p-CoOx/n-SnO2 nanostructures: New highly selective materials for H2S detection

Abstract

Nanostructures p-CoO x /n-SnO 2 based on tin oxide nanowires have been prepared by two step CVD technique and characterized in detail by XRD, XRF, XPS, HAADF-STEM imaging and EDX-STEM mapping. Depending on the temperature of decomposition of cobalt complex during the second step of CVD synthesis of nanostructures cobalt oxide forms a coating and/or isolated nanoparticles on SnO 2 nanowire surface. It was found that cobalt presents in +2 and +3 oxidation states. The measurements of gas sensor properties have been carried out during exposure to CO (14 ppm), NH 3 (21 ppm), and H 2 S (2 ppm) in dry air. The opposite trends were observed in the effect of cobalt oxide on the SnO 2 gas sensitivity when detecting CO or NH 3 in comparison to H 2 S. The decrease of sensor signal toward CO and NH 3 was attributed to high catalytic activity of Co 3 O 4 in oxidation of these gases. Contrary, the significant increase of sensor signal in the presence of H 2 S was attributed to the formation of metallic cobalt sulfide and removal of the barrier between p-CoO x and n-SnO 2 . This effect provides an excellent selectivity of p-CoO x /n-SnO 2 nanostructures in H 2 S detection.

LaFeO3 Nanofibers for High Detection of Sulfur-Containing Gases

“…The smart engineering of novel and complex architectures through strategies such as patterning [27][28][29], surface modification [30] and nanostructuration [19,20,31] have been explored aiming 5 for higher device performances, as well as the low-cost and large-scale manufacturing of gas sensing devices. One-dimensional (1D) oxide nanostructures are highly suitable for the integration of active gas sensing materials due to their superior charge transport, high specific surface area, miniaturization and detection capabilities [32][33][34][35][36][37][38][39][40][41]. The search for cost-effective, high-throughput nanostructuring strategies has driven the research towards electrospinning.…”

Dip-coating decoration of Ag2O nanoparticles on SnO2 nanowires for high-performance H2S gas sensors

“…15 Nano-heterostructures are oen utilized owing to their small size and high surface-tovolume ratio, 17,18 and many efforts have been devoted to the fabrication of p-n heterojunctions for increasing H 2 S-sensing performance. [19][20][21][22][23][24] The most common p-type metal oxides used to form heterojunctions with n-type SnO 2 semiconductor are CuO, 18,25 NiO, 26,27 and Co 3 O 4 (ref. 24) because of their easy sul-dation into CuS, NiS, and CoS, respectively.…”

An effective H2S sensor based on SnO2 nanowires decorated with NiO nanoparticles by electron beam evaporation

“…14,20 Using other abundant materials to functionalise the surface of SnO 2 to enhance its sensing performance has becomes one of the priorities in recent years. 21,22 The common materials used to functionalise the surface of n-type SnO 2 to enhance H 2 S sensing performance include p-type semiconductors, such as CuO and nickel oxide (NiO); these materials are applied to utilise the synergic effects of p-n heterojunction and catalytic activity of decorated materials. 22,23 The p-type NiO is highly reactive with H 2 S, that is, H 2 S can convert NiO into NiS; 24 thus, this material is currently used to decorate or functionalise SnO 2 to enhance its H 2 S-sensing performance.…”

“…21,22 The common materials used to functionalise the surface of n-type SnO 2 to enhance H 2 S sensing performance include p-type semiconductors, such as CuO and nickel oxide (NiO); these materials are applied to utilise the synergic effects of p-n heterojunction and catalytic activity of decorated materials. 22,23 The p-type NiO is highly reactive with H 2 S, that is, H 2 S can convert NiO into NiS; 24 thus, this material is currently used to decorate or functionalise SnO 2 to enhance its H 2 S-sensing performance. 25 Several researchers have studied the decoration of SnO 2 nanomaterials by NiO nanoparticles to enhance their gas sensing performance.…”