Leveraging acoustic and mechanical wave phenomena to fabricate Cu(2-x)CoxP2O7 as electrocatalysts for energy storage and electrochemical water splitting application Pavithra Karthikesan, Sugasri Chinnasamy, Harshini Sharan, Jayachandran Madhavan, Alagiri Mani Applied Physics Letters, 2026 The development of renewable energy systems require the unification of efficient energy storage and hydrogen production facilities. Trifunctional electrocatalysts function as a single system which synchronously enables charge storage, hydrogen evolution reaction (HER), and oxygen evolution reaction (OER), providing a congruent platform. Systematic synthesis techniques promote the enhancement of catalytic activity, and long-term stability. In this context, low-frequency ultrasound (∼20 kHz) induces severe cavitation with the resultant physical forces generating radicals that primarily drive sonochemical processes. In this work, we employed a mechanical wave-assisted synthesis method to prepare Cu(2-x)CoxP2O7. The resulting electrocatalyst delivers an impressive specific capacitance of 681 F g−1, maintaining a cycling stability of 81% after enduring 30 000 cycles. The constructed symmetric supercapacitor attains an energy density of 17.4 Wh kg−1 and a power density of 699 W kg−1. Furthermore, CuCoP2O7 delivers strong bifunctional activity, necessitating merely 64 mV for HER and 288 mV for OER to reach a current density of 10 mA cm−2 while also facilitating overall water splitting by attaining 20 mA cm−2 at 1.60 V. Remarkably, the electrocatalyst achieves a Faradaic efficiency of 97.5%, demonstrating its outstanding effectiveness in facilitating oxygen and hydrogen evolution. These multifunctional electrocatalysts establish a pathway toward scalable, high-performance devices that integrate electrochemical energy storage with sustainable hydrogen production.
Positional Isomerism and Chlorine-Driven Crystal Packing Effects in Acridinium-Based Organic Ionic Pairs for TADF Veerapandian Vallapandian, Rajaboopathi Mani, Ivo B. Rietveld, Aarifa Muhammed Ashraf, Alagiri Mani ACS Applied Optical Materials, 2025 Three precisely engineered acridinium-based ionic pairs─acridinium 5-chlorosalicylate (Ac5ClSA), acridinium salicylate (AcSA), and acridinium 3-chlorosalicylate (Ac3ClSA) ─ contain each a well-defined donor-acceptor (D - -A + ) arrangement. This deliberate molecular design enables efficient thermally activated delayed fluorescence (TADF) for organic light-emitting diodes (OLEDs) applications. These acridinium-based ionic pairs exemplify how the positional isomerism of the chlorine substituent tunes solid-state fluorescence, by offering low Δ E ST, different molecular packings that control charge transfer characteristics, and enabling emission color tuning in the region red to green. Their suitability for TADF was theoretically predicted through density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations, which demonstrated decoupled HOMO–LUMO orbitals with Δ E ST < 0.026 eV. The lifetime measurements confirm the presence of delayed fluorescence, with distinct lifetimes for triplet and singlet excitons, confirming the TADF. All three ionic pairs exhibit exciplex-type excited states, driven by electrostatic interactions between the anionic salicylates and the cationic acridinium ion. FT-IR analysis confirmed the presence of an NH + bond at 2331 cm –1 for all three ionic pairs, confirming the proton transfer from salicylic to acridine. Ac5ClSA demonstrated the highest photoluminescence quantum yield (PLQY) of 13%. Furthermore, all the ionic pairs were doped with PMMA polymer with 10, 20, and 30% concentrations to optimize the emission property and to study electrostatic interactions. Cyclic voltammetry (CV) results aligned well with DFT-calculated HOMO values, demonstrating the intramolecular and intermolecular charge transfer (ICT) characteristics. The thermal stability of ionic pairs is high as expected, due to their ionic nature. This study establishes that the ionic pairs are promising candidates for next-generation TADF and deepens our understanding of structure–property relationships that guide the rational design for controlled emission characteristics.
Unveiling the Nickel–Manganese Sulfide Electrocatalyst for Enhanced Overall Alkaline Water Splitting Harshini Sharan, Angappan Kausalya, Senthilkumar Lakshmipathi, Jayachandran Madhavan, Pavithra Karthikesan, Alagiri Mani ACS Applied Energy Materials, 2025 Harnessing earth-abundant electrocatalysts for efficient water splitting is a key pursuit in the development of sustainable energy technologies. In this study, plate-like Nickel–manganese sulfide (NMS) was in situ grown on nickel foam, via a simple one-step hydrothermal approach, yielding a binder free electrocatalyst. The synergistic interplay between Ni and Mn in the sulfide matrix, combined with the conductive substrate, endows NMS with an exceptional bifunctional activity for overall water splitting in an alkaline medium. The NMS-based electrolyzer delivers a low cell voltage of 1.69 V at 10 mA/cm 2 and presents a remarkable stability over 150 h under 1 M KOH electrolyte. Notably, theoretical studies from density functional theory (DFT) strongly reinforce the experimental findings, highlighting NMS as a highly efficient bifunctional electrocatalyst. Thus, the viability of this system is positioned as a promising and scalable alternative to precious metal-based electrocatalysts.
Electrochemical Enhancement of Copper in a Nickel-Iron Layered Double Hydroxide Catalyst for Alkaline Oxygen Evolution Reactions Jayachandran Madhavan, Deepak Arumugam, Pavithra Karthikesan, Harshini Sharan, Shankar Ramasamy, Sajan Raj Sasirajan Littleflower, Alagiri Mani Inorganic Chemistry, 2025 The development of an efficient and cost-effective oxygen evolution reaction (OER) catalyst is important in increasing the overall efficiency of the electrochemical water splitting process to produce green hydrogen. In this work, the substitution of copper in NiFe layered double hydroxide (LDH) was utilized to improve the sluggish kinetics of the water oxidation process. The simple in situ hydrothermal method was used to introduce copper into the NiFe LDH structure. All of the prepared catalysts displayed a sheet-like morphology, with the optimized NiCuFe LDH sample exhibiting a BET specific surface area of 117.5 m2 g–1. The optimized Cu-substituted LDH exhibited a superior performance in the alkaline water splitting process by requiring a lower overpotential of 230 mV to attain a current density of 10 mA cm–2, accompanied by a low Tafel constant of 47.7 mV dec–1, by outperforming the pristine NiFe LDH. The electronic structure modification of NiFe LDH by Cu atoms favors the OER process, which is verified by the density functional theory (DFT). Further, the optimized electrode was utilized in real-world conditions of the saline–alkaline electrolyte for water splitting, necessitating a minimal overpotential of 247.5 mV to oxidize water, and the electrode demonstrated long-term stability. Thus, NiCuFe LDH is a potential OER catalyst for large-scale electrochemical water splitting applications.
Smart Solutions for Hand Rub Dispenser B. Puviyarasi, M. Alagiri, P. Gubhenthiran, P. Keerthana, S. Megala 2023 Intelligent Computing and Control for Engineering and Business Systems Iccebs 2023, 2023