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A general strategy for bimetallic Pt-based nano-branched structures as highly active and stable oxygen reduction and methanol oxidation bifunctional catalysts
Nano Research 2020, 13 (3): 638-645
Published: 07 March 2020
Downloads:35

The morphology and size of Pt-based bimetallic alloys are known to determine their electrocatalytic performance in reactions relevant to fuel cells. Here, we report a general approach for preparing Pt-M (M = Fe, Co and Ni) bimetallic nano-branched structure (NBs) by a simple high temperature solution-phase synthesis. As-prepared Pt-M NBs show a polycrystalline structure and are rich in steps and kinks on the surface, which promote them favorable bifunctional catalytic properties in acidic electrolytes, specifically in terms of the oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR). Specially, Pt-Co NBs/C catalyst shows 6.1 and 5.3 times higher in specific activity (SA) and mass activity (MA) for ORR than state-of-the-art commercial Pt/C catalysts, respectively. Moreover, it exhibits a loss of 4.0% in SA and 14.4% in MA after 10,000 cycles of accelerated durability tests (ADTs) compared with the initial activities. In addition, we also confirmed the superior MOR activity of Pt-Co NBs/C catalyst in acidic electrolytes. For Pt-M NBs with other alloying metals, the ORR and MOR activities are both higher than commercial catalysts and are in the sequence of Pt-Co/C > Pt-Fe/C > Pt-Ni/C > commercial Pt/C (or PtRu/C). The improved activities and durability can benefit from the morphological and compositional effects. This synthesis approach may be applied to develop bifunctional catalysts with enhanced ORR and MOR properties for future fuel cells designs.

Research Article Issue
Engineering defects and adjusting electronic structure on S doped MoO2 nanosheets toward highly active hydrogen evolution reaction
Nano Research 2020, 13 (1): 121-126
Published: 05 December 2019
Downloads:28

The electrocatalytic hydrogen evolution reaction (HER) is one of the most promising ways for low-cost hydrogen production in the future. In this work, hetero S atoms were introduced into the MoO2 to enhance the catalytic activity by simultaneously adjusting electron structure, engineering lattice defect, and increasing oxygen vacancies. And the S doped MoO2 nanosheets with proper S doping amount show the enhanced performance for HER. The optimized catalyst shows a small onset overpotential as low as 120 mV, a low overpotential of 176 mV at the current density of 10 mA/cm2 which is decreased 166 mV compared to that of the pristine MoO2 nanosheets, a low Tafel slope of 57 mV/decade, and a high turnover frequency of 0.13 H2/s per active site at 150 mV. This finding proposes an effective strategy to prepare nonprecious metal oxide catalyst for enhancing HER performance by rationally doping hetero atoms.

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