Sustainable Energy & Fuels最新文献

Redox flow batteries (RFBs) are promising energy storage systems to support renewable energy sources and overcome the limitations imposed by their intermittent and unpredictable nature. As a developing technology, the cost of key components, namely the membrane, electrolyte, and electrodes, present a major hurdle to widespread integration. This work describes the performance of non-woven carbon fiber (NWCF) electrodes derived from low-cost petroleum pitch and produced using a scalable, inexpensive melt-blowing process. Compared to commercial polyacrylonitrile (PAN)-based carbon fiber felt, pitch-based carbon fibers have increased graphitic content, tensile strength, and electrical conductivity. Greenhouse gas emissions for pitch-based carbon fibers are estimated to be significantly lower than that of PAN-based carbon fibers. When RFBs with unoptimized NWCF electrodes are evaluated in zinc iodide electrolytes, the voltage and power density (83 mW cm⁻²) are slightly lower compared to RFBs with PAN-derived carbon felts (104 mW cm⁻²) @ 100 mA cm⁻². RFBs fabricated with oxidized low-cost NWCF electrodes show nearly identical battery performance to those prepared with commercial PAN-derived carbon felts in vanadium electrolytes (peak power density of 137 mW cm⁻²vs. 139 mW cm⁻², respectively). Because of their low-cost precursor and cheaper processing methods, NWCF electrodes offer a promising solution to reducing the cost of RFB electrode materials, and with further optimization, these electrodes will likely result in improved battery performance.

The desire to meet energy demands drives us to develop environment-friendly, renewable, and sustainable energy sources. In this study, a catechin (tea dye)-adsorbed cellulose paper-based triboelectric nanogenerator (TAC-TENG) is suggested as an alternative solution. The material employed is tea dust extract incorporated cellulose paper, which are inexpensive, readily available, and eco-friendly. Triboelectric nanogenerator is an electrical energy-harvesting technology, capable of harvesting any kind of low-frequency mechanical energy as an energy source for powering small electronic devices. The proposed TAC-TENG could directly power up 12 white LEDs and store up to 2.08 μJ with a 1 μF capacitor in 80 s. A better performance was displayed by the tea dye-adsorbed cellulose paper than the pristine one. Thus, the proposed TENG could become more relevant and may have a vivid impact in the nearest future. The proposed TAC-TENG could be employed in self-powered portable and wearable small electronic devices.

Perovskite solar cells (PSCs) have achieved high power conversion efficiencies (PCEs). However, surface defects present a major challenge to further improving their performance. Fluorine-substituted materials have been widely utilized to passivate surface defects and improve the photovoltaic performance and stability of PSCs. In this study, post-treatment of the methylamine-lead iodide (MAPbI₃) perovskite surface was performed using 4-fluoroaniline trifluoroacetate (P-F-PMATFA), and the surface defects of the perovskite were passivated via an F atom, which reduced the energy barrier between the perovskite film (PVK) and hole transport layer (HTL). Consequently, the PCE of P-F-PMATFA treated solar cells based on the MAPbI₃ perovskite increased from 19.19 to 21.01% with low open-circuit voltage (V_OC) loss (0.44 V). Further, P-F-PMATFA treated perovskite devices exhibited long-term stability, owing to the higher hydrophobicity of fluorinated materials. The post-treatment strategy demonstrated in this study shows wide application potential in the field of photovoltaic devices owing to its ability to passivate surface defects and improve material stability.

The development of H₂ production technology through formic acid dehydrogenation (FADH), a liquid organic hydrogen carrier, has attracted considerable attention for hydrogen energy utilization. Catalysts play a vital role in FADH. Therefore, it is essential to understand the reaction mechanism and to develop efficient catalysts. Traditionally, theoretical calculations and kinetic isotope effects have been used to analyze the reaction mechanisms; however, achieving accurate kinetic analysis has remained challenging. In response, we devised an analytical method using in situ UV-vis spectroscopy for the kinetic analysis of FADH. The evaluation of the initial hydride formation and H₂ evolution rates from dynamic changes observed by in situ UV-vis spectroscopic analysis using a charge coupled device array detector on a millisecond scale suggested the necessity of improving both steps for designing highly active catalysts.

The chemical structure of L-alanine is similar to that of L-lactic acid and its polymerisation product, poly(L-alanine) (poly-L-Ala), is a biodegradable nylon. There is a need for a method capable of synthesizing L-alanine, a monomer of poly-L-Ala, from a biobased material with a renewable energy source. In this work, visible-light driven L-alanine from biobased material pyruvate and ammonium ions with a system consisting of triethanolamine, water-soluble zinc porphyrin, pentamethylcyclopentadienyl coordinated rhodium complex, NAD⁺ and L-alanine dehydrogenase from Bacillus subtilis is established. In particular, the conversion yield for pyruvate to L-alanine was improved up to 100% in this system after 24 h irradiation.

The bolaform surfactant C₆H₁₃-N⁺(CH₃)₂-C₆H₁₂-N⁺(CH₃)₂-C₆H₁₂-O-C₆H₄-C₆H₄-O-C₆H₁₂-N⁺(CH₃)₂-C₆H₁₂-N⁺(CH₃)₂-C₆H₁₃ (BC_PH-6-6-6) was synthesized and used to guide the synthesis of hierarchical ZSM-5 nanosheets (HZN) for use as zeolite catalysts. The number of acidic sites and the Al distribution in the zeolite pores were varied by changing the amounts of sodium sulfate and Al in the initial gel. The X-ray diffraction, Fourier transform infrared spectroscopy, scanning electronic microscopy, NH₃ temperature programmed desorption, ²⁷Al magic angle spinning nuclear magnetic resonance spectroscopy and N₂ adsorption/desorption were used to characterize these materials. These zeolites each had a well-developed hierarchical system and specific surface areas as high as 631 m² g⁻¹, indicating that the BC_PH-6-6-6 formed lamellar micelles based on π–π stacking. Interconnected hierarchical pore structures were retained after the templating agent was removed. The HZN sample exhibited a 90° rotational intergrowth structure and retained a large number of lamellae. The same material had a high concentration of acidic sites and contained Al in a tetrahedral coordination framework. The catalytic cracking of oleic acid using this zeolite gave light olefin yields up to 52.2% at 500 °C, exceeding the performance of conventional ZSM-5 (38.9%), and the catalyst remained active for up to 60 h. At 450 °C, the BTX selectivity of 6.72% obtained with this material also exceeded that from the conventional ZSM-5. These results were attributed to the connected hierarchical pores of the HZN, which promoted diffusion and provided higher carbon resistance.

This work investigates the application of liquid phase exfoliated Mo-based transition metal dichalcogenide (TMDC) two-dimensional (2D) nanosheets integrated with multi-walled carbon nanotubes (MWCNTs) as a novel electrode material for high-performance supercapacitors. The structural, functional, and morphological analyses were performed by XRD, FESEM, XPS, and Raman spectroscopy, which augmented the successful formation of TMDC nanosheets and their nanocomposites with MWCNTs. Structural and morphological characterization studies revealed the successful synthesis of the 2D nanosheets and their intimate integration with the MWCNTs, forming a porous network. Raman spectra confirmed the presence of vibrational bands for TMDC nanosheets (A_1g and E_2g) and their nanocomposites with MWCNTs (D and G bands). The optical characterisation studies (UV and PL) confirmed the exfoliation of TMDC nanosheets with band gaps of 1.87 eV and 1.67 eV for MoS₂ and MoSe₂, respectively. From the electrochemical characterisation studies, the values of specific capacitance were found to be 3338.29 F g⁻¹ and 2776.59 F g⁻¹ for MoS₂/MWCNT and MoSe₂/MWCNT electrodes with energy densities of 102.42 W h kg⁻¹ and 85.18 W h kg⁻¹, respectively. These nanocomposites retained 84% of the initial specific capacitance over 4000 repeated charge/discharge cycles. These nanocomposites may be used as potential materials for the fabrication of next generation devices for energy storage.

To improve its photoelectrocatalytic water oxidation properties, the BiVO₄ photoanode was integrated with TiO₂ modified by Indoline D102 dye and copper(II) meso-tetra(4-carboxyphenyl)porphyrin (CuTCPP). The dye was used as a redox mediator, whereas CuTCPP served as a co-catalyst for light-driven water oxidation. The systematic modifications on photoanodes were meticulously characterized by SEM, XRD, UV-Vis spectrometry, and potentiostatic analyses. Modification of the BiVO₄ photoanode with TiO₂ followed by D102 and CuTCPP (BiVO₄/TiO₂/D102-CuTCPP) demonstrates a remarkable improvement in photoelectrocatalytic water oxidation properties compared to those of the unmodified BiVO₄ film. An increase of power density up to 20 fold was observed under 100 mW cm⁻² light irradiation at a bias potential of 1.27 V_RHE. The system also demonstrated good stability, with a photocurrent retention of around 97% of the initial photocurrent over a 20 minutes period and retaining 69% of its initial value after 2 hours of continuous operation. Furthermore, the photoelectrocatalytic water splitting exhibited a high faradaic efficiency of oxygen evolution at approximately 97%. These excellent performances were attributed to the synergy of dye and co-catalyst co-assembly by forming a cascade hole transfer mechanism which improves the water oxidation kinetics and reduces the electron–hole recombination rate of BiVO₄ in the photoanode system.

The sustainability of aluminum electrolysis spent cathode carbon (SCC) is currently an urgent environmental issue that needs to be addressed. In this work, fluorine doped carbon aerogels (SCC-FCAs) were prepared by a series of auxiliary purification methods using the graphite phase and fluoride salt phase of SCC in aluminum electrolysis. The obtained SCC-FCAs were used for electrocatalytic synthesis of H₂O₂ and their performance was evaluated. The experimental results showed that the selectivity of SCC-FCA-500 (heat treatment at 500 °C) reached 87.2%, and the highest yield could reach 900.1 mmol g⁻¹ h⁻¹. The density functional theory calculation results showed that the covalent C–F bond model has weaker adsorption capacity for *OOH than the semi-ionic C–F bond. In addition, the intersite of the semi-ionic C–F in SCC-FCA-500 is the active site for the adsorption of the intermediate *OOH. This work proposed a self-synthesis strategy of using SCC from aluminum electrolysis, which provided a case for the high-value utilization of SCC in the direction of new energy resources.

This paper analyzes the substitution of conventional fuels with hydrogen-rich fuel derived from ammonia for two different types of container ships, focusing on technical, environmental, and economic perspectives. Four operation modes are investigated including marine diesel oil (MDO), dual-fuel (50 : 50 and 25 : 75 percentages of MDO : H₂-rich fuel) and pure H₂-rich fuel. The environmental impact of using H₂-rich fuel is assessed based on the tank-to-wake and well-to-wake CO₂-equivalent emissions, considering different ammonia production pathways. The results reveal that all the alternative modes exhibit decreased tank-to-wake emissions compared to MDO. The minimum reduction percentage is related to the 50 : 50 mode at about 44%, and an average well-to-wake reduction of 3.5 and 6.3 g per t NM is achievable by using blue and green ammonia, respectively. Moreover, to avoid any increase in the total costs of alternative modes compared to the reference mode, the future ammonia fuel price should be less than 384 $ per t. The research demonstrates that H₂-rich fuel is a viable alternative fuel for container ships, providing notable environmental benefits. While initial costs are higher, long-term economic advantages can be achieved through carbon pricing.