Nanostructured hybrid based on graphene and tantalum bromide octahedral clusters for room temperature detection of ammonia

Identifier:  imarina:9681563

Handle: https://hdl.handle.net/20.500.11797/imarina9681563

Authors:  Nisar A; Santos-Betancourt A; Hernández JS; Güell F; Feliz M; Llobet E

Abstract:
This paper reports for the first time a nanohybrid based on octahedral tantalum bromide Ta<inf>6</inf>Br<inf>12</inf> cluster units supported onto graphene (Ta<inf>6</inf>Br<inf>12</inf>@graphene) for room temperature detection of ammonia. The Ta<inf>6</inf>Br<inf>12</inf>@graphene nanomaterial was prepared from [{Ta<inf>6</inf>Br<inf>12</inf>}Br<inf>2</inf>(H<inf>2</inf>O)<inf>4</inf>]·4H<inf>2</inf>O cluster precursor and graphene nanoplatelets and integrated into a chemiresistive device. To comprehensively characterize the nanostructured hybrid, it was thoroughly investigated using powder X-ray diffraction (PXRD), Raman spectroscopy, field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy with energy-dispersive X-ray spectroscopy (HRTEM-EDX), and X-ray photoelectron spectroscopy (XPS). Significant changes in the electrical resistivity were obtained when Ta<inf>6</inf>Br<inf>12</inf>@graphene was exposed to NH<inf>3</inf> at room temperature, exhibiting a response of 18% towards 100 ppm NH<inf>3</inf>, compared with approximately 0.8% for bare graphene, demonstrating the enhanced sensing performance imparted by the Ta<inf>6</inf>Br<inf>12</inf> clusters. At low NH<inf>3</inf> concentrations, the Ta<inf>6</inf>Br<inf>12</inf>@graphene sensor achieved a sensitivity of 0.39% ppm⁻¹ approximately 19 times higher than that of bare graphene (0.02% ppm⁻¹). Furthermore, the nanohybrid displayed low cross-sensitivity towards common interfering gases, including NO<inf>2</inf>, CO, CO<inf>2</inf>, H<inf>2</inf>, and benzene, confirming its excellent selectivity for NH<inf>3</inf> detection under realistic operating conditions. Additionally, the influence of ambient humidity on sensor performance was investigated, revealing that while moisture affects the baseline resistance of the sensing layer, the Ta<inf>6</inf>Br<inf>12</inf>@graphene nanomaterial retained its ability to detect and discriminate NH<inf>3</inf> even under humid conditions.