Advanced Materials and Processes Research Institute

Hybrid materials, as a consequence of the synergistic effect, enormously tune the electrical, optical, optoelectronic, and other functional properties of various material systems. Recently, layered hybrid materials have largely been sought for greater control of functional properties. However, tribo-engineering with layered hybrid materials has not been well explored and has yet to be fully understood to advance moving mechanical components. Here, we develop a variety of layered hybrid materials based on a combination of multilayer graphene (mGR), multilayer graphene oxide (mGO), boron nitride (BN), and tungsten disulfide (WS2) and probe their tribological effectiveness using a ball-on-disk low-load tribometer. We demonstrate that solution-processed hybrid flakes coatings of BN and WS2 on stainless steel 304 (SS) are not tribologically resilient. However, when combined with mGO and mGR-based compositions, even BN and WS2-based hybrid flakes coatings reveal enhanced tribological performance due to synergistic effects. Developed BN_mGR and WS2_mGO binary hybrids, as well as BN_WS2_mGR and BN_WS2_mGO ternary hybrids, reduced friction by 32%, 59%, 29%, and 40%, respectively, compared to bare SS. We demonstrate that the WS2_mGO binary hybrid flakes coating yields a low coefficient of friction (COF) and high wear resistance. To further enhance its survival under rigorous tribological conditions, particularly at higher loads, we engineer its formulation. The resulting WS2_mGO_14 formulation exhibits the lowest friction with an average COF of ~ 0.09, reducing the friction of bare SS by 87%, and the highest wear resistance at a normal load of 0.1 N. Moreover, it maintained its tribological effectiveness at higher normal loads up to 4 N, outperforming all other hybrid flakes coatings and various other WS2_mGO formulations studied in this work. Microscopic and spectroscopic studies by FESEM, Raman, and FTIR are conducted to gain fundamental insight into friction and wear control mechanisms of the WS2_mGO hybrid. This work discovers that the inclusion of carbon-based layered material is mandatory to achieve low friction and high wear resistance in BN and WS2-based material systems and developing slippery surfaces.

ABSTRACT The growing concern over greenhouse gas emissions and climate change has led to substantial advancements in carbon capture and utilization (CCU) technology. Carbon nanofiber (CNF)-based materials are effective solutions due to their high thermal stability, large surface area, adjustable porosity, and modifiable surface chemistry. This review critically examines recent innovations in CNF-based materials for CO₂ capture, with an emphasis on two key dimensions: (i) synthesis and functionalization strategies that govern adsorption performance and (ii) the scalability, energy footprint, and techno-economic feasibility of their practical deployment. Fabrication approaches, such as electrospinning and chemical vapor deposition (CVD), are examined for their role in tailoring CNF structures to enhance adsorption efficiency. They are evaluated both for their structural tuning capabilities, production scalability, energy footprint, and cost-effectiveness Functionalization strategies – including nitrogen doping, amine modifications, and integration with metal-organic frameworks (MOFs) – are analyzed concerning their influence on binding affinity, selectivity, and reversibility, thereby improving CO₂ adsorption capacity, selectivity, and regeneration potential.Different CNF-based materials, such as K₂CO₃-CNF, nitrogen-doped CNF, amine-functionalized CNF, and hydrazine-modified CNF, are discussed, each exhibiting unique adsorption properties. The role of pore size distribution, particularly the interplay between microporous and mesoporous structures, is analyzed for its effect on CO₂ diffusion kinetics and adsorption capacity. Polyacrylonitrile-derived CNF depicted the highest CO₂ adsorption capacity of 58 mmol/g, attributed to its large surface area, porosity, and functional groups. Beyond laboratory performance, this review highlights challenges in industrial translation – including material regeneration, mechanical integrity, and cost-effectiveness – while outlining opportunities for integrating CNF-based systems into sustainable CCU technologies.