Carbon nanotube-supported Cu3N nanocrystals as a highly active catalyst for oxygen reduction reaction

A controllable synthesis of a hybrid electrocatalyst consisting of copper(I) nitride nanoparticles (Cu3N) grown on carbon nanotubes (CNTs) by plasma enhanced atomic layer deposition (ALD) is presented. The island growth mechanism during ALD led to the formation of uniformly distributed Cu3N nanoparticles on the surface of CNTs. The size of copper nitride particles strongly influenced the electrocatalytic properties, and it could be precisely tuned by controlling the cycle number of ALD. The Pt-free non-precious nanocrystals coupling with CNTs exhibited pronounced electrocatalytic activity for oxygen reduction reaction (ORR). Koutecky-Levich analysis on the ORR current densities indicated that the Cu3N@CNT electrodes in alkaline media follow a mixed two- and four-electron transfer ORR pathway, whose mass activities are comparable to that of a typical Pt/C electrode. This report reveals a dry process to fabricate a well-dispersed metal nitride on a selected support material as an ORR catalyst that could enhance the catalytic activity by synergistic chemical coupling effects.