PdPb nanocrystals have drawn considerable attention due to their excellent catalytic properties, while their practical applications have been impeded by the severe degradation of activity, which is caused by the adsorption of intermediates (especially CO) during the operation. Herein, we first present porous PdPb alloys with the incorporation of amorphous Pb(OH)2 species as highly active and stable electrocatalysts. Alloying Pd with Pb species is initially proposed to optimize the Pd-Pd interatomic distance and adjust the d-band center of Pd. Importantly, the amorphous Pb(OH)2 species are beneficial to promoting the formation of OHad and the removal of COad. Therefore, PdPb-Pb(OH)2 catalysts show a mass activity of 3.18 A mgPd-1 and keep excellent stability for the ethanol oxidation reaction (EOR). In addition, further CO stripping and a series of CO poisoning experiments indicate that PdPb-Pb(OH)2 composites possess much better CO tolerance benefiting from the tuned electronic structure of Pd and surface incorporation of Pb(OH)2 species.
The lack of efficient catalysts has become a major obstacle to the large-scale commercialization of electrochemical CO2 reduction (ECR). Two-dimensional semi-metallic PtBi2 has garnered increasing attention due to its distinctive topological properties, superconductivity, and abundant active centers. In this work, comprehensive density functional theory calculations were performed to investigate the ECR performance of PtBi2 monolayer. An advanced constant potential model was employed to resolve the theory and experiment contradictions caused by ignoring the charge effect throughout the ECR process in the traditional constant charge model. We also simulated the polarization curve using the microkinetic method. We derived the current density of formate formation at different potentials and compared it with experimental values. Our results show that the limiting potential (UL) of formate formation on PtBi2 monolayer is −0.26 V, which is much lower than that of bismuth-based catalysts (−0.49 V) widely reported. The competitive CO and H2 formation can be suppressed (UL > −1.0 V). Especially at −0.54 V vs SHE, PtBi2 monolayer achieves a large current density (about ∼200 mA/cm2). Based on the electronic structure analysis, we found that the coinfluence of the intrinsic spin–orbit coupling effect and Pt–Bi synergistic effect is the fundamental reason for an enhanced *OCHO adsorption on PtBi2. Our work provides a promising candidate PtBi2 monolayer for formate formation and a systematic research framework for designing advanced ECR catalysts.
Revealing the relationships between geometric structure and electrochemical stability of Pt-based nanostructures is significant to catalyst development for the ethanol oxidation reaction (EOR) in an acidic media. Herein, we proposed the controllable construction of PtxBiy nanostructures with a continuous structural evolution by a simple colloidal synthesis. As the Bi feeding decreased, the inhibition effect of Bi3+ on the epitaxial growth of Pt nanoparticles (NPs) was diminished, and PtxBiy nanostructures transformed from nanoparticle aggregates to nanodendrites, which induced the generation of PtBi–Bi2O3 heterogeneous nanostructures by the electrochemical reactivation process. Benefiting from the modification of Bi species and nanodendrites, the optimal Pt2Bi1 catalysts showed superior structural stability and catalytic durability with a high mass activity of 482.6 mA mgPt–1, which was 2.2 times that of commercial Pt/C. This work not only prepared a series of Pt-based heterogeneous nanostructures, but also provided an effective approach for high-performance EOR based on the structure–performance relationship.
Abstract A single device combining the functions of a CO 2 electrolyzer and a formate fuel cell is a new option for carbon‐neutral energy storage but entails rapid, reversible and stable interconversion between CO 2 and formate over a single catalyst electrode. We report a new catalyst with such functionalities based on a Pb–Pd alloy system that reversibly restructures its phase, composition, and morphology and thus alters its catalytic properties under controlled electrochemical conditions. Under cathodic conditions, the catalyst is relatively Pb‐rich and is active for CO 2 ‐to‐formate conversion over a wide potential range; under anodic conditions, it becomes relatively Pd‐rich and gains stable catalytic activity for formate‐to‐CO 2 conversion. The bifunctional activity and superior durability of our Pb–Pd catalyst leads to the first proof‐of‐concept demonstration of an electrochemical cell that can switch between the CO 2 electrolyzer/formate fuel cell modes and can stably operate for 12 days.
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