Pyroelectrocatalytic Disinfection Using the Pyroelectric Effect of Nano- and Microcrystalline LiNbO₃ and LiTaO₃ Particles

Abstract

LiNbO 3 (LN) and LiTaO 3 (LT) materials of polar crystal structure exhibit a spontaneous polarization that can be changed by temperature. This phenomenon, commonly known as the pyroelectric effect, leads to the generation of surface charges that in turn are the source for a pyroelectrocatalytic or pyroelectrochemical activity of these materials described in this paper. It can also be regarded as a selective conversion of thermal via electrical to chemical energy based on the pyroelectric effect. In this context, we have investigated the impact of thermally excited pyroelectric LN and LT nano-and microcrystalline powder materials on the bacterium Escherichia coli in aqueous solutions. Powders have been prepared both by milling of commercially available single crystals and by precursorbased solution routes. Our results show that in dependence on the crystallite size and surface area of the pyroelectric particulate material in direct contact with the cells and/or their culture solution, a high antimicrobial activity can be achieved. On the basis of further experimental results of oxidative conversion of the fluorescent dye 2′,7′-dichlorofluorescin, a disinfection mechanism including the formation of reactive oxygen species at the pyroelectric particle surface is proposed. The phenomenon is discussed in analogy to the well-established photocatalytic disinfection mechanism.

Enhanced photocatalytic performance over Bi4Ti3O12 nanosheets with controllable size and exposed {0 0 1} facets for Rhodamine B degradation

“…The self-induced internal electric fields are perpendicular to the nanosheets of Bi 4 Ti 3 O 12 . The effect of the polarization in ferroelectric materials has proven to be responsible for good photocatalytic activities [56]. When the Bi 4 Ti 3 O 12 nanosheets exposed with {0 0 1} facets are irradiated by visible-light, photoinduced electron-hole pairs are formed and then driven apart by the internal electric fields [57].…”

LiNbO3: A photovoltaic substrate for massive parallel manipulation and patterning of nano-objects

“…49,83 Reported applications in the biological area include self-assembly of yeast cells as illustrated in Figure 19 49 and disinfection of aqueous solutions containing nano-and micro-crystalline powders of lithium niobate and lithium tantalite. 48 Main advantages of PV tweezers over these alternative methods are the flexibility of the light patterns to induce particle patterning, the reconfiguration capabilities, and the simpler methodology. Anyhow, a deeper comparative analysis of these effects is in order.…”

“…87 For this type of applications, one should also mention that the pyroelectric fields developed in micro-and nano-crystalline LiNbO 3 has been successfully used as a disinfection mechanism by killing E. coli bacteria in aqueous solution. 48 Finally, another related applications manipulate different kind of bio-objects using PV tweezers. For instance, in Ref.…”

“…1D and 2D patterns are considered separately. To complete the analysis in Section V other alternative methods using LiNbO 3 , such as those based on UV illumination of periodic poling of the structure (PPLN) 35,47 or in the pyroelectric (PY) effect, 22,48,49 will be briefly discussed for comparison purposes. In Section VI, a variety of applications of PV tweezers that are mostly in a preliminary stage, are reviewed.…”

Synthesis and characterization of LiNbO 3 nanocrystals prepared by the aerosol assisted chemical vapor deposition method

“…On the other hand, recently, the interest on the synthesis of nanoscale materials has increased greatly due to their interesting properties with potential technological application emerging from the dimensional confinement. This has sparked interest in the synthesis of nanosized LiNbO 3 including nanowires and nanoparticles [7][8][9][10][11]. In particular, in this work we worked with lithium niobate nanoparticles.…”