Redefining selectivity paradigms in electrochemical nitrogen reduction reaction on confined dual-atom catalysts
The premature decay of electrochemical nitrogen reduction reaction (eNRR) performance at low electrode potentials remains a major obstacle to practical applications, primarily due to competition from the hydrogen evolution reaction (HER). A new paradigm capable of transcending current selectivity constraints is urgently required to advance eNRR toward industrial implementation. In this work, we propose two practical selectivity descriptors (ΔΔG and ΔU) based on a systematic investigation of the potential-dependent competition between eNRR and HER on confined dual-atom catalysts. The descriptor ΔΔG (ΔG_N2 − ΔG_H) identifies the potential range where N2 adsorption dominates over H adsorption, while ΔU (U_cross – U_eNRR) specifies the potential range to trigger direct eNRR, offering a quantitative benchmark for rational catalyst design. Ideal catalysts should maintain N2-preferential adsorption across a broad potential window to facilitate direct eNRR. Guided by this insight, we demonstrate that confined dual-atom configurations with optimized interatomic distances can simultaneously achieve both overwhelming N2 adsorption and sufficient activation, thereby overcoming conventional selectivity limitations. This strategy enables ammonia synthesis with industrially relevant production rates and current density even at elevated potentials. Our mechanistic insights not only elucidate the root causes of performance limitations in eNRR but also offer a rational design framework for developing high-performance catalysts across a broad range of electrochemical transformations.