Siqi Deng

Atmospheric pressure plasma (APP) has emerged as a versatile tool for the functionalization, modification, and synthesis of carbon-based materials. This review summarizes the historical development, underlying principles, and current progress of APP in material science, with a particular focus on carbon nanomaterials. The fundamentals of plasma parameters are introduced to highlight their roles in driving plasma–surface interactions and establish the diagnostics for these parameters. Recent advances in gas-phase and plasma–liquid systems and the influence of different plasma chemistries have led to different material functionalization results, which are discussed. Applications of plasma-treated carbon in energy storage, environment, and biomedicine are critically reviewed, demonstrating significant improvements in electrochemical performance, adsorption efficiency, and biocompatibility. Finally, current challenges are outlined alongside future perspectives on integrating APP. This review aims to provide a comprehensive reference for researchers seeking to exploit APP as a green and scalable platform for next-generation carbon materials.

Sulfonated carbon catalysts, as a type of solid protonic acid, have been widely recommended for various applications. However, syntheses of them typically require strict conditions, posing challenges in efficiency and environmental impact. Herein, we report a rapid, acid-free method to introduce sulfonic and sulfate ester groups onto carbon nanotubes (CNTs) by simply stirring them in an aqueous sodium persulfate solution (Na₂S₂O₈) at room temperature. Within 45 min, the treated CNTs reached sulfur-containing acid densities up to 0.34 mmol g⁻¹ without thermal treatment and hazardous reagents. The resulting catalyst demonstrated effective performance in terms of cellulose hydrolysis, attaining 31.6% conversion and 23.2% glucose yield. The process requires only the energy input of magnetic stirring, underscoring its environmental and practical advantages. This simple approach provides a sustainable and cost-effective alternative for the preparation of carbon-based catalysts, offering significant potential for biomass conversion and other green-chemistry applications.

Low‐temperature plasma‐assisted nitrogen fixation is a promising method for organic‐polluted soil/water remediation, that improves N‐fertilizer performance and mitigates ammonia emission. Our study explores a novel approach: plasma bubbles‐assisted ammonia treatment, and investigates the role played by various reactive substances in the oxidation of ammonia. The specific reaction pathways and the contribution of OH radicals in the ammonia oxidation process in O₂ plasma treatment are determined. Air emerges as the optimal feed gas owing to a positive feedback loop in the reaction between NO₂⁻ and H₂O₂. Air plasma treatment enriches N in the ammonia solution and minimizes ammonia loss during treatment. This study offers new insights into an advanced plasma‐assisted ammonia treatment method.

Although sulfonated carbon catalysts are considered promising solid acid catalysts for cellulose conversion, most carbon sulfonation processes require concentrated sulfuric acid (18 M) at elevated temperatures. This work investigates a novel sulfonation mechanism for carbon acid catalysts via a gas–liquid interfacial plasma sulfonation system under atmospheric pressure conditions with a dilute sulfuric acid solution (1 M) at 38 °C, and the by-products of the plasma sulfonation process were investigated by in-situ and ex-situ diagnosis. The results show that a high gas temperature (>1050 K) around the plasma allows H₂SO₄ droplet decomposition, and active species (•OH, SO₃, and HOSO₂•) generated at the gas–liquid interface were grafted on the defects of the carbon materials and subsequently formed sulfonic acid groups (0.36 mmol g⁻¹) and total acid groups (4.16 mmol g⁻¹) on the carbon network. This study aimed to provide significant insight into the understanding of the sulfonation mechanisms of an emerging plasma-based process for carbon acid catalysts, which is important for the further development of an environmentally friendly sulfonation process for acid catalysts for biomass conversion.