MXenes, a new class of 2D transition metal carbides and carbonitrides, show great promise in supercapacitors, Li‐ion batteries, fuel cells, and sensor applications. A unique combination of their metallic conductivity, hydrophilic surface, and excellent mechanical properties renders them attractive for transparent conductive electrode application. Here, a simple, scalable method is proposed to fabricate transparent conductive thin films using delaminated Ti3C2MXene flakes by spray coating. Homogenous films, 5–70 nm thick, are produced at ambient conditions over a large area as shown by scanning electron microscopy and atomic force microscopy. The sheet resistances (
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A simple and environmentally‐friendly approach was developed to synthesize 2D CuO nanosheets using electrochemical deposition. The formed 2D CuO nanosheets (NSs) exhibit numerous advantageous properties such as no toxicity, high electrical conductivity, large active surface area, and a p‐type semiconducting nature with a band gap of 1.2 eV. A sensitive electrochemical sensor was constructed for the amperometric detection of glucose to take advantage of these characteristics. The fabricated sensor displayed an excellent sensitivity of 2710 μA mM−1 cm−2along with a wide linear range of 0.001–1.0 mM and a lower limit of detection of 0.8 μM (S/N=3). Additionally, the modified electrode possesses high selectivity and good stability. The outstanding electrocatalytic performance of the electrode is attributed to a large active surface area, unique structural morphology, and the high conductivity of the 2D CuO nanosheets.
more » « less- Award ID(s):
- 2046105
- NSF-PAR ID:
- 10495987
- Publisher / Repository:
- Chemistry Europe
- Date Published:
- Journal Name:
- ChemistrySelect
- Volume:
- 8
- Issue:
- 25
- ISSN:
- 2365-6549
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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null (Ed.)2D nickel phthalocyanine based MOFs (NiPc-MOFs) with excellent conductivity were synthesized through a solvothermal approach. Benefiting from excellent conductivity and a large surface area, 2D NiPc-MOF nanosheets present excellent electrocatalytic activity for nitrite sensing, with an ultra-wide linear concentration from 0.01 mM to 11 500 mM and a low detection limit of 2.3 μM, better than most reported electrochemical nitrite sensors. Significantly, this work reports the synthesis of 2D conductive NiPc-MOFs and develops them as electrochemical biosensors for non-enzymatic nitrite determination for the first time.more » « less
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Neurotransmitters are small molecules involved in neuronal signaling and can also serve as stress biomarkers.1Their abnormal levels have been also proposed to be indicative of several neurological diseases such as Alzheimer’s disease, Parkinson’s disease, Huntington disease, among others. Hence, measuring their levels is highly important for early diagnosis, therapy, and disease prognosis. In this work, we investigate facile functionalization methods to tune and enhance sensitivity of printed graphene sensors to neurotransmitters. Sensors based on direct laser scribing and screen-printed graphene ink are studied. These printing methods offer ease of prototyping and scalable fabrication at low cost.
The effect of functionalization of laser induced graphene (LIG) by electrodeposition and solution-based deposition of TMDs (molybdenum disulfide2and tungsten disulfide) and metal nanoparticles is studied. For different processing methods, electrochemical characteristics (such as electrochemically active surface area: ECSA and heterogenous electron transfer rate: k0) are extracted and correlated to surface chemistry and defect density obtained respectively using X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. These functionalization methods are observed to directly impact the sensitivity and limit of detection (LOD) of the graphene sensors for the studied neurotransmitters. For example, as compared to bare LIG, it is observed that electrodeposition of MoS2on LIG improves ECSA by 3 times and k0by 1.5 times.3Electrodeposition of MoS2also significantly reduces LOD of serotonin and dopamine in saliva, enabling detection of their physiologically relevant concentrations (in pM-nM range). In addition, chemical treatment of LIG sensors is carried out in the form of acetic acid treatment. Acetic acid treatment has been shown previously to improve C-C bonds improving the conductivity of LIG sensors.4In our work, in particular, acetic acid treatment leads to larger improvement of LOD of norepinephrine compared to MoS2electrodeposition.
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Future work includes expanding the plasma chemistry and conditions, studying the effect of precursor mixture in laser-induced solution-based functionalization, and understanding the interplay between molecule-material system. Work is also underway to improve the machine learning model by using nonlinear learning models such as neural networks to improve the sensor sensitivity, selectivity, and robustness.
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Y. Lei, D. Butler, M. C. Lucking, F. Zhang, T. Xia, K. Fujisawa, T. Granzier-Nakajima, R. Cruz-Silva, M. Endo, H. Terrones, M. Terrones, A. Ebrahimi,
Sci. Adv. 6 , 4250–4257 (2020).V. Kammarchedu, D. Butler, A. Ebrahimi,
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Adv. Mater. 31 , 1–12 (2019). -
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Abstract Electrochemical sensors for mercury ion detection would ideally demonstrate wide linear detection ranges (LDRs), ultratrace sensitivity, and high selectivity. This work presents an electrochemical sensor based on metallic 1T phase tungsten disulfide (WS2) microflowers for the detection of trace levels of Hg2+ions with wide LDRs, ultratrace sensitivity, and high selectivity. Under optimized conditions, the sensor shows excellent sensitivities for Hg2+with LDRs of 1 n
m –1 µm and 0.1–1 mm . In addition to this, the limit of detection of the sensor toward Hg2+is 0.0798 nm or 79.8 pm , which is well below the guideline value recommended by the World Health Organization. The sensor exhibits excellent selectivity for Hg2+against other heavy metal ions including Cu2+, Fe3+, Ni2+, Pb2+, Cr3+, K+, Na+, Ag+, Sn2+, and Cd2+. The thus‐obtained excellent sensitivity and selectivity with wide LDRs can be attributed to the high conductivity, large surface area microflower structured 1T‐WS2, and the complexation of Hg2+ions with S2−. In addition to good repeatability, reproducibility, and stability, this sensor shows the practical feasibility of Hg2+detection in tap water suggesting a promising device for real applications. -
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Abstract Electrochemical upcycling of nitrate into ammonia at ambient conditions offers a sustainable synthesis pathway that can complement the current industrial NH3production from the Haber–Bosch process. One of the key rate‐limiting steps is the effective desorption of gaseous or interfacial bubble products, mainly NH3with some minor side products of nitrogen and hydrogen, from the electrode surfaces to sustain available sites for the NO3−reduction reaction. To facilitate the gaseous product desorption from the catalytic sites, hydrophobic polytetrafluoroethylene (PTFE) nanoparticles are blended within a CuO catalyst layer, which is shown to eliminate the undesirable accumulation and blockage of electrode surfaces and largely decouples the electron‐ and phase‐transfer processes. The NH3partial current density normalized by the electrochemically active surface area (ECSA) increases by nearly a factor of 17.8 from 11.4 ± 0.1 to 203.3 ± 1.8 mA cm−2ECSA. The DFT and ab‐initio molecular dynamics simulations suggest that the hydrophobic PTFE nanoparticles may serve as segregated islands to enhance the spillover and transport the gaseous products from electrocatalysts to the PTFE. Thus, a higher ammonia transfer is achieved for the mixed PTFE/CuO electrocatalyst. This new and simple strategy is expected to act as inspiration for future electrochemical gas‐evolving electrode design.
