Sustainable Energy & Fuels最新文献

Aqueous Zn-ion batteries (ZIBs) are promising alternatives to lithium-ion batteries because of their inherent safety, raw material abundance (e.g., 10 million metric tons of available zinc in India, and Australia is the second largest zinc producer), and cost-effectiveness. This study focuses on utilising redox-active organic materials with quinone moieties, namely, 5- and 6-nitro 2,3-dichloro 1,4-naphthoquinone (5-DCNNQ) and (6-DCNNQ), and their mixtures in a 3 : 1 ratio as cathode materials for aqueous ZIBs. Although the introduction of the nitro group reduced the solubility of the active material in the electrolyte, the isomer mixture DCNNQmix cathode, with the high voltage characteristic of 5-DCNNQ and the high capacity characteristic of 6-DCNNQ, exhibited a higher capacity and cyclability than either material. The battery retained its capacity even after 9600 charge–discharge cycles.

Visible light-driven water splitting to produce hydrogen (H₂) is a promising strategy for harnessing renewable solar energy for the sustainable production of green fuel. Consequently, the design of materials with optimal absorption of sunlight/visible light is therefore of great importance. In this context, covalent organic frameworks (COFs), designed by rational selection of organic building blocks, represent promising semiconducting materials for photocatalytic hydrogen generation, offering a potential alternative to achieve efficient water splitting for H₂ generation. Herein, we demonstrate the use of a donor–acceptor COF (ETTA-BT) with benzothiadiazole (BT) moieties as the strong electron acceptor for efficient photocatalytic hydrogen generation. Interestingly, under visible light irradiation (λ ≥ 420 nm), the ETTA-BT COF exhibited superior photocatalytic performance with an H₂ generation rate of 890 μmol g⁻¹ h⁻¹, which is very high as compared to ETTA-TP COF without such a donor–acceptor system. The improved catalytic performance of ETTA-BT over ETTA-TP COF has been attributed to the donor–acceptor phenomenon, which facilitates improved charge separation and migration through the “push–pull” effect. This work represents a demonstration of the application of a donor–acceptor COF for efficient and sustainable photocatalytic H₂ generation.

Replacing the alkyl side chains in 2,2′-((2Z,2′Z)-((4,4,9,9-tetrahexyl-4,9-dihydro-s-indaceno[1,2-b:5,6-b′]dithiophene-2,7-diyl)bis(methanylylidene))bis(3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile (IDIC) with polar diethylene glycol to form the hydrophilic acceptor 2,2′-((2Z,2′Z)-((4,4,9,9-tetrakis(2-(2-(2-methoxyethoxy)ethoxy)ethyl)-4,9-dihydro-s-indaceno[1,2-b:5,6-b′]dithiophene-2,7-diyl)bis(methaneylylidene))bis(3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile (IDIC-DEG) induced vertical phase separation (VPS) with the hydrophobic donor poly[(2,5-bis(2-hexyldecyloxy)phenylene)-alt-(5,6-difluoro-4,7-di(thiophen-2-yl)benzo[c]-thiadiazole)] (PPDT2FBT) due to surface energy differences, leading to IDIC-DEG accumulation near the ZnO bottom layer. The photoelectrochemical properties of PPDT2FBT : IDIC and PPDT2FBT : IDIC-DEG blends were studied and compared. The VPS in PPDT2FBT : IDIC-DEG optimized charge extraction in photoelectrochemical cells and stable ZnO/IDIC-DEG interface prevented delamination in water. The DEG side chain also increased the dielectric constant and water uptake, reducing charge transfer resistance, resulting in significantly improved photocurrent and photoanode stability.

Efficient electrocatalysts are anticipated to mitigate the high overpotential and slow kinetics of water splitting, which is a feasible way to produce hydrogen as an environmentally friendly renewable fuel. However, the development of low-cost catalysts with high activity and stability is still challenging. Herein, a Ni complex, [Ni(Me₃pyclen)(CH₃CN)₂](ClO₄)₂ (1), with a macrocyclic pyridine-triamine ligand was developed as an efficient molecular catalyst for electrocatalytic water oxidation, which occurred at an onset overpotential of only 520 mV and attained a high faradaic efficiency of 93% under neutral conditions. The single-site catalytic mechanism involving proton-coupled electron transfer (PCET) processes of both the Ni center and the ligand was proposed based on the electrochemical test results. Furthermore, comparative studies on the catalytic behaviors of 1 and its derivative all-amine coordinated Ni complex [Ni(12-TMC)(OAc)]PF₆ (2) illustrated that the stability of 1 was dependent on the hybridization form of the coordinated nitrogen atom, avoiding the decomposition of 2 into nickel-hydroxides during oxygen evolution. Therefore, the pyridine-triamine ligand shows its superiority in constructing a homogeneous electrochemical water oxidation system over the all-amine-based ligand.

Green energy carriers play a pivotal role in the transition towards the pervasive use of variable renewable electricity, as they allow for efficient storage, transportation, and utilization of excess electricity generated in specific regions and/or over different time frames. In this paper, we analyze the cost-optimality of transporting eight liquid or gaseous green energy carriers, including H₂, via pipelines and shipping, over distances from 250 to 3000 km. To provide a more comprehensive deployability evaluation beyond purely cost-based criteria, we introduce several novel concepts that allow comparing green energy carriers on the basis of safety, applicability, and end-use characteristics. Our study reveals that H₂ exhibits significantly higher costs compared to other energy carriers across both transportation modes. For a pipeline and shipping distance of 250 km, we calculate H₂ transportation costs of 1.4 and 8.1 m€ per PJ, respectively, while for alternative carriers costs range from 0.1 to 0.7 and 0.2 to 3.1 m€ per PJ. For a distance of 3000 km, H₂ transportation costs through pipeline and shipping are estimated at 18.6 and 10.3 m€ per PJ, respectively, whereas for alternative carriers the cost ranges from 1.2 to 7.6 and 0.3 to 4.0 m€ per PJ. An integration of additional selection criteria, however, implies that the practical deployability differs significantly across different green energy carriers, and that no one-to-one relationship exists between deployability and transportation costs.

Sustainable development of the energy storage market requires a gradual shift from lithium-ion batteries to other types of devices. While potassium-ion batteries attracted a lot of attention during the last decade, they are still far from real practical implementation, since basically all the cell components are not optimized. In particular, gel polymer electrolytes commonly used in advanced lithium batteries are very rare for their potassium analogs. The cost-effective and technologically very convenient approach to form quasi-solid polymer electrolytes in situ by polymerization of 1,3-dioxolane induced by the electrolyte salt (LiPF₆) is not applicable for potassium batteries since KPF₆ does not initiate the polymerization. Herein, we have addressed this challenge and proposed using NOPF₆ as an additive launching the dioxolane polymerization reaction resulting in electrolyte gelation directly within the cell. The first potassium batteries with a dioxolane-derived gel polymer electrolyte were fabricated and a spectacular enhancement in the battery cyclability upon addition of NOPF₆ has been demonstrated. Furthermore, a thorough investigation of the dioxolane polymerization reaction by GC-MS allowed us to identify a series of key intermediates and by-products and unravel important mechanistic details, such as the oxonium ion stabilization pathway and the nature of the formed terminal groups in the polymer chains. Both newly generated fundamental knowledge and the proposed self-solidifying electrolyte formulation are expected to be particularly valuable for the further development of advanced gel polymer electrolytes for different types of batteries.

The application of Direct Air Capture (DAC) for extracting CO₂ from the atmosphere has a great potential to reduce net CO₂ emissions and help achieve climate goals. Besides storing the separated CO₂, it can be used as a carbon feedstock for producing CO₂-neutral e-fuels, marking a critical research focus area. Despite advancements in various DAC technologies and processes, their large-scale implementation remains limited, among other reasons, because of the large amounts of energy required to power such processes. This article explores the utilization of DAC for water-conscious production of methanol in sunny regions, using cost-efficient photovoltaic power. The selected approach is presented, which involves a process on demonstrator scale with amine-based DAC for CO₂ and water separation from air, high-temperature electrolysis using solid oxide electrolysis cells (SOEC) for syngas production, and subsequent methanol synthesis. We also discuss alternative methods, potential locations, and implementation strategies, highlighting the advantages but also the challenges of producing green methanol in sunny regions outside Germany.

Realizing high-performance and long-life rechargeable zinc–air batteries (ZABs) requires developing efficient and robust bifunctional electrocatalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), as the low efficiency and short lifetime of bifunctional oxygen electrocatalysts greatly limit the practical application of rechargeable ZABs. Herein, based upon multi-component-dependent electrocatalytic activity and selectivity, we propose to synthesize a promising bifunctional oxygen electrocatalyst enriched with highly ORR-active atomically dispersed Fe–N_x sites and exceptionally efficient FeNi nanoparticles for the OER. Owing to this integration, the developed catalyst Ni₃@Fe-N-GNS exhibits a small potential gap for catalyzing both the ORR and OER, accordingly making it an ideal electrocatalyst for rechargeable Zn–air batteries. Impressively, when used as an air electrode, the corresponding ZAB exhibits a high peak power density of 171 mW cm⁻², a small charge–discharge voltage gap of 0.71 V at 5 mA cm⁻², and excellent charge–discharge cycling stability without much deviation after 180 h of a continuous run. The present work proposes a new avenue for the rational design of bifunctional electrocatalysts to make advances in electrochemical energy technologies.

The development of microalgal biorefineries, utilizing high-value coproducts, offers a strategy to lower biofuel production costs, while the use of saline-tolerant microalgal species contributes to reducing freshwater consumption. This study evaluates the life cycle performance of saline microalgae cultivation and conversion at a national scale by analyzing economics, greenhouse gas (GHG) emissions, marginal GHG avoidance cost (MAC), water scarcity footprints, land-use change emissions, and resource availability. The Algal Biomass Assessment Tool (BAT) is applied for site selection, while algae farm and conversion models are used for techno-economic analysis (TEA). The Greenhouse Gases, Regulated Emissions, and Energy use in Technologies (GREET) model is employed for life cycle assessment (LCA) by integrating the outputs from BAT and TEA. Our findings demonstrate that electricity and nutrient consumption are the primary drivers of base case GHG emissions, while biomass yield is the key factor determining both GHG emissions and economic performance. Saline microalgal biorefineries can achieve a MAC limit of $80–200/tonne when high-value bio-coproducts, such as whey protein concentrate, are benchmarked, contingent on supply-demand conditions and other market drivers. However, this reduction may not be compatible with current carbon prices. Further increase in biomass yield, reductions in energy and nutrient usage, and the careful selection of high-value protein coproduct targets with high conventional GHG emissions during the design stage are recommended. Additionally, saline microalgal biorefineries show great potential in addressing water stress, as the electricity requirements for desalinating brackish and saline water are relatively low compared to the overall system electricity demand.

The primary obstacles to addressing the current climate change problem include a rise in worldwide energy consumption, a restricted availability of fossil fuels, and the escalating carbon emissions associated with fossil fuels. Consequently, there is a pressing need to investigate sustainable alternatives to fossil fuels. Biorefineries present a potentially viable avenue for the sustainable production of fuel, as they employ a range of technologies to convert biomass into biofuels. This research aims to examine the cultivation of bacterial biomass and biodiesel production using a biorefinery approach. This process achieves a removal efficiency of 96, 93, and 98% for CO₂, SO_2, and NO, respectively, and a bacterial biomass of 274 g cultivated in a 20 L integrated bioreactor. The biomass entails extracting lipids (58% w/w) to generate biodiesel (91% w/w). The metabolic pathway followed by bacteria to reduce flue gas and produce lipids was analyzed to improve the production of lipids and biodiesel. A life cycle assessment was performed to assess the environmental impacts during the process. Implementing alternative and safe chemicals can potentially mitigate the adverse effects of processes and GWP100. The techno-economic analysis aimed to systematically examine the capital investment required to set up a bacterial biorefinery as compared to conventional fuel refineries. The findings indicated that the bacterial biorefinery had a net present value of $193 per litre of biodiesel produced. A bacterial biorefinery holds promise in fostering a circular economy characterized by sustainable practices and systems that aim to minimize waste, optimize resource utilization, and encourage the reuse and recycling of materials.