Achieving Net-Zero emissions by 2050 and mitigating climate change demand efficient catalytic conversion of CO2 into valuable chemicals and fuels, a cornerstone for a sustainable circular carbon economy. This review comprehensively summarizes recent progress and critical catalyst properties in key thermal heterogeneous CO2 conversion processes, specifically dry reforming of methane, reverse water-gas shift, CO2-to-methanol synthesis, and the Sabatier reaction. For dry reforming of methane, overcoming coke deposition and metal sintering through optimized oxygen storage capacity, metal dispersion, and catalyst morphology is essential. In the reverse water-gas shift reaction, noble metal catalysts supported on reducible oxides exhibit superior intrinsic activity, but developing stable, cost-effective alternatives such as Mo-based transition metal carbides and dual-functional single-atom catalysts is imperative. CO2-to-methanol synthesis critically relies on precise engineering of metal–oxide interfaces and oxygen vacancies, with In2O3-based catalysts and strategic vacancy engineering demonstrating high potential. The Sabatier reaction, predominantly using Ni-based catalysts, requires improved catalytic stability and activity through advanced morphology control, incorporation of secondary metals, and alternative energy-assisted methods (e.g., plasma, mechanochemical).Overall, continued emphasis on catalyst–physicochemical property relationships, scalable synthesis, alternative energy integration, and techno-economic analyses will drive advances towards practical and efficient catalytic CO2 conversion within a circular carbon economy framework.
The substantial increase in CO2 emissions from various point sources has become a major contributor to the greenhouse effect, intensifying global warming and exacerbating climate instability. Addressing the rising levels of atmospheric CO2 requires innovative and sustainable mitigation strategies. Integrated carbon capture and conversion (ICCC) is an emerging approach that enables the simultaneous capture and conversion of CO2 into intermediates, such as methane (CH4), carbon monoxide (CO), and syngas, via methanation, reverse water-gas shift (RWGS), and dry reforming of methane (DRM). These intermediates can be further upgraded into value-added liquid fuels via methanol synthesis or the Fischer-Tropsch route, directly supporting the production of renewable methanol and SAF. ICCC could potentially reduce the need for CO2 compression and transport, may lower the energy-intensive requirements for sorbent regeneration, and reduce the reactor systems typically associated with conventional processes. This review critically examines advancements in ICCC technologies, focusing on the design and optimization of dual-function materials (DFMs) and the synergistic interactions between adsorbents and catalysts. It explores optimized reaction pathways, material stability, and the techno-economic feasibility of ICCC systems, while addressing the effects of key operational parameters. Challenges such as thermal sintering, catalyst deactivation, and impurities (e.g., O2, H2O, sulfur species) are addressed. Practical implementation issues, including gas switching between oxidising and reducing atmospheres, purge losses, H2 utilization, product dilution and cyclic reactor heat management, are also discussed as critical determinants of scale-up feasibility. By integrating insights from materials science, process engineering, and economic analysis, this study identifies the material and process conditions under which ICCC may offer advantages over separated capture and conversion routes. The review also highlights that practical deployment remains conditional on long-term DFM stability, realistic gas switching, impurity tolerance, low-carbon H2 availability, heat integration, and reactor-scale validation.
Over the past decade, the pursuit of rapid, scalable, and cost-effective graphene synthesis strategies has intensified, driven primarily by graphene's exceptional structural, electrical, and thermal properties, which underpin its transformative potential in energy storage, electronics, and sensing. However, conventional synthesis methods (e.g., chemical vapor deposition [CVD] and exfoliation) suffer from inherent bottlenecks, including high mass-production costs and limited scalability, making rapid, energy-efficient, and scalable graphene manufacturing an increasingly critical priority to meet the accelerating demand for high-performance carbon materials. This review systematically examines three emerging non-conventional synthesis platforms, direct laser writing (DLW), Joule heating (JH), and atmospheric-pressure plasma (APP) and highlights their distinctive advantages (e.g., rapid processing, feedstock versatility, intrinsic process intensification) and inherent limitations relative to conventional CVD and exfoliation routes. A unified mechanistic analysis is presented, focusing on localized thermofluidic behavior, ultrafast nonequilibrium carbon transformations, defect evolution pathways, and graphitic domain formation across these techniques. Structure–property correlations relevant to energy storage devices, including supercapacitors and various battery systems, are systematically discussed. The review further highlights key challenges in achieving process uniformity, mechanistic predictability, and industrial scalability, while outlining timely opportunities for advancing these methods through integration with emerging reactor concepts, sustainable carbon feedstocks, and hybrid manufacturing strategies. Collectively, these insights position DLW, JH, and APP as promising cornerstones for next-generation rapid graphene synthesis, and this work aims to provide a comprehensive perspective to inspire innovations in process design and mechanistic understanding.
Flammable mixtures of dusts with gases or liquids occur in the process and energy industries. Most research about these so-called ”hybrid mixtures” was, and still is, about coal dust with the admixture of methane because of their occurrence in the mining industry. In the modern industry, hybrid mixture explosions play an increasing role in many existing processes like spray-drying, or in emerging technologies like the direct reduction of iron ore with hydrogen or nuclear/fusion reactors. While some safety characteristics of one of the component substances stay the same or are unaffected by the concentrations that occur in the process, others are severely influenced by only traces of the other substance.This review paper shows in which processes and applications hybrid mixtures pose a risk and gives an overview of the research conducted in the last 150 years. Findings that are reproducible and represent current proven knowledge are stated and compared to each safety characteristic containing only solid particles, gases or liquids as combustible substances. Additionally, fundamental studies on the mechanisms of flame propagation in hybrid mixtures are reviewed. The significance of these studies in enhancing our understanding of explosion behaviors in hybrid mixtures is also discussed. An outlook on what has been missing so far in the literature, is also given comparing the knowledge of single substances with their mixtures, why this might not have been investigated, and where the challenges lie.
Direct air capture (DAC) has emerged as a scalable strategy for atmospheric CO2 removal, with material innovations being central to its advancement. This review explores recent developments in DAC materials, including solid sorbents and liquid solutions, with a focus on their design, performance, and scalability. Key properties such as CO2 sorption capacity, kinetics, and stability under diverse conditions are critically analyzed. Emerging materials, including metal-organic frameworks (MOFs), amine-functionalized adsorbents, and advanced polymeric materials, are examined for their potential to enhance efficiency and reduce energy consumption. Challenges related to material synthesis, regeneration, and long-term durability are discussed alongside strategies for integrating these materials into scalable DAC systems. While previous reviews have addressed DAC scrubbers, a systematic yet comprehensive classification was lacking. This review fills that gap by categorizing DAC materials into a structured quadrant and compiling both foundational studies and recent advancements into detailed tables, providing a clear and organized overview of the field's progression. By synthesizing breakthroughs and identifying future directions, this review underscores the need for innovative materials to drive down costs, improve performance, and facilitate large-scale deployment of DAC in climate mitigation efforts.
