Bifunctional CuS/Cl-terminated greener MXene electrocatalyst for efficient hydrogen production by water splitting.

Metal sulfides and 2D materials are the propitious candidates for numerous electrochemical applications, due to their superior conductivity and ample active sites. Herein, CuS nanoparticles were fabricated on 2D greener HF-free Cl-terminated MXene (Ti3C2Cl2) sheets by the hydrothermal process as a proficient electrocatalyst for the hydrogen evolution reaction (HER) and overall water splitting. CuS/Ti3C2Cl2 showed an overpotential of 163 mV and a Tafel slope of 77 mV dec-1 at 10 mA cm-2 for the HER. In the case of the OER, CuS/Ti3C2Cl2 exhibited an overpotential of 334 mV at 50 mA cm-2 and a Tafel slope of 42 mV dec-1. Moreover, the assembled CuS/Ti3C2Cl2||CuS/Ti3C2Cl2 electrolyzer delivered current density of 20 mA cm-2 at 1.87 V for overall water splitting. The CuS/Ti3C2Cl2 electrocatalyst showed excellent stability to retain 96% of its initial value for about 48 hours at 100 mA cm-2 current density. The synthesis of CuS/Ti3C2Cl2 enriches the applications of MXene/metal sulfides in efficient bifunctional electrocatalysis for alkaline water splitting.

Fabrication of ionic liquid stabilized MXene interface for electrochemical dopamine detection.

Development of MXene (Ti3C2Cl2)-based sensing platforms by exploiting their inherent active electrochemistry is highly challenging due to their characteristic poor stability in air and water. Herein, we report a cost-effective methodology to deposit MXene on a conductive graphitic pencil electrode (GPE). MXenes can provide active surface area due to their clever morphology of accordion-like sheets; however, the disposition to stack together limits their potential applications. A task-specific ionic liquid (1-methyl imidazolium acetate) is utilized as a multiplex host material to engineer MXene interface via π-π interactions as well as to act as a selective binding site for biomolecules. The resulting IL-MXene/GPE interface proved to be a highly stable interface owing to good interactions between MXene and IL that inhibited electrode leaching and boosted electron transfer at the electrode-electrolyte interface. It resulted in robust dopamine (DA) oxidation with amplified faradaic response and enhanced sensitivity (9.61 µA µM-1 cm-2) for DA detection. This fabricated sensor demonstrated large linear range (10 µM - 2000 µM), low detection limit (702 nM), high reproducibility, and good selectivity. We anticipate that such platform will pave the way for the development of stable and economically viable MXene-based sensors without sacrificing their inherent properties. Scheme 1 Schematic illustration of the IL-MXene/GPE fabrication and oxidative process towards non-enzymatic dopamine sensor.