Highly Selective Synthesis of Monoclinic-Phased Platinum-Tellurium Nanotrepang for Direct Formic Acid Oxidation Catalysis

Designing efficient formic acid oxidation reaction (FAOR)catalystswith remarkable membrane electrode assembly (MEA) performance in adirect formic acid fuel cell (DFAFC) medium is significant yet challenging.Herein, we report that the monoclinic-phased platinum-telluriumnanotrepang (m-PtTe NT) can be adopted as a highlyactive, selective, and stable FAOR catalyst with a desirable directreaction pathway. The m-PtTe NT exhibits the highspecific and mass activities of 6.78 mA cm(-2) and3.2 A mg(Pt) (-1), respectively, which are35.7/22.9, 2.8/2.6, and 3.9/2.9 times higher than those of commercialPt/C, rhombohedral-phased Pt2Te3 NT (r-Pt2Te3 NT), and trigonal-phasedPtTe(2) NT (t-PtTe2 NT), respectively.Simultaneously, the highest reaction tendency for the direct FAORpathway and the best tolerance to poisonous CO intermediate can alsobe realized by m-PtTe NT. More importantly, evenin a single-cell medium, the m-PtTe NT can displaya much higher MEA power density (171.4 mW cm(-2))and stability (53.2% voltage loss after 5660 s) than those of commercialPt/C, demonstrating the great potential in operating DFAFC device.The in-situ Fourier transform infrared spectroscopyand X-ray photoelectron spectroscopy jointly demonstrate that theunique nanostructure of m-PtTe NT can effectivelyoptimize dehydrogenation steps and inhibit the CO intermediate adsorption,as well as promote the oxidation of noxious CO intermediate, thusachieving the great improvement of FAOR activity, poisoning tolerance,and stability. Density functional theory calculations further revealthat the direct pathway is the most favorable on m-PtTe NT than r-Pt2Te3 NTand t-PtTe2 NT. The higher activationenergy to produce CO and the relatively weaker binding with CO of m-PtTe NT result in the better CO tolerance. This work achievesremarkable FAOR and MEA performances of advanced Pt-based anodic catalystsfor DFAFCs via a phase engineering strategy.