Multivalent Sulfur Vacancy-Rich NiCo 2 S 4 @MnO 2 Urchin-Like Heterostructures for Ambient Electrochemical N 2 Reduction to NH 3 .

Innovative advances in the exploitation of effective electrocatalytic materials for the reduction of nitrogen (N 2 ) to ammonia (NH 3 ) are highly required for the sustainable production of fertilizers and zero-carbon emission fuel. In order to achieve zero-carbon footprints and renewable NH 3 production, electrochemical N 2 reduction reaction (NRR) provides a favorable energy-saving alternative but it requires more active, efficient, and selective catalysts. In current work, sulfur vacancy (Sv)-rich NiCo 2 S 4 @MnO 2 heterostructures are efficaciously fabricated via a facile hydrothermal approach followed by heat treatment. The urchin-like Sv-NiCo 2 S 4 @MnO 2 heterostructures serve as cathodes, which demonstrate an optimal NH 3 yield of 57.31 µg h -1  mg cat -1 and Faradaic efficiency of 20.55% at -0.2 V versus reversible hydrogen electrode (RHE) in basic electrolyte owing to the synergistic interactions between Sv-NiCo 2 S 4 and MnO 2 . Density functional theory (DFT) simulation further verifies that Co-sites of urchin-like Sv-NiCo 2 S 4 @MnO 2 heterostructures are beneficial to lowering the energy threshold for N 2 adsorption and successive protonation. Distinctive micro/nano-architectures exhibit high NRR electrocatalytic activities that might motivate researchers to explore and concentrate on the development of heterostructures for ambient electrocatalytic NH 3 generation.