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We report in this article a detailed study on how to stabilize a first-row transition metal (M) in an intermetallic L10-MPt alloy nanoparticle (NP) structure and how to surround the L10-MPt with an atomic layer of Pt to enhance the electrocatalysis of Pt for oxygen reduction reaction (ORR) in fuel cell operation conditions. Using 8 nm FePt NPs as an example, we demonstrate that Fe can be stabilized more efficiently in a core/shell structured L10-FePt/ Pt with a 5 À Pt shell. The presence of Fe in the alloy core induces the desired compression of the thin Pt shell, especially the two atomic layers of Pt shell, further improving the ORR catalysis. This leads to much enhanced Pt catalysis for ORR in 0.1 M HClO4 solution (at both room temperature and 60 °C) and in the membrane electrode assembly (MEA) at 80 °C. The L10-FePt/Pt catalyst has a mass activity of 0.7 A/mgPt from the half-cell ORR test and shows no obvious mass activity loss after 30 000 potential cycles between 0.6 and 0.95 V at 80 °C in the MEA, meeting the DOE 2020 target (<40% loss in mass activity). We are extending the concept and preparing other L10-MPt/Pt NPs, such as L10-CoPt/Pt NPs, with reduced NP size as a highly efficient ORR catalyst for automotive fuel cell applications. [ABSTRACT FROM AUTHOR]

Tuning the performance of nanoparticle (NP) catalysts by controlling the NP surface strain has evolved as an important strategy to optimize NP catalysis in many energy conversion reactions. Here, we present our new study on using an eigenforce model to predict and experiments to verify the strain-induced catalysis enhancement of the oxygen reduction reaction (ORR) in the presence of L1 0 -CoMPt NPs (M = Mn, Fe, Ni, Cu, Ni). The eigenforce model allowed us to predict anisotropic (that is, two-dimensional) strain levels on distorted Pt(111) surfaces. Experimentally, by preparing a series of 5 nm L1 0 -CoMPt NPs, we could push the ORR catalytic activity of these NPs toward the optimum region of the theoretical two-dimensional volcano plot predicted for L1 0 -CoMPt. The best ORR catalyst in the alloy NP series we studied is L1 0 -CoNiPt, which has a mass activity of 3.1 A/mg Pt and a specific activity of 9.3 mA/cm 2 at room temperature with only 15.9% loss of mass activity after 30 000 cycles at 60 °C in 0.1 M HClO 4 .

Stabilizing a 3d-transition metal component M from an MPd alloy structure in an acidic environment is key to the enhancement of MPd catalysis for various reactions. Here we demonstrate a strategy to stabilize Cu in 5 nm CuPd nanoparticles (NPs) by coupling the CuPd NPs with perovskite-type WO 2.72 nanorods (NRs). The CuPd NPs are prepared by controlled diffusion of Cu into Pd NPs, and the coupled CuPd/WO 2.72 are synthesized by growing WO 2.72 NRs in the presence of CuPd NPs. The CuPd/WO 2.72 can stabilize Cu in 0.1 M HClO 4 solution and, as a result, they show Cu, Pd composition dependent activity for the electrochemical oxidation of formic acid in 0.1 M HClO 4 + 0.1 M HCOOH. Among three different CuPd/WO 2.72 studied, the Cu 48 Pd 52 /WO 2.72 is the most efficient catalyst, with its mass activity reaching 2086 mA/mg Pd in a broad potential range of 0.40 to 0.80 V (vs RHE) and staying at this value after the 12 h chronoamperometry test at 0.40 V. The synthesis can be extended to obtain other MPd/WO 2.72 (M = Fe, Co, Ni), making it possible to study MPd-WO 2.72 interactions and MPd stabilization on enhancing MPd catalysis for various chemical reactions.

We report a seed-mediated growth of 2.3 nm AgPd nanoparticles (NPs) in the presence of 40 × 5 nm WO 2.72 nanorods (NRs) for the synthesis of AgPd/WO 2.72 composites. The strong interactions between AgPd NPs and WO 2.72 NRs make the composites, especially the Ag 48 Pd 52 /WO 2.72 , catalytically active for dehydrogenation of formic acid (TOF = 1718 h -1 and E a = 31 kJ/mol) and one-pot reactions of formic acid, 2-nitrophenol, and aldehydes into benzoxazoles in near quantitative yields under mild conditions. The catalysis can also be extended to the one-pot reactions of ammonium formate, 2-nitroacetophenone, and aldehyde for high yield syntheses of quinazolines. Our studies demonstrate a new catalyst design to achieve a green chemistry approach to one-pot reactions for the syntheses of benzoxazoles and quinazolines.