Interstitial B-Doping in Pt Lattice to Upgrade Oxygen Electroreduction Performance
Zijie Mao, Chen Ding, Xuan Liu, Qing Zhang, Xianxian Qin, Hong Li, Fan Yang, Qing Li, Xia‐Guang Zhang, Junliang Zhang, Wen–Bin Cai
Abstract
The dissolution of M in currently popular Pt–M alloy catalysts (M = Co, Ni, and Fe) during the oxygen reduction reaction (ORR) may deter their wide application in proton exchange membrane fuel cells (PEMFCs). In this work, interstitial B-doping in the Pt lattice is instead used to design a durable and active ORR catalyst, by taking advantage of its unique regulation of the electronic structure of surface Pt sites. 3 nm Pt–B nanoparticles on carbon black (Pt–B/C) are obtained using dimethylamine borane (DMAB) as a reductant and the B source in a mixed H2O–ethylene glycol precursor solution. The formation of the B-doped Pt catalyst is verified by inductively coupled plasma-atomic emission spectrometry, X-ray diffractometry, and spherical aberration-corrected scanning transmission electron microscopy. Both half-cell and single-cell tests indicate that the as-synthesized Pt–B/C catalyst outperforms the commercial Pt/C(com) in terms of activity and durability. In particular, the Pt–B/C-based PEMFC exhibits an initial maximum power density 1.24 times as high as the Pt/C(com)-based one under otherwise same conditions, with a 15% decay for the former versus a 45% decay for the latter after 30 000 cycles of the accelerated degradation test (ADT). Comparative DFT calculations on B-doped and undoped Pt(111) surfaces reveal that the lowered Pt d-band center and the strong interaction of Pt–B bonding weaken the binding of OH and O species to surface Pt sites and lessen oxidative disruption of surface Pt atoms. This interstitial metalloid doping in conjunction with the simple and scalable synthesis protocol enables the Pt–B/C to be a competitive ORR catalyst for the PEMFCs.