Elucidation of the nature of hydrogen interactions with palladium nanoparticles is expected to play an important role in the development of new catalysts and hydrogen-storage nanomaterials. A facile scaled-up synthesis of uniformly sized single-crystalline palladium nanoparticles with various shapes, including regular nanocubes, nanocubes with protruded edges, rhombic dodecahedra, and branched nanoparticles, all stabilized with a mesoporous silica shell is developed. Interaction of hydrogen with these nanoparticles is studied by using temperature-programmed desorption technique and by performing density functional theory modeling. It is found that due to favorable arrangement of Pd atoms on their surface, rhombic dodecahedral palladium nanoparticles enclosed by {110} planes release a larger volume of hydrogen and have a lower desorption energy than palladium nanocubes and branched nanoparticles. These results underline the important role of {110} surfaces in palladium nanoparticles in their interaction with hydrogen. This work provides insight into the mechanism of catalysis of hydrogenation/dehydrogenation reactions by palladium nanoparticles with different shapes.

Background Hydroxychloroquine and ivermectin received widespread attention after initial studies suggested that they were effective against COVID-19. However, several of these studies were later discredited. Objectives We explored the impact of scientific articles, public announcements and social media posts on hydroxychloroquine and ivermectin purchases in the USA and Canada during the COVID-19 pandemic. Methods We conducted a retrospective, population-based time series analysis of retail hydroxychloroquine and ivermectin purchases in the USA and Canada from February 2016 through to December 2021, using IQVIA’s Multinational Integrated Data Analysis database. We fitted the purchasing rates with interventional autoregressive integrated moving average models. We used Google Trends to identify the most influential interventions to include in the models. Results There were significant pulse increases in hydroxychloroquine purchases in March 2020 in both the USA (P < 0.0001) and Canada (P < 0.0001). For ivermectin, there were no significant changes in April 2020 in either the USA (P = 0.41) or Canada (P = 0.16); however, significant pulse increases occurred from December 2020 to January 2021 in both the USA (P = 0.0006) and Canada (P < 0.0001), as well as significant ramp increases from April to August 2021 in both the USA (P < 0.0001) and Canada (P = 0.02). The increases in ivermectin purchases were larger in the USA than in Canada. Conclusions Increases in hydroxychloroquine and ivermectin purchasing rates aligned with controversial scientific articles and social media posts. This highlights the importance of scientific integrity and disseminating accurate epidemiologic information during pandemics.