Rapid atmospheric-pressure-plasma processed nanomaterials for electrochemical energy harvesting and storage devices

摘要

Summary form only given. Nanostructured screen-printed electrodes featured with high specific surface area are commonly used in electrochemical devices for energy harvesting and storage applications. The fabrication of these nanostructured electrodes via low-cost screen-printing techniques usually involves high-temperature furnace calcination processes. To lower the thermal budget for device fabrication, reducing the processing time is highly desirable. In this study, an ultrashort process was developed for the fabrication of photoanodes and counter electrodes in dye-sensitized solar cells (DSSCs) and nanocomposite electrodes in supercapacitors by using an atmospheric pressure plasma jet (APPJ) technology. Owing to the synergistic effect of the temperature and the reactivity of the plasma jet, comparable cell performance was successfully demonstrated when the conventional furnace calcination processes for the solution-processed nanostructured electrodes were replaced by ultrashort nitrogen APPJ treatments. To determine the endpoint of the APPJ treatment, optical emission spectroscopy analysis was carried out during the process. For DSSC photoanode fabrication, APPJ treatments as short as 1 to 2 min were successfully used to sinter the nanoporous TiO2 layer, to simultaneously deposit particulate TiO2 scattering layer along with the sintering process, and to produce a dual-scale porous TiO2 layer from a mixture of TiO2 nanoparticle paste and NaCl solution. For catalytic counter electrode fabrication, APPJ processes with treatment durations of 1 min, 11 sec, 5 sec have been applied to facilitate the formation of Pt nanoparticles, reduced graphene oxide (rGO) foams, and carbon nanotube (CNT)/TiO2 composites from solution-processed precursor films. For supercapacitor applications, the required APPJ processing duration were merely 5 and 15 sec for the Fe2O3/CNT composite and rGO on carbon cloth, respectively. In particular, we observed the morphology of the carbon-based material could be modified by the APPJ treatment, by which the catalytic activity of the carbon nanomaterial-based counter electrode could be enhanced. This new methodology reduces the processing time and thermal budget, providing a facile approach for the production of cost-effective electrochemical devices for energy harvesting and storage applications.