Enhancement of NH 3 Production in Electrochemical N 2 Reduction by the Cu-Rich Inner Surfaces of Beveled CuAu Nanoboxes.

The global ammonia yield is critical to the fertilizer industry as the global food demand is highly dependent on it, whereas, NH ₃ is also a key chemical for pharmaceutical, textile, plastic, explosive, and dye-making industries. At present, the demand for NH ₃ is fulfilled by the Haber-Bosch method, which consumes 1-3% of global energy and causes 0.5-1% CO ₂ emission every year. To reduce emissions and improve energy efficiency, the electrochemical nitrogen gas reduction reaction (N ₂ RR) has received much attention and support after the funding announcement by the U.S. Department of Energy. In this work, we have created hollow CuAu nanoboxes with Cu-rich inner walls to improve the NH ₃ Faradaic efficiency in N ₂ RR. These beveled nanoboxes are produced in different degrees of corner and edge etching, which produces both polyhedral and concave structures. In N ₂ RR, the binary CuAu nanoboxes enhanced NH ₃ production compared to individual Au and Cu nanocubes. The results of DFT calculations suggest the Cu-rich inner walls in the hollow beveled CuAu nanoboxes play a major role in their performance by reducing the free energy Δ G _*NNH for the potential-determining step to form *NNH (* + N ₂ (g) + H ⁺ + e ^- → *NNH). Meanwhile, the results in 10-cycle and solar-illuminated N ₂ RR indicate the beveled CuAu nanoboxes are not only robust electrocatalysts but show promise in photocatalysis as well.