Fabrication and modeling of laser ablated NiO nanoparticles decorated SnO2 based formaldehyde sensor

In this study, we have reported the fabrication of p-NiO/n-SnO2 heterojunction based formaldehyde (HCHO) sensor by decorating the surface of pre-deposited SnO2 thin film with laser ablated NiO nanoparticles (NPs). In atmospheric air, NiO NPs were produced by a moving laser beam on the surface of pure (99.99%) Ni pellet to decorate sputtered deposited SnO2 thin film directly to form NiO/SnO2 p-n heterojunction. After fabrication, gas sensing properties of NiO/SnO2 sensor were investigated systemically towards HCHO and it exhibited higher response (Ra/Rg) of about 31.04 towards 50 ppm HCHO at 210 degrees C with good selectivity compared with pristine SnO2 sensor. Moreover, adsorption (Ka) and desorption rate constant (Kd), response time (tau res), recovery time (tau rec) and surface coverage (theta) of NiO/SnO2 sensor were extracted from experimental data using Langmuir gas adsorption-desorption model via curve fitting method and the models demonstrated the irreversible type of gas sensing behaviour towards HCHO. The experimental results revealed that the laser ablation method has a great potential to use as alternative chemical free surface decoration route to fabricate metal oxide heterojunction based sensors for the detection of formaldehyde or other toxic gases.

Automated summary

In this study, a p-NiO/n-SnO2 heterojunction-based formaldehyde (HCHO) sensor was fabricated by decorating the surface of pre-deposited SnO2 thin film with laser-ablated NiO nanoparticles. The gas sensing properties of the sensor were systematically investigated, and it showed a higher response towards 50 ppm HCHO compared to the pristine SnO2 sensor. The study demonstrated that laser ablation methods have great potential as a chemical-free surface decoration route for metal oxide heterojunction-based sensors.