Shubham Kumar Parate

Rationally designed, multifunctional, highly efficient, robust, and cost-effective non-precious-metal-based bifunctional oxygen electrocatalysts have attracted substantial interest in the field of clean energy over the last few decades. A catalyst designed with surface charge-storage-like properties is of great significance for sustainable Zn–air batteries. However, preparing such an interface requires complex synthesis and purification. Here, we used binary CoNi alloy nanoparticles as nuclei in a single-step pyrolytic synthesis to create a novel hybrid of nickel-anchored nitrogen-doped carbon nanotubes (CNTs). The improved sample showcases a bifunctional interface capable of both oxygen evolution and reduction, along with efficient EDLC-type surface charge storage. As a result, the hybrid structure exhibits capacitive characteristics, making it a potential candidate for supercapacitor-assisted zinc–air battery configurations. This superstructure (CoNi/CNTs) enabled ZAB to reach an open-circuit voltage of 1.447 V and a power density of 141.29 mW/cm2. This promising performance is attributed to the active surfaces of the N-doped compartmentalized CNTs. Furthermore, the synergistic interactions between the catalytically active carbon centers, anchoring ultrasmall Ni clusters, and CoNi alloy nanoparticles further improve the catalytic activity. Our findings emphasize the potential for clean-energy applications by demonstrating the practical benefits of integrating charge-storage-like properties in the catalyst architecture for sustainable Zn–air batteries.

Resistive switching in SrCoO _2.5 has been variably attributed to localized filamentary conduction and lattice‐scale oxygen redox; as a topotactic oxide capable of reversible oxygen exchange with minimal lattice disruption, it provides a model system to resolve this distinction, which is critical because the underlying mechanism governs switching stability, reproducibility, and device design. Here, we address this issue by directly comparing Au/SrCoO _2.5 /Nb‐SrTiO ₃ and SrRuO ₃ /SrCoO _2.5 /Nb‐SrTiO ₃ heterostructures using electrical transport measurements combined with operando bias‐dependent x‐ray absorption and hard x‐ray photoelectron spectroscopy, providing direct sensitivity to lattice‐oxygen‐driven redox processes. Devices with an oxygen‐inert Au electrode exhibit polarity‐restricted switching, whereas the oxygen‐active SrRuO ₃ electrode exhibits switching under both bias polarities within the investigated voltage window, consistent with participation of both interfaces in the bias‐induced redox response. Operando spectroscopy reveals electrode‐dependent modulation of the Co valence, while complementary structural and vibrational measurements show no macroscopic lattice change but clear local rearrangements of the oxygen coordination, indicating an interface‐controlled, spatially distributed redox mechanism. These results identify electrode oxygen‐exchange capability as an important parameter governing switching polarity and redox dynamics in topotactic transition‐metal oxides. The combined electrical and spectroscopic observations further support the contribution of a distributed redox mechanism to the switching process.

Aqueous zinc‐ion batteries are emerging as potential candidates to cater low‐cost stationary energy storage due to the abundance, economic and ecological benignity of zinc. Among the various cathode materials, vanadium‐based compounds have garnered significant attention owing to their structural diversity, Zn ²⁺ storage capability, and high theoretical capacity. The electrochemical activities in these cathodes can be tuned by modulating their structure, particle morphology, surface coatings and local structural (dis)ordering. This study probes the role of disorder on the electrochemical performance of ZnV ₂ O ₄ spinel cathodes. Without any surface or structural optimization, ZnV ₂ O ₄ delivers a specific capacity of 150 mAh g ⁻¹ with stability over ≈1000 cycles at a current density of 1 A g ⁻¹ . Using operando and ex situ techniques – including electron microscopy, X‐ray diffraction, X‐ray absorption, and Raman spectroscopy – it is revealed that initial cycling induces a conversion reaction, forming a disordered Zn‐deficient vanadium oxide phase. This phase enables reversible Zn ²⁺ (co)insertion, enhancing long‐term performance. This findings highlight the critical role of disorder dynamics in tuning the electrochemical behavior of spinel ZnV ₂ O ₄ , offering valuable insights for designing advanced spinel cathodes for secondary zinc‐ion batteries.

The anisotropic light-matter interactions in 2D materials have garnered significant attention for their potential to develop futuristic polarization-based optoelectronic devices such as photodetectors and photoactuators. In this study, we investigate the polarization-dependent interactions in ferroelectric 3R α-In₂Se₃ using Angle-Resolved Polarized Raman Spectroscopy with different excitation lasers. Our experimental findings supported by complementary Density Functional Theory calculations demonstrate that the light-matter interactions depend not only on the crystallographic orientation but also on the excitation energy. Highly anisotropic 3R crystal structure, confirmed by scanning transmission electron microscopy, facilitates significant optical anisotropy, driven by a complex interplay of electron-photon and electron-phonon interactions, which is reflected in the complex nature of the Raman tensor elements. Additionally, this anisotropy is reflected in the material's electrical response under light illumination. Remarkably, the anisotropic photoresponse can be tuned by both polarization and the wavelength of the incident light, making In₂Se₃ a promising material for advanced polarization-sensitive photodetection applications.

Electrically induced amorphization is uncommon and has so far been realized by pulsed electrical current in only a few material systems, which are mostly based on the melt–quench process¹. However, if the melting step can be avoided and solid-state amorphization can be realized electrically, it opens up the possibility for low-power device applications^2,3,4,5. Here we report an energy-efficient, unconventional long-range solid-state amorphization in a new ferroic β″-phase of indium selenide nanowires through the application of a direct-current bias rather than a pulsed electrical stimulus. The complex interplay of the applied electric field perpendicular to the polarization, current flow parallel to the van der Waals layer and piezoelectric stress results in the formation of interlayer sliding defects and coupled disorder induced by in-plane polarization rotation in this layered material. On reaching a critical limit of the electrically induced disorder, the structure becomes frustrated and locally collapses into an amorphous phase⁶, and this phenomenon is replicated over a much larger microscopic-length scale through acoustic jerks^7,8. Our work uncovers previously unknown multimodal coupling mechanisms of the ferroic order in materials to the externally applied electric field, current and internally generated stress, and can be useful to design new materials and devices for low-power electronic and photonic applications.

Lead-free, silicon compatible materials showing large electromechanical responses comparable to, or better than conventional relaxor ferroelectrics, are desirable for various nanoelectromechanical devices and applications. Defect-engineered electrostriction has recently been gaining popularity to obtain enhanced electromechanical responses at sub 100 Hz frequencies. Here, we report record values of electrostrictive strain coefficients (M₃₁) at frequencies as large as 5 kHz (1.04×10⁻¹⁴m²/V²at 1 kHz, and 3.87×10⁻¹⁵m²/V²at 5 kHz) using A-site and oxygen-deficient barium titanate thin-films, epitaxially integrated onto Si. The effect is robust and retained upon cycling upto 6 million times. Our perovskite films are non-ferroelectric, exhibit a different symmetry compared to stoichiometric BaTiO₃and are characterized by twin boundaries and nano polar-like regions. We show that the dielectric relaxation arising from the defect-induced features correlates well with the observed giant electrostriction-like response. These films show large coefficient of thermal expansion (2.36 × 10⁻⁵/K), which along with the giantM₃₁implies a considerable increase in the lattice anharmonicity induced by the defects. Our work provides a crucial step forward towards formulating guidelines to engineer large electromechanical responses even at higher frequencies in lead-free thin films.

Lead-free, silicon compatible materials showing large electromechanical responses comparable to, or better than conventional relaxor ferroelectrics, are desirable for various nanoelectromechanical devices and applications. Defect-engineered electrostriction has recently been gaining popularity to obtain enhanced electromechanical responses at sub 100 Hz frequencies. Here, we report record values of electrostrictive strain coefficients (M₃₁) at frequencies as large as 5 kHz (1.04×10^− 14 m²/V² at 1 kHz, and 3.87×10^− 15 m²/V² at 5 kHz) using A-site and oxygen-deficient barium titanate thin-films, epitaxially integrated onto Si. The effect is robust and retained even after cycling the devices > 5000 times. Our perovskite films are non-ferroelectric, exhibit a different symmetry compared to stoichiometric BaTiO₃ and are characterized by twin boundaries and nano polar-like regions. We show that the dielectric relaxation arising from the defect-induced features correlates very well with the observed giant electrostrictive response. These films show large coefficient of thermal expansion (2.36 ⋅ 10^− 5/K), which along with the giant M₃₁ implies a considerable increase in the lattice anharmonicity induced by the defects. Our work provides a crucial step forward towards formulating guidelines to engineer large electromechanical responses even at higher frequencies in lead-free thin films.