Hydrothermally synthesized Copper Oxide (CuO) superstructures for ammonia sensing

Area of Science:

• Materials Science
• Environmental Science
• Nanotechnology

Background:

• Ammonia (NH3) emissions exceed environmental protection agency (EPA) thresholds, necessitating effective NH3 sensors.
• Metal oxide nanostructures, particularly copper oxide (CuO), show promise for gas sensing applications.

Purpose of the Study:

• To synthesize morphology-controlled, 3-dimensional CuO superstructures for enhanced NH3 detection.
• To investigate the influence of synthesis parameters on CuO nanostructure morphology, surface area, and pore distribution.
• To evaluate the room-temperature NH3 sensing performance of synthesized CuO nanostructures.

Main Methods:

• Surfactant-free hydrothermal synthesis using a water/ethylene glycol (EG) mixture to control CuO superstructure morphology.
• Characterization of nanostructures using BET surface analysis to determine surface area and pore distribution.
• Gas sensing measurements using an indigenous setup to assess room-temperature NH3 detection capabilities.

Main Results:

• Hierarchical CuO superstructures (snowflake, flower, hollow-sphere, urchin-like) were successfully synthesized with tunable dimensions.
• Ethylene glycol addition significantly influenced surface area and pore diameter, enhancing it from 6nm to 14nm.
• Hollow-sphere CuO nanostructures exhibited maximum sensitivity (150%) to 600ppm NH3, with rapid response and recovery times (6 min).

Conclusions:

• The hydrothermal synthesis strategy offers a versatile method for producing shape-controlled CuO hierarchical materials.
• Morphology-dependent gas sensing properties were observed, highlighting the potential of tailored nanostructures.
• The developed CuO nanostructures are highly suitable for advanced NH3 sensing applications and environmental monitoring.