Enhanced Salinity Gradient Energy Generation through Pore Number Control in Atomically Thin MoS2Membrane Mukesh Kumar, Simran Nasa, D. Manikandan, Akshitha, Samriddhi Kushwaha, Sumanta Sekhar Samal, Manoj Varma, Pramoda K. Nayak Energy and Fuels, 2026 Salinity gradient, or “blue”, energy offers a sustainable route to convert the chemical potential difference between seawater and freshwater into electricity. Monolayer molybdenum disulfide (MoS 2 ) has recently emerged as a promising nanofluidic material owing to its atomic thickness, chemical stability, and tunable surface charge. Here, we investigate the scaling behavior of salinity-gradient energy harvesting using chemical vapor deposition (CVD)-grown monolayer MoS 2 membranes containing 20 nm nanopores suspended on silicon nitride substrates. Ion transport measurements were conducted in an automated diffusion cell with large reservoirs (10 L) to ensure stable bulk concentrations under KCl gradients from 10 to 1000. The generated osmotic power increases with nanopore number, rising from 84 nW (single pore) to 230 nW (four pores), corresponding to power densities of (0.1–0.3) × 10 6 W m –2 at low porosities (0.04–0.16%). The observed increase in current and power with rising salinity reflects surface-charge-influenced ion transport combined with high ionic flux through atomically thin nanopores. Poisson–Nernst–Planck simulations performed using experimentally relevant geometries reproduce the observed scaling trends and suggest that ionic transport through multiple nanopores can be treated as approximately additive under the present pore spacing. These findings provide fundamental insight into nanoscale ion transport and power scaling in CVD-grown MoS 2 nanopore membranes, informing the development of scalable nanofluidic blue-energy systems.
Reversible Charge Inversion Enables Field-Programmable Nanofluidic Memristor and Synapse for Neuromorphic Applications D. Manikandan, Suman Chakraborty Nano Letters, 2026 Memristors, whose conductance depends on their past electrical history, are the foundation of emerging brain-inspired artificial computing architectures. Here, we demonstrate a unipolar memristor in which both ionic conductance and electroosmotic flow exhibit pronounced hysteresis, enabling dual-mode memory in charge and water transport. Strikingly, this behavior emerges without structural asymmetry or chemical modification. Instead, it originates from a novel mechanism, which involves a reversible transition in a nanoconfined system driven by charge inversion, where counterions overcompensate surface charge. This transition marks a boundary between two distinct electrostatic states in response to an applied electric field. We harness this unique mechanism to emulate synaptic plasticity and implement learning and classification in artificial neural networks and convolutional models. These findings establish a new class of field-tunable aqueous platforms, unlocking opportunities in neuromorphic logic, adaptive computing, biointerfacing, and real-time environmental sensing.
In Situ Simultaneous Growth of Layered SnSe2 and SnSe: a Linear Precursor Approach Manab Mandal, Prahalad K. Barman, Sagar Chowdhury, D. Manikandan, Nilanjan Basu, Pramoda K. Nayak, Kanikrishnan Sethupathi Advanced Materials Interfaces, 2025 The synthesis of layered tin diselenide (SnSe2) and tin selenide (SnSe) can be achieved independently through distinct nucleation pathways using chemical vapor deposition (CVD). This study successfully achieves the simultaneous growth of SnSe₂ and SnSe, two structurally and functionally distinct tin selenide phases, through hot‐wall CVD. For the first time, this is accomplished through an innovative yet facile synthesis method involving a linear arrangement of precursor granules, which effectively overcame the typical limitations of synthesizing SnSe2 and SnSe from Se powder and SnI₂ granules. The dual‐phase growth is realized through precise control of precursor gradients, substrate temperature, and growth duration, with selenium stoichiometry and thermodynamic stability criteria dictated phase formation. A transport model is proposed to describe precursor concentration distribution and reaction rates, elucidating shape evolution and the combined growth of SnSe2 and SnSe. This study enhances the understanding of competitive growth dynamics and highlights the potential for multifunctional lateral heterostructures and phase‐engineered materials for optoelectronic and thermoelectric applications.
Massively Improved Water Desalination Performance Using Phase-Engineered MoS2 Nanopores D. Manikandan, Suman Chakraborty Nano Letters, 2025 Water scarcity affects billions globally, particularly in regions with limited freshwater resources, making the development of scalable and energy-efficient desalination technologies imperative. Advances in nanotechnology have led to the emergence of 2D nanoporous membranes, offering a promising route toward sustainable water purification. Here, using molecular dynamics simulations, we demonstrate that phase-engineered molybdenum disulfide (MoS2) membranes (1T and 1T' phases) significantly outperform their conventional 2H phase configuration in water desalination. These engineered structures exhibit an extraordinary ∼150% increase in water flux while maintaining exceptional ion rejection rates above 99%, surpassing the performance of other two-dimensional (2D) materials. This enhancement is attributed to the material's preferential phases, where the metallic nature and improved charge screening enhance water affinity, while structural distortions create smoother energy landscapes that enable faster water transport. These inferences establish the phase-engineered MoS2 membranes as a disruptive alternative to conventional reverse osmosis membranes, advancing the next-generation, energy-efficient desalination technologies.
Salinity gradient induced blue energy generation using two-dimensional membranes D. Manikandan, S. Karishma, Mukesh Kumar, Pramoda K. Nayak Npj 2d Materials and Applications, 2024 Salinity gradient energy (SGE), known as blue energy is harvested from mixing seawater with river water in a controlled way using ion exchange membranes (IEMs). Using 2D materials as IEMs improves the output power density from a few Wm−2 to a few thousands of Wm−2 over conventional membranes. In this review, we survey the efforts taken to employ the different 2D materials as nanoporous or lamellar membranes for SGE and provide a comprehensive analysis of the fundamental principles behind the SGE. Overall, this review is anticipated to explain how the 2D materials can make SGE a viable source of energy.
All-Atom Molecular Dynamics Simulations of Communication Between Nanochannel Arrays D. Manikandan, Pramoda K. Nayak ACS Applied Nano Materials, 2023 The stacking of nanochannels in an array is a promising method for scaling nanoscale phenomena to large-scale systems. However, the scalability of single-nanochannel transport characteristics to a large-scale system (i.e., nanochannel arrays) is limited due to interchannel communications. Here, we report the communication between nanochannels in the array using an all-atom molecular dynamics (MD) simulation. In this simulation, a silicon nitride nanochannel array is integrated with the bulk reservoirs, and an electric field is applied across the reservoirs. Intriguingly, the simulations reveal a distinct pattern of communications between nanochannels and are mapped for the first time in the ohmic and nonohmic regions. In the ohmic region, individual channel current increases from the center channel to the channel near the boundary of the reservoir. Surprisingly, this pattern is reversed for the nonohmic region and the center channel shows a higher current compared to the other channels. This behavior may be attributed to the electro-osmotic instability (EOI) controlling the different length propagation of the extended space charge region into the individual channels. Further, we show the scaling law of the nanochannel conductance with the number of channels in both regions. This study offers useful insights for designing nanochannel arrays to improve the process efficiency of applications such as power generation, desalination, drug delivery, ionic logic gates, and circuits.
Strain relaxation in monolayer MoS2 over flexible substrate Nilanjan Basu, Ravindra Kumar, D. Manikandan, Madhura Ghosh Dastidar, Praveen Hedge, Pramoda K. Nayak, Vidya Praveen Bhallamudi Rsc Advances, 2023 Strain relaxation in 1L MoS2 transpires through crack formation at around 4.5% of strain.
Laser-Assisted Scalable Pore Fabrication in Graphene Membranes for Blue-Energy Generation Sharad Kumar Yadav, Manikandan D, Chob Singh, Mukesh Kumar, Aswathy G, Sundara Ramaprabhu, Vishal V. R. Nandigana, Pramoda K. Nayak Chemphyschem, 2023 The osmotic energy from a salinity gradient (i. e. blue energy) is identified as a promising non‐intermittent renewable energy source for a sustainable technology. However, this membrane‐based technology is facing major limitations for large‐scale viability, primarily due to the poor membrane performance. An atomically thin 2D nanoporous material with high surface charge density resolves the bottleneck and leads to a new class of membrane material the salinity gradient energy. Although 2D nanoporous membranes show extremely high performance in terms of energy generation through the single pore, the fabrication and technical challenges such as ion concentration polarization make the nanoporous membrane a non‐viable solution. On the other hand, the mesoporous and micro porous structures in the 2D membrane result in improved energy generation with very low fabrication complexity. In the present work, we report femtosecond (fs) laser‐assisted scalable fabrication of μm to mm size pores on Graphene membrane for blue energy generation for the first time. A remarkable osmotic power in the order of μW has been achieved using mm size pores, which is about six orders of magnitudes higher compared to nanoporous membranes, which is mainly due to the diffusion‐osmosis driven large ionic flux. Our work paves the way towards fs laser‐assisted scalable pore creation in the 2D membrane for large‐scale osmotic power generation.
Pulsed Carrier Gas Assisted High-Quality Synthetic 3 R-Phase Sword-like MoS2: A Versatile Optoelectronic Material Ramesh Rajarapu, Prahalad Kanti Barman, Renu Yadav, Rabindra Biswas, Manikandan Devaraj, Saroj Poudyal, Bubunu Biswal, Vijay Laxmi, Gopal K. Pradhan, Varun Raghunathan, Pramoda K. Nayak, Abhishek Misra ACS Nano, 2022 Synthesizing a material with the desired polymorphic phase in a chemical vapor deposition (CVD) process requires a delicate balance among various thermodynamic variables. Here, we present a methodology to synthesize rhombohedral (3R)-phase MoS2 in a well-defined sword-like geometry having lengths up to 120 μm, uniform width of 2-3 μm and thickness of 3-7 nm by controlling the carrier gas flow dynamics from continuous mode to pulsed mode during the CVD growth process. Characteristic signatures such as high degree of circular dichroism (∼58% at 100 K), distinct evolution of low-frequency Raman peaks and increasing intensity of second harmonic signals with increasing number of layers conclusively establish the 3R-phase of the material. A high value (∼844 pm/V) of second-order susceptibility for few-layer-thick MoS2 swords signifies the potential of MoS2 to serve as an atomically thin nonlinear medium. A field effect mobility of 40 cm2/V-s and Ion/Ioff ratio of ∼106 further confirm the electronic-grade standard of this 3R-phase MoS2. These findings are significant for the development of emerging quantum electronic devices utilizing valley-based physics and nonlinear optical phenomena in layered materials.
Electrodiffusioosmosis induced negative differential resistance in micro-to-millimeter size pores through a graphene/copper membrane Sharad Kumar Yadav, D. Manikandan, Chob Singh, Mukesh Kumar, Vishal V. R. Nandigana, Pramoda K. Nayak Nanoscale Advances, 2022 Membrane surface charge induced electro-osmotic flow (EOF) is key to create negative differential resistance (NDR). Charge polarization induced EOF dominates over diffusio-osmosis, causing the backflow of low concentration/conductivity solution into the pore, causing NDR.
