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Besides developing a large number of catalysts for hydrogen evolution reaction (HER) in alkaline electrolytes, its conversion efficiency remained low. Herein, we have developed mixed-dimensional heterostructures of niobium disulfide (NbS2) with graphene foam grown on nickel foam (NbS2-Gr-NF). The strong lateral fusion results in activating the catalytic sites of NbS2, the three-dimensional substrate provides easy access of electrolyte to active sites and increased electrochemically active surface area, while enhanced conductivity provides faster transfer of electrons to and from active sites. Therefore, NbS2-Gr-NF heterostructures resulted in an exceptionally high current density of 500 mA cm−2 at a very low overpotential of 306 mV in 1 M KOH solution and even can achieve the current density values of 914 mAcm−2 at 338 mV only at a slight increase in overpotential (32 mV). Moreover, a Tafel value of ~72 mV dec−1 confirms that as-developed heterostructure provides fast reaction kinetics where the reaction is mainly controlled by the Volmer step. Achieving such high current density at a faster rate with high stability makes NbS2-Gr-NF heterostructures a potential candidate for water-splitting, especially in alkaline electrolytes.

Hydrogen production from water splitting is highly desired for the green and clean energy device but remains a great challenge. In this regard, cobalt-phthalocyanine (PyCoPc) and composite of PyCoPc with graphene oxide (GO) were fabricated and used as catalyst for the energy conversion. The as-synthesized PyCoPc/GO exhibits an efficient hydrogen evolution reaction due to the low overpotential ~253 mV at a 10 mA cm−2 current density with a Tafel slope ~96 mV dec−1 in alkaline media. Our study reveals that the active area of the catalyst was controlled with the help of π − π stacking interaction between GO and PyCoPc. Technologically, a highly efficient PyCoPc catalyst was developed for hydrogen evolution reaction.

Graphene derivatives are useful in sensing applications owing to the exciting electrical, chemical, mechanical and structural properties. In this regard, graphene foam (GF) might have fruitful influence for sensing applications due to its porous morphology. However, lack of surface functionalities bottleneck its use in gas sensors but graphene oxide (GO) contains surface functionalities which have already been very useful for sensing application point of view. Herein, we fabricated GF via Chemical Vapor Deposition and GO via Hummers method. Both GF and GO are accessed by using different characterization tools and GO coated GF is used for sensing different alcohols (i.e. Isopropanol, Ethanol, and Methanol). The GO/GF system is highly sensitive to isopropanol due to the presence of high/low energy binding sights on the surface and molecular structure of isopropanol.

Morphotropic phased boundary (MPB) existent Bi0.5(K0.2Na0.8)0.5TiO3:xwt%MnO2 (BKNT:xMn) ceramic system is fabricated to investigate the ferroelectric and piezoelectric properties. All the ceramic samples have maintained the tetragonal (P4mm)-rhombohedral (R3c) structural duality due to MPB regional investigation of BKNT. The addition of MnO2 in BKNT has improved the multifunctional properties of the material at x ​= ​0.15. BKNT:0.15Mn ceramic has shown the maximum density of 6.98 ​g/cm3, remnant polarization (Pr) ​∼ ​32.5 ​μC/cm2, high impedance of ∼108 ​Ω, d33 of 206 ​pC/N, which are much improved properties than pure single phase BKNT and Bi0.5K0.5TiO3 ceramics. The dependence of dielectric constant (er) on temperature suggests the relaxor behavior and the high Curie temperature (TC) ​∼ ​410 ​°C for BKNT:0.15Mn ceramic, higher than the TC ​∼ ​360 ​°C of pure BKNT ceramic. The poled ceramics have maintained the stable piezoelectric properties till 300 ​°C. The introduction of multivalence Mn has improved the multifunctional properties of the material significantly, making it a strong candidate to be utilized in actuators and sensors.

In present work, Nickel (Ni) substituted Mn-Co ferrite nanoparticles, with doping content varying from 0 to 0.1, have been synthesized. The inverse spinel structure of doped cobalt ferrite has been claimed by X-ray diffractometer with average particle size of 20 nm. The decrease in lattice parameter and increase in X-ray density has been found with increase in Ni concentration in ferrite structure. Fourier transform infrared spectroscopy analysis showed two vibrational frequency bands (υ1 and υ2) for octahedral and tetrahedral sites depicting the formation of spinel ferrite. In addition, Transmission electron microscopy analyses were carried out to investigate particle size, which indicates that TEM and XRD analyses are in agreement. Magnetic analyses depict that coercivity value increases from 635 Oe to 841 Oe in Ni doped Mn-Co ferrite. Exchange interactions between Ni and Mn0.2Co0.8-xFe2O4 result for enlargement in coercivity and shift in hysteresis loop towards positive direction along the field axis. The increment in magnetic coercive field and exchange bias has been observed as temperature decreases. Enhanced magnetic properties at low temperature are attributed to magneto-crystalline anisotropy and surface effects.

Highly ordered and reproducible Gd nanowires have been reported via DC electrodeposition method. In this regard, templates with different diameters 100 nm, 50 nm and 20 nm were utilized. Shape morphology, reproducibly and homogeneity of nanowires were investigated with field emission scanning electron microscopy (FE-SEM). Morphological analyses confirm as required diameter, length and aspect ratio. Structurally, body centered cubic (bcc) phase was observed with Rietveld refinement of X-ray diffraction (XRD) patterns for all diameters. Magnetic investigations are including zero field cooled (ZFC) and field cooled (FC) and hysteresis measurement by using physical property measurement system (PPMS). These magnetic analyses of nanowires embedded in AAO templates predict mix phase with superparamagnetic and ferromagnetic clusters.

Graphene foam (GF) infiltrated with polymer attracts researchers toward practical pressure sensing applications, especially tactile sensors. However, interface between polymer and graphene plays a vital role under a specific type and amount of pressure. Herein, we have investigated the impact of static and dynamic pressure upon GF-polymer. A recovery time of ∼ 0.1 s is detected during static pressure sensing. Unlike static pressure, GF-polymer samples are highly sensitive to dynamic load, and a quick recovery time ∼ 0.06 s is detected. The sensitivity of the dynamic pressure sensor ∼ 1.17 ± 0.1 Pa−1 is almost double compares to the sensitivity of the static pressure sensor ∼ 2.1 ± 0.3 Pa−1. Technologically, tactile sensors exert pressure in different forms and GF-polymer is an excellent choice for forming a pressure sensor. The present study will help develop efficient tactile sensors.