Four researchers — Carbon Lab alumni and collaborators from ARCI, IITH, NIT Warangal, and NIT Tiruchirappalli — delivered a session that ranged from industrial waste valorisation to photocatalytic microplastic degradation, tracing the extraordinary versatility of carbon as a functional material.
Technical Session 1 was chaired by a current Carbon Lab researcher and featured four presentations united by a single ambition: demonstrating that carbon, in its multiple structural avatars, is not merely a material of the past (pencil lead, industrial lubricant) or of the present (lithium-ion battery anode), but a material of the future — versatile enough to address energy storage, environmental remediation, and next-generation sensing within a single research programme.
Carbon Fibers: India’s Strategic Blind Spot
The session opened with a presentation on carbon fiber synthesis and its strategic implications for India. Carbon fiber — a material whose combination of high tensile strength, low weight, and chemical inertness makes it indispensable in aerospace, hydrogen storage vessels, and premium automotive components — is currently imported by India in nearly its entirety. The precursor material, polyacrylonitrile (PAN) at the high molecular weights required for aerospace-grade fiber, presents the first barrier; the manufacturing process, which demands exquisite control over tension, temperature gradients, and carbonisation atmosphere along continuous kilometers of filament, presents the second.
The speaker mapped India’s existing carbon fiber capacity — limited and operating at specifications below the requirements of critical applications — and framed the challenge explicitly as a national security issue. If India’s aerospace programme, its hydrogen vehicle ambitions, and its advanced defence platforms depend on a supply chain controlled by foreign manufacturers, no amount of materials science excellence at the laboratory level translates into genuine technological sovereignty. The path forward, the presenter argued, requires a coordinated national programme analogous to what China launched two decades ago — one that simultaneously develops indigenous PAN precursors, carbonisation equipment, and downstream application partners.
Hard Carbon for Sodium-Ion Batteries: The Consistency Challenge
The second presentation addressed hard carbon as an anode material for sodium-ion (Na-ion) batteries — a chemistry that has attracted intense global interest as a lithium-independent alternative for grid storage and low-cost electric mobility. Hard carbon’s appeal is that it can be synthesised from virtually any carbon-containing bio-waste: orange peel, Jamun seed, rice husk, low-grade coal. The Carbon Lab has demonstrated routes from each of these feedstocks. The problem, exhaustively documented in this presentation, is batch-to-batch consistency.
Hard carbon’s sodium storage mechanism operates through two pathways: adsorption of sodium ions onto the surface of defect-rich graphene layers, and diffusion of sodium into nanoscale closed pores that act as tiny reservoirs. The balance between these two pathways — and the initial Coulombic efficiency (ICE), which measures how much sodium is irreversibly lost in the first charge cycle — depends critically on the precise microstructure of the carbon: pore size distribution, interlayer spacing, defect density. When that microstructure varies between batches, so does performance. Hard carbons derived from bio-waste achieve ICEs in the range of 60–70%, meaning 30–40% of sodium capacity is permanently lost on the first cycle — a figure that must be dramatically improved before commercial viability is assured.
“The distinction in Carbon Lab is not just the publications or patents. It is the culture — the professional way the entire lab is handled. That is something extraordinary.”
The presenter argued, in dialogue with the session’s audience, that computational modelling — specifically, the use of atomistic simulations to predict how varying the open-pore to closed-pore ratio affects ICE — could dramatically accelerate optimisation. This was precisely the collaboration gap that the panel discussion had flagged. The question from the floor by the computational chemist, and the experimental researcher’s candid admission that such conversations almost never happen in Indian laboratories, underscored a structural deficit that both sessions identified but neither fully resolved.
Carbon Nanotubes as Photocatalytic Scaffolding: Microplastic Remediation
The third presentation, delivered by Dr. Manipuja Ila, an alumna of the Carbon Lab now at NIT Tiruchirappalli, represented the lab’s environmental remediation work at its most chemically sophisticated. The target: photocatalytic degradation of polystyrene microplastics — arguably among the most intractable pollutants of the Anthropocene, accumulating in marine and freshwater environments, entering food chains, and resisting conventional water treatment processes.
The approach deployed a Z-scheme heterojunction photocatalyst — a configuration in which two photocatalysts are placed in physical contact, each harvesting different portions of the solar spectrum, with electron-hole recombination pathways engineered to maximise the availability of highly reactive species for oxidative degradation. Specifically, Dr. Ila’s group incorporated single-wall carbon nanotubes (SWCNTs) onto silver-doped titanium dioxide (Ag⁺/TiO₂), exploiting the CNT’s dual role as an electron mediator and a visible-light sensitiser that shifts TiO₂’s working range from UV-only (band gap 3.2 eV) to visible light (band gap reduced to 2.8 eV with Ag doping).
The results were compelling within the constraints of a laboratory-scale batch study. Bare TiO₂, excited by UV light, achieved merely 7% mass loss of polystyrene microplastics over 120 hours. Ag-doped TiO₂ alone achieved 38%. The full Z-scheme composite — Ag-doped TiO₂ heterojunctioned with SWCNTs — achieved 57.84% mass loss, with the advanced photocatalyst also reducing total organic carbon (TOC) from 78.78 ppm to 55.27 ppm, confirming that genuine mineralisation (not merely surface modification) was occurring. GCMS analysis verified that the intermediate degradation products were less toxic than the parent polystyrene, a crucial safety criterion for any remediation technology intended for real water systems.
The work remains at laboratory scale. Translating photocatalytic degradation from batch reactors to continuous flow systems — with real-world microplastics that carry adsorbed contaminants, and at concentrations and volumes relevant to water treatment infrastructure — represents a formidable scale-up challenge. Dr. Ila was candid about this gap. But the foundational chemistry, establishing that visible-light-driven Z-scheme heterojunctions can degrade recalcitrant plastic polymers without producing more toxic byproducts, is a contribution of genuine scientific significance.
Battery Recycling as Circular Science: Turning Degraded Anodes into Functional Cathodes
The session’s final presentation, by Dr. Puja, currently at NIT Tiruchirappalli, addressed the approaching crisis of end-of-life lithium-ion batteries with unusual ingenuity. The problem: by 2030, an estimated 3.7 to 4 million tonnes of lithium-ion batteries will reach end-of-life globally, generating an environmental hazard of unprecedented scale. Graphite, comprising approximately 20–28% by weight of a typical cell’s anode, represents a significant fraction of that waste — and graphite, as the presenter noted, is both a strategically controlled material (dominated globally by Chinese production) and a chemically versatile one.
Dr. Puja’s group has developed a methodology for recovering spent graphite from end-of-life batteries and upcycling it — not merely restoring it to its original anode function but transforming it into a functional cathode material for next-generation aqueous batteries. The recovery process involves discharging batteries using NaCl solution or electrochemical methods, dismantling the cell, sonicating the anode to release the graphite, and then treating it with thermal, acid (H₂SO₄ with pyrolysis), or alkaline (KOH) processes to restore crystallographic structure and remove SEI layer impurities.
The recovered and upcycled graphite was then composited with MnO₂ as a cathode material for aqueous zinc-ion batteries — a chemistry that offers significantly improved safety and cost profiles compared to lithium-ion systems for large-scale stationary storage. The MnO₂/recovered-graphite composite addressed three intrinsic weaknesses of bare MnO₂ (poor conductivity, structural instability, dissolution in aqueous electrolytes), demonstrating stable cycling up to 2,000 cycles at 0.5 A/g. A parallel investigation into aqueous aluminium-ion batteries, using Prussian Blue analogues composited with recovered graphite, showed high-rate performance at 5 A/g — an impressive figure for aqueous chemistries, which have historically sacrificed power density for safety.
The elegance of this research lies in its circularity: a material discarded as industrial waste at the end of one battery’s life becomes the functional component of a safer, cheaper, more sustainable battery architecture. It is exactly the kind of work that the summit’s thematic framework — Carbon Research Yielding Sustainable Technological Advances for Life — was designed to honour.
– Sai Chaitanya Puligadda
