Nest-Type ZNC⊂PtZn<sub>δ</sub>/C as a Highly Efficient Catalyst for Methanol Electro-Oxidation
Chenjia Liang, Siyuan Zhao, Yingxuan Zhao, Yida Xu, Xianghao Wang, Qing Liu, Xiangke Guo, Nianhua Xue, Luming Peng, Weiping Ding
Abstract
For promotion of direct methanol fuel cells (DMFCs), a nest-type electrocatalyst with a Zn-N x -C (abbreviated as ZNC) nest framework surrounding the catalytic Pt centers has been designed and revealed to be more practical than a common Pt/C catalyst with all active sites barrier-free exposed. The ZNC nest is constructed by the pyrolysis of ZIF-8, which tightly surrounds the Pt centers, using a preparation strategy of anchoring and self-assembly. After pyrolysis, a small amount of Zn enters the Pt lattice, besides the ZNC nest framework. The Pt centers are dual-modulated by the alloying-Zn and the electronic doping from the nest framework through the Mott–Schottky effect. Additionally, the ZNC nest not only increases the local concentration of methanol at the catalytic centers but also enhances the stability of the catalyst for the methanol oxidation reaction by inhibiting the agglomeration of Pt. As a result, the mass-specific activity and area-specific activity of ZNC⊂PtZn δ /C achieved 1.54 A mg Pt –1 and 1.60 mA cm Pt –2, which are 4.1 and 2.6 times that of a commercial Pt/C, respectively. It also shows a much better CO* intermediate tolerance and cyclic stability compared with that of the commercial Pt/C. We envision that the electrocatalyst with nest-type catalytic centers reflecting the properties of synergistic catalysis will give an impetus to the progress of DMFCs.