Multivalent Sulfur Vacancy-Rich NiCo₂S₄@MnO₂ Urchin-Like Heterostructures for Ambient Electrochemical N₂ Reduction to NH₃

Innovative advances in the exploitation of effective electrocatalytic materials for the reduction of nitrogen (N-2) to ammonia (NH3) are highly required for the sustainable production of fertilizers and zero-carbon emission fuel. In order to achieve zero-carbon footprints and renewable NH3 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 NiCo2S4@MnO2 heterostructures are efficaciously fabricated via a facile hydrothermal approach followed by heat treatment. The urchin-like Sv-NiCo2S4@MnO2 heterostructures serve as cathodes, which demonstrate an optimal NH3 yield of 57.31 mu g 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-NiCo2S4 and MnO2. Density functional theory (DFT) simulation further verifies that Co-sites of urchin-like Sv-NiCo2S4@MnO2 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 NH3 generation.