Nanoparticles Synthesis: an organometallic approach
Since 2000, I’ve developed new chemical routes using soluble organometallic or metal-organic precursors as an alternative to conventional colloidal chemistry and gas phase thin film deposition. I’ve explored the organometallic synthesis of metallic nanocrystals and the non-aqueous sol-gel synthesis along two major research axes. The first consists in the batch synthesis of nanospheres and nanowires, which are then assembled. In the second approach, the organometallic precursor is directly targeted to the substrate and reacts on the spot.
My group synthesizes reactive organometallic complexes and study the thermolysis and chemical reduction of these complexes to yield nanostructures. We have demonstrated that designed reactive organometallic precursors could be decomposed to form metallic coatings directly on almost any substrate with unique control. (Nanoscale 2012, 4, 762 (COVER ARTICLE))
This approach allows direct synthesis on the plastic substrate, with the use of standard coating equipment such as spin coating. The synthetic pathway has been very successful with manganese, cobalt, nickel and copper alloys and compounds, together with the discovery of size dependent electronic properties (magnetic moment, anisotropy, plasmon) (PRL 2002, 89 (3), 037203, Angew. Chem. 2006, 45, 420, JACS 2005, 127, 15034) and hydrodynamic behaviors (PRL 2014, 112, 188301; Soft Matter 2014, 10 (27), 4913).
Electrocatalysts and Electrode Materials
The metallic nanoparticles are used as electrocatalysts or electrode materials in electrochemical devices (Fuel cells or Batteries). The organometallic syntheses described above lead to “clean surface” nanoparticles and tailored interfaces. Typically, colloidal syntheses have been successful to control the size of nanospheres, we have brought the control to the shape and crystallographic facets of the nanocrystals. This approach has been applied to monometallic and bimetallic systems (JPCB 2003, 107, 6997; JPCC 2013, 117(6), 3093; JPCC 2014, 118, 10455). The transition metal nanocrystals display high electrocatalytic activities in Alkaline Membrane Fuel Cells.
Electrochemical devices: understanding down to the nanoscale through electron magnetism
One of the challenges in energy storage consists in the investigation of new electrode materials and comprehension of the mechanism of lithium uptake. New ways to get real–time information on the performances of the battery are continuously sought. The development of in-situ techniques can provide unique understanding of the mechanisms, successes and failures of electrochemical devices. The development of in-situ (or in operando) characterization techniques brings valuable information on chemical processes since the interpretation of ex situ measurements brings a partial picture of the chemical reactions. We envision several future developments that would stem from our novel approach of bottom-up elaboration of nanomaterials. The nano-composites offer a unique platform with active elements and probes so that these real-time measurements actually map the electrodes and reveal the nature of their interfaces.
We have been the first laboratory to introduce the electron magnetic measurements in post-mortem analyses (Chem. Mater. 2009, 21 (15), 3684) and the first group to publish the operando electron magnetic measurements (Energy and Environmental Science, 2014, 7, 2012). These in-situ measurements allowed us proposing a new electrochemical mechanism on the high energy density anodic material FeSb2.
Such an approach provides a deep understanding of the material response to electrochemical processes down to the nanoscale.