We present a stable inkjet printable graphene ink, formulated in isopropyl alcohol via liquid phase exfoliation of chemically pristine graphite with a polymer stabilizer. The rheology and low deposition temperature of the ink allow uniform printing. We use the graphene ink to fabricate counter electrodes (CE) for natural and ruthenium-based dye-sensitized solar cells (DSSCs). The repeatability of the printing process for the CEs is demonstrated through an array of inkjet-printed graphene electrodes, with ~5% standard deviation in the sheet resistance. As photosensitizers, we investigate natural tropical dye extracts from Pennisetum glaucum, Hibiscus sabdariffa and Caesalpinia pulcherrima. Among the three natural dyes, we find extracts from C. pulcherrima exhibits the best performance, with ~0.9% conversion efficiency using a printed graphene counter electrode and a comparable ~1.1% efficiency using a platinum (Pt) CE. When used with N719 dye, the inkjet-printed graphene CE shows a ~3.0% conversion efficiency, compared to ~4.4% obtained using Pt CEs. Our results show that inkjet printable graphene ink, without any chemical functionalization, offers a flexible and scalable fabrication route, with a material cost of only ~2.7% of the equivalent solution processed Pt-based electrode.

A new class of superhydrophobic surface based on multiple hybrid coatings is proposed and prepared to improve mechanical and reproduction stability. It does not only show a large water contact angle (ca. 174.5°) but also a slight decrease (ca. 6.4%) of water contact angle after 100 mechanical abrasion cycles. Furthermore, the water contact angle changes slightly (relative standard deviation, 0.14%) for the three superhydrophobic surfaces prepared with the same procedure. The application of superhydrophobic multiple hybrid coatings in corrosion protection is further investigated by the Tafel polarization curves and electrochemical impedance spectroscopy. The superhydrophobic multiple hybrid coatings showed lower corrosion current (1.4 × 10–11 A/cm2), lower corrosion rate (ca. 1.6 × 10–7 mm/year), and larger polarization resistance (7.9 × 104 MΩ cm2) in 3.5 wt % NaCl aqueous solution compared to other superhydrophobic coatings reported in previous works. This work not only confirms the formation of robust superhydrophobic surface for real application in corrosion protection but also provides a new model of superhydrophobic surface based on multiple hybrid coatings with high mechanical, chemical, and reproduction stability for various applications.

A new class of superhydrophobic surface based on assembly of nanoparticles were fabricated for improving mechanical durability and anti-icing performance under ultra-low temperature. Furthermore, the anti-icing performance and mechanism of the yielded superhydrophobic surface was investigated by a high speed video and thermal infrared imaging equipment. The frozen time of water droplets could be prolonged to 372.0s when exposed glass slides with superhydrophobic surface to an ultra-low temperature of -40.0℃. This outstanding anti-icing performance is attributed to the unique structure of the superhydrophobic surface based on assembly of nanoparticles, which possesses good free-energy barrier and low heat transfer rate. This study thus opens up an avenue for the design and fabrication of superhydrophobic surface with good durability and anti-icing performance under ultra-low temperature.

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