Pt Nanoparticle–Mn Single-Atom Pairs for Enhanced Oxygen Reduction
Xiaoqian Wei, Shaojia Song, Weiwei Cai, Yunqing Kang, Qie Fang, Ling Ling, Yingji Zhao, Zexing Wu, Xiaokai Song, Xingtao Xu, Sameh M. Osman, Weiyu Song, Toru Asahi, Yusuke Yamauchi, Chengzhou Zhu
Abstract
The intrinsic roadblocks for designing promising Pt-based oxygen reduction reaction (ORR) catalysts emanate from the strong scaling relationship and activity–stability–cost trade-offs. Here, a carbon-supported Pt nanoparticle and a Mn single atom (Pt NP –Mn SA /C) as in situ constructed Pt NP –Mn SA pairs are demonstrated to be an efficient catalyst to circumvent the above seesaws with only ∼4 wt % Pt loadings. Experimental and theoretical investigations suggest that Mn SA functions not only as the “assist” for Pt sites to cooperatively facilitate the dissociation of O 2 due to the strong electronic polarization, affording the dissociative pathway with reduced H 2 O 2 production, but also as an electronic structure “modulator” to downshift the d -band center of Pt sites, alleviating the overbinding of oxygen-containing intermediates. More importantly, Mn SA also serves as a “stabilizer” to endow Pt NP –Mn SA /C with excellent structural stability and low Fenton-like reactivity, resisting the fast demetalation of metal sites. As a result, Pt NPs –Mn SA /C shows promising ORR performance with a half-wave potential of 0.93 V vs reversible hydrogen electrode and a high mass activity of 1.77 A/mg Pt at 0.9 V in acid media, which is 19 times higher than that of commercial Pt/C and only declines by 5% after 80,000 potential cycles. Specifically, Pt NPs –Mn SA /C reaches a power density of 1214 mW/cm 2 at 2.87 A/cm 2 in an H 2 –O 2 fuel cell.