Operando Nanoscale Sensors in Catalysis: All Eyes on Catalyst Particles

Abstract

An era of circularity requires robust and flexible catalysts and reactors. We need profound knowledge of catalytic surface reactions on the local scale (i.e., angstrom–nanometer), whereas the reaction conditions, such as reaction temperature and pressure, are set and controlled on the macroscale (i.e., millimeter–meter). Nanosensors operating on all relevant length scales can supply this information in real time during operando working conditions. In this Perspective, we demonstrate the potential of nanoscale sensors, with special emphasis on local molecular sensing with shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) and local temperature sensing with luminescence thermometry, to acquire new insights of the reaction pathways. We also argue that further developments should be focused on local pressure measurements and on expanding the applications of these local sensors in other areas, such as liquid-phase catalysis, electrocatalysis, and photocatalysis. Ideally, a combination of sensors will be applied to monitor catalyst and reactor “health” and serve as feedback to the reactor conditions.

Sub‐Second Time‐Resolved Surface‐Enhanced Raman Spectroscopy Reveals Dynamic CO Intermediates during Electrochemical CO2 Reduction on Copper

“…External signal enhancement through Shell‐Isolated Nanoparticles is necessary to study flat Cu electrodes. [9b] After performing an anodic treatment at 1.55 V for 120 s, the Raman signal associated with surface oxide species increases in signal/noise ratio, but again disappears within a second during subsequent reduction at −0.4 V (Figure S4). In addition to the disappearance of the CuO x Raman signal, a clear peak at 1060 cm −1 is observed one second after the onset of a sufficient cathodic bias (Figure 1 d ).…”

Boltzmann Thermometry in Cr3+‐Doped Ga2O3 Polymorphs: The Structure Matters!

“…With this aim, electrical, mechanical and optical techniques were demonstrated to be effective in terms of resolution. [1,2] However, for the development of contactless thermometers, required in many applications such as biological sensing [3][4][5] and catalysis [6][7][8] but also for temperature measurements of moving objects [9] or to follow noninvasively the phase transition temperature of materials, [10] the luminescence intensity ratio (LIR) technique was demonstrated to be particularly flexible. [11][12][13] The ratiometric concept of using two emissions to probe the temperature allows to overcome some of the limitations affecting the thermometric performance of luminescent thermometers based on a single emission, as in the case of Cr 3+ -Ln 3+ codoped materials.…”

Water–active site interactions in zeolites and their relevance in catalysis

“…The rationalization of the role of water during zeolite synthesis and the conversion of biomassderived molecules requires improvement of our knowledge about the elementary reaction steps involved. In that respect, in situ and operando analytical methods, applicable in aqueous media or in the presence of steam, are of a great help [102], as has been recently demonstrated in, for example, the MTO reaction over HSAPO-34 when co-feeding water with in situ UV-Vis microspectroscopy and confocal fluorescence microscopy [68] and the oligomerization of furfuryl alcohol over HZSM-5 with single-molecule fluorescence microscopy [103].…”