Search Results (3,339)

Electrochemical CO₂ reduction reaction (CO₂RR) is a key technology for achieving carbon neutrality and efficient utilization of renewable energy, capable of converting CO₂ into high-value-added carbon-based fuels and chemicals. Copper (Cu)-based catalysts have attracted significant attention due to their unique performance in generating multi-carbon (C₂₊) products such as ethylene and ethanol; however, there are still many controversies regarding their complex reaction mechanisms, active sites, and the dynamic evolution of intermediates. In situ Raman spectroscopy, with its high surface sensitivity, applicability in aqueous environments, and precise detection of molecular vibration modes, has become a powerful tool for studying the structural evolution of Cu catalysts and key reaction intermediates during CO₂RR. This article reviews the principles of electrochemical in situ Raman spectroscopy and its latest developments in the study of CO₂RR on Cu-based catalysts, focusing on its applications in monitoring the dynamic structural changes of the catalyst surface (such as Cu⁺, Cu⁰, and Cu²⁺ oxide species) and identifying key reaction intermediates (such as *CO, *OCCO(*O=C-C=O), *COOH, etc.). Numerous studies have shown that Cu-based oxide precursors undergo rapid reduction and surface reconstruction under CO₂RR conditions, resulting in metallic Cu nanoclusters with unique crystal facets and particle size distributions. These oxide-derived active sites are considered crucial for achieving high selectivity toward C₂₊ products. Time-resolved Raman spectroscopy and surface-enhanced Raman scattering (SERS) techniques have further revealed the dynamic characteristics of local pH changes at the electrode/electrolyte interface and the adsorption behavior of intermediates, providing molecular-level insights into the mechanisms of selectivity control in CO₂RR. However, technical challenges such as weak signal intensity, laser-induced damage, and background fluorescence interference, and opportunities such as coupling high-precision confocal Raman technology with in situ X-ray absorption spectroscopy or synchrotron radiation Fourier transform infrared spectroscopy in researching the mechanisms of CO₂RR are also put forward. Full article

In this study, cottonseed oil biodiesel and waste lard biodiesel were produced through a transesterification process and blended with conventional diesel at different ratios (B10 and B20). The performance and emission characteristics of these fuels were systematically evaluated in a single-cylinder, four-stroke, water-cooled diesel engine operating at speeds of 1000–1800 rpm under a constant 50% load. The physicochemical properties of the fuels were analyzed, and engine parameters including brake-specific fuel consumption (BSFC), brake thermal efficiency (BTE), exhaust gas temperature (EGT), and emissions of carbon monoxide (CO), hydrocarbon (HC), carbon dioxide (CO₂), and nitrogen oxides (NOx) were measured. The results demonstrated that, compared with diesel, biodiesel blends significantly reduced CO, HC, and CO₂ emissions. At 1800 rpm, the LB20 blend showed reductions of 31.03% in CO, 47.06% in HCs, and 19.14% in CO₂ relative to diesel. These reductions are mainly attributed to the higher oxygen content and lower hydrogen-to-carbon ratio of biodiesel, which promote more complete combustion. However, all biodiesel blends exhibited higher NOx emissions than diesel, with the increase being more pronounced at higher blend ratios. At 1800 rpm, the LB20 blend recorded the highest NOx emissions, which were 20.63% higher than those of diesel under the same condition. In terms of performance, biodiesel blends showed higher BSFC and lower BTE compared with diesel, mainly due to their lower calorific value and higher viscosity. The lowest BTE and the highest BSFC were both observed with the LB20 blend, at 22.64% and 358.11 g/kWh, respectively. Full article

This study investigates the application and transformation potential of smart city concepts along Zhongyang Road in Hsinchu City, Taiwan. By introducing evaluation mechanisms such as the Smart City Maturity Index (SCMI) and the Composite Key Performance Indicator (CKPI), the research systematically analyzes the effectiveness of implementations across areas including transportation, energy, governance, and citizen engagement. Furthermore, Formula (1) is applied to assess the improvement in average delay time after the integration of smart technologies, while Formula (2) quantifies the annual energy savings achieved by replacing conventional streetlights with solar-powered ones, demonstrating tangible energy-saving and carbon-reduction benefits. The findings indicate that cross-sector collaboration and technological integration can significantly enhance urban operational efficiency and sustainability, providing valuable insights for the development of other new towns. Full article

Given that the stock of coal gangue is increasing annually, and especially considering the problem of resource utilization after the spontaneous combustion of coal gangue accumulations with large thickness, the post-spontaneous combustion of coal gangue (SC coal gangue) from Yangquan, Shanxi, was selected as a research object. After crushing and screening, SC coal gangue was used as a coarse and fine aggregate, and through concrete mix design and a trial mix of concrete and mix ratio adjustment, concrete of strength grade C20 was obtained. Through experiments, the strength, elastic modulus, frost resistance, carbonation depth and other performance indicators of the concrete were measured. Using the SC coal gangue concrete, a 20 mm thick SC coal gangue panel was designed and manufactured. Through experimental tests, the bearing capacity, hanging force, impact resistance, impermeability and other properties of the board met the requirements of the relevant standards for building wallboard. For the SC coal gangue panel composite rock wool, its heat transfer coefficient decreased by 34.0%, air sound insulation was $\ge 45 \mathrm{d}\mathrm{B}$, and the self-weight of the external wallboard was reduced by 37.5%, so the related performance was better than the requirements of the current standard. The research results have been successfully applied to an office building project in Shanxi, China. Using SC coal gangue to make the external wallboard of the building, the reduction and recycling of solid waste are realized. In addition, the production of wall panels has been industrialized, thereby improving the construction efficiency. Full article

The increasing share of renewable energy sources in power grids demands greater load flexibility from thermal power plants. Circulating Fluidized Bed (CFB) combustion systems, while offering fuel flexibility and high thermal inertia, face challenges in maintaining hydrodynamic and thermal stability during load transitions. This study investigates partial flue gas recirculation (FGR) as a strategy to enhance short-term load flexibility in a 1 MW_th CFB pilot plant fired exclusively with solid recovered fuel. Two experimental test series were conducted. Under conventional operation, where fuel and fluidization air are reduced proportionally, load reductions to 86% and 80% led to operating regime shift. Particle entrainment from the riser to the freeboard and loop seal decreased, circulation weakened, and the temperature difference between bed and freeboard zone increased by 71 K. Grace diagram analysis confirmed that the system approached the boundary of the circulating regime. In contrast, the partial FGR strategy maintained total fluidization rates by replacing part of the combustion air with recirculated flue gas. This stabilized pressure conditions, sustained particle circulation, and limited the increase in the temperature difference to just 7 K. Heat extraction in the freeboard remained constant or improved, despite slightly lower flue gas temperatures. While partial FGR introduces a minor efficiency loss due to the reheating of recirculated gases, it significantly enhances combustion stability and enables low-load operation without compromising fluidization quality. These findings demonstrate the potential of partial FGR as a control strategy for flexible, waste-fueled CFB systems and supports its application in future low-carbon energy systems. Full article

This paper provides a systematic review of the latest advancements in metal-organic frameworks (MOFs) and covalent organic frameworks (COFs) for electrocatalytic carbon dioxide reduction. Both materials exhibit high specific surface areas, tunable pore structures, and abundant active sites. MOFs enhance CO₂ conversion efficiency through improved conductivity, optimized stability, and selective regulation—including bimetallic synergy, pulse potential strategies, and tandem catalysis. COFs achieve efficient catalysis through precise design of single or multi-metal active sites, optimization of framework conjugation, and photo/electro-synergistic systems. Both types of materials demonstrate excellent selectivity toward high-value-added products (CO, formic acid, C₂⁺ hydrocarbons), but they still face challenges such as insufficient stability, short operational lifespan, high scaling-up costs, and poor electrolyte compatibility. Future research should integrate in situ characterization with machine learning to deepen mechanistic understanding and advance practical applications. Full article

Advanced oxidation processes (AOPs) utilizing peroxymonosulfate (PMS) have recently gained attention for effectively removing organic dyes. Biochar, a carbon-based material, can act as a catalyst carrier for PMS activation. This study developed a nitrogen-doped biochar catalyst (NCMR800–2) from waste Chinese medicine residue (CMR) through one-step pyrolysis to efficiently remove Rhodamine B (RhB) from wastewater. Results indicate that NCMR800–2 rapidly achieved complete removal of 20 mg/L Rhodamine B (RhB), the primary focus of this study, within 30 min, while maintaining high degradation efficiencies for other pollutants and significantly outperforming the unmodified material. The material demonstrates strong resistance to ionic interference and operates effectively across a wide pH range. Quenching experiments and in situ testing identified singlet oxygen (¹O₂) as the primary active species in RhB degradation. Electrochemical analysis showed that nitrogen doping significantly enhanced the electrical conductivity and electron transfer efficiency of the catalyst, facilitating PMS decomposition and RhB degradation. Liquid chromatography–mass spectrometry (LC-MS) identified intermediate products in the RhB degradation process. Seed germination experiments and TEST toxicity software confirmed a significant reduction in the toxicity of degradation products. In conclusion, this study presents a cost-effective, efficient catalyst with promising applications for removing persistent organic dyes. Full article

This study proposes a Cooperative Traffic Controller System (CTS), an urban eco-network control system that leverages Multi-Agent Reinforcement Learning (MARL), to address urban road congestion and environmental pollution. The proposed system synergizes traffic signal timing optimization and speed guidance control, simultaneously enhancing network efficiency, reducing carbon emissions, and minimizing energy consumption. A Beta-enhanced Soft Actor-Critic (SAC) algorithm is applied to achieve the joint optimization of the traffic signal phasing and vehicle speed coordination. Experimental results show that in large-scale networks, the improved SAC reduces the average delay time per vehicle by approximately one minute, reduces CO₂ emissions by more than double, and reduces fuel consumption by 56%. Comparative analyses of the algorithm versus the PPO and standard SAC demonstrate its superior performance in complex traffic scenarios—specifically in congestion mitigation and emissions reduction. Full article

This study systematically explores the mechanisms and application potential of biochar in remediating heavy metal-contaminated soils. Particular emphasis is placed on the role of raw materials and pyrolysis conditions in modulating key physicochemical properties of biochar, including its aromatic structure, porosity, cation exchange capacity, and ash content, which collectively enhance heavy metal immobilization. The direct remediation mechanisms are categorized into six pathways: physical adsorption, electrostatic interactions, precipitation, ion exchange, organic functional group complexation, and redox reactions, with particular emphasis on the reduction in toxic Cr⁶⁺ and the oxidation of mobile As³⁺. In addition to direct interactions, biochar indirectly facilitates remediation by enhancing soil carbon sequestration, improving soil physicochemical characteristics, stimulating microbial activity, and promoting plant growth, thereby generating synergistic effects. The study evaluates combined remediation strategies integrating biochar with phytoremediation and microbial remediation, highlighting their enhanced efficiency. Moreover, practical challenges related to the long-term stability, ecological risks, and economic feasibility in field applications are critically analyzed. By synthesizing recent theoretical advancements and practical findings, this research provides a scientific foundation for optimizing biochar-based soil remediation technologies. Full article

This study aimed to evaluate the effects of specific LED light spectra on the growth and physiology of Changchuan No. 3 Capsicum annuum L. seedlings. The experimental design involved exposing pepper seedlings to six different spectral light combinations for 7, 14, and 21 days, with the treatments consisting of 2R1B1Y (red/blue/yellow = 2:1:1), 2R1B1FR (red/blue/far-red = 2:1:1), 2R1B1P (red/blue/purple = 2:1:1), 4R2B1G (red/blue/green = 4:2:1), 2R1B1G (red/blue/green = 2:1:1), and 2R1B (red/blue = 2:1). The results demonstrated distinct spectral regulation of seedling development: compared to the white light (CK), the 2R1B1FR (far-red light supplementation) treatment progressively stimulated stem elongation, increasing plant height and stem diameter by 81.6% and 25.9%, respectively, at day 21, but resulted in a more slender stem architecture. The 2R1B1G (balanced green light) treatment consistently promoted balanced growth, culminating in the highest seedling vigor index at the final stage. The 2R1B1P (purple light supplementation) treatment exhibited a strong promotive effect on root development, which became most pronounced at day 21 (126% increase in root dry weight), while concurrently enhancing soluble sugar content and reducing oxidative stress. Conversely, the 2R1B1Y (yellow light supplementation) treatment increased MDA content by 70% and led to a reduction in chlorophyll accumulation, while 2R1B (basic red–blue) resulted in lower biomass accumulation compared to the superior spectral treatments. The 4R2B1G (low green ratio) treatment showed context-dependent outcomes. This study elucidates how targeted spectral compositions, particularly involving far-red and green light, can optimize pepper seedling quality by modulating photomorphogenesis, carbon allocation, and stress physiology. The findings provide a mechanistic basis for designing efficient LED lighting protocols in controlled-environment agriculture to enhance pepper nursery production. Full article

Rapid population growth and accelerating urbanization are intensifying the demand for construction materials, particularly concrete, which is predominantly produced with Portland cement and natural aggregates. This reliance imposes substantial environmental burdens through resource depletion and greenhouse gas emissions. Within the framework of sustainable construction, recycled aggregates and industrial by-products such as fly ash, slags, crushed glass, and other secondary raw materials have emerged as viable substitutes in concrete production. At the same time, three-dimensional concrete printing (3DCP) offers opportunities to optimize material use and minimize waste, yet it requires tailored mix designs with controlled rheological and mechanical performance. This review synthesizes current knowledge on the use of recycled construction and demolition waste, industrial by-products, and geopolymers in concrete mixtures for 3D printing applications. Particular attention is given to pozzolanic activity, particle size effects, mechanical strength, rheology, thermal conductivity, and fire resistance of recycled-based composites. The environmental assessment is considered through life-cycle analysis (LCA), emphasizing carbon footprint reduction strategies enabled by recycled constituents and low-clinker formulations. The analysis demonstrates that recycled-based 3D printable concretes can maintain or enhance structural performance while mix-level (cradle-to-gate, A1–A3) LCAs of printable mixes report CO₂ reductions typically in the range of ~20–50% depending on clinker substitution and recycled constituents—with up to ~48% for fine recycled aggregates when accompanied by cement reduction and up to ~62% for mixes with recycled concrete powder, subject to preserved printability. This work highlights both opportunities and challenges, outlining pathways for advancing durable, energy-efficient, and environmentally responsible 3D-printed construction materials. Full article

The activation of persulfate (PS) to oxidize and degrade 2,4-dichlorophenol (2,4-DCP) in aqueous solution represents a prevalent advanced oxidation technology. This study established a PS activation system using sulfide-modified nanoscale zero-valent iron supported on biochar (S-nZVI@BC). The optimal conditions included a PS:2,4-DCP mass ratio of 70:1 and S-nZVI@BC:PS of 1.5:1. The activator had excellent stability after being reused five times, which lead to high cost-effectiveness and sustainable usability. This system exhibited broad pH adaptability (3–11), with enhanced efficiency under acidic/neutral conditions. Chloride ion, nitrate, and carbonate had effects during the degradation. During the initial degradation phase, S-nZVI@BC played a primary role, with a greater contribution rate of adsorption than reduction. Fe⁰ played a dominant role in the PS activation process; reactive species—including HO•, SO₄•⁻, and O₂•⁻—were identified as key agents in subsequent degradation stages. The overall degradation processes comprised three distinct stages: dechlorination, ring-opening, and mineralization. Full article

The escalating problem of nitrate pollution, coupled with the environmental burden of the Haber-Bosch process, has spurred intense interest in the electrocatalytic nitrate reduction reaction (eNO₃RR) as a sustainable route for simultaneous wastewater treatment and ammonia production. However, the efficiency and selectivity of eNO₃RR are hampered by the multi-step proton-coupled electron transfer process and the competing hydrogen evolution reaction. This review provides a comprehensive and critical overview of recent advances in understanding and designing catalysts for eNO₃RR. We begin by elucidating the fundamental mechanisms and key reaction pathways, followed by a discussion on how critical parameters (e.g., electrolyte microenvironment, applied potential, reactor design) dictate performance. Further discussion of recent advances in catalysts, including single-metal catalysts, alloy catalysts, transition metal compounds, single-atom catalysts, carbon-based non-metal catalysts, and composite catalysts, highlights their significant roles in enhancing both the efficiency and selectivity. A distinctive feature of this review is its consistent critical assessment of catalysts through the dual lenses of practicality and sustainable development. Finally, we outline prevailing challenges and propose future research directions aimed at developing scalable and commercially viable electrocatalytic systems for green nitrogen management. Full article

As one of the primary contributors to carbon emissions in China, the transportation sector plays a pivotal role in achieving green and low-carbon development. Considering the spatio-temporal dependency characteristics of transportation carbon emissions driven by economic interactions and population mobility among provinces, this study proposes a predictive framework for transportation carbon emissions based on a spatio-temporal attention mechanism from the perspective of multi-province spatio-temporal synergy. First, the study conducts transportation carbon emission accounting by considering both transportation fuel consumption and electricity usage, followed by feature selection using an enhanced STIRPAT model. Second, it integrates the spatio-temporal attention mechanism with graph convolutional neural networks to construct a multi-province transportation carbon emission collaborative prediction model. Comparative experiments highlight the superior performance of deep learning methods and spatio-temporal correlation modeling in multi-province transportation carbon emission collaborative prediction. Finally, three future development scenarios are designed to analyze the evolution paths of transportation carbon emissions. The results indicate that technological innovation can significantly improve the efficiency of transportation emission reduction. Moreover, given that the eastern region and the central and western regions are at distinct stages of development, it is essential to develop differentiated emission reduction strategies tailored to local conditions to facilitate a green and low-carbon transformation in the transportation sector. Full article

Ti-bearing blast furnace slag (TBS), a byproduct of vanadium–titanium magnetite smelting, serves as an important secondary resource for titanium recovery. However, the complex mineralogical composition and finely dispersed nature of titanium in TBS present significant challenges for efficient extraction. This review systematically examines four major titanium extraction routes: hydrometallurgical leaching, pyrometallurgical smelting, molten salt electrolysis, and selective precipitation, focusing on their limitations and recent improvements. For instance, conventional acid leaching suffers from acid mist release, a colloidal formation that hinders titanium recovery, and waste acid pollution. The adoption of concentrated sulfuric acid roasting activation effectively suppresses acid mist emission and prevents colloidal generation. Pyrometallurgical approaches are hampered by high energy consumption and substantial carbon emissions, which can be alleviated through the use of gaseous reductants to enhance reaction efficiency and reduce environmental impact. Molten electrolysis faces issues such as polarization and undesirable dendritic deposition; these are mitigated by employing liquid metal cathodes integrated with vacuum distillation to achieve high-purity titanium products. Selective precipitation struggles with strict crystallization conditions and low separation efficiency, though advanced techniques like supergravity separation show improved extraction performance. We propose an integrated technical strategy termed “Online conditioning driven by waste heat-mineral phase reconstruction-directional crystallization-optimized liberation.” This approach utilizes the inherent waste heat of slag combined with electromagnetic stirring to enhance homogeneity and promote efficient titanium recovery, offering a sustainable and scalable solution for industrial TBS treatment. Full article