Organic-inorganic halide perovskite quantum dots (PQDs) constitute an attractive class of materials for many optoelectronic applications. However, their charge transport properties are inferior to materials like graphene. On the other hand, the charge generation efficiency of graphene is too low to be used in many optoelectronic applications. Here, we demonstrate the development of ultrathin phototransistors and photonic synapses using a graphene-PQD (G-PQD) superstructure prepared by growing PQDs directly from a graphene lattice. We show that the G-PQDs superstructure synchronizes efficient charge generation and transport on a single platform. G-PQD phototransistors exhibit excellent responsivity of 1.4 × 108 AW–1 and specific detectivity of 4.72 × 1015 Jones at 430 nm. Moreover, the light-assisted memory effect of these superstructures enables photonic synaptic behavior, where neuromorphic computing is demonstrated by facial recognition with the assistance of machine learning. We anticipate that the G-PQD superstructures will bolster new directions in the development of highly efficient optoelectronic devices.

The synthesis routes and the electrochemical performance evaluation of transition metal dichalcogenide (TMD) based supercapacitor electrodes are discussed.

MXenes are the class of two-dimensional transition metal carbides and nitrides that exhibit unique properties and are used in a multitude of applications such as biosensors, water purification, electromagnetic interference shielding, electrocatalysis, supercapacitors, and so forth. Carbide-based MXenes are being widely explored, whereas investigations on nitride-based ones are seldom. Among the nitride-based MXenes obtained from their MAX phases, only Ti 4 N 3 and Ti 2 N are reported so far. Herein, we report a novel synthesis of V 2 NT x (T x is the surface termination) obtained by the selective removal of “Al” from V 2 AlN by immersing powders of V 2 AlN in the LiF–HCl mixture (salt–acid etching) followed by sonication to obtain V 2 NT x (T x = −F, −O) MXene which is then delaminated using the dimethyl sulfoxide solvent. The V 2 NT x MXene is characterized by X-ray diffraction studies, field emission scanning electron microscope imaging, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and high-resolution transmission electron microscope imaging. Supercapacitor electrodes are prepared using V 2 NT x MXenes and their electrochemical performances are examined by cyclic voltammetry, galvanostatic charge/discharge measurement, and electrochemical impedance spectroscopy. The V 2 NT x MXene electrode exhibits a specific capacitance of 112.8 F/g at a current density of 1.85 mA/cm 2 with an energy and power density of 15.66 W h/kg and 3748.4 W/kg, respectively, in 3.5 M KOH aqueous electrolyte. The electrode exhibits an excellent capacitance retention of 96% even after 10,000 charge/discharge cycles. An asymmetric supercapacitor fabricated with V 2 NT x as a negative electrode and Mn 3 O 4 nanowalls as a positive electrode helps obtain a cell voltage of 1.8 V in aqueous KOH electrolyte.

Ultra-flexible supercapacitors with brush-like electrodes consisting of carbon nanotube/polypyrrole nanocomposites exhibit a gravimetric capacitance of 305 F g−1.

Recent advances in the field of energy storage devices such as supercapacitors and batteries have helped mankind to cater to their power demands to a greater extent. 2D materials‐based electrodes have attracted great interest in the recent past due to their unique properties such as large surface area, good electronic conductivity, excellent electrochemical properties, and good chemical, electrochemical, and thermal stabilities, which are essential requirements for a supercapacitor electrode to obtain high‐performance. In this review, we discuss the recent advancements in the field of 2D materials such as MXenes, transition metal dichalcogenides, phosphorene, and their composites as electrodes in high‐performance supercapacitors. The electrochemical performances of these 2D materials‐based electrodes in symmetric, asymmetric, and battery‐type hybrid supercapacitors are reviewed. Emphasis is given to the recent developments on the battery‐type hybrid supercapacitors fabricated using these 2D materials‐based electrodes. The future perspectives of these materials in the next‐generation energy storage are also briefly discussed.