Strain effects in core-shell PtCo nanoparticles: a comparison of experimental observations and computational modelling

Design and screening of bimetallic catalysts for nitric oxide reduction by CO: a study of kinetic Monte Carlo simulation based on first-principles calculations

Nitric oxide (NO) emissions pose a significant environmental challenge, and the development of effective catalysts for NO reduction is crucial. This study investigates the potential of striped bimetallic catalysts for NO reduction by CO using kinetic Monte Carlo (KMC) simulations based on first-principles calculations. The simulations reveal that the activity on the striped Ni-Pt-Pt (111) surface is 1-2 orders of magnitude higher than that on the terraced Ni-Pt-Pt (111) surface at the same temperatures, demonstrating the importance of defect engineering. Sensitivity analysis identifies CO oxidation as the rate-determining step, although the 2N* association barrier is higher than CO oxidation, highlighting the need to consider reaction conditions in kinetic simulations. Volcano plots based on the formation energies of NO* and CO* successfully predict the striped Ni-Pd-Pd (111) and Ni-Rh-Rh (111) surfaces as optimal catalysts, which were further validated through DFT calculations and ab initio molecular dynamics simulations. This study offers valuable insights for designing high-performance bimetallic catalysts for NO reduction and underscores the importance of considering specific reaction conditions in kinetic simulations.

Antioxidant Nanozymes: Mechanisms, Activity Manipulation, and Applications

Antioxidant enzymes such as catalase, superoxide dismutase, and glutathione peroxidase play important roles in the inhibition of oxidative-damage-related pathological diseases. However, natural antioxidant enzymes face some limitations, including low stability, high cost, and less flexibility. Recently, antioxidant nanozymes have emerged as promising materials to replace natural antioxidant enzymes for their stability, cost savings, and flexible design. The present review firstly discusses the mechanisms of antioxidant nanozymes, focusing on catalase-, superoxide dismutase-, and glutathione peroxidase-like activities. Then, we summarize the main strategies for the manipulation of antioxidant nanozymes based on their size, morphology, composition, surface modification, and modification with a metal-organic framework. Furthermore, the applications of antioxidant nanozymes in medicine and healthcare are also discussed as potential biological applications. In brief, this review provides useful information for the further development of antioxidant nanozymes, offering opportunities to improve current limitations and expand the application of antioxidant nanozymes.

Strain Relaxation in Metal Alloy Catalysts Steers the Product Selectivity of Electrocatalytic CO2 Reduction

Strain engineering in bimetallic alloy structures is of great interest in electrochemical CO₂ reduction reactions (CO₂RR), in which it simultaneously improves electrocatalytic activity and product selectivity by optimizing the binding properties of intermediates. However, a reliable synthetic strategy and systematic understanding of the strain effects in the CO₂RR are still lacking. Herein, we report a strain relaxation strategy used to determine lattice strains in bimetal MNi alloys (M = Pd, Ag, and Au) and realize an outstanding CO₂-to-CO Faradaic efficiency of 96.6% and show the outstanding activity and durability toward a Zn-CO₂ battery. Molecular dynamics (MD) simulations predict that the relaxation of strained PdNi alloys (s-PdNi) is correlated with increases in synthesis temperature, and the high temperature activation energy drives complete atomic mixing of multiple metal atoms to allow for regulation of lattice strains. Density functional theory (DFT) calculations reveal that strain relaxation effectively improves CO₂RR activity and selectivity by optimizing the formation energies of *COOH and *CO intermediates on s-PdNi alloy surfaces, as also verified by in situ spectroscopic investigations. This approach provides a promising approach for catalyst design, enabling independent optimization of formation energies of reaction intermediates to improve catalytic activity and selectivity simultaneously.

Resolving the nanoparticles' structure-property relationships at the atomic level: a study of Pt-based electrocatalysts

Achieving highly active and stable oxygen reduction reaction performance at low platinum-group-metal loadings remains one of the grand challenges in the proton-exchange membrane fuel cells community. Currently, state-of-the-art electrocatalysts are high-surface-area-carbon-supported nanoalloys of platinum with different transition metals (Cu, Ni, Fe, and Co). Despite years of focused research, the established structure-property relationships are not able to explain and predict the electrochemical performance and behavior of the real nanoparticulate systems. In the first part of this work, we reveal the complexity of commercially available platinum-based electrocatalysts and their electrochemical behavior. In the second part, we introduce a bottom-up approach where atomically resolved properties, structural changes, and strain analysis are recorded as well as analyzed on an individual nanoparticle before and after electrochemical conditions (e.g. high current density). Our methodology offers a new level of understanding of structure-stability relationships of practically viable nanoparticulate systems.