Rahul Vaish’s research while affiliated with Indian Institute of Technology Mandi and other places

Bi3TiVO9 powder was used as a tribocatalyst for the removal of Rhodamine B (RhB) dye via tribocatalysis process. Bi3TiVO9 ceramic powder was synthesized using the solid-state reaction method and characterized using Raman spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The tribocatalytic activity was systematically evaluated at different stirring speeds of 200, 400, and 500 rpm, demonstrating a strong dependence on rotational speed. The maximum degradation efficiency of approximately 91% was achieved within 3 hours at 500 rpm. Additionally, the effect of pH on the degradation process was investigated, revealing enhanced catalytic performance under acidic conditions. The highest degradation rate, with a rate constant of 9.7 × 10⁻³ min⁻¹, was observed at pH 3. Further, experimental observations showed that tribocatalytic efficiency was influenced by the reaction vessel material, with a glass beaker (91%) outperforming polyethylene (53%), and by the PTFE bead size, where a larger surface area enhanced degradation. Scavenger experiments further identified superoxide radicals (O2⁻) as the dominant reactive oxygen species responsible for facilitating the degradation process.

This study presents an innovative approach to developing capacitive touch and proximity sensors by utilizing a pencil to draw interdigitated capacitors (IDCs) on non-conductive construction materials such as cement, cement fiberboard, stone, and brick. Moving beyond flexible substrates like paper, this work focuses on rigid materials, achieving a linear resistance of approximately 22 Ω/cm on cement. The sensors demonstrate high responsiveness making them suitable for real-time Human-Building Interaction (HBI) applications. Additionally, the sensor exhibits a sensitivity of about 0.04 pF/cm in proximity sensing, highlighting its effectiveness in multi-sensory applications. This low-cost, eco-friendly fabrication method has significant potential to transform HBI use cases by offering a practical, durable solution for constructing touch-sensitive walls and other interactive surfaces.

NaNbO3 crystals were fabricated in the 60B2O3–30Na2O–10Nb2O5 glass system. The fabrication of parent glass was done via the melt quench technique, and then crystallization was achieved through controlled heat treatment. The formation of crystallites was successfully observed and confirmed using X‐ray diffraction and Raman spectroscopy. The elemental analysis of the present constituent in the glass and glass‐ceramics was performed using X‐ray photoemission spectroscopy. The morphological characteristics were investigated through field emission scanning electron microscopy (FE‐SEM). The transparency of the samples was evaluated by the UV–vis spectroscopy, and it has been established that the samples were transparent even after the partial crystallization. Prepared samples were used to degrade methylene blue dye via photocatalysis. The emergence of glass‐ceramics as a photocatalyst has been established with a degradation rate of 68% in 240 min with a rate constant of 4.5 × 10³ min⁻¹.

The phenomenon of photostriction, which involves generating mechanical actuation in response to light, is observed in a very limited number of materials from ferroelectric, semiconductors, and organic material classes. This limited choice of materials, combined with their responsiveness to narrow light spectra, has constrained the broader adoption of photostriction in practical applications. This study introduces a novel approach by integrating photovoltaic and electrostrictive couplings in composites made of a photovoltaic matrix with ferroelectric inclusions, yielding an apparent photostrictive effect. By leveraging the simultaneous action of both photovoltaic and electrostrictive effects, the composite efficiently converts irradiated optical energy into mechanical energy, enabling mechanical actuation across a broader range of materials and light spectra. First, we develop a computational framework for intertwined multiphysics coupling of the photovoltaic effect with nonlinear electrostriction, based on a novel constitutive model. Then, to evaluate all the effective properties that define the composite's behavior, we introduce a multiphysics-coupled homogenization framework capable of computing elastic, electrostrictive, dielectric, and thermal properties. Finally, a shell finite element formulation based on the assumptions of first-order shear deformation theory is used to analyze the behavior of the homogenized photo-electrostrictive composite based actuator. This study demonstrates the feasibility of the proposed composite by examining the deflection response of structures laminated with this photostrictive composite. Several case studies are conducted to provide insights into the development and characterization of photo-electrostrictive composites, which hold great potential for applications in mechanical actuation, shape morphing, and beyond.

Sonocatalysis and tribocatalysis, utilizing high-frequency vibrations and low-frequency friction, respectively, are emerging fields in environmental remediation. Sonocatalysis utilizes an ultrasonicator to generate radicals. Tribocatalysis, on the other hand, requires high frictional energy achieved through rotational energy. In present study, a centrosymmetric brownmillerite material Ca2Fe2O5 was prepared by solid oxide route reaction. To analyze the phase, morphology, and vibrational modes of sample, X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and Raman spectroscopy were employed, respectively. Furthermore, diffuse reflectance spectroscopy (DRS) and X-ray photoelectron spectroscopy (XPS) were utilized to evaluate the absorbance and chemical composition. Experiments were performed on Methylene blue (MB) dye (10 mgL⁻1). During sonocatalysis, ∼ 57% degradation efficacy was observed. In tribocatalysis, ∼ 71% degradation was observed in 12 h. Further, parametric study was done on various rpm of 200, 400, and 600. Results indicated that as rpm was increased, degradation efficacy was enhanced. Mechano-catalytic active dye degradation using Ca2Fe2O5.