Copper Oxide Nanorod/Reduced Graphene Oxide Composites for NH₃ Sensing

Abstract

The NH 3 sensing performance of copper oxide (CuO) nanorods can be enhanced with reduced graphene oxide (rGO) composites (i.e., CuO:rGO) due to their favorable Fermi level alignments and improved carrier mobility. However, the conductivity and the active sites in CuO:rGO are highly determined by the preparation techniques. Hence, we attempt to unravel the role of different chemical routes (wet chemical synthesis and hydrothermal preparation techniques) on the NH 3 sensor device performance of CuO:rGO. Morphological imaging reveals the formation of 1D structures in both preparation techniques, and the role of graphene oxide on the evolution of CuO nanorods is discussed. Firstprinciples calculations probe the interactions between CuO:rGO and NH 3 , and the structure is optimized for the most stable configuration. The absorption binding energies of the CuO:rGO−NH 3 systems are measured to be 1.36 eV, which is much higher than those of the metal−rGO composites. For 50 ppm of NH 3 , the sensor response is measured to be 3.87 and 6.29 for chemically and hydrothermally synthesized CuO:rGO, respectively. The enhanced response of hydrothermal CuO:rGO is due to the more active sites induced on the CuO nanorod surface by rGO and the favorable band bending at the rGO−CuO interface.

Cu2O/MXene/rGO Ternary Nanocomposites as Sensing Electrodes for Nonenzymatic Glucose Sensors

“…As the amount of MGA increases, the crystallite size of Cu 2 O decreases until it reaches the saturation level of MGA loading in the composites (MGA-75). It might be due to the variation of the OH concentration in the complex solution during the synthesis of MGA−Cu 2 O composites as per Sivalingam et al 31 Furthermore, the Raman spectra of the bare Cu 2 O, MXene, aerogel, and their composites were recorded in two spectral regions (100−800 and 1000−1800 cm −1 ) to understand the structural integrity and the Froḧlich electron−phonon interaction of the composites. From Figure 2a, the peaks at 123, 202, 251, 361, and 599 cm −1 correspond to the in-plane (E g ) and out-of-plane (A 1g ) vibrations of the surface functional groups attached to Ti and carbon atoms in the MXene sheets.…”

Room-Temperature Ammonia Gas Sensor Based on Ti3C2Tx MXene/Graphene Oxide/CuO/ZnO Nanocomposite

“…The high NH 3 selectivity and sensitivity of CuO/ZnO nanocomposite may be related to more oxygen free radicals on the surface to promote a redox reaction for releasing more free electrons to CuO/ZnO that can strongly interact with NH 3 molecules at room temperature. , Comparing with pristine CuO and ZnO, the CuO/ZnO nanocomposite exhibited the strongest interaction energy with NH 3 molecule (CuO (1.10 eV), ZnO (1.56 eV), and CuO/ZnO (1.76 eV)) calculated based on the density functional theory (DFT) method . Therefore, the decoration of CuO/ZnO nanocomposite could help to increase the sensitivity and accelerate the response and recovery times, − which are one of the major problems in MXene-based gas sensing applications.…”

Room-Temperature NH3 Sensors Based on Polyaniline-Assembled Graphitic Carbon Nitride Nanosheets

“…), transition-metal sulfides (WS 2 , MoS 2 , SnS 2 , etc. ), and carbon nanomaterials (graphene, carbon nanotubes, graphite quantum dot, etc.). However, NH 3 sensors based on these materials face the challenges of high operating temperature and poor selectivity, which significantly limit the development of NH 3 sensors .…”