A quick and versatile one step metal–organic chemical deposition method for supported Pt and Pt-alloy catalysts

Abstract

A simple, modified Metal-Organic Chemical Deposition (MOCD) method for Pt, PtRu and PtCo nanoparticle deposition onto a variety of support materials, including C, SiC, B₄C, LaB₆, TiB₂, TiN and a ceramic/carbon nanofiber, is described. Pt deposition using Pt(acac)₂ as a precursor is shown to occur <i>via</i> a mixed solid/liquid/vapour precursor phase which results in a high Pt yield of 90-92% on the support material. Pt and Pt alloy nanoparticles range 1.5-6.2 nm, and are well dispersed on all support materials, in a one-step method, with a total catalyst preparation time of ∼10 hours (2.4-4× quicker than conventional methods). The MOCD preparation method includes moderate temperatures of 350 °C in a tubular furnace with an inert gas supply at 2 bar, a high pressure (2-4 bar) compared to typical MOCVD methods (∼0.02-10 mbar). Pt/C catalysts with Pt loadings of 20, 40 and 60 wt% were synthesised, physically characterised, electrochemically characterised and compared to commercial Pt/C catalysts. TEM, XRD and <i>ex situ</i> EXAFS show similar Pt particle sizes and Pt particle shape identifiers, namely the ratio of the third to first Pt coordination numbers modelled from <i>ex situ</i> EXAFS, between the MOCD prepared catalysts and commercial catalysts. Moreover, electrochemical characterisation of the Pt/C MOCD catalysts obtained ORR mass activities with a maximum of 428 A g_Pt ^-1 at 0.9 V, which has similar mass activities to the commercial catalysts (80-160% compared to the commercial Pt/C catalysts).