Exploiting Synergies in Catalysis and Gas Sensing using Noble Metal‐Loaded Oxide Composites

Abstract

Noble metal/metal oxide nanocomposites are very important in various fields of catalysis and play an evenly important role in gas sensing. Although there are many similarities regarding the choice of materials, the synthesis and the fundamental mechanisms, both research fields have been mostly treated independently up to now. In both fields, open questions regarding the elementary steps in the interaction of the gases with the active species and the role of the noble metal, the semiconducting metal oxide support and the interface remain. In this concept article, we first outline the importance of such composites in catalysis and gas sensing focussing on Pt/Pd, as well as CeO2 and SnO2 as transition metal oxides. Next, the state of art of both fundamental and relevant surface reactions and electronic mechanisms are described. Finally, we highlight the synergy of jointly exploring catalysis and gas sensing of noble metal/metal oxide nanocomposite materials and the benefit for both research fields if they are dealt with simultaneously using advanced characterization and operando methods, sophisticated preparation techniques, testing of the performance, and predictive theoretical modelling.

Microfluidically synthesized Au, Pd and AuPd nanoparticles supported on SnO2 for gas sensing applications

“…Gas sensing has become increasingly important in our society due to technical innovations and the higher living standard [1][2][3][4]. Semiconducting metal oxide (SMOX) based materials are widely applied in the field of gas sensing for safety, quality control and personnel protection.…”

Trends and Advances in the Characterization of Gas Sensing Materials Based on Semiconducting Oxides

“…The surface chemistry is mainly investigated by Diffuse Reflectance Infrared Fourier-Transform Spectroscopy (DRIFTS) [ 28 , 39 , 40 , 41 ] and Raman spectroscopy [ 27 , 42 ]. An overview of operando methods for SMOX gas sensors is given in Figure 1 [ 14 ]. A detailed discussion of in-situ and operando spectroscopic techniques is given elsewhere [ 15 , 30 ].…”

“…The development of gas sensors is still based on trial and error rather than on knowledge-based approaches, which enable a rational design of sensing materials based on the understanding of fundamental processes [ 14 ]. The fundamental understanding involves a detailed knowledge on the relationship of structures, properties and functionality (structure-function-relationship) as well as on the connection of synthesis routes and obtained structures.…”

Review—System-on-Chip SMO Gas Sensor Integration in Advanced CMOS Technology

“…The ways in which a noble metal atom can influence the sensing film is described in some detail in several recent works 156,157 and are partially summarized in Figure 22. The two primary mechanisms are chemical and electrical sensitization.…”

“…If the valence state of the metal ion is different from that of the replaced cation, additional acceptor or donor states can be introduced. 157 Particularly doping with Pt leads to a lowered resistance of the sensing film and an enhanced CO oxidation due to the increased number of oxygen vacancies generated. 157,159…”