Two-dimensional NiO nanosheets with enhanced room temperature NO₂sensing performance via Al doping

Abstract

High-performance gas sensors based on metal oxides operated at room temperature are of great interest due to their energy saving and cost effective characteristics. How to improve the sensitivity of metal oxide gas sensors and enable their room-temperature operation are challenging for their realistic applications. In this work, we have designed and fabricated Al-doped NiO nanosheets for greatly enhanced NO detection at room temperature. Different amounts of Al were doped into two-dimensional (2D) NiO nanosheets via a fast and facile microwave assisted solvent-thermal technique. Sensing tests of the as-fabricated devices indicated that Al doping could significantly affect the gas-sensing properties of the NiO nanosheets due to increased oxygen vacancies as well as the formation of Lewis acid and base sites. When 12 at% of Al was added to the raw materials, the response value of the device to 10 ppm NO was enhanced more than 35 times compared with those of pure NiO nanosheets. In addition, when the amount of Al reached 20 at%, it took only 200 s for the gas sensor to achieve full recovery, which was a breakthrough for room temperature gas sensors based on metal oxides. Above all, the excellent performances of the as-fabricated devices make Al-doped NiO nanosheets a potential candidate for NO sensing applications. This design strategy can also give guidance for designing high-performance gas sensors based on other similar 2D sensing materials.

Advances in designs and mechanisms of semiconducting metal oxide nanostructures for high-precision gas sensors operated at room temperature

“…112 The aim of this topical review is to critically evaluate the design and structure of SMON-based gas sensors that may help guide the design of new devices. The performance of these SMON based gas sensors operated at RT could be improved significantly by modifying the SMONs using noble metal nanoparticles, [113][114][115][116] metal ions, [117][118][119] composites of multiple SMONs [120][121][122][123] and carbon nanomaterials. [124][125][126] In addition, not only the quantity of chemisorbed oxygen species, 127 defects 128 and element compositions 129,130 on the surface of SMONs, but also the structural properties, i.e., porosity, 131 heterojunction properties [132][133][134] and conductivity 135,136 can affect the RT gas sensing performance.…”

“…Chemical and electronic sensitization of the SMONs can be realized by adding noble metals on their surface and thus can remarkably enhance their sensing properties. Surface modifications and introduction of defects on the surfaces and interfaces such as introduction of heterojunctions 134 and vacancies 117 influence the sensing performance of SMON sensing materials. Addition of carbon nanomaterials on the surface of SMONs can also significantly improve their conductivity and enhance their sensitivities at RT.…”

“…The amount of dopant Al 3+ ions was found to significantly affect the gas sensing properties of NiO nanosheets. 117 Al 3+ doped NiO nanosheets have introduced many new oxygen vacancies due to aliovalent ion doping. Superoxide complexes such as Ni 2+ -O 2 À are easily formed on the surface of the NiO due to the existence of oxygen vacancies.…”

One-step synthesis and decoration of nickel oxide nanosheets with gold nanoparticles by reduction method for hydrazine sensing application

“…Recently, NiO nanosheets morphology got enormous interest for the various applications due to their extremely high surface area, ultrafine thickness, remarkable properties [22][23][24][25][26][27][28][29][30][31][32][33][34][35]. For example, Wang et al synthesized network NiO nanosheets and utilized for the construction of high-performance lithium-sulfur battery [22].…”

“…nanosheets were also used for gas and ion sensing [32][33][34]. Sun et al reported synthesis of NiO nanosheets decorated on TiO2 nanorods and used for improved photocatalytic activity [35].…”