This article focuses on the atomic force microscopy-infrared (AFM-IR) technique and its recent technological developments. Based on the detection of the photothermal sample expansion signal, AFM-IR combines the high spatial resolution of atomic force microscopy with the chemical identification capability of infrared spectroscopy to achieve submicrometric physico-chemical analyses. Since the first publication in 2005, technological improvements have dramatically advanced the capabilities of AFM-IR in terms of spatial and spectral resolution, sensitivity, and fields of applications. The goal of this paper is to provide an overview of these developments and ongoing limitations. We summarize recent progress in AFM-IR implementations based on the major AFM contact, tapping, and peak force tapping modes. Additionally, three new trends are presented, namely, AFM-IR applied to mineral samples, in fluid and a novel, purely surface sensitive AFM-IR configuration, to probe top layers. These trends demonstrate the immense potential of the technique and offer a good insight into the scope of AFM-IR.

International audienceMicrostructure of Supported Cobalt Fischer-Tropsch Catalysts — The structures of metallic cobalt particles supported on silica (with and without Ru promoter) and on alumina have been investigated in-situ by conventional and anomalous X-ray diffraction. Comparison with simulated XRD patterns shows the structure to consist of a defect phase characterised by the presence of stacking faults, the density of which is directly related to the temperature at which the cobalt oxide is reduced. Controlled modification of the cobalt microstructure, while maintaining the same support and promoter has been achieved with limited variation of the particle size, notably via CO – H2 treatment leading to the formation and decomposition of cobalt carbide. Independently of the support or the presence of a promoter, low reduction temperatures increase the tendency to form hexagonal close packed (hcp) structure whilst at high reduction temperatures face centred cubic (fcc) stacking is preferentially formed. The catalytic activity for CO conversion in Fischer-Tropsch conditions is greatly increased for catalysts with a majority of hcp stacking compared to those containing predominantly fcc phase particles