Piezotronic modulations in electro- and photochemical catalysis
- PDF / 1,861,521 Bytes
- 6 Pages / 585 x 783 pts Page_size
- 83 Downloads / 234 Views
Introduction Research on advanced catalysts for electrochemical processes, particularly relevant to energy and the environment, is currently attracting increasing attention in various science and technology disciplines. Understanding and facilitating the charge-transfer kinetics at heterogeneous interfaces are the predominate strategy to advance electrochemical catalyst design and performance. Piezotronics is an emerging concept to tune the charge separation and transport properties at heterojunctions.1–3 The core of piezotronics lies in the coupling between electrical polarizations and the internal electric field formed at the heterojunction interfaces.4–6 The unique band-tuning ability of the piezotronic effect provides a revolutionary paradigm to exceed the performance cap in many electrochemical systems.7 As electrochemical catalysis is sensitive to the electronic band structure at the solid–liquid interface, introducing an additional polarization to that interface can help manipulate the interfacial energy landscape, and thereby modulate the catalytic performance. Such a unique coupling opens a promising application direction for piezotronics leading a new route toward ultimate performance gain of electrochemical catalysis. Piezotronics modulation can be implemented by using strained piezoelectric materials or the permanent polarization
of ferroelectric materials, both of which are generally treated as surface polarization in this article. The operational conditions of piezotronics are not restricted by other factors, such as with or without light or an external bias. All of these conditions are discussed here. In addition, the piezoelectric polarization can be directly used as an exclusive driving force to catalyze electrochemical reactions—this has been called piezocatalysis, a new concept in energy transformation and catalysis.8
Piezoelectric polarization—Influence on near-surface energetics Charged oxide surfaces support subsurface space-charge layers that can enhance the separation of photogenerated carriers and thereby reduce recombination losses. Beyond the trivial solution of polarizing the oxides with an external bias, there are two mechanisms for creating charged oxide surfaces. The first is to alter the pH of the solution that is in contact with the oxide surface.9,10 This uniformly changes the charge state on the surface, similar to an external bias, and can be used with samples of any form factor. The second mechanism is to select materials that naturally have charged domains on their surfaces because of their crystallography or microstructure. There are three types of complex oxides that intrinsically have charged surface domains. The first type is comprised of
Xudong Wang, Department of Materials Science and Engineering, University of Wisconsin–Madison, USA; [email protected] Gregory S. Rohrer, Department of Materials Science and Engineering, Carnegie Mellon University, USA; [email protected] Hexing Li, Shanghai University of Electric Power, China; [email protected] doi:10.1557/mrs.201
Data Loading...
