Methanol-reduced Pd nanoparticles anchored on B,N-CDs@CNT hybrid for oxygen reduction reaction

The development of highly active oxygen reduction reaction (ORR) catalysts with low-loading of precious metals is imperative but remains a great challenge. Herein, Pd/B,N-CDs@CNT composite catalysts was designed with Pd nanoparticles immobilized on hybrid support composed of B,N-doped carbon dots (B,N-CDs) and the multi-wall carbon nanotubes (CNT) using a simple methanol reduction method. The deposited Pd nano-particles exhibit clean surface, low crystallinity and surface distortion. The Pd/B,N-CDs@CNT catalyst shows significantly enhanced ORR activity, with the mass activity about 5-6 times higher than that of commercial Pt/C. Thus prominent ORR performance is mainly attributed to the unique microstructure of Pd nanoparticles. Moreover, the composited B,N-CDs and the doped B, N heteroatoms further improve the ORR perfor-mance, in which B,N-CDs supply more absorption sites, the formation of N-Pd facilitates the electron transfer, B doping can promote the adsorption of oxygenated species and weaken the strong interaction between Pd and C. Furthermore, the B, N co-doping plays a synergistic effect. This strategy provides a simple and mild method for designing highly efficient electrocatalysts with ultra-low precious metals in alkaline electrolytes.(c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.