Hereterogeneous Catalysis

 

Facet-engineering of nanoparticles (NPs) by morphology control has been intensively studied as an efficient approach to further enhance their (photo)catalytic performance. However, various processing steps and post-treatments used during the preparation of facet-engineered NPs always generate different surface active sites which may affect their (photo)catalysis. On the other hand, traditional surface techniques adopted for the study of facet activity such as PL, EPR, XPS and Raman are not truly surface specific but the analyses range from top few layers to bulk (not from a specific facet surface). Accordingly, it has been very difficult to correlate facet-dependent results and always lead to different interpretations even disagreements among researchers during the past decades.

 

New methodology for surface investigation

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

In an aim to identify the true active site, we have developed a new probe-assisted NMR technique which allows a genuine differentiation of surface active sites from various facets of a crystallite. Just as XRD giving structure-fingerprint of a crystal bulk, this surface-fingerprint methodology can provide not only qualitative (chemical shift) but also quantitative (peak intensity) surface information for unambiguous activity correlation. Our methodology for facet characterization therefore gives new insights to resolve the current debates and confusions in some facet-dependent properties in literature. Most importantly, our effort to catalysis can largely benefit the fundamental understanding of reaction mechanism and the rational design of new catalysts, which is crucial for filling the gap between the model catalysts used in surface science and the real catalysts found in practical applications.

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Enigma behind the NMR signal

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Do you enjoy playing puzzle? and at the same time making the world a better place? Currently, the facet-fingerprint of ZnO (shown above) and TiO2 surface has been disclosed in  J. Am. Chem. Soc. and Nat. Commun.. But this is just the start of our journey, more catalysts are quening and waiting for you to unravel their surface mystery and make most use of them accordingly.