By converting this hazardous waste into advanced nanoporous carbon electrodes, the researchers demonstrate that cigarette butts can serve as an unexpected yet highly effective resource for supercapacitors. The resulting devices exhibit high energy and power densities alongside exceptional long-term stability, highlighting a rare combination of environmental remediation and technological value.
The rising demand for fast, reliable, and sustainable energy storage is challenging conventional technologies such as lithium-ion batteries. Supercapacitors offer a compelling alternative because they store energy through electrostatic charge accumulation, enabling rapid charging, high power output, and long cycle life. Their performance, however, strongly depends on electrode materials, particularly surface area, pore structure, and electrical conductivity. Biomass-derived porous carbons have attracted growing interest as sustainable and tunable electrode materials. Among them, cigarette butts—mainly composed of cellulose and cellulose acetate—represent an underutilized biomass resource whose polymeric structure makes them promising precursors for advanced porous carbons when properly processed.
A study (DOI:10.48130/een-0025-0016) published in Energy & Environment Nexus on 13 January 2026 by Leichang Cao’s team, Henan University, only addresses the urgent challenge of managing millions of tons of cigarette butt waste generated each year, but also points to a scalable pathway for producing sustainable, low-cost electrode materials for next-generation energy storage systems.
The study first employed a hydrothermal carbonization–pyrolysis activation strategy to convert waste cigarette butts into N,O co-doped hierarchical nanoporous biochars (CNPBs), followed by systematic structural, chemical, and electrochemical characterization to elucidate structure–performance relationships. Cigarette butts were hydrothermally carbonized to form nitrogen-containing hydrochar with stacked spherical morphologies, and subsequently activated using potassium hydroxide (KOH) at different ratios and temperatures to tune pore architecture. Scanning electron microscopy revealed that the initially dense, smooth carbon spheres evolved into three-dimensional scaffold-like porous structures after KOH activation, with increasing KOH ratios transforming spheres into looser, honeycomb-like mesoporous networks that favor rapid ion and electron transport. Nitrogen adsorption–desorption analyses showed that all activated CNPBs exhibited highly developed micro–mesoporous structures, with the optimal sample (CNPB-700-4) achieving an ultra-high specific surface area of 2,133.5 m² g⁻¹ and a balanced pore size distribution (1–3 nm), enabling efficient charge storage and electrolyte diffusion. X-ray diffraction and Raman spectroscopy further demonstrated that moderate activation temperature (700 °C) preserved favorable graphitization while limiting excessive defect formation, whereas higher temperatures induced structural disorder. Elemental analysis and XPS confirmed uniform incorporation of nitrogen and oxygen functional groups, including pyridinic and pyrrolic nitrogen species, which contribute additional pseudo-capacitance and enhanced conductivity. Corresponding electrochemical tests in a three-electrode system revealed that CNPB-700-4 delivered the highest specific capacitance of 344.91 F g⁻¹ at 1 A g⁻¹, excellent rate capability, and low internal resistance, with 95.44% capacitance retention after 10,000 cycles. When assembled into a symmetric two-electrode supercapacitor, the material achieved a high energy density of 24.33 Wh kg⁻¹ and a power density of 373.71 W kg⁻¹, outperforming many biomass-derived and commercial activated carbons. Together, these results demonstrate that the controlled hydrothermal–activation method directly governs pore structure, surface chemistry, and graphitization, which synergistically underpin the outstanding electrochemical performance of cigarette butt–derived CNPBs.
The results show that cigarette butts, traditionally viewed as hazardous waste, can be transformed into high-value energy storage materials. The resulting supercapacitors are well suited for fast-charging, long-life applications such as grid stabilization, regenerative braking, and portable electronics. Importantly, this work presents a scalable and eco-friendly waste-to-resource strategy that aligns with circular economy principles, simultaneously reducing environmental pollution and supporting sustainable energy technologies.
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References
DOI
Original Source URL
https://doi.org/10.48130/een-0025-0016
Funding information
The authors are thankful for the support from the China Postdoctoral Science Foundation (Grant No. 2023M731169), the Ministry of Human Resources and Social Security's Research and Selected Funding Project For Overseas Returnees (J24018Y), the Key Scientific Research Projects of Universities in Henan Province (Grant No. 23A610006), the Key Science and Technology Department Project of Henan Province (Grant No. 222102320252), and the Yellow River Scholar Program of Henan University.
About Energy & Environment Nexus
Energy & Environment Nexus is a multidisciplinary journal for communicating advances in the science, technology and engineering of energy, environment and their Nexus.
Experimental study
Not applicable
N,O co-doped hierarchical nanoporous biochar derived from waste cigarette butts for high-performance energy-storage application
13-Jan-2026
The authors declare that they have no competing interests.