Maria S. Sokolikova

IrO₂ is one of the most widely investigated electrocatalysts for oxygen evolution reaction in an acidic environment. Increasing the mass activity is an effective way of decreasing the loading of Ir, to ultimately reduce costs. Here, we demonstrate the crystal-phase engineering of two different potassium iridate polymorphs obtained by designing a selective solid-state synthesis of either one-dimensional K_0.25IrO₂ nanowires with a hollandite crystal structure or two-dimensional KIrO₂ hexagonal platelets. Both structures present increased specific and mass electrocatalytic activities for the water oxidation reaction in acidic media compared to commercial rutile IrO₂ of up to 40%, with the 1D nanowires outperforming the 2D platelets. XANES, extended X-ray absorption fine structure, and X-ray diffraction investigations prove the structural stability of these two different allotropes of KxIrO₂ compounds upon electrocatalytic testing. These low-dimensional nanostructured 1D and 2D KxIrO₂ compounds with superior mass activity to commercial IrO₂ can pave the way toward the design of new electrocatalyst architectures with reduced Ir loading content for proton exchange membrane water electrolyzer (PEMWE) anodes.

Aqueous zinc ion batteries (ZIBs) are attracting increasing attention due to their low cost, earth abundance, and safety. So far, they have been regarded as a promising battery system for large scale grid applications, while here, we demonstrate prospects of their use to power portable devices. We report the fabrication of a rechargeable ZIB with interdigitated geometry capable of powering a commercial sensor for days. A full battery was assembled using aqueous and scalable formulations with a printed anode based on zinc powder and carbon black, a printed colloidal electrolyte, and a printed MnO₂ cathode. The anode withstands more than 500 h of galvanostatic plating/stripping with a low overpotential of ∼32.2 mV, and the ZIB displays a capacity of ∼1.3 mAh/cm² (∼129 mAh/g) and retains ∼66% of its capacity after 100 cycles. Finally, we show how this battery can power a Bluetooth proximity sensor, providing a voltage of 3.2 V for more than 3 days of continuous operation.

Aqueous zinc ion batteries (ZIBs) are attracting increasing attention due to their low cost, earth abundance and safety. So far, they have been regarded as a promising battery system for large scale grid applications, and here we demonstrate prospects of their use to power portable devices. We have fabricated fully 3D printed and rechargeable ZIB with interdigitated geometry capable to power a commercial sensor for days. A full battery was assembled using aqueous and scalable formulations with a printed anode based on zinc powder and carbon black, a printed colloidal electrolyte and a printed MnO2 cathode. The anode withstands more than 500h of galvanostatic plating/stripping with a low overpotential of ~32.2 mV and the ZIB displays a capacity of ~1.3 mAh/cm² and a capacity retention of ~66% after 100 cycles. Finally, we show how this battery can power a Bluetooth proximity sensor for more than 3 days of continuous operation

Creatinine detection via dual binding affinity for silver nanoparticles and silver ions.

Durable and dissolution-free 3D printed VS ₂ electrodes for water-in-salt electrolyte Zn-ion batteries were reported.

Biosensors based on graphene field effect transistors (GFETs) have the potential to enable the development of point-of-care diagnostic tools for early stage disease detection. However, issues with reproducibility and manufacturing yields of graphene sensors, but also with Debye screening and unwanted detection of nonspecific species, have prevented the wider clinical use of graphene technology. Here, we demonstrate that our wafer-scalable GFETs array platform enables meaningful clinical results. As a case study of high clinical relevance, we demonstrate an accurate and robust portable GFET array biosensor platform for the detection of pancreatic ductal adenocarcinoma (PDAC) in patients' plasma through specific exosomes (GPC-1 expression) within 45 min. In order to facilitate reproducible detection in blood plasma, we optimized the analytical performance of GFET biosensors via the application of an internal control channel and the development of an optimized test protocol. Based on samples from 18 PDAC patients and 8 healthy controls, the GFET biosensor arrays could accurately discriminate between the two groups while being able to detect early cancer stages including stages 1 and 2. Furthermore, we confirmed the higher expression of GPC-1 and found that the concentration in PDAC plasma was on average more than 1 order of magnitude higher than in healthy samples. We found that these characteristics of GPC-1 cancerous exosomes are responsible for an increase in the number of target exosomes on the surface of graphene, leading to an improved signal response of the GFET biosensors. This GFET biosensor platform holds great promise for the development of an accurate tool for the rapid diagnosis of pancreatic cancer.

3D printed electrodes of 1T′/1T MoS ₂ /TiS ₂ nanosheets without conductive additives have been demonstrated to perform for durable supercapacitors.

Nanomaterial morphology, chemical composition and 1T′/2H crystal phase tuning is achieved in colloidal W _x Mo _{1− x} Se ₂ nanosheets synthesised by a direct colloidal reaction.

Tuning the charge transport properties of two-dimensional transition metal dichalcogenides (TMDs) is pivotal to their future device integration in post-silicon technologies. To date, co-doping of TMDs during growth still proves to be challenging, and the synthesis of doped WSe₂, an otherwise ambipolar material, has been mainly limited to p-doping. Here, we demonstrate the synthesis of high-quality n-type monolayered WSe₂ flakes using a solid-state precursor for Se, zinc selenide. n-Type transport has been reported with prime electron mobilities of up to 10 cm² V⁻¹ s⁻¹. We also demonstrate the tuneability of doping to p-type transport with hole mobilities of 50 cm² V⁻¹ s⁻¹ after annealing in air. n-Doping has been attributed to the presence of Zn adatoms on the WSe₂ flakes as revealed by X-ray photoelectron spectroscopy (XPS), spatially resolved time of flight secondary ion mass spectroscopy (SIMS) and angular dark-field scanning transmission electron microscopy (AD-STEM) characterization of WSe₂ flakes. Monolayer WSe₂ flakes exhibit a sharp photoluminescence (PL) peak at room temperature and highly uniform emission across the entire flake area, indicating a high degree of crystallinity of the material. This work provides new insight into the synthesis of TMDs with charge carrier control, to pave the way towards post-silicon electronics.

Extrusion-based 3D printing, enables programming of device geometries not achievable with other manufacturing techniques. The fabrication of miniaturized energy storage devices is in increasing demand to enable energy autonomy in on-chip technologies. Here, we demonstrate a new fabrication route of such devices, by robocasting viscoelastic inks of atomically thin transition metal dichalcogenide sheets. We have formulated inks based on the direct exfoliation of TMD nanosheets, suspended in a hydrogel-carrier environment. By tailoring the rheological properties of the ink to aid the intrinsic shear-inducing extrusion flow, we have demonstrated 3D printed micro electrodes for symmetric supercapacitors. With the rational design of 3D electrodes, exposed 2D nanosheets unveil rapid surface non-faradaic electrostatic charges and continuous charge transfer reactions, which translates into a higher capacitance and rate capability. The highlights in this work lead to an important leap for TMDs-based 3D printed energy storage devices.