Found 36 results
Open Access
Review
03 September 2025Defect Engineering in Carbon-Based Metal-Free Catalysts: Active Sites, Reduction Mechanisms, and 3D Architectures for Sustainable 4-Nitrophenol Reduction
Nitrophenols (NPs), classified as priority pollutants due to their significant toxicity, persistence, and bioaccumulation potential, pose severe threats to ecosystems and human health. Catalytic reduction, particularly the conversion of NPs like 4-nitrophenol (4-NP) to less toxic aminophenols using sodium borohydride (NaBH4), represents a promising remediation strategy. While conventional metal-based catalysts face limitations including high cost, poor durability, and potential metal leaching, carbon-based metal-free catalysts (C-MFCs) have emerged as highly efficient, sustainable, and cost-effective alternatives. However, the precise reaction mechanisms governing NP reduction over C-MFCs remain ambiguous, and significant debate surrounds the nature of the active sites and the structure-activity relationships dictating performance. This review systematically elucidates the catalytic sites and associated reduction mechanisms in C-MFCs. We comprehensively summarize design principles centered on defect engineering strategies, encompassing single-atom (N, S, B, P, O), dual-atom (B,N; N,S; N,P), and tri-atom (B,N,F; N,P,F) doping, alongside non-doping defects such as edge and pore defects. The critical structure-performance relationships linking these engineered active sites to catalytic activity (e.g., turnover frequency, TOF) are analyzed, integrating experimental evidence and theoretical insights. Furthermore, strategies for constructing three-dimensional architectures to enhance active site accessibility and catalyst stability are highlighted. This work provides fundamental insights to guide the rational design of next-generation high-performance C-MFCs for sustainable nitrophenol pollution control.
Open Access
Article
03 September 2025From Fossil to Future: Trade, Technology and Clean Energy Transitions in High-Impact Developing Economies
This study examines the impact of economic growth, renewable energy equipment imports, and energy use on CO2 emissions in seven developing countries over the period 2000–2021, employing second-generation panel estimators (Augmented Mean Group AMG, The Common Correlated Effects Mean Group CCEMG) that account for cross-sectional dependence and slope heterogeneity. Results show that economic growth and energy use significantly increase emissions, while renewable energy equipment imports display no direct or robust mitigating effect. This limited impact likely reflects adoption and integration challenges and the absence of complementary policies, underscoring the need for strategies that link imports to technology transfer and domestic manufacturing capacity. Granger causality tests indicate that growth and renewable energy imports drive emissions, highlighting the necessity for integrated green industrial policies, carbon pricing mechanisms, and sustainable finance instruments. These findings suggest that, for developing economies, achieving low-carbon growth requires a coordinated policy mix that aligns environmental objectives with economic development goals.
Open Access
Article
28 August 2025Initiation of Surface Processes by Resonance IR Laser Excitation—State and Perspectives
A possibility to initiate surface reactions by resonant IR laser radiation has been studied. Several systems have been tried, including those with linkage isomerism, such as CO bound to cations in zeolites, decomposition of adsorbed unstable molecules like ozone or HN3, reactions of vibrationally excited molecules with coadsorbed species, or the effect of resonance excitation of hydroazide acid HN3 upon its ability to induce the protonation of dimethylpyridine adsorbed on silanol groups of silica. In almost all the experiments, the changes caused by irradiation were weak, and isotopic selectivity was rather poor. The choice of systems and possible ways to improve their characteristics are discussed as well as the perspectives of their usage for isotope separation or other practical tasks.
Open Access
Case Report
22 August 2025Root Cause Identification of Vibration and Wear Due to Strainer Obstruction in Hydrocarbon Processing Compressors
This study examines the root causes of vibration and wear in centrifugal compressors, particularly emphasising strainer obstruction in hydrocarbon processing environments. Strainer fouling is primarily driven by deposits from inlet gas compositions and deviations in operating conditions, which restrict flow, increase vibration, and accelerate component degradation. A combined methodology was applied to investigate these issues, including baroscopic inspection of compressor internals, chemical analysis of deposited materials, and evaluation of operational records against design specifications. Maintenance histories and strainer cleaning frequencies were also reviewed to establish links between performance decline and operating practices. The findings show that chemical cleaning is the most effective and cost-efficient solution, outperforming high-pressure water jet cleaning and full compressor overhauls by minimising downtime, restoring flow dynamics, and improving mechanical stability. Successful implementation across multiple compressors confirmed its scalability and reliability. This research validates chemical cleaning as a preferred maintenance strategy, delivering significant operational and economic benefits while extending compressor service life.
Open Access
Article
18 August 2025Ethanothermal Synthesis of Dual Emissive Supramolecular Carbon Dots from Naphthalenediol and Quinones with Aggregate Tuned Fluorescence
Carbon dots (CDs) have attracted considerable interest due to their unique photoluminescence and broad potential in sensing, bioimaging, and optoelectronics. However, precise control of their emission properties through molecular design and understanding of supramolecular aggregation remain challenging. Here, nitrogen-doped carbon dots (H-CDs) with green fluorescence are synthesized via an ethanol-mediated solvothermal method using 1,3-dihydroxynaphthalene as a rigid π-conjugated carbon source and 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) as both oxidant and nitrogen donor. The synthesis involves complex molecular transformations yielding amorphous supramolecular carbon dots stabilized mainly by noncovalent interactions. Characterization confirmed abundant oxygen- and nitrogen-containing functional groups and an amorphous structure devoid of crystalline residues. Hierarchical H-type aggregation driven by π-π stacking and hydrogen bonding governs the photophysical behavior of the H-CDs, inducing a concentration-dependent evolution from blue-emitting monomers to green-emitting supra-CDs, accompanied by particle growth, red-shifts in the emission spectrum, and a pronounced elongation of the fluorescence lifetime. Temperature- and salt-dependent studies reveal that emission intensity increases with rising temperature and low ionic strength, due to distorted H′-aggregates with weak excitonic coupling and electrostatic screening of surface charges. These insights deepen the understanding of structure-property relationships in carbon dots and offer guidance for tailoring their photophysical properties for advanced optoelectronic applications.
Open Access
Review
07 August 2025Progress in the Study of Transition Metal-Based Carbon Nanotube Composites for Electrochemical Hydrogen Evolution
Hydrogen is an efficient, clean, and economical energy source, primarily due to its remarkably high energy density. Electrolytic water is considered an attractive and feasible method for hydrogen production. The high cost and scarcity of traditional Pt-based catalysts limit their large-scale application. Transition metals (TMs)-based composites, particularly those integrated with carbon nanotubes (CNTs), have emerged as promising alternatives due to their high conductivity, surface area, and ability to enhance the catalytic properties of TMs. Currently, there is no systematic summary of TMs-based CNTs composites for electrochemical hydrogen evolution reaction (HER). In this review, the main synthesis methods, including the wet chemical method, chemical vapor deposition, and electrochemical techniques, were first summarized. Then, the latest advancements of TMs/CNTs composites, focusing on their structure, electronic properties and superior HER catalytic performance, were systematically discussed. The catalytic mechanisms are meticulously examined, with particular emphasis on the pivotal role of CNTs in enhancing charge transfer and stabilizing metal nanoparticles. Finally, this review addresses the current challenges and future development directions for HER catalysts.
Open Access
Article
21 July 2025Mechanism Obstacles and Path Breakthroughs for International Low-Carbon Technology Sharing
The deepening of global climate governance urgently needs to solve the institutional predicament between the monopoly and sharing of low-carbon technologies. In analyzing the institutional obstacles to the sharing of low-carbon technology, the study found significant asymmetric conflicts between developed and developing countries in technology supply, institutional rules, and market dynamics. The current international rule system (such as the Agreement on Trade-Related Aspects of Intellectual Property Rights and Bilateral Investment Agreement) has solidified the “central-periphery” pattern of technology distribution through tools such as “prohibition provisions on compliance requirements” and “green patent barriers”, resulting in developing countries facing dual pressures of “compliance costs” and “technology dependence”. In contrast, developed countries have fallen into the predicament of “innovation involution” due to the mismatch of technological application scenarios. Based on the theory of the technology life cycle and the perspective of subject complementarity, there is a structural mutual benefit space in the supply and demand of low-carbon technologies among different countries: developing countries can shorten the industrial decarbonization cycle through technology sharing, while developed countries rely on technology diffusion to digest excess capacity and consolidate their dominance in rules. By deconstructing the practical effectiveness of the low-carbon patent sharing platform and the defensive patent licensing model, it is highly feasible to reconstruct the technology sharing incentive framework with the “open-source mechanism”. Constructing a multi-level incentive mechanism to promote corporate participation, introducing dynamic defensive patent commitments, strengthening institutional capacity building, establishing a coordinated regulatory mechanism, and enhancing stakeholder compliance mechanisms are institutional optimization pathways. These provide a legal basis for harmonizing the exclusivity of intellectual property rights with the public nature of climate governance, and also offer strategic references for China’s participation in the formulation of global low-carbon technology regulations.
Open Access
Article
26 June 2025Law and Governance of Carbon Border Adjustments
Measured against the legally binding international climate targets, climate policy must be massively accelerated on a worldwide scale. In the absence of effective global policy instruments, a central role can be played by combinations of regional quantity governance systems, such as the EU Emissions Trading System, and additional border adjustments, such as the newly established EU Carbon Border Adjustments (CBAM). This is to avoid mere emissions shifting to other states, to encourage these states also to pursue ambitious climate protection, and to avoid competitive disadvantages for domestic industries. This paper analyzes the ecological effectiveness of the CBAM—measured against the Paris climate targets—and its compatibility with world trade law. It combines a qualitative governance analysis with methods of legal interpretation. It is demonstrated that the CBAM does not raise any concerns under WTO law and can be classified as an ecologically effective measure supporting ambitious climate protection. However, the faster and more consistent introduction of the CBAM would be ecologically more effective.
Open Access
Article
25 June 2025Synthesis and Characterization of Micron-Sized Spherical Calcium Carbonate Regulated by Sodium Carboxymethyl Cellulose
Spherical calcium carbonate particles were prepared with sodium carboxymethyl cellulose (CMC) as an addition agent by using a double decomposition reaction. We studied the effects of the additional amount of CMC on the morphology and crystal forms of calcium carbonate. The morphology and size of the product were characterized by using a scanning electron microscope (SEM). We found that with the continuous increase of the additional amount of CMC, the number of prepared spherical calcium carbonate particles gradually increases. When the additional amount of CMC is 50% of the mass of calcium carbonate generated by the reaction, all calcium carbonate becomes micron-scale spherical calcium carbonate particles. The method can be used for the preparation of spherical calcium carbonate. The X-ray diffraction (XRD) was used to test the crystal form of calcium carbonate prepared by adding different qualities of CMC. It has been found that both calcite type and vaterite type calcium carbonate exist, but with the increase of the additional amount of CMC, the number of fingerprint peaks and amplitude deviated from the baseline increased gradually. These results show that the proportion of amorphous calcium carbonate is significantly increased as the additional amount of CMC increases. The study provides a reference for exploring the preparation conditions of calcium carbonate microcapsules and the mechanism of crystal form transformation.
Open Access
Article
26 May 2025Electric Vehicles, Artificial Intelligence, and Climate Policy
This article explores the environmental implications of electrification and artificial intelligence (AI) infrastructure, emphasizing the importance of aligning technological development with climate goals. There is a lack of academic literature that explains and analyses such issues. Section 1 assesses the climate efficacy of promoting electric vehicles (EVs) and electric heating in regions where electricity is primarily coal-based. While electrification offers substantial climate benefits when powered by clean energy, lifecycle analyses reveal that EVs in coal-reliant grids may emit more greenhouse gases than internal combustion engine vehicles. Similarly, the climate performance of electric heat pumps depends on the carbon intensity of electricity sources. The section advocates for integrated policies that simultaneously promote electrification and grid decarbonization, enhancing emissions reductions and public health while mitigating the negative impacts of increased demand on polluting power plants. Section 2 uses Saudi Arabia as a case study and examines the environmental impact of AI data centers in the context of Saudi Arabia’s energy and climate policies. It highlights AI infrastructure’s energy and water intensity and its potential to strain environmental resources. To align AI development with national sustainability goals, the article recommends policies such as siting data centers near renewable energy sources, enforcing environmental efficiency standards, fostering R&D partnerships, mandating sustainability reporting, and expanding power purchase agreements and demand response participation. These measures aim to ensure responsible AI growth within climate-aligned frameworks. The implications of this study are that electrification and AI infrastructure can significantly reduce emissions and improve efficiency if powered by clean energy, but they also risk increasing environmental strain unless technological growth is carefully aligned with climate and sustainability goals.
