Sustainable Energy & Fuels最新文献

In this study, MgO/Mg(OH)₂ based adsorbents were prepared via freeze-drying and electrospinning techniques, and their CO₂ adsorption capacities were investigated. The synthesized adsorbents were characterized by XRD, N₂-Ads–Des, FESEM, XPS, and CO₂-TPD, while their CO₂ capture efficiency and mechanism were evaluated by TGA and FTIR spectroscopy, respectively. The adsorbent prepared via freeze-drying displayed nearly 6.2 wt% CO₂ adsorption at room temperature compared to only 5.4 wt% by the adsorbent prepared via electrospinning. This adsorbent's superior CO₂ capture capacity was attributed to the high basic strength of the active sites and the presence of a substantial amount of surface oxygen vacancies/defects. The adsorbent prepared via freeze-drying exhibited abundant surface basic sites, which led to enhanced CO₂ molecule interaction with the O²⁻ (strong sites), Mg–O pairs (medium sites), and OH group (weak sites) forming firmly fixed unidentate/monodentate, bidentate chelate and bidentate bridged carbonates, respectively. Although both physical and chemical adsorption coexisted in the process, the CO₂ adsorption was mainly presided over by the chemisorption sites. The high surface basicity of the adsorbents dominated BET surface area in governing the CO₂ capture capacity. For the first time in this research, the freeze-drying technique was applied to enlighten the facile, sustainable, and scalable synthesis of magnesium-based adsorbents for efficient CO₂ capture at room temperature.

Fructose is considered a key intermediate in the preparation of green energy chemicals, especially 5-hydroxymethylfurfural. Herein, we report the highest fructose production using glucose over a heterobimetallic metal–organic framework (MOF) catalyst. The catalyst was designed by employing tantalum and niobium species as combinatorial metal nodes that can offer favorable Lewis acid centers for glucose isomerization. To bridge the metal nodes, we introduced SO₃H groups by employing a conventional sulfuric acid treatment. It can also improve the catalytic activity through modulation of the Lewis/Brønsted acidic density and influence the catalyst's intrinsic characteristics that can be beneficial for the reaction. The Nb@S-Ta MOF catalyst comprising Ta, Nb and sulfur (S) species exhibited favorable microporous and acidic characteristics, and it afforded a maximum fructose yield (40%) and selectivity (73%) using glucose under microwave conditions within 7 min at 100 °C in a water medium. The conversion was determined to follow first-order kinetics (k_G = 3.82 × 10⁻⁵ s⁻¹) and was temperature-dependent (E_a = 39.99 kJ mol⁻¹). Furthermore, theoretical DFT modeling verified the favorable interaction between glucose and metal nodes towards isomerization (as sulfur bridges both Ta and Nb), with a binding energy E_B of −3.95 eV for Nb@S-Ta MOF + glucose. However, the catalyst exhibited a less fair durability for recycling, which was caused by extended leaching of Ta (up to 24% after the 4th cycle) and acidic centre's deactivation through possible humin deposition.

A novel strategy to increase laccase heterogeneous expression by Pichia pastoris was developed via exploring vanillin-sensitive promoters by culture of the yeast under vanillin stress followed by transcriptome analysis. Two endogenous promoters with significant response to vanillin were screened out with green fluorescent protein as a reporter protein. Subsequently, these promoters were combined with the laccase gene lacc 6 from Pleurotus ostreatus in single-promoter and double-promoter modes for enhancing laccase production. The laccase activity of the supernatant broth reached 285.7 U L⁻¹, being 18–60% higher than that of the control group. The enhancement of the laccase production was mainly ascribed to the increased transcription level of gene lacc 6 as revealed by transcriptome analysis. The recombinant yeast also could efficiently remove vanillin in the fermentation medium. Therefore, the strategy developed in this work could not only improve laccase production by Pichia pastoris, but also eliminate vanillin stress by the recombinant yeast. To improve the efficiency of laccase utilization and avoid the recovery and separation of laccase from the treated hydrolysate, a novel system was further developed based on the principle of a liquid flow fuel cell (LFFC), in which laccase was employed as a cathodic catalyst for the oxygen reduction reaction (ORR) with 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) as a mediator and Ag₂O as a anode catalyst. The LFFC system could well eliminate aldehyde stress factors thus improving the fermentability of dilute acid hydrolysate of biomass. This work thus can provide new ideas for boosting the efficiency of biomass bioconversion to produce biofuels and chemicals.

Ultra-thin SnO₂ films, fabricated at low temperatures, exhibit outstanding performance as electron transport layers (ETLs) in perovskite solar cells (PSCs). To better understand the electron transport characteristics of SnO₂ films, we investigated photovoltaic (PV) properties in relation to the film thickness and oxidation state of Sn. Herein, SnO₂ films were prepared by a novel two-step process: metallic Sn films were deposited using a sputtering technique, followed by heat treatment at various temperatures. This method offers facile control of the Sn oxidation state and prevents pinhole formation in the resulting SnO₂ films. We found that a SnO₂ ETL with a thickness of 15 nm provided the optimal power conversion efficiency (PCE), while increasing the thickness beyond 20 nm significantly decreased the PCE. Heat treatment temperatures were also varied during the conversion from Sn to SnO₂ films to control the oxidation states of Sn. An optimal PCE of 21.30% on average was achieved from the SnO₂ films heat-treated at 420 °C, whereas annealing at 470 and 520 °C resulted in relatively lower PCEs. X-ray photoelectron spectroscopy (XPS) analysis revealed that SnO₂ films heat-treated at 320, 370, 420, 470, and 520 °C contained 28%, 20%, 14%, 7%, and negligible levels of Sn²⁺, respectively. Hence, the presence of small amounts of Sn²⁺ and oxygen vacancies in ultra-thin SnO₂ films seems to have beneficial effects on PV performance, although they can also induce charge recombination. We also applied various photoelectrochemical analysis tools to analyze the electron transport and charge recombination properties of SnO₂ films prepared under different conditions.

The development of clean energy leads to a significant increase in decommissioned wind turbine blades, which have become a new type of solid waste. Glass fiber, which is the main component of these blades, can be recycled through pyrolysis. However, the deficiencies in size and mechanical properties of recycled glass fibers preclude their further high-value utilization. This paper presents an innovative approach to the high-value utilization of recycled glass fibers as Si and Al sources for the synthesis of Si–Al MCM-41 mesoporous molecular sieves by the alkali fusion–hydrothermal method. The influences of the templating agent ratio, water ratio, pH, hydrothermal temperature, and hydrothermal time on the synthesis of molecular sieves during the hydrothermal synthesis process were investigated. The results show that the MCM-41 molecular sieve synthesized under optimal conditions exhibited a uniform mesoporous structure, with a specific surface area of 831 m² g⁻¹ and a uniform distribution of Si and Al elements. Additionally, it exhibits an adsorption capacity of 223 mg g⁻¹ for alkaline pollutant rhodamine B. This research provides a viable path for the high-value utilization of recycled glass fibers and establishes a novel synthesis approach for MCM-41 with excellent adsorption performance.

A sustainable and smooth transition from fossil-fuel-based energy to a clean hydrogen economy requires affordable hydrogen storage and transportation solutions. Ammonia is a desirable hydrogen carrier option due to its high hydrogen content (17.6 wt%), being devoid of a carbon footprint, its ease of liquefaction (∼33.4 °C at 1 atm or 20 °C at 8.46 atm), and the century-old well-established infrastructure for the manufacture and transportation of NH₃. However, breaking the NH₃ bonds to regain the stored hydrogen requires catalysts for dehydrogenation of NH_x (x = 1–3) and then quick associative desorption of N from the active metal center under reaction conditions. This review highlights recent advancements in catalyst design strategies, performance, and challenges associated with understanding the intricate relationship between the catalyst structure and activity. Here, mechanisms of decomposition/oxidation of noble and transition metals are discussed, which provide a strong foundation for heterogeneous catalyst design in terms of charge transfer and the synergistic effects between active metal sites and supports. This evolves as a crucial factor for the reduction at decomposition temperatures. This review also emphasizes the recent development of homogeneous catalytic ammonia decomposition (AD)/oxidation (AO) at low temperatures (<100 °C) using a series of metal (M = Cr, Mn, Fe, Ni, Cu, Mo, Os and Ru) complexes. Its molecular reaction mechanisms and pathways to develop efficient catalysts have been discussed extensively.

Poly(vinylidenefluoride-trifluoroethylene) (P(VDF-TrFE)) commonly exhibits a very high degree of polarity in pristine condition. Still, highly piezoelectric inorganic fillers are incorporated into P(VDF-TrFE) to improve its piezoelectric energy harvesting performance and dielectric polarization. Here we incorporate a non-piezoelectric hydroxide filler, namely ZnSn(OH)₆ (ZS), into P(VDF-TrFE) and study the effect of this filler on the polarity and piezoelectricity of the resulting composite systems. The amount of polar phase of pristine P(VDF-TrFE) was observed to be as high as ∼88.5% which slightly increased to ∼91% for 1 wt% ZS loaded P(VDF-TrFE) and then abruptly decreased for higher amounts of filler loading. For the 10 wt% ZS loaded P(VDF-TrFE) the polar phase decreased to ∼56%. This result has been explained here on the basis of hydrogen bonding interaction which has been intentionally facilitated here through the use of a ZnSn(OH)₆ filler that contains a large number of –OH groups available for said interaction. The piezoelectricity of the composite films, as observed from PFM (Piezoresponse Force Microscopy) investigation, also showed a similar trend of variation of the piezoelectric properties of the composite films as compared to their polar phase. Owing to its high piezoelectricity, the 1 wt% ZS loaded P(VDF-TrFE) film was further used here for mechanical energy harvesting and different kinds of mechanosensing applications. The piezoelectric nanogenerator made up of this film delivered a high output power density (∼50 μW cm⁻²) with ∼83.5% efficiency.

Correction for ‘Multilayer Ti₃C₂T_x MXene electrode decorated with polypyridine for efficient symmetric supercapacitors’ by Peng Lin et al., Sustainable Energy Fuels, 2024, https://doi.org/10.1039/D4SE00892H.

Using a diverse heterogeneous nanocatalyst, aminolysis represents a promising approach for the chemical recycling of discarded PET waste bottles into a valuable monomer bis(2-hydroxyethyl) terephthalamide (BHETA). This study reports the solution combustion synthesis of a nanostructured Nb₂O₅ material for the catalytic aminolysis of PET waste bottles using ethanolamine. The Nb₂O₅ nanocatalyst calcined at 450 °C (Nb₂O₅-450) exhibited robust catalytic performance with a 92% isolated yield of the BHETA monomer and complete PET conversion under mild conditions compared with several homogeneous and heterogeneous catalysts. The Nb₂O₅-450 nanocatalyst has a unique morphology with both nanosheet and nanorod particles. The Nb₂O₅-450 nanocatalyst, possessing strong acid sites and more oxygen vacancies as estimated by NH₃-TPD and O 1s XPS analyses, respectively, induced electron deficiency in the carbonyl carbon of PET. This electron-deficient characteristic facilitated the aminolysis reaction, wherein ethanolamine attacked the carbonyl carbon, initiating the reaction toward the formation of BHETA. The purity and structure of BHETA were confirmed through NMR, FT-IR, TGA/DSC, and powder XRD techniques. The 1 wt% Nb₂O₅ catalyst exhibited reasonably good catalytic reusability for up to five cycles. The characterization of the Nb₂O₅-450 nanocatalyst before and after the reaction highlighted its structural stability, affirming the sustainable nature of the catalyst for valorizing PET waste into value-added monomers.

The incorporation of nanocellulose (NC) with cellulose derivatives, specifically hydroxypropyl methylcellulose (HPMC), hydroxypropyl cellulose (HPC), and hydroxyethyl cellulose (HEC), resulting in a solid polymer electrolyte (SPE). The impact of the hydroxyl group on these cellulose derivatives on the nano cellulose-based solid polymer electrolyte (SPE) was examined in terms of its physical characteristics and electrochemical efficiency. Molecular docking simulations were employed to examine the interaction between LiTFSI and hydroxyl groups in the polymer matrix, seeking to gain a greater understanding of the dissociation mechanism of LiTFSI and facilitate the mobility of the Li cation. The XPS and FTIR spectra prove that the HPMC/NC composite solid polymer electrolyte (SPE) polymer chain forms a novel interaction bond with the TFSI anion. Consequently, it enables simple transport of a large number of free Li⁺ ions, leading to a significant ionic conductivity of 1.05 × 10⁻³ S cm⁻¹. The lithium transfer number for the composite of HPMC, HPC, and HEC in NC composite was 0.59, 0.35, and 0.49, respectively. The HPMC/NC composite (4 V) exhibits a more excellent lithium battery potential range compared to HPC (2.5 V) and HEC (3 V) as identified through linear sweep voltammetry (LSV). The aforementioned discoveries suggest that the presence of a hydroxyl structure in the HPMC/NC composition led to the highest mechanical qualities and enhanced electrochemical performance. This indicates that the hydroxyl group in HPMC/NC can serve as a solid polymer electrolyte for lithium-ion batteries and effective energy storage.