N-doped carbon nanotubes engineered with graphdiyne toward enhanced oxygen reduction reaction

Metal-free electrocatalysts for the oxygen reduction reaction (ORR) have attracted significant attention due to their stability and low-cost. However, compared to traditional platinum-based catalysts, their activity still requires enhancement. Herein, we explored an approach to modulate the activity of metal-free ORR catalysts by the in situ growth of graphdiyne (GDY) on N-doped carbon nanotubes (NCNT). The in situ growth of GDY can effectively protect the catalysts during the reaction process. GDY promotes charge transfer at the hetero-interface, thereby regulating the electron density around the ORR active sites. Consequently the oxygen adsorption and activation of the NCNT/GDY heterostructure (NCNT@GDY) are improved, leading to enhanced catalytic activity and four-electron selectivity of the heterostructure. This work demonstrates that the preparation of heterogeneous structures can effectively modulate the catalytic activity of catalysts, an approach that can be extended to the design of other ORR catalysts. • NCNT@GDY was successfully prepared by a mild and widely applicable in-situ growth method. • Graphdiyne layer could enhance the catalytic performance of NCNT@GDY in oxygen reduction reaction (ORR). • The ORR activity of NCNT@GDY compared with NCNT is explored by DFT methods.