Extending the lifetime of electrocatalytic materials is a major challenge in electrocatalysis. Here, we employ atomic layer deposition (ALD) to coat the surface of carbon black supported platinum nanoparticles (Pt/CB) with an ultra-thin layer of silicon dioxide (SiO2) to prevent deactivation of the catalyst during H2 evolution. Our results show that after an accelerated durability test (ADT) the current density at −0.2 V vs. reversible hydrogen electrode (RHE) of the unprotected Pt/CB catalyst was reduced by 34%. By contrast, after coating the Pt/CB catalyst with 2 SiO2 ALD cycles, the current density at the same potential was reduced by 7% after the ADT procedure, whereas when the Pt/CB sample was coated with 5 SiO2 ALD cycles, the current density was reduced by only 2% after the ADT. Characterization of the Pt particles after electrochemical testing shows that the average particle size of the uncoated Pt/CB catalyst increases by roughly 16% after the ADT, whereas it only increases by 3% for the Pt/CB catalyst coated with 5 cycles of SiO2 ALD. In addition, the coating also strongly reduces the detachment of Pt nanoparticles, as shown by a strong decrease in the Pt concentration in the electrolyte after the ADT. However, 20 cycles of SiO2 ALD coating results in an over-thick coating that has an inhibitory effect on the catalytic activity. In summary, we demonstrate that only a few cycles of SiO2 ALD can strongly improve the stability of Pt catalyst for the hydrogen evolution reaction.@en

N-doped carbon materials can be efficient and cost-effective catalysts for the electrochemical CO₂ reduction reaction (CO₂RR). Activators are often used in the synthesis process to increase the specific surface area and porosity of these carbon materials. However, owing to the diversity of activators and the differences in physicochemical properties that these activators induce, the influence of activators used for the synthesis of N-doped carbon catalysts on their electrochemical performance is unclear. In this study, a series of bagasse-derived N-doped carbon catalysts is prepared with the assistance of different activators to understand the correlation between activators, physicochemical properties, and electrocatalytic performance for the CO₂RR. The properties of N-doped carbon catalysts, such as N-doping content, microstructure, and degree of graphitization, are found to be highly dependent on the type of activator applied in the synthesis procedure. Moreover, the overall CO₂RR performance of the synthesized electrocatalysts is not determined only by the N-doping level and the configuration of the N-dopant, but rather by the overall surface chemistry, where the porosity and the degree of graphitization are jointly responsible for significant differences in CO₂RR performance.

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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.

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