Sustainable Energy & Fuels最新文献

Flexible perovskite solar cells (F-PSCs) are highly promising for harvesting solar energy in various environments, both indoors and outdoors. Nonetheless, one of the main hurdles to the widespread commercial use of F-PSCs is the thermal evaporation of the metal top electrode, a time-consuming process that substantially increases the cost related to both raw materials and fabrication equipment. Consequently, developing effective alternatives is essential for harnessing the full potential of this technology. One promising approach is to replace the top metal electrode with carbon-based materials, which can effectively serve as both the hole transport layer (HTL) and back electrode. These materials are low cost and compatible with inexpensive, simple, and scalable deposition techniques, such as blade coating. However, HTL-free carbon-based PSCs (C-PSCs) currently suffer from power conversion efficiency (PCE) lower than their metal counterparts, due to inefficient charge transfer and collection, associated with an ineffective perovskite (PVK) and carbon electrode interface. By utilizing a suitable HTL between the PVK and the carbon electrode, the charge extraction can be effectively improved and the interfacial recombination reduced. Throughout this work, a screening of suitable hole transport materials (HTMs) was carried out to select the most promising candidate to improve the performance of C-PSCs on flexible substrates. Copper(I) thiocyanate (CuSCN) was employed as the HTL with a wide band gap (3.5–3.8 eV). At the optimized concentration of 10 mg ml⁻¹, a PCE of 9.4% was achieved on 1 cm² flexible devices. The results obtained were compared with the performance of F-PSCs with gold top electrodes using organic PTAA as the HTL as state-of-the-art reference. The optimization of the HTL allowed for the demonstration of a significant improvement in the performance of the device, which could pave the way for the large-scale commercialization of PSCs with low environmental impact and promising cost-effectiveness.

Enhancing charge storage and balancing energy and power densities in a supercapacitor requires a hybrid approach. To this end, a material with high porosity, good crystalline stability, and an adjustable framework could be integrated with a 2D defect-containing material that has a large surface area. A hydrothermally synthesized Zn(II)-based coordination polymer, [Zn(IPA)₂(2-MI)₂]_n (MZ) [IPA: isophthalic acid, 2MI: 2-methylimidazole], and in situ fabricated heterocomposites with MZ anchored on graphene oxide (GO) and reduced graphene oxide (RGO) interlayer sheets are presented here. MZ and its heterocomposites were characterized using spectroscopic (SC-XRD for MZ, UV-visible, FT-IR, PXRD with Rietveld refinement, and XPS) and nanoscopic (FE-SEM with EDX, and HR-TEM) techniques to confirm their structural compositions. The topological underlying net of MZ shows the uninodal 2C1 net topology. The synergistic effect between MZ and GO/RGO delivered good supercapacitance (SC) properties. Three electrode-based electrochemical analysis (1 M KCl, 1 M KOH, 1 M Na₂SO₄) revealed that GMZ23 and RGMZ11 exhibited better performance in 1 M KCl aqueous electrolyte than MZ. Furthermore, symmetric (SSC) and asymmetric supercapacitor (ASC) devices were designed and tested. The RGMZ11 ASC device provided the specific capacitance (Sp. Cp.) of 154.53 F g⁻¹ (specific capacity-247.48 C g⁻¹), the energy density (E. D.) of 54.99 W h kg⁻¹, and the power density (P. D.) of 160 W kg⁻¹ at a 0.2 A g⁻¹ current density in 1 M TEABF₄ (DMSO) electrolyte. Up to 75% of the capacitance of RGMZ11 was retained after 10 000 charge–discharge cycles at a current density of 5 A g⁻¹. Moreover, the capacitive and diffusion-controlled processes were examined using the Dunn method and it was found that the optimized device follows a diffusion-controlled process at lower scan rate. The optimized RGMZ11 was successfully utilized to make a multi-color disco LED and a red LED glow. The above study suggests that the RGMZ11 heterocomposite shows good performance for SC applications.

Precursor structure engineering is a fundamental strategy for regulating the physicochemical properties of g-C₃N₄, which can promote the development of efficient photocatalysts. Herein, hexamethylenetetramine (HMTA) with a stable three-dimensional cage-like spatial configuration, was successfully incorporated into a melamine–cyanuric acid supramolecular complex via a hydrothermal method. Furthermore, a novel N-defect-rich porous g-C₃N₄ was obtained through thermal pyrolysis of this HMTA-regulated supramolecular precursor. The presence of N defects and the resulting midgap states which were proved to be induced by HMTA-regulated precursor structure engineering could effectively enhance the light absorption and promote the separation of photogenerated carriers of g-C₃N₄. As a result, the HMTA-regulated g-C₃N₄ exhibited an enhanced H₂-evolution activity of 2.77 mmol g⁻¹ h⁻¹, which was 5.8 times that of pristine g-C₃N₄. This work proposes a molecular-level structure engineering strategy of g-C₃N₄ by rationally incorporating functional molecules into the precursor, offering valuable insights for developing highly efficient photocatalysts.

Dye-sensitized photoelectrochemical cells (DS-PECs), devices inspired by photosynthesis, are being developed to advance the goal of using the sun as the sole source of energy for converting abundant resources to fuel and valuable chemicals. Herein, we report compact and vertically aligned titanium dioxide nanotubes grown through self-organized electrochemical anodization as semiconducting materials functionalized with a molecular copper(I) bis(diimine)-based acceptor–chromophore–donor to yield a photoanode capable of carrying out oxidative processes. The ability of these dye-sensitized photoanodes to drive oxidative processes is further confirmed photoelectrochemically through activation of a molecular iridium(III) water oxidation pre-catalyst where ultimately a Faradaic efficiency of 84% is found for O₂ production.

Microsilicon (μ-Si) anodes exhibit promising capacity and energy density as lithium-ion battery (LIB) anodes. However, their application is affected by large volume changes, surface pulverization, poor interfacial contact, and limited cyclic stability. Here, we report an integrated methodology to protect μ-Si particles by coating the particle surface and integrating the coated Si particles with a quasi-solid-state (gel) electrolyte to achieve high performance and long-term stability. High-resolution transmission electron microscopy and X-ray photoelectron spectroscopy showed that the μ-Si particles were successfully coated with a polydopamine (PD) layer via a wet-chemical process to achieve PD@Si. Moreover, a quasi-solid-state electrolyte composed of LiTFSI/N-methylacetamide deep eutectic solvents and acrylate monomers was optimized to accommodate the volume change endured by μ-Si based anode during cycling. The as-prepared quasi-solid-state electrolyte exhibited a high ionic conductivity (1.63 × 10⁻³ S cm⁻¹) at room temperature. Integrating PD@Si with the modified quasi-solid-state electrolyte delivered a superior stability upon cycling, maintaining a high specific capacity of 1000 mA h g⁻¹ in the quasi-solid-state electrolyte at a current density of 1 A g⁻¹ after 100 cycles in a half-cell battery. Furthermore, post-cycling analyses demonstrated that electrode cracking and delaminating were reduced with the co-utilization of coating and quasi-solid-state electrolyte. These results proved that μ-Si microparticle-based electrodes could be applied to high-energy quasi-solid-state batteries.

The quest to find an effective non-precious metal-based catalyst for the hydrogen evolution process has recently garnered widespread attention. Platinum (Pt) and other platinoids are the preferred catalyst for the hydrogen evolution reaction (HER). However, their widespread application is restricted by the scarcity of rare earth reserves and the consequent elevated costs. In this work, we synthesized a distinctive 1T/2H phase structure via a facile hydrothermal technique. Pristine MoSe₂ and Cu–MoSe₂ were deposited on a carbon cloth (CC) and were directly employed as electrodes in HERs, without the use of binders. The structures and basal planes of the as-prepared pristine MoSe₂@CC as well as 3% and 5%Cu–MoSe₂@CC samples were analysed via XRD, and their morphology was examined using field emission scanning electron microscopy (FESEM), revealing that each carbon fibre's surface was evenly covered with wrinkled nano petals in the shape of nanosheets. Elemental mapping using energy dispersive X-ray spectroscopy (EDX) revealed the coexistence of Cu, Mo, and Se, uniformly dispersed over the sample, and their corresponding energy states and binding energies were analysed using X-ray photoelectron spectroscopy (XPS). Findings indicated a substantial reduction in binding energy when copper was present on MoSe₂, which caused the metallic-semiconductor (1T/2H) phase to dominate. This meticulously developed architecture when coated on a carbon fibre substrate exhibited remarkable HER activity with a low onset potential of −113 mV vs. RHE (reversible hydrogen electrode), a Tafel slope of 87.2 mV per decade and excellent cycle stability of 80 h. In addition, density functional theory (DFT) studies conducted on the novel structure predicted that the introduction of Cu⁺ ions into the MoSe₂ monolayer can make interfacial semiconducting MoSe₂ transform into metallic MoSe₂. This transformation is beneficial for speeding up charge transfer between the interfaces, promoting H atom adsorption and desorption kinetics and thus accelerating sluggish HER kinetics, thereby enhancing its catalytic performance. In brief, the present findings provide experimental and theoretical insights into developing advanced functional catalysts using phase engineering for energy-conversion applications.

Enhanced Geothermal Systems (EGS) offer a promising solution to decarbonizing electricity grids by providing clean firm power. We use the BRIDGES gas-electric capacity expansion model – a multi-sector energy model that optimizes energy system investment, retirements, and hourly dispatch over multiple time horizons – to explore the techno-economic impacts of integrating EGS into California's electricity and gas end-use sectors. This least-cost model co-optimizes for system expansion to meet electricity and heating demands, subject to gradually decreasing emission targets to reach a net-zero economy in 2045. We evaluated multiple EGS-focused scenarios by varying drilling depth, seismic exclusion zones, and dispatch flexibility. This allowed us to determine the influence of these factors on system capacity, costs, and emission reductions. Results showed that allowing drilling depths up to 7 km yielded up to 82 GW of EGS capacity by 2045, reducing the total system capacity requirement by 40% and system costs by 8.6% compared to cases without EGS. Flexible EGS dispatch further decreased system costs by 12.3%, although it accelerated reservoir depletion in the long term. EGS also reduced reliance on power-to-gas systems and supported electrification of heating, decreasing the total power-to-gas capacity by 50% compared to cases without EGS. This study demonstrated that EGS could be a critical component in achieving California's 2045 net-zero emissions target, offering significant cost reductions and enhanced system reliability across both the electricity and gas sectors.

Shale oil involves high refinery costs, making it less attractive than conventional oil. Using shale oil for high-value hydrogen (H₂) production may be a solution. However, H₂ is currently generated as a passive by-product, or even used as a raw material to produce refined oil, during oil shale processing, and H₂ as the target product is not well understood. This study proposed a novel concept of full H₂ production from oil shale to boost its competitiveness and clean utilization. The conceptual route of the shale-to-hydrogen process was designed with six components. A model system was established to simulate and analyze the influence of multiple key operating parameters on H₂ production, and energy and exergy analyses were conducted. The results show that the proposed shale-to-hydrogen process can produce H₂ that is suitable for industrial applications. Meanwhile, a global carbon capture rate of 90.18% is achieved and the exhaust gas is in accordance with the emission standard. Within these specifications, the output of the shale-to-hydrogen process is 303.91 Nm³-H₂/t-shale, which meets the standard for industrial hydrogen, and the energy efficiency and exergy efficiency of the whole system are 53.08% and 31.51%, respectively. This study provides a promising technology choice for H₂ production and high-value utilization of oil shale.

There is a strong drive to use Li and Na metals as anode materials for lithium and sodium batteries due to their high specific energy. However, Li and Na metals are susceptible to dendrite growth and exhibit low melting points (180.5 °C for Li and 98 °C for Na). The low melting points can lead to internal short-circuits and catastrophic failure of the battery. Here, we show that batteries using Li and Na metal electrodes are short-circuiting internally when the melting points of these metals are reached. We demonstrated this with four different solid electrolytes in lithium and sodium batteries, using symmetric-, half-, and anode-free cells and through extensive impedance measurements and direct visualisation via operando digital microscopy. The temperature required to melt these metals in batteries is often reached under various operating conditions. In light of these facts, using Li and Na metals as electrodes in commercial batteries should be reconsidered.

Fluoride ion batteries using quaternary ammonium fluoride-based liquid electrolytes have recently demonstrated promising performance. While liquid electrolytes are desirable for their high ionic conductivity at room temperature, finding solvent-fluoride salt systems with both high solubility and stability has been challenging. In this study, we synthesize novel asymmetric anhydrous quaternary ammonium fluoride salts with varying structural bulkiness to reveal how structural variations influence chemical properties such as solubility, ionic conductivity, and stability. The new fluoride salt electrolytes were successfully employed in a half-cell with BiF₃ electrodes, achieving 80% of the 302 mA h g⁻¹ theoretical capacity. We find that increasing the size of the cation led to higher conductivities for fluoride salts in bis(2,2,2-trifluoroethyl) ether solution. However, we also observe a loss of thermostability with increasing cation size. Optimizing this trade-off between ionic conductivity and thermostability will likely be critical for the future development of quaternary ammonium fluoride electrolytes.