Nanostructuring Pt‐Pd Bimetallic Electrocatalysts for CO₂ Reduction Using Atmospheric Pressure Atomic Layer Deposition

Abstract

Preparing supported nanoparticles with a well‐defined structure, uniform particle size, and composition using conventional catalyst synthesis methods, such as impregnation, precipitation, and deposition‐precipitation is challenging. Furthermore, these liquid phase methods require significant solvent consumption, which has sustainable issues and requires complex purification processes, usually leaving impurities on the catalyst, affecting its selectivity and activity. In this work, we employed atomic layer deposition (ALD, a vapor phase synthesis method) to synthesize electrocatalysts with well‐controlled core‐shell and alloy structures for CO2 reduction to formic acid. With this approach, the structural control of the catalysts is down to the atomic scale, and the effect of core‐shell and alloy structure on Pt−Pd bimetallic catalysts has been investigated. It is shown that the Pt−Pd alloy catalyst displays a 46 % faradaic efficiency toward formic acid, outperforming Pt@Pd and Pd@Pt core‐shell structures that show faradaic efficiencies of 22 % and 11 %, respectively. Moreover, both core‐shell bimetallic catalysts (Pd@Pt and Pt@Pd) are not stable under electroreduction conditions. These catalysts restructure to more thermodynamically stable structures, such as segregated clusters or alloy particles, during the electrochemical reduction reaction, altering the catalytic selectivity.

Atomic/molecular layer deposition strategies for enhanced CO2 capture, utilisation and storage materials

“…The use of ALD offers the advantage of tuning the size, structure, and composition of electrocatalysts to greatly enhance the electrochemical reduction of CO 2 . [275][276][277][278] Besides the importance of catalysis, the support materials are another key factor in affecting the performance of electrocatalytic CO 2 reduction. For example, carbon materials are one of the most popular substrates for both noble and transition metal catalysts due to their abundant resources, large surface area and porous structures.…”

“…The use of ALD offers the advantage of tuning the size, structure, and composition of electrocatalysts to greatly enhance the electrochemical reduction of CO 2 . 275–278…”

Dimension Control of Platinum Nanostructures by Atomic Layer Deposition: From Surface Chemical Reactions to Applications

“…9 Besides Pt nanoparticles, other Pt-based nanostructures developed by ALD such as core/shell nanoparticles and nanocomposites have been demonstrated to have outstanding performance in electrocatalytic reactions. 51,58,63,113,206,207 Taking the advantages of the selective growth of Pt on Pd rather than on SiO 2 , Cao et al employed ALD to fabricate Pd/ Pt core/shell nanoparticles. 206 The use of ALD enabled controlling the thickness of the Pt shell down to a single atomic layer.…”