Novel Approach to Synthesize Nanostructured Gallium Oxide for Devices Operating in Harsh Environmental Conditions

The importance of Ga2O3-based material for harsh environmental applications has attracted the interest of researchers in exploring various fabrication and growth techniques of Ga2O3-based nanomaterials using effective and low-cost processes. Herein, a demonstration to improve the wettability of liquid gallium on a rough silicon surface is presented. To control the roughness process, the silicon surface was patterned and groove-shape structures on the silicon were created using a photoelectrochemical (PEC) etching technique. Gallium oxide nanostructures were grown by thermal oxidation from liquid Ga in the presence and the absence of a silver thin film used as a catalyst. Scanning Electron Microscopy (SEM) was used to observe the morphology of the nanostructures grown on the roughed surface of the silicon substrate. The conformal deposition of Ga2O3 nanostructures inside the grooves of the PEC etched silicon surface was observed. The presence of Ag catalyst was found to completely change the morphology of Ga2O3. This method is recommended for the sustainable and low-cost synthesis of nanostructured gallium oxide for applications, including gas sensing.

Research on Catalytic Denitrification by Zero-Valent Iron (Fe0) and Pd-Ag Catalyst

This study primarily focused on how to effectively remove nitrate by catalytic denitrification through zero-valent iron (Fe0) and Pd-Ag catalyst. In order to get better catalytic performance, response surface methodology (RSM), instead of the single factor experiments and orthogonal tests, was firstly applied to optimize the condition parameters of the catalytic process. Results indicated that RSM is accurate and feasible for the condition optimization of catalytic denitrification. Better catalytic performance (71.6% N2 Selectivity) was obtained under the following conditions: 5.1 pH, 127 min reaction time, 3.2 mass ration (Pd: Ag), and 4.2 g/L Fe0, which was higher than the previous study designed by the single factor experiments (68.1%) and orthogonal tests (68.7%). However, under the optimal conditions, N2 selectivity showed a mild decrease (69.3%), when the real wastewater was used as the influent. Further study revealed that the cations (e.g., K+, Na+, Ca2+, Mg2+, and Al3+) and anions (e.g., Cl-, HCO3-, and SO42-) exist in wastewater may have distinctive influence on N2 selectivity. Finally, the reaction mechanism and kinetic model of catalytic denitrification were further studied.