Electronic band structure and electrocatalytic performance of cu₃n nanocrystals

High-density discrete Cu₃N nanocrystals were deposited on XC-72 carbon black by plasma-enhanced atomic layer deposition (PEALD). This heterostructured noble-metal-free catalyst served as a high-performance electrocatalyst for enhanced oxygen reduction reaction (ORR). The electronic band structure of Cu₃N was determined by ultraviolet photoelectron spectroscopy (UPS) and UV-vis spectrophotometry. The work function (φ) of the Cu₃N nanocrystals was calculated to be 5.04 eV, which is lower than that of Pt (â5.60 eV). With lower energy barrier, Cu₃N would exhibit stronger electron transfer to cause ORR than typical Pt catalyst. The UPS analysis also confirmed the synergistic coupling effect between the Cu₃N nanocrystals and the carbon support. Coupled with the XC-72, the Cu₃N200/C showed even smaller φ (=4.34 eV) than pure Cu₃N nanocrystals. Thus, the Cu₃N200/C electrocatalyst prepared with 200 ALD cycles exhibited similar ORR catalytic activity, significantly improved mass activity, and potentially greater durability than its Pt/C counterpart in alkaline solution. The fabrication of Cu₃N by PEALD and its good performance in ORR suggest a promising alternative of non-noble-metal electrocatalyst for application in fuel cells.