In-situ FTIR spectroscopy investigation of carbon-supported PdAuNi electrocatalysts for ethanol oxidation

Abstract

• Adding Au and Ni to Pd/C enhances its ethanol oxidation performance. • In-situ FTIR studies suggest acetate is the ethanol oxidation final product. • Adding Ni and Au to Pd/C does not enhance the ethanol CO 2 selectivity. • The SBIPA method produces the ethanol most active catalyst. This work demonstrates novel in situ measurements of direct ethanol fuel cells (DEFCs), and shows that the synthesis procedure can exert a substantial influence over their activity, with exceptional activity demonstrated for a trimetallic PdAuNi/C catalyst prepared via NaBH 4 -2-propanol reduction (SBIPA). Furthermore, in situ Fourier transform infrared (FTIR) spectroscopy shows that the final ethanol electrooxidation reaction (EOR) over all catalysts investigated is acetate, thereby yielding valuable insights into the reaction mechanism. DEFCs present a sustainable net-zero technological solution which can supply diverse energy needs without increasing greenhouse gas (GHG) emissions. Ethanol can be produced from biomass precusors, and therefore its direct application in fuel cells can mitigate climate change and ensure environmental sustainability. In this work, PdAuNi/C catalysts are synthesized via three synthetic routes and applied in EOR. The catalysts are charachrterised via X-ray diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS). Their electrocatalytic performance is evaluated by cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS). SBIPA exhibits excellent electrocatalytic results with an oxidation current peak of 9.6 A/mg Pd . This is 4 times greater than that recorded for its monometallic counterpart prepared via the same procedure. It is, also, over twice as great as the other two trimetallic samples prepared by alternative protocols. Although adding Au and Ni to Pd significantly enhances EOR activity, it does not increase the CO 2 yield of EOR.