Maneesh Chandran

The integration of lead zirconate titanate (PZT) on a single crystal diamond substrate enables the realization of micro/nano electromechanical systems devices, such as high-frequency surface acoustic wave (SAW) devices. However, depositing a PZT thin film directly on a single crystal diamond without a buffer layer is always challenging due to the formation of an undesired pyrochlore phase. In this work, we report the realization of a perovskite PZT thin film directly on a single crystal diamond (100) substrate via the sol–gel synthesis method for the first time. Structural analysis using x-ray diffraction and Raman spectroscopy confirmed the formation of the perovskite phase at an optimal annealing temperature of 600 °C. Ferroelectric characterization revealed a remanent polarization of 15.35 µ C cm ⁻² , and a coercive field of 154.03 V cm ⁻¹ . The film exhibited a minimal leakage current of approximately 10 ⁻¹² A. The resonant behavior of the device at GHz frequencies is validated by the presence of acoustic modes using COMSOL Multiphysics. These results highlight the potential of PZT/diamond heterostructures for high-performance SAW applications.

Oil/water separation using hydrophobic g-C₃N₄ coated natural rubber foam.

Oil/water separation using g-C ₃ N ₄ /Bi ₂ S ₃ foam.

Despite numerous limitations, graphene characterization using scanning tunneling microscopy is an important aspect of graphene research. In the present study, an ambient, large effective field of view scanning tunneling microscope (A‐LEF‐STM) is used as a more practical extension of a standard STM for analyzing chemical vapor deposited (CVD)‐graphene: A rigid sample stage, which allows the tip to be relocated to any point over an area of 3.5 × 3.5 mm, is attached to the latter. This simple enhancement allows rough patches spanning hundreds of nanometers on any sample to be easily circumnavigated, almost always without damaging the tip. Ripples and multi‐layer regions including those with twisted bi‐layers, in a graphene sheet grown on a copper foil using CVD, are located using the augmented manoeuvrability, and imaged in high‐definition from micron to angström scales. Insights relating to the resolution with which surfaces of varying roughness can be imaged are developed using simulations and a careful analysis of the scanning process. The enhanced field of view is also utilized to verify the extent of graphene coverage over the entire sample area. The acquired images of single and multi‐layer depositions are carefully interpreted. The applicability of this end‐to‐end characterization process for other samples is also discussed. Overall, this study demonstrates the potential benefits of the A‐LEF‐STM as an eminent characterization tool, complementary to a Raman spectrometer, for CVD‐graphene and other two‐dimensional materials.

Recent advances in photocatalysis include the development of floating catalysts since they assure efficient and rapid recollection of the catalysts from the purified liquid, besides enhancing the availability of photons at the catalytic surface. Bismuth ferrite (BiFeO3 and BFO) is a multifunctional perovskite material renowned for its excellent photocatalytic properties. Since bandgap of BFO falls in the visible spectrum, BFO nanoparticles could be combined with a suitable floating substrate to develop efficient visible light photocatalysts. Here, we report the synthesis of BFO–polydimethylsiloxane (PDMS) hybrids for photocatalytic applications, where sol-gel–synthesized BFO nanoparticles are immobilized on a floating porous PDMS sponge. The successful incorporation of the nanoparticles on PDMS is confirmed using Raman spectroscopy, scanning electron microscopy, and energy dispersive x-ray spectroscopy. The photocatalytic activity of the floating catalysts was studied by monitoring the degradation of malachite green dye under visible light irradiation. The effect of the amount of BFO immobilized, and the area and thickness of the PDMS sponge on the photocatalytic activity of the floating catalysts were investigated. An efficiency of 80.5% was obtained when the weight of BFO immobilized on the PDMS sponge was 5 mg. The method yields degradation efficiencies comparable with or higher than that of conventional BFO powder catalysts, even with 6–18 times less catalyst loading. The method introduces the fabrication of recyclable floating photocatalysts of notable efficiency using significantly less amount of BFO nanoparticles, which could be further modified by approaches such as doping, functionalization, or composite formation.