Magnetic nanoparticles (MNPs) are of high significance in sensing as they provide viable solutions to the enduring challenges related to lower detection limits and non-specific effects. The rapid expansion in the applications of MNPs creates a need to overview the current state of the field of MNPs for sensing applications. In this Review, the trends and concepts in the literature are critically appraised in terms of the opportunities and limitations of MNPs used for the most advanced sensing applications. The latest progress in MNP sensor technologies is overviewed with a focus on MNP structures and properties, as well as the strategies of incorporating these MNPs into devices. By looking at recent synthetic advancements, and the key challenges that face NP-based sensors, this Review aims to outline how to design, synthesize and use MNPs to make the most effective and sensitive sensors.
Single Pt atom catalysts on non-active carbon supports have been key targets for electrochemical reactions because the high exposure of active Pt leads to record-high activities. PtRu alloy catalysts are the most active for the methanol oxidation reaction (MOR) as the Ru atoms decrease CO poisoning of the active Pt. To combine the exceptional activity of single atom Pt catalysts with the bene ts of an active Ru support we must overcome the synthetic challenge of forming single Pt atoms on noble metal nanoparticles. We have developed a concept to grow and spreads Pt islands on faceted Ru branched nanoparticles to make single Pt atom on Ru catalysts. By following the spreading process with in situ TEM, we show that the formation of single atoms is thermodynamically driven by the formation of strong Pt-Ru bonds and a lowering of surface area. The single Pt atom on Ru catalysts successfully limit CO poisoning during MOR to produce record current density and mass activity over time.
MainThe methanol oxidation reaction (MOR) is the limiting reaction for the direct methanol fuel cell because CO-poisoning prevents high current densities over time 1 . CO poisoning is one of the most signi cant issues limiting the long-term use of catalysts for reactions such as MOR, ethanol oxidation and formic acid oxidation, where CO intermediates form 2,3 . Pt is the most active MOR catalyst, however CO ads intermediates bind strongly to poison the Pt sites, thus preventing access of methanol to these active sites 4 . CO poisoning occurs by the formation of CO ads bound on top of three Pt atoms in a triangular arrangement 5,6 . As a consequence, single atom catalysts are a promising target to overcome CO poisoning if Pt atoms can be dispersed on a support without formation of these triangular arrangements of Pt atoms.
Achieving stability with highly active Ru nanoparticles for electrocatalysis is a major challenge for the oxygen evolution reaction. As improved stability of Ru catalysts has been shown for bulk surfaces with low-index facets, there is an opportunity to incorporate these stable facets into Ru nanoparticles. Now, a new solution synthesis is presented in which hexagonal close-packed structured Ru is grown on Au to form nanoparticles with 3D branches. Exposing low-index facets on these 3D branches creates stable reaction kinetics to achieve high activity and the highest stability observed for Ru nanoparticle oxygen evolution reaction catalysts. These design principles provide a synthetic strategy to achieve stable and active electrocatalysts.
The direct growth of Pt islands on lattice mismatched Ni nanoparticles is a major synthetic challenge and a promising strategy to create highly strained Pt atoms for electrocatalysis. By using very mild reaction conditions, Pt islands with tunable strain were formed directly on Ni branched particles. The highly strained 1.9 nm Pt-island on branched Ni nanoparticles exhibited high specific activity and the highest mass activity for HER in pH 13 electrolyte. These results show the ability to synthetically tune the size of the Pt islands to control the strain to give higher HER activity.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.