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Nanoparticles are an indispensable part of our lives. From electronic devices to drug delivery to catalysis and energy storage, nanoparticles have found various important applications. Out of the many synthetic strategies to generate nanoparticles, electrodeposition has stood out due to its cost effectiveness, low time consumption and simplicity. However, traditional electrodeposition techniques have suffered from controlling the size, shape, morphology and microstructure of nanoparticles. Here, we use a technique called nanodroplet‐mediated electrodeposition, where nanodroplets carrying the metal salt precursor collide with a negatively‐biased electrode. In this work, we use this nanodroplet‐mediated electrodeposition technique along with transmission electron microscopy, selected‐area electron diffraction and high‐angle‐annular dark‐field scanning transmission electron microscopy to show control over the microstructure of single nanoparticles. Along with that, we use X‐ray photoelectron spectroscopy to get mechanistic insights behind the alteration of microstructure observed. Having achieved a control over the microstructure, we show the application by synthesising polycrystalline alloys at room temperature and evaluating the electrocatalytic behavior of the different microstructures towards the hydrogen evolution reaction. This fundamental work of controlling microstructures of single nanoparticles and its applications in alloy synthesis and electrocatalysis opens a new avenue of tuning nanoparticles for various applications. 

Triple-barrel electrodes can monitor temperature and freezing events in microdroplets in real time, delivering enhanced temporal resolution and standalone insights into the ice nucleation and the thermoelectrochemical properties of aqueous systems. 

The curious chemistry observed in microdroplets has captivated chemists in recent years and has led to an investigation into their ability to drive seemingly impossible chemistries. One particularly interesting capability of these microdroplets is their ability to accelerate reactions by several orders of magnitude. While there have been many investigations into which reactions can be accelerated by confinement within microdroplets, no study has directly compared reaction acceleration at the liquid|liquid and gas|liquid interfaces. Here, we confine glucose oxidase, one of life’s most important enzymes, to microdroplets and monitor the turnover rate of glucose by the electroactive cofactor, hexacyanoferrate (III). We use stochastic electrochemistry to monitor the collision of single femtoliter water droplets on an ultramicroelectrode. We also develop a measurement modality to robustly quantify reaction rates for femtoliter liquid aerosol droplets, where the majority of the interface is gas|liquid. We demonstrate that the gas|liquid interface accelerates enzyme turnover by over an order of magnitude over the liquid|liquid interface. This is the first apples-to-apples comparison of reaction acceleration at two distinct interfaces that indicates that the gas|liquid interface plays a central role in driving curious chemistry.