CoFe₂O₄ Nanoparticles Grown within Porous Al₂O₃ and Immobilized on Graphene Nanosheets: A Hierarchical Nanocomposite for Broadband Microwave Absorption

Abstract

Demands to develop efficient microwave-absorbing materials are increasing with the advancement of information technology and the exponential rise in the usage of electromagnetic devices. To reduce electromagnetic interference and to overcome the adverse effects caused by microwave exposure resulting from the excessive usage of electromagnetic devices, microwave absorbers are very necessary. In addition, radar-absorbing materials are essential for stealth technology in military applications. Herein, we report a nanocomposite in which CoFe 2 O 4 (CF) nanoparticles were grown within the porous structure of Al 2 O 3 (PA), and this CoFe 2 O 4 -loaded Al 2 O 3 (PA–CF) nanocomposite was immobilized on the surface of nanometer-thin graphene sheets (Gr). Owing to the hierarchical structure created by the constituents, the (60PA-40CF) 90 -Gr 10 nanocomposite exhibited excellent microwave-absorption properties in the X-band region with a reflection loss (RL) value of ∼−30.68 dB (∼99.9% absorption) at 10.71 and 9.04 GHz when thicknesses were 2.0 and 2.3 mm, respectively. This nanocomposite demonstrated its competence as a lightweight, high-performance microwave absorber in the X-band region, which can be utilized in the applications of pioneering stealth technology.

Investigation of MnCo2O4 Spinel Loaded onto Porous γ-Al2O3 as an Electrocatalyst for Water-Splitting Performance

“…The crystalline nature of the Al 2 O 3 /Mn–Co nanocomposite was identified by the XRD pattern. Figure a shows diffraction peaks at 2θ = 19.2, 36.8, 45.7, 60.3, and 66.4°, corresponding to the crystal planes (111), (311), (400), (511), and (440) of γ-Al 2 O 3 [JCPDS No: 10–0425]. , Furthermore, the diffraction peaks that emerged at 2θ = 30.56, 36.03, 37.67, 43.8, 54.39, 57.96, and 63.68° matched well with the (220), (311), (222), (400), (422), (511), and (440) planes of MnCo 2 O 4 with a cubic crystal system [JCPDS No: 23–1237]. − …”

“…The peak located at 651 cm –1 is related to the Mn–O bond. Furthermore, the broad peak at a range of ∼1300 to 2500 cm –1 denotes the presence of γ-Al 2 O 3 . ,− …”

Spent Tea-Waste-Derived Porous Carbon-Supported Truncated Octahedral Cu2O for Highly Efficient Energy Storage Devices

“…Figure b shows the high-resolution Cu 2p XPS spectrum, which manifested two narrow peaks at 932.7 (Cu 2p 3/2 ) and 952.5 eV (Cu 2p 1/2 ) and was devoid of any satellite peaks. , These indicated the oxidation state of Cu in Cu 2 O–PC TW composite to be (+1). The O 1s XPS spectrum was deconvoluted into two peaks at 530.8 and 532 eV representing Cu–O bonds and surface functional groups consisting of oxygen, respectively (Figure c). , In the C 1s XPS spectrum (Figure d), the binding energy peaks corresponding to C–C, C–O, and O–CO appeared at 284.6, 286.4, and 288.4 eV, respectively. , The XPS analysis data of the pure Cu 2 O is presented in Figure S6. It was observed that compared to pure Cu 2 O, the binding energies of Cu 2p in the Cu 2 O–PC TW composite showed a negative shift of ∼0.1 eV.…”

2D-Ti3C2Tx MXene-supported Cu2S nanoflakes for supercapacitors and electrocatalytic oxygen evolution reaction

“…2e displays the O 1s XPS spectrum, which was deconvoluted into two peaks, representing M–O–M (531.3 eV) and oxygen-containing functional groups (533.1 eV). 44 The high-resolution F 1s XPS spectrum is shown in Fig. 2f, which consists of two peaks at 685.7 and 688.8 eV, corresponding to F–Ti and F–O, respectively.…”