Core–shell structured PtCu/C applied in a high-temperature direct ethanol electroreformer to produce green H2 at reduced energy demand with high CO2 selectivity: performance and techno-economic analyses

Abstract

Three different electrocatalysts have been prepared, characterized, and applied to a high-temperature direct ethanol polymer electrolyte membrane electroreformer (DEPEME) based on the removal of surface Cu from the initial Pt_xCu/C (x = 3, 1, and 1/3) raw materials. The resulting structure consisted of a Pt-enriched shell on a PtCu alloy core deposited on C [alloyed Pt_xCu@Pt_yCu/C (y ≫ x)], achieved after the acid treatment of the prepared catalysts, in a core–shell (CS) configuration. This structure is confirmed by X-ray diffraction, which evidences the formation of a PtCu alloy, whereas X-ray photoelectron spectroscopy reveals an enriched Pt shell. Finally, transmission electron microscopy images revealed the dispersed deposition of metal nanoparticles at the nanoscale range. Regarding the electrochemical performance, the CS materials displayed enhanced CO tolerance and ethanol electro-oxidation (EEO) performance, characterized by increased current density and a lower onset potential compared to Pt/C. These results were corroborated at the high-temperature DEPEME condition of 150 °C. Moreover, the monitoring of the EEO products revealed that the CS PtCu materials notably enhanced the selectivity for CO₂, resulting in a desirable combination of high hydrogen production rate (0.205 kg of H₂ m⁻² h⁻¹) and CO₂ selectivity (close to 50%) at a reduced energy consumption (25.46 kWh kg H₂⁻¹). Finally, a techno-economic analysis presents the potential of using ethanol produced in a sugarcane plant from bagasse (second-generation) and estimates the cost of H₂ produced compared to that of a PEM water electrolyzer.