Multifunctional Green-Synthesized Cu2O-Cu(OH)2 Nanocomposites Grown on Cu Microfibers for Water Treatment Applications Hala Al-Jawhari, Nuha A. Alhebshi, Roaa Sait, Reem Altuwirqi, Laila Alrehaili, et al. Micro, 2025 Free-standing copper oxide (Cu2O)-copper hydroxide (Cu(OH)2) nanocomposites with enhanced catalytic and antibacterial functionalities were synthesized on copper mesh using a green method based on spinach leaf extract and glycerol. EDX, SEM, and TEM analyses confirmed the chemical composition and morphology. The resulting Cu2O-Cu(OH)2@Cu mesh exhibited notable hydrophobicity, achieving a contact angle of 137.5° ± 0.6, and demonstrated the ability to separate thick oils, such as HD-40 engine oil, from water with a 90% separation efficiency. Concurrently, its photocatalytic performance was evaluated by the degradation of methylene blue (MB) under a weak light intensity of 5 mW/cm2, achieving 85.5% degradation within 30 min. Although its application as a functional membrane in water treatment may raise safety concerns, the mesh showed significant antibacterial activity against both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria under both dark and light conditions. Using the disk diffusion method, strong bacterial inhibition was observed after 24 h of exposure in the dark. Upon visible light irradiation, bactericidal efficiency was further enhanced—by 17% for S. aureus and 2% for E. coli. These findings highlight the potential of the Cu2O-Cu(OH)2@Cu microfibers as a multifunctional membrane for industrial wastewater treatment, capable of simultaneously removing oil, degrading organic dyes, and inactivating pathogenic bacteria through photo-assisted processes.
Electrochemical Performance of Biocompatible TiC Films Deposited through Nonreactive RF Magnetron Sputtering for Neural Interfacing Roaa Sait, Hala Al-Jawhari, Aisha Ganash, Shofarul Wustoni, Long Chen, et al. ACS Biomaterials Science and Engineering, 2024 The efficacy of neural electrode stimulation and recording hinges significantly on the choice of a neural electrode interface material. Transition metal carbides (TMCs), particularly titanium carbide (TiC), have demonstrated exceptional chemical stability and high electrical conductivity. Yet, the fabrication of TiC thin films and their potential application as neural electrode interfaces remains relatively unexplored. Herein, we present a systematic examination of TiC thin films synthesized through nonreactive radio frequency (RF) magnetron sputtering. TiC films were optimized toward high areal capacitance, low impedance, and stable electrochemical cyclability. We varied the RF power and deposition pressure to pinpoint the optimal properties, focusing on the deposition rate, surface roughness, crystallinity, and elemental composition to achieve high areal capacitance and low impedance. The best-performing TiC film showed an areal capacitance of 475 μF/cm2 with a capacitance retention of 93% after 5000 cycles. In addition, the electrochemical performance of the optimum film under varying scanning rates demonstrated a stable electrochemical performance even under dynamic and fast-changing stimulation conditions. Furthermore, the in vitro cell culture for 3 weeks revealed excellent biocompatibility, promoting cell growth compared with a control substrate. This work presents a novel contribution, highlighting the potential of sputtered TiC thin films as robust neural electrode interface materials.
Flexible and Disposable Gas Sensors Based on Two-Dimensional Materials Farah Ma'ashi, Areej Aljarb, Hala Al-Jawhari Key Engineering Materials, 2024 Transition metal dichalcogenides (TMDCs) nanomaterials, in particular Molybdenum disulfide (MoS2), have been employed frequently as a basis for flexible gas sensors due to their extreme sensitivity to gas molecules, super mechanical and electrical properties, and large surface area. This work aims to study the behavior of the flexible gas sensor made of 2D-MoS2 under exposure to nitrogen dioxide (NO2) gas at the part per million (ppm) level. The mono-layered MoS2 was successfully synthesized by Chemical Vapor Deposition (CVD). The formation of MoS2 layers was confirmed by Raman spectroscopy and Photoluminescence (PL). Two different gas-sensing devices were fabricated by transferring two MoS2 samples (obtained from two positions inside the CVD tube) onto paper substrates. Specifically, upstream sample Sup was obtained from an area near the MoO3 source, and downstream sample Sdown was obtained from an area far from the MoO3 source. Both sensors showed a good response to a concentration as low as (1.5 ppm) of NO2. Although a high response of 62.8% along with a fast response of 9 sec were recorded by Sdown, the sensor showed a slow recovery time of 42 sec. On the other hand, Sup showed good stability with an appropriate response of 36.8% along with a reasonable response time and recovery times of 20 and 27 sec, respectively. Such behavior could be accredited to the difference in the reactivity in both MoS2 samples. This work opens the way for further improvements in manufacturing MoS2-based flexible gas sensors.
Large-Area Metal-Semiconductor Heterojunctions Realized via MXene-Induced Two-Dimensional Surface Polarization Tianchao Guo, Xiangming Xu, Chen Liu, Yizhou Wang, Yongjiu Lei, et al. ACS Nano, 2023 Direct MXene deposition on large-area 2D semiconductor surfaces can provide design versatility for the fabrication of MXene-based electronic devices (MXetronics). However, it is challenging to deposit highly uniform wafer-scale hydrophilic MXene films (e.g., Ti3C2Tx) on hydrophobic 2D semiconductor channel materials (e.g., MoS2). Here, we demonstrate a modified drop-casting (MDC) process for the deposition of MXene on MoS2 without any pretreatment, which typically degrades the quality of either MXene or MoS2. Different from the traditional drop-casting method, which usually forms rough and thick films at the micrometer scale, our MDC method can form an ultrathin Ti3C2Tx film (ca. 10 nm) based on a MXene-introduced MoS2 surface polarization phenomenon. In addition, our MDC process does not require any pretreatment, unlike MXene spray-coating that usually requires a hydrophilic pretreatment of the substrate surface before deposition. This process offers a significant advantage for Ti3C2Tx film deposition on UV-ozone- or O2-plasma-sensitive surfaces. Using the MDC process, we fabricated wafer-scale n-type Ti3C2Tx–MoS2 van der Waals heterojunction transistors, achieving an average effective electron mobility of ∼40 cm2·V–1·s–1, on/off current ratios exceeding 104, and subthreshold swings of under 200 mV·dec–1. The proposed MDC process can considerably enhance the applications of MXenes, especially the design of MXene/semiconductor nanoelectronics.
Green Synthesized Cu2O-Cu(OH)2@Cu Nanocomposites with Fenton-like Catalytic Properties for the Degradation of Cationic and Anionic Dyes Hala A. Al-Jawhari, Nuha A. Alhebshi Crystals, 2022 In this work, we introduce an environmental and sustainable approach to grow free standing heterogeneous Cu2O-Cu(OH)2 nanocomposites on a Cu mesh using spinach leaf extract and glycerol. Structural characterizations for samples annealed at 200 °C revealed that there is more Cu(OH)2 than Cu2O on the mesh surface. The photocatalytic activity of the green synthesized catalyst was studied for degradation of a cationic dye methylene blue (MB), an anionic dye methyl orange (MO) and a mixture of both dyes. The effect of changing the dye’s initial pH value on the photodegradation process was explored. After 40 min of irradiation under sunlight, with a maximum intensity of 5 mW/cm2, a basic MB dye (pH-11) showed about 80% color removal with an average kinetic rate of 94.5 m·min−1. In contrast, 93% of the acidified MO dye (pH-2) was degraded with an average kinetic rate of 126.5 m·min−1. Moreover, the versatility of the Cu2O-Cu(OH)2@Cu mesh was evaluated using a remarkable selective separability for a mixture of MB and MO at pH = 2, in the dark and under normal sunlight. Such promising outcomes indicate the potential of our green composites to degrade dyes as both photocatalysts under daylight and as Fenton-like catalysts in darkness.
