Energy & Fuels最新文献

The recovery of heavy metals and the capture and conversion of CO₂ are both highly energy-intensive processes. Nevertheless, they exhibit considerable synergistic potential, and integrating these technologies presents a promising approach for improving environmental sustainability while lowering operational costs. In this study, we utilized density functional theory (DFT) calculations to elucidate the mechanism through which nitrogen-doped graphene (NG) surfaces simultaneously capture five heavy metal atoms from coal-fired power plant flue gas and catalyze the in situ electrochemical reduction of CO₂ to CH₃OH and CH₄. Calculations of electronic properties reveal that the NG surface exhibits strong binding affinity toward all investigated heavy metals except Hg. Analysis of reaction pathways indicates that Cd@C–N₄ demonstrates the minimal overpotential (0.32 eV) among the examined systems. This study, underpinned by density functional theory calculations, illustrates the feasibility of simultaneously attaining heavy metal recovery and electrocatalytic CO₂ reduction. Additionally, it offers a theoretical framework for employing NG adsorbents to capture and stabilize heavy metals in coal-fired power plants, along with their subsequent use for in situ CO₂ electrocatalysis.

Na₄Fe₃(PO₄)₂P₂O₇ (NFPP) has emerged as a promising cathode material for sodium-ion batteries, but intrinsically low electronic conductivity and sluggish Na⁺ ion diffusion severely limit performance. Conventional strategies involving in situ carbon incorporation during synthesis fail to establish a continuous conductive network because the resulting carbon is unevenly distributed. In this study, a uniform polypyrrole (PPy) coating layer was introduced onto the surface of NFPP particles through a mild oxidative polymerization process. The intrinsic carbon layer serves as a homogeneous anchoring platform for pyrrole adsorption. This enables surface-directed polymerization to form a continuous and thickness-controlled PPy shell without disturbing the NFPP crystal structure. This carbon–polymer integrated network increases interfacial charge-transfer and accelerates Na⁺ ion diffusion, enabling NFPP@PPy-II to deliver high reversible capacity and superior rate capability. Notably, the composite retains over 90% of its capacity after 1000 cycles at a high rate of 10 °C, highlighting its exceptional cycling durability.

Direct air capture (DAC) technologies, particularly adsorption-based systems, are advancing rapidly as a form of negative emission technologies (NETs). DAC technologies represent a promising engineering approach to addressing diffuse CO₂ emissions and provide several deployment advantages, including flexibility and scalability. However, a critical yet often overlooked challenge of adsorption-based DAC is the limited stability of CO₂ sorbent materials, which undermines sustainability and hinders large-scale deployment. While most research has focused on developing adsorbents with high CO₂ selectivity and capacity, stability remains a crucial criterion, investigated in some studies through multicycle testing and exposure to accelerated degradation environments. This review provides a brief overview of DAC adsorbent types, followed by a detailed analysis of existing studies on the stability of solid sorbents under DAC operating conditions, highlighting key findings and research gaps. The thermal, oxidative, and hydro(thermal) stability of different adsorbents are discussed, along with the influence of operational variables on degradation mechanisms. Findings indicate that, while thermal degradation is generally not the primary concern at the moderate regeneration temperatures typical of DAC, oxidative degradation in the presence of oxygen can be severe, particularly for amine-based sorbents. Hydro(thermal) stability is found to depend largely on the properties of the support material. Ultimately, this review aims to guide the development of efficient and durable CO₂ adsorbents, contributing to the design of more sustainable DAC systems.

The need for rapid, permanent CO₂ storage strategies in basalt is critical for climate mitigation given rising global emissions. The first-order estimates suggest significant geological CO₂ storage potential in Indian basalts of up to 316 Gt; however, scientific gaps persist in understanding mineral carbonation dynamics, particularly regarding kinetic variation and mineral efficiency on short time scales. This study targets these gaps by systematically quantifying carbonation efficiency and sequestration rates in the Deccan Volcanic Province basalts at 25 bar and 50 °C, analyzing variation across 30- and 60-day intervals. An integrated methodology included rigorous preinjection mineralogical characterization (optical microscopy, XRD, XRF) followed by controlled CO₂-water-basalt reactions in fabricated pressurized reactors. The reaction was monitored by using ICP-MS and TGA to determine precise rates of elemental dissolution and carbonate formation. From 30 to 60 days, the carbonation efficiency of Ca increased markedly from 34.62% to 61.76%, that of Mg from 16.36% to 19.74%, and that of Fe from 11.25% to 15.83%, culminating in a total carbonation efficiency jump from 55.22% to 77.28% from 30 to 60 days. Furthermore, over time, the sequestration rates increased from 160.03 to 252.15 g CO₂/kg basalt, driven by sustained mineral dissolution and secondary carbonate precipitation, as captured by direct SEM-EDS and confirmed by TGA. Notably, data reveal that reaction proceeds forward due to increasing pH, increasing mineral surface accessibility, and favorable fluid composition result in significant efficiency gains over 60 days, with further improvements probable on extended time scales. The novelty of this study lies in real-time, multiscale tracking of both elemental and total carbonation performance under laboratory conditions, thereby providing scalable, permanent CO₂ storage technology deployment.

Owing to their excellent safety characteristics, low manufacturing cost, and remarkable theoretical capacity, aqueous zinc–iodine batteries (AZIBs) are a promising system for future energy storage applications. Nevertheless, the practical deployment of these batteries is greatly restricted by sluggish redox reaction kinetics and the polyiodide intermediate migration, known as the shuttle effect. In this study, we design a three-dimensional carbon nanotube (CNT)-doped reduced graphene (RGO) loaded with silver nanoparticles (Ag NPs) (Ag NPs/CNT-RGO) as a cathode host for AZIBs. The interconnected conductive network constructed from RGO and CNT provides efficient electron/ion transport channels, while uniformly dispersed Ag NPs on the surface of CNT-RGO act as catalytic centers to improve the iodine redox reaction rate and suppress polyiodide migration. Benefiting from these synergistic effects, Ag NPs/CNT-RGO can serve as a high-quality iodine cathode carrier material. The I₂@Ag NPs/CNT-RGO cathode delivers a high capacity of 168 mAh g^–1 at 20 C and demonstrates outstanding cycling durability, retaining 90% of its initial capacity after 60000 cycles. This study elucidates the catalytic role of Ag NPs in promoting reversible iodine redox chemistry and provides a new high-performance cathode design strategy for AZIBs.

CO₂ injection has emerged as a promising technique for enhancing the shale oil recovery. During oil extraction from nanopores, phase separation of the CO₂–oil mixture can significantly influence shale oil production. However, current studies on oil extraction always ignore the role of dynamic phase change at the pore scale. In this study, a multicomponent multiphase lattice Boltzmann model was applied to simulate the phase separation of the CO₂–oil mixture during extraction. Our simulations reveal three distinct stages of oil extraction from a dead-end nanopore. In the first stage, oil is steadily extracted when the pressure remains above the bubble point. As phase separation begins, liquid flow declines sharply due to the strong capillary resistance. In the third stage, residual oil is either extracted or trapped, depending on pore size and wettability. We further investigated oil extraction from a nanoporous medium. Unlike dead-end pores, improved pore connectivity suppresses the emergence of the three extraction stages. Once phase separation occurs, oil transport in small pores is severely impeded by confinement effects. In contrast, a large fraction of oil is extracted from large pores, contributing over 75% of total recovery. Oil–wet surfaces promote oil extraction from large pores but hinder oil recovery in small pores. Moreover, increasing the CO₂ concentrations consistently improves oil extraction in both types of pores.

The growing demand for proficient, sustainable energy storage and supply technologies has sparked the development of advanced ionomer membranes, electrodes, and metal catalysts. These membranes have critical functions in electrochemical devices, such as fuel cells, electrolyzers, and batteries, by facilitating proton transfer and providing essential reactant barriers. Perfluorosulfonic acid (PFSA) membranes are often favored for their superior proton conductivity and chemical, mechanical, and thermal stability. In proton exchange membrane fuel cells (PEMFC), they feature a sophisticated multilayer system, membrane electrode assembly (MEA) comprising the ionomer membrane, electrode, catalyst layer, and gas diffusion layer (GDL), with bipolar plates (BPs), and end plates used to connect several fuel cells in a stack. However, the lack of recycling processes for the deteriorated ionomer membrane from end-of-life (EoL) secondary sources leads to the accumulation of costly membranes that pose environmental risks and present a significant sustainability challenge due to high material costs. To address these issues, research is focused on sustainable recovery processes for ionomer membranes through dissolution using less hazardous solvents, aiming to minimize waste, maintain membrane integrity, and reduce power input. The objective of this review article is to present an overview of the recent recovery and recycling processes of ionomer membranes from EoL fuel cells and highlight some of the limitations of the membrane recycling processes as sustainable measures.

Designing a single high-performance electrode compatible with both hybrid supercapacitors and metal-ion capacitors remains a significant challenge. Here, we present an organic−inorganic hybrid electrode, VEG-VO@MoOSe (VMS), synthesized via a solvothermal approach by in situ coupling of vanadyl ethylene glycolate-assisted vanadium oxide (VEG-VO) with Mo and Se precursors. This integration induces the formation of MoOSe over MoSe₂, generating lattice mismatches, rich defect sites, and expanded interlayer spacing. These structural features increase active sites and modulate the electronic environment, collectively promoting efficient ion diffusion and charge storage. The incorporation of vanadium oxide (VO₂) extends pseudocapacitive behavior within the electric double-layer (EDL) framework, enabling a hybrid charge storage mechanism combining capacitive, pseudocapacitive, and faradaic processes. The VMS2 electrode exhibits a high specific capacitance of 589.7 F g⁻¹ at 1 A g⁻¹, significantly surpassing that of MoSe₂. The VMS2//MnO₂ hybrid supercapacitor achieves a power density of 7.99 kW kg⁻¹ at an energy density of 48.33 Wh kg⁻¹, while a Sn-ion capacitor (Sn//VMS2/GF) delivers a specific capacity of 154.1 mAh g⁻¹, with a peak energy density of 141.8 Wh kg⁻¹, retaining 82.4% capacity over 4000 cycles. These results highlight VMS2 as a multifunctional electrode that bridges the EDL and pseudocapacitive storage modes for advanced hybrid energy devices.

The formation of methane hydrates is a promising route for safe and efficient natural gas storage, but slow nucleation kinetics and foaming from surfactant promoters hinder their practical use. To address these challenges, this study evaluates a new class of highly effective kinetic biopromoters synthesized from d-glucono-1,5-lactone and 11 amino acids (GDL+AA). Methane hydrate formation was investigated in high-pressure autoclaves under static and dynamic conditions, complemented by differential scanning calorimetry (DSC), visual observation, pelletization, stability testing, molecular dynamics, and quantum chemical simulations. GDL+AA compounds exhibited a pronounced promoting effect at low concentration (0.05 wt %), initiating hydrate formation in 19–25 min compared with 54 min for sodium dodecyl sulfate (SDS) and 45 min for the unmodified amino acids. Methane uptake reached 0.160 mol/mol, and water-to-hydrate conversion was 88–96% in high-pressure autoclave tests. DSC experiments confirmed higher hydrate formation onset temperature (−9 °C for GDL+Met vs SDS: −16 °C; Met: −16 °C) and higher water to hydrate conversion (99.3% for GDL+Met vs SDS: 70.0%; Met: 28.7%). Visual observations under static conditions corroborated accelerated hydrate growth. Molecular dynamics and quantum-chemical calculations elucidated the mechanism of action of the GDL+AA derivatives. No foaming occurred in the GDL+AA systems during formation or dissociation. Hydrate pellets from GDL+AA showed high density and mechanical strength and high methane retention stability for engineering applications. Chemical modification with gluconic acid significantly enhanced the kinetic performance compared with unmodified amino acids. The synthesis is water-based and mild and uses biocompatible, biodegradable materials, aligning with green chemistry principles. GDL+AA compounds are scalable, efficient, and environmentally sustainable promoters of solidified natural gas.

Direct cofiring of biomass in coal-fired power plants is a cost-effective strategy for decarbonization. This study systematically investigates the effects of biomass cofiring ratios (0–30%) and feeding methods (cofeeding vs separate feeding) in a 100 kW drop tube furnace, focusing on combustion, emissions, and ash behavior. Increasing the biomass ratio enhanced fuel burnout to a maximum of 98.5% and advanced ignition, but elongated the flame by shifting the flame center downward. A critical trade-off in pollutant control was identified: separate feeding created a pronounced air-staging effect, reducing NOx emissions by an average of approximately 25% compared to cofeeding. Conversely, cofeeding promoted in situ SO₂ capture by facilitating alkali-sulfur reactions; at a 30% ratio, cofeeding achieved a sulfur retention rate of 8.49%, which is nearly double that of separate feeding (4.63%), thereby verifying the dominant role of alkali-induced sulfur sequestration. While NOx emissions peaked at a 10% cofiring ratio before declining, biomass addition severely increased slagging risks, evidenced by a decrease in the ash softening temperature (ST) by over 150 °C (from 1494 to 1329 °C). This was attributed to the reaction of alkali metals (K, Na) with aluminosilicates to form low-melting-point minerals like K/Na-feldspar, leading to ash agglomeration. These findings provide crucial guidance for optimizing cofiring operations.