Bimetallic and surface-functionalized aerogels for the efficient electroreduction of CO2 to added-value products

点击翻译按钮获取中文摘要

In the ongoing transition towards the generalized use of emission-neutral energy production, storage and conversion technologies, the use of intermittent electricity to electrochemically reduce CO2 into added-value chemicals (e.g., CO or HCOO−) is increasingly appealing. However, the commercial success of this CO2-valorization approach passes by the development of co-electrolysis cells capable of reaching current densities ≥ 200 mA∙cmgeom-2, which in terms requires highly-dispersed and -active materials for catalyzing the reactions taking place inside the cell. Among these, the electroreduction of CO2 is particularly challenging, not only due to the large overpotential that it requires, but also in sight of the difficulties associated to the control of its product selectivity. These key features can be optimized by tuning the adsorption properties of the reaction’s intermediates on the catalyst’s surface, e.g., by shifting the position of its d-band center or by adding other adsorbates that modify the interactions among these intermediates and the surface. The work presented herein explores both of these approaches by tackling the synthesis of high surface area, tridimensional nano-networks (aerogels) with bi-metallic compositions (PtPd or AuCu alloys/cores-hells) or with their surface functionalized with adsorbed N-containing ligands, respectively. Following a systematic study of the effect of various synthesis parameters on the aerogels’ structure and surface vs. bulk composition, electrochemical measurements complemented by operando X-ray absorption spectroscopy will shed light on the extent to which these parameters determine the gels’ reactivity. The subsequent implementation of selected aerogels in an in-house co-electrolysis cell will allow (for the first time) to verify whether the reactivity trends observed in aqueous electrochemical tests (customarily used in the field) extend to the application-relevant co-electrolysis setup. Most importantly, these results will serve to assess the commercial feasibility of this CO2-to-products approach, in terms of the maximum efficiencies and product-specific currents (i.e., operative potentials and selectivities) attainable in this device.