Tuning atomic Pt site surface on PtAu alloy toward electro-oxidation of formic acid. (July 2022)

• Record Type: Journal Article
• Authors: Zheng, Jin-Hong; Zhang, Jialin; Li, Guang; Zhang, Jun-Ming; Zhang, Bin-Wei; Jiang, Yan-Xia; Sun, Shi-Gang
• Is Part Of: Materials today energy. Volume 27(2022)
• Publication Date: 2022-07
• Subjects: Formic acid electro-oxidation -- Surface composition modulation -- Pt-based alloy -- Site effect -- Intermediate; Energy development -- Periodicals; Energy industries -- Periodicals; Power resources -- Periodicals; Energy policy -- Periodicals; Energy development; Energy industries; Energy policy; Power resources; Electronic journals; Periodicals; 621.042
• DOI: 10.1016/j.mtener.2022.101028
• Languages: English
• ISSNs: 2468-6069

Abstract

Abstract: PtAu alloy is considered to be a promising catalyst for the formic acid (HCOOH) electro-oxidation reaction. Nevertheless, the mechanism of HCOOH electro-oxidation on various surface compositions of PtAu is still unclear. Here, a series of ∼5 nm PtAu catalysts from Pt50 Au50 to atomically dispersed Pt surface is successfully prepared. We reveal that the electro-oxidation HCOOH mechanism depends on the surface Pt sites; i.e., when PtAu alloy surface tunes to surface atomic Pt site, their mechanisms will change from a dual pathway mechanism to a direct pathway. Therefore, PtAu alloy (Pt5 Au95 ) with atomic Pt sites surface showed an excellent activity with 104.8 mA cm −2 at 0.24 V (normalized by the Pt active surface area), which is five times higher than that of Pt50 Au50 (19.3 mA cm −2 at 0.24 V) toward HCOOH electro-oxidation. Significantly, external reflection in-situ Fourier transform infrared spectroscopy (FTIRS) results furtherly prove that the atomic Pt sites surface on PtAu alloy will prevent the formation of CO poisoning intermediate and undergo the direct pathway to form CO2 . Moreover, attenuated total reflection (ATR) in-situ FTIRS results also demonstrate that the bridge formic acid anion on PtAu alloy is not a real intermediate for electro-oxidation HCOOH. Graphical abstract: Image 1 Highlights: The atomic Pt site surface on PtAu alloy is obtained by a two-step strategy. PtAu alloy with atomic Pt site surface possesses an excellent performance toward FAOR via the direct pathway. In-situ FTIRS results reveal that the bridge formic acid anion on PtAu alloy is not a real intermediate for FAOR. A derivative method is proposed to find the hidden or shoulder peak in CVs.