. Specifically, the BCC PdCu MAs exhibit excellent ARR performance with high ethylamine selectivity of 90.91%, Faradaic efficiency of 88.60%, yield rate of 316.0 mmol h−1 g−1Pd+Cu and long-term stability for consecutive electrolysis within 20 h at −0.55 V vs. reversible hydrogen electrode, outperforming than those of FCC PdCu MAs. Under the membrane electrode assembly system, BCC PdCu MAs also demonstrate excellent ethylamine yield rate of 389.5 mmol h−1 g−1Pd+Cu. Density functional theory calculation reveals that the d-d orbital coupling in BCC PdCu MAs results in an evident correlation effect for the interaction of Pd and Cu sites, which boosts up the Cu sites electronic activities to enhance ARR performance. Our work opens a new route to develop efficient ARR electrocatalysts from the perspective of crystalline structure transformation.