First-principles Insights into Cu-Decorated GaN Monolayers for Sensing CO and HCHO in Dry-Type Transformers.

This work using first-principles theory studies the sensing properties of Cu-decorated GaN (Cu-GaN) monolayers as a promising candidate for the detection of CO and HCHO in dry-type transformers. The Cu dopant prefers to be trapped on the TN site of the GaN surface with an E b of -1.13 eV. Chemisorption is identified for the two gas adsorption systems, given the large adsorption energy (E ad) of -1.35 and -1.09 eV. Caused by the chemisorption, the electronic property of the Cu-GaN monolayer is significantly deformed, narrowing its band gap of 0.548 eV to 0.00 eV, exhibiting metallic property, in two gas systems. Combined with the desirable recovery property for CO and HCHO desorption from the Cu-GaN surface, it could be proposed that the Cu-GaN monolayer is a promising gas sensor for toxic gas detection in dry-type transformers, so as to evaluate the operation status of the power system and guarantee safe working conditions for the maintenances.