Kai Peng,Weiqi Zhang,Narayanamoorthy Bhuvanendran,Qiang Ma,Qian Xu,Lei Xing,Lindiwe Khotseng,Huaneng Su
Pt-based alloy nanomaterials with nanodendrites (NDs) structures are efficient electrocatalysts for methanol oxidation reaction (MOR), however their durability is greatly limited by the issue of transition metals dissolution. In this work, a facile trace Ir-doping strategy was proposed to fabricate Ir-PtZn and Ir-PtCu alloy NDs catalysts in aqueous medium, which significantly improved the electrocatalytic activity and durability for MOR. The as-prepared Ir-PtZn/Cu NDs catalysts showed distinct dendrites structures with the averaged diameter of 4.1 nm, and trace Ir doping subsequently improved the utilization of Pt atoms and promoted the oxidation efficiency of methanol. The electrochemical characterizations further demonstrated that the obtained Ir-PtZn/Cu NDs possessed enhanced mass activities of nearly 1.23 and 1.28-fold higher than those of undoped PtZn and PtCu, and approximately 2.35 and 2.67-fold higher than that of Pt/C in acid medium. More excitingly, after long-term durability test, the proposed Ir-PtZn and Ir-PtCu NDs still retained about 88.9% and 91.6% of its initial mass activities, which further highlights the key role of Ir-doping in determining catalyst performance. This work suggests that trace Ir-doping engineering could be a promising way to develop advanced electrocatalysts toward MOR for direct methanol fuel cell (DMFC) applications.
Mingjin Du,Binling Chen,Yong Hu,Jianyi Chen,Jun Nie,Guiping Ma
Pt-based alloy nanoparticles/porous-structured nanofibers nanocomposites, Pt-Ni/pCNFs and Pt-Ag-Ni/pCNFs, were successfully prepared via electrospinning, dip-molding, carbonization and replacement reaction as electrocatalysts for methanol oxidation reaction (MOR). The alloy nanoparticles with average diameter of 180 nm were uniformly embedded on the surface of pCNFs . Taking advantages of the three factors alloy system and porous nanofiber structure, Pt-Ag-Ni/pCNFs catalyst exhibits the higher electrocatalytic activity for methanol (the maximum current density is ca. 19.6 mA cm −2 ) than that of Pt-Ni/pCNFs. In addition, Pt-Ag-Ni/pCNFs also shows an excellent electrocatalytic stability of methanol and superior sensitivity for methanol (0.0022 mA cm -2 mM -1 ). A proposed mechanism of Pt-Ag-Ni/pCNFs for MOR was proposed in the research. This research could provide a novel strategy for the preparation of MOR electrocatalysts.
Pt-based intermetallic alloys with high activity and stability are promising for accelerating the cathodic oxygen reduction reaction (ORR) and large-scale application of proton exchange membrane fuel cells. So far, facile synthesis of Pt-based alloys in less time is desirable but still challenging. Herein, based on the traditional wet impregnation method, facile in situ reduction of H2PtCl6 and alloying with a hybrid nanostructure mainly doped with Fe single atoms as well as small amounts of Fe-based nanoparticles and oxides were developed to fabricate highly dispersed PtFe nanoparticles loaded on a mesoporous Fe–N–C support. Alloying of Pt derived from H2PtCl6 with various iron-based species existing in forms of single-atom, metallic, and oxide states was confirmed by systematic characterization, and the Fe content in the support is important for PtFe alloy formation, and the corresponding electrochemical performance promotion has been identified. The as-synthesized best-performance PtFe/Meso-PDA-5 catalyst delivered a high potential of 0.925 V at a current density of 3 mA cm–2 and achieved a high mass activity of 497.5 mA mgPt–1 at 0.9 V for the ORR in 0.1 M HClO4. More importantly, only 17.9% mass activity loss was observed after 10k potential cycles of the accelerated deterioration test. The present work provides a strategy for facile synthesis of Pt-based alloy nanomaterials for ORR catalysis and highlights the importance of supports in alloy formation.
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