Sustainable Energy & Fuels最新文献

The manufacture of a novel type of gas diffusion electrode (GDE) for the electroreduction of CO_2, based on nanoporous anodic alumina gas diffusion layers (GDLs), is described. The GDE consists of an array of aligned pores hydrophobised via silanisation, on top of which a layer of a silver or copper catalyst was deposited. The versatility of the fabrication method allows for controlled pore apertures on both sides of the membrane and controlled thickness, further enabling the tailoring of the GDLs' properties to a given type of catalyst.

Single atom Fe sites, doped in CN materials, exhibit outstanding electrochemical activity for CO₂-to-CO conversion. The pyrolysis of ZIF8 is a controllable method for fabricating isolated single atom metal sites. In this study, we propose a new strategy to increase the ratio of Fe in ZIF8 precursors by synergistically replacing Zn²⁺ with Bi³⁺ and Fe³⁺. After precursor pyrolysis, the obtained Bi/Fe–N–C catalysts, consisting of Bi sites and pyrrole-type Fe–N_x sites, serve as efficient electrocatalysts for the CO₂RR. The results show that the optimized catalyst loaded with 94.8 mg per kg_Cat Fe exhibits a high FE_CO of >90.1% over a wide potential range of −0.4 to −0.7 V_RHE (98.2% at −0.5 V_RHE). Insights into the electrochemical reaction mechanism show that this successful design of Bi/Fe–N–C catalysts can provide a stable catalytic site to form *COOH, thus achieving energy-efficient electrochemical CO₂ reduction to CO.

Low-concentration CMM (coal mine methane) (CH₄ <30%) is mostly extracted during coal mining, which discharges directly into the air from mining shafts. Herein, recent advances in CH₄ recovery from coal mine gases are summarized. Among them, studies on the use of different adsorbents (activated carbon, zeolites, and metal–organic frameworks (MOFs)) and adsorption processes are extensively reviewed for use with low-concentration CMM. MOFs demonstrate superior performance due to their tunable pore geometries and customizable surface functionalization. These characteristics enable MOFs to achieve higher CH₄ selectivity than traditional activated carbon or zeolite adsorbents. Current research focuses on scaling up these advanced MOF materials and optimizing pressure swing adsorption (PSA) processes for industrial implementation. Compared to alternative separation technologies, such as membrane separation and cryogenic distillation, PSA exhibits distinct advantages for treating low-concentration CH₄ (1–30%). PSA demonstrates better performance in both product purity and recovery rates while maintaining higher technical and economic feasibility. Future research should focus on optimizing the PSA process and integrating it with other technologies. Such developments could provide economic incentives for the widespread adoption of CH₄ recovery systems in coal mining operations.

The modeling of underground hydrogen (H₂) storage (UHS) requires understanding the thermodynamics of H₂-containing gas mixtures as they approach local equilibrium during storage while subjected to temperature gradients and gravity segregation. Previous investigations using a model based on irreversible thermodynamics have shown the need for experimental measurements of hydrogen thermal diffusion in natural gas to better understand hydrogen composition versus depth during UHS. This work presents thermal diffusion measurements for H₂ in methane (CH₄) at varying temperatures and compositions. The effect on thermodynamic modeling is discussed, and the effect of other cushion gases such as carbon dioxide (CO₂) is also explored. For the H₂–CH₄ system, it was found that the thermal diffusion factor (α_T) increases as a function of composition and temperature, with values ranging from α_T = 0.22–0.36 for H₂ mole fractions ranging from x_H2 = 0.3−0.7. At a fixed composition of 50% H₂ and 50% CH₄, α_T ranged from 0.21 to 0.29 for a median temperature ranging from 250 K to 450 K. Using these values, a reference ideal gas enthalpy of 3.5 kJ mol⁻¹ for CH₄ while setting the reference ideal gas enthalpy of H₂ to 0 kJ mol⁻¹ is needed to properly match the model with the experimental observations at a constant median temperature. For experiments at varying median temperature, a correlation is needed between the enthalpy of the reference ideal gas of CH₄ and the departure of the median temperature from the reference state temperature to match adequately the model with the experimental values. The effect of adding these thermal considerations leads to a more homogeneous mix of H₂ with its cushion gas than previously anticipated. Further study of UHS operations could include the effects of shut-in time to determine gas purity during production cycles.

Herein, N, S co-doped carbon fibers encapsulating hollow Sb nanocrystals (h-Sb@NS-CNFs) were synthesized by a simple ion exchange and electrospinning process. The hollow Sb nanocrystals, in conjunction with the confinement effect of the carbon fibers, can offer faster Na⁺ pathways, decrease the Na⁺ diffusion barriers, and effectively mitigate the structural degradation of the electrode caused by the volume changes of Sb, thereby extending the cycle life of batteries. Additionally, the dual-element co-doping strategy employing nitrogen and sulfur provides more active sites for the Na⁺ reaction and increases the electronic conductivity while simultaneously enhancing the ionic diffusion kinetics, as indicated by density functional theory (DFT) and kinetic analysis. Therefore, h-Sb@NS-CNF exhibits excellent cyclic stability (305.3 mAh g⁻¹ at 2 A g⁻¹ for 900 cycles) and a high-rate capacity (209.3 mAh g⁻¹ at 10 A g⁻¹) as an anode material for sodium-ion batteries.

To advance the application of liquid organic hydrogen carriers (LOHCs) in flow batteries, the mechanism and performance of CoO/NF for the electrocatalytic hydrogenation (ECH) of quinoxaline—prepared by a low-melting-point ionic liquid electrodeposition method—are systematically investigated. The quinoxaline/tetrahydroquinoxaline conversion reaction catalyzed with CoO/NF results in superior ECH activity with low charge transfer impedance (1.624 ohm) and a Tafel slope of 103 mV dec⁻¹; the efficiency of quinoxaline conversion is 99.84%, and the selectivity of tetrahydroquinoxaline formation is 98.73%. The hydrogen in the hydrogenation reaction comes from water, and the active hydrogen atoms (H*) generated on the cobalt surface via the Volmer step are the key intermediates. The electrocatalyzed quinoxaline/tetrahydroquinoxaline reaction is an efficient system for hydrogen storage in flow batteries, providing a scientific basis for hydrogen energy storage and conversion in LOHC-based flow batteries.

Developing efficient and flexible ionic thermoelectric (i-TE) materials is essential for converting low-grade waste heat into usable electrical energy. In this study, we present a new biomimetic strategy for designing high-performance eutectogels that integrate a cesium chloride–ethylene glycol deep eutectic solvent (CsCl:EG DES) with a poly(vinyl alcohol) (PVA)–sodium hydroxide (NaOH) polymer matrix. The resulting CsCl:EG/PVA–NaOH eutectogel exhibits outstanding thermoelectric performance, achieving a record-high Seebeck coefficient of 1.65 mV K⁻¹ at 355 K, significantly surpassing previously reported PVA/NaOH hydrogels and marking the first successful demonstration of thermoelectric operation in the CsCl–EG system. Comprehensive structural and morphological characterization using FTIR, SEM, and EDX confirms the formation of a robust, well-developed bicontinuous network in which CsCl:EG domains are uniformly distributed within the crosslinked PVA matrix. This architecture enables p-type thermoelectric behavior, where directional ionic transport of Na⁺, Cs⁺, Cl⁻, and OH⁻ ions through interconnected percolation pathways is driven by a thermal gradient. Complementary molecular dynamics simulations (GROMACS) further validate the experimental findings, predicting a Seebeck coefficient of 2.06 mV K⁻¹ within the 298–358 K range. The simulations elucidate that the strong hydrogen-bonding network and the presence of multiple mobile ion species facilitate efficient thermodiffusion while maintaining low phonon transport. The synergistic combination of engineered ionic migration channels and phonon-scattering interfaces yields an optimal balance between a high Seebeck coefficient and low thermal conductivity. These features make the CsCl:EG/PVA–NaOH eutectogel a promising candidate for flexible, sustainable thermoelectric devices capable of harvesting low-grade waste heat under ambient conditions.

High-quality silver nanowires (Ag-NWs) with diameters below 200 nm were successfully deposited on glass substrates using a facile spray coating technique, forming transparent conductive electrodes (TCEs) for use in perovskite solar cells (PSCs). The impact of film thickness on the structural purity, surface morphology, optical behavior, and electrical transport properties of the Ag-NW films was thoroughly examined using advanced characterization techniques, including XRD, XPS, FE-SEM, FIB, AFM, UV-visible-NIR spectroscopy, Hall effect analysis, and four-probe resistance studies. The FE-SEM and FIB analyses revealed that the Ag-NWs possessed diameters ranging from 42 to 180 nm and lengths from 2.01 µm to 2.5 µm. Notably, the Ag-3 NW film demonstrated enhanced optical and electrical transport characteristics, achieving an exceptional figure of merit (45.02 × 10⁻⁴ Ω⁻¹) and low sheet resistance (18.1 Ω □⁻¹). The PSC devices incorporating the Ag-NW electrodes exhibited a remarkable efficiency of 11.6%, highlighting their potential for next-generation solar energy applications. Hence, the results obtained confirm the viability of Ag-NW thin films in advancing PSC technology.

This study presents a detailed investigation into the photocatalytic properties of facet-engineered bismuth oxybromide (BiOBr) using the pattern illumination time-resolved phase microscopy (PI-PM) technique. BiOBr, recognized for its excellent visible-light photocatalytic capabilities, was synthesized with controlled facet exposure to enhance its reactivity and efficiency in degrading organic pollutants. The experimental focus was on assessing the facet-dependent behavior of photo-excited charge carriers within BiOBr under various scavenger conditions. The PI-PM method allowed for the direct imaging of dynamic charge carrier processes at the microscale, offering information on the active charge carrier types (electrons and holes) on the photocatalyst surface. Detailed analyses when exposed to scavengers revealed distinct behaviors across different facets (001, 010, and 102). Key findings include the identification of dominant charge carriers responsible for the enhanced photocatalytic activity of different facets. For instance, the (010) facet showed a pronounced reactivity of holes, whereas the (102) facet was predominantly active via electron-mediated processes. This facet-specific activity underlines the importance of surface properties in optimizing photocatalytic efficiency. Through the application of PI-PM, this research not only provides a deeper understanding of the mechanistic pathways in photocatalysis but also demonstrates the critical role of surface facets in determining the overall performance of BiOBr as a photocatalyst.

H₂ generation via water splitting and CO₂ conversion to value-added chemicals are two key reactions that have immense importance for deep decarbonization. Being energy-intensive processes, water splitting and CO₂ conversion are often carried out in the presence of catalysts. Electrocatalysis, photocatalysis and thermocatalysis are three major catalytic conversion pathways for such conversions. To boost the energy efficiency of the catalytic conversions, the role of an external magnetic field (as an external physical force) has been explained in detail in this review. Fundamentals of water splitting and CO₂ conversion, the underlying mechanism in the presence of a magnetic field, and the role of different types of magnetic fields and their effect on the chemical conversion and energy efficiency of the mentioned processes have been elaborated in this article. In conclusion, the future scope to utilize the present magnetic field-based green process at a large scale has been discussed elaborately.