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Surface functionalization of semiconductor nanoparticles plays a significant role in the manipulation of the nanoparticle physicochemical properties and diverse applications. Conventional points of anchor involve mercapto, carboxyl and phenol moieties, forming largely nonconjugated interfacial linkages. In this personal account, we summarize recent progress in surface functionalization of semiconductor nanoparticles with olefin and acetylene derivatives, where the formation of conjugated interfacial bonds leads to ready manipulation of the nanoparticle optical and electronic properties, by using Si and TiO₂nanoparticles as the illustrating examples. Finally, a perspective is included where the promises and challenges of structural engineering of semiconductor nanoparicles are highlighted.

 

Janus nanoparticles capped with a hydrophobic and hydrophilic hemisphere of mercapto ligands can self‐assemble into hollow, emulsion‐like nanostructures in controlled media. As the nanoparticle emulsions are chiroptically active exhibiting a plasmonic circular dichroism absorption in the visible range, they can be exploited as a unique chiral nanoreactor by selective encapsulation ofd‐enantiomer into the water phase of the water‐in‐oil emulsions for directional functionalization of the nanoparticles and endow the resulting nanoparticles with select chirality. This is demonstrated in the present study with gold Janus nanoparticles functionalized with (hydrophobic) hexanethiolates and (hydrophilic) 3‐mercapto‐1,2‐propandiol, andd,l‐cysteine is used as the molecular probe. Experimental results demonstrate thatd‐cysteine is the preferred enantiomers entrapped within the nanoparticle emulsions, where the ensuing ligand exchange reaction is initially confined to the hydrophilic face of the Janus nanoparticles. This suggests that with a deliberate control of the reaction time, chiral Janus nanoparticles can be readily prepared by ligand exchange reactions even with a racemic mixture of ligands.

 

Single atoms of select transition metals supported on carbon substrates have emerged as a unique system for electrocatalysis because of maximal atom utilization (≈100%) and high efficiency for a range of reactions involved in electrochemical energy conversion and storage, such as the oxygen reduction, oxygen evolution, hydrogen evolution, and CO₂reduction reactions. Herein, the leading strategies for the preparation of single atom catalysts are summarized, and the electrocatalytic performance of the resulting samples for the various reactions is discussed. In general, the carbon substrate not only provides a stabilizing matrix for the metal atoms, but also impacts the electronic density of the metal atoms due to strong interfacial interactions, which may lead to the formation of additional active sites by the adjacent carbon atoms and hence enhanced electrocatalytic activity. This necessitates a detailed understanding of the material structures at the atomic level, a critical step in the construction of a relevant structural model for theoretical simulations and calculations. Finally, a perspective is included highlighting the promises and challenges for the future development of carbon‐supported single atom catalysts in electrocatalysis.

 

Rational design of single-metal atom sites in carbon substrates by a flexible strategy is highly desired for the preparation of high-performance catalysts for metal-air batteries. In this study, biomass hydrogel reactors are utilized as structural templates to prepare carbon aerogels embedded with single iron atoms by controlled pyrolysis. The tortuous and interlaced hydrogel chains lead to the formation of abundant nanowrinkles in the porous carbon aerogels, and single iron atoms are dispersed and stabilized within the defective carbon skeletons. X-ray absorption spectroscopy measurements indicate that the iron centers are mostly involved in the coordination structure of FeN 4 , with a minor fraction (ca. 1/5) in the form of FeN 3 C. First-principles calculations show that the FeN x sites in the Stone-Wales configurations induced by the nanowrinkles of the hierarchically porous carbon aerogels show a much lower free energy than the normal counterparts. The resulting iron and nitrogen-codoped carbon aerogels exhibit excellent and reversible oxygen electrocatalytic activity, and can be used as bifunctional cathode catalysts in rechargeable Zn-air batteries, with a performance even better than that based on commercial Pt/C and RuO 2 catalysts. Results from this study highlight the significance of structural distortions of the metal sites in carbon matrices in the design and engineering of highly active single-atom catalysts.