An integrated electrocoagulation - Electrocatalysis water treatment process using stainless steel cathodes coated with ultrathin TiO2 nanofilms.

Anodic electrocoagulation processes can remove broad varieties of pollutants in industrial wastewater. However, some stubborn contaminants may still remain in effluents after the treatment and cause environmental issues. To further improve the efficiency of pollutant removal, we have coupled electrocatalysis with electrocoagulation and applied an atomic layer deposition (ALD) enabled TiO2 ultrathin overcoating at a nanometer scale on a stainless steel cathode. The electrocatalytic overcoating increased the elimination efficiency of organics and microorganisms, likely due to the electro-generation of adequate reactive oxygen species (ROS). The thickness of TiO2 nanofilm was controlled by the number of ALD cycles, and it was found that nanofilms processed with 50-100 cycles led to the maximum benefit of pollutant removal. By using the novel electrocoagulation-electrocatalysis cell to treat synthetic wastewater, a remarkable removal of 99.92% of E. Coli, 92.1% of suspended solids, 98.3% of heavy metal ions, and 88.8% of methylene blue was observed. This hybrid electrochemical treatment process may have the potential to treat wastewater at a larger scale.

Anisotropic, lightweight, strong, and super thermally insulating nanowood with naturally aligned nanocellulose.

There has been a growing interest in thermal management materials due to the prevailing energy challenges and unfulfilled needs for thermal insulation applications. We demonstrate the exceptional thermal management capabilities of a large-scale, hierarchal alignment of cellulose nanofibrils directly fabricated from wood, hereafter referred to as nanowood. Nanowood exhibits anisotropic thermal properties with an extremely low thermal conductivity of 0.03 W/m·K in the transverse direction (perpendicular to the nanofibrils) and approximately two times higher thermal conductivity of 0.06 W/m·K in the axial direction due to the hierarchically aligned nanofibrils within the highly porous backbone. The anisotropy of the thermal conductivity enables efficient thermal dissipation along the axial direction, thereby preventing local overheating on the illuminated side while yielding improved thermal insulation along the backside that cannot be obtained with isotropic thermal insulators. The nanowood also shows a low emissivity of <5% over the solar spectrum with the ability to effectively reflect solar thermal energy. Moreover, the nanowood is lightweight yet strong, owing to the effective bonding between the aligned cellulose nanofibrils with a high compressive strength of 13 MPa in the axial direction and 20 MPa in the transverse direction at 75% strain, which exceeds other thermal insulation materials, such as silica and polymer aerogels, Styrofoam, and wool. The excellent thermal management, abundance, biodegradability, high mechanical strength, low mass density, and manufacturing scalability of the nanowood make this material highly attractive for practical thermal insulation applications.