  Despite the immense potential of Dual Single-Atom Compounds (DSACs), the
challenges in their synthesis process, including complexity, stability, purity,
and scalability, remain primary concerns in current research. Here, we present
a general strategy, termed "Entropy-Engineered Middle-In Synthesis of Dual
Single-Atom Compounds" (EEMIS-DSAC), which is meticulously crafted to produce a
diverse range of DSACs, effectively addressing the aforementioned issues. Our
strategy integrates the advantages of both bottom-up and top-down paradigms,
proposing a new insight to optimize the catalyst structure. The as-fabricated
DSACs exhibited excellent activity and stability in the nitrate reduction
reaction (NO3RR). In a significant advancement, our prototypical CuNi DSACs
demonstrated outstanding performance under conditions reminiscent of industrial
wastewater. Specifically, under a NO3- concentration of 2000 ppm, it yielded a
Faradaic efficiency (FE) for NH3 of 96.97 %, coupled with a mass productivity
of 131.47 mg h-1 mg-1 and an area productivity of 10.06 mg h-1 cm-2.
Impressively, even under a heightened NO3- concentration of 0.5 M, the FE for
NH3 peaked at 90.61 %, with mass productivity reaching 1024.50 mg h-1 mg-1 and
an area productivity of 78.41 mg h-1 cm-2. This work underpins the potential of
the EEMIS-DSAC approach, signaling a promising frontier for high-performing
DSACs.
