Enhancement of NH Production in Electrochemical N 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 is also a key chemical for pharmaceutical, textile, plastic, explosive, and dye-making industries. At present, the demand for NH is fulfilled by the Haber-Bosch method, which consumes 1-3% of global energy and causes 0.5-1% CO emission every year. To reduce emissions and improve energy efficiency, the electrochemical nitrogen gas reduction reaction (NRR) 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 Faradaic efficiency in NRR. These beveled nanoboxes are produced in different degrees of corner and edge etching, which produces both polyhedral and concave structures. In NRR, the binary CuAu nanoboxes enhanced NH 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 for the potential-determining step to form NNH ( + N(g) + H + e → *NNH). Meanwhile, the results in 10-cycle and solar-illuminated NRR indicate the beveled CuAu nanoboxes are not only robust electrocatalysts but show promise in photocatalysis as well.