Sustainable Energy & Fuels最新文献

Hydrovoltaic devices generate power from the transfer of ambient thermal energy involved in water evaporation. To date, hydrovoltaic research has focused mainly on identifying and optimizing materials for use in high-performing devices. While progress has been made towards the real-world application of hydrovoltaic devices, questions remain regarding the specific mechanism of power generation and the overall role of ions. Herein, we demonstrate that ions play an integral role in the functioning of graphite-based hydrovoltaic devices, and the presence of ions is essential for hydrovoltaic power generation in devices with both connected and disconnected electrodes. Probing the performance of devices in a variety of protic, aprotic, and organic solvents, we show that hydrovoltaic devices cease generating power in non-ionic liquids but can be ‘activated’ through the introduction of ionic salts. Recognizing the key role played by ions in hydrovoltaic devices provides further insight into the mechanism of power generation and can help guide the development of devices in the future.

Design of highly active and durable electrocatalysts for CO₂ utilization and conversion into value-added chemicals in a green manner is central to addressing the global concerns of energy crisis and climate change for a sustainable future. Herein, we used rigorous first principles simulations to comprehensively screen and explore the CO₂ reduction activity of twelve different two-dimensional ordered double transition metal MXenes. Our results indicate that all twelve MXenes show metallic characteristics and can significantly activate CO₂ with strong binding energy (−1.60 to −2.40 eV). The van der Waals and solvation effects in general have little impact on the CO₂ binding energy; however, Hubbard correction is found to significantly influence the CO₂ binding on these catalysts. Electronic structure analysis reveals that charge redistribution from MXene catalysts to antibonding states of CO₂ results in strong hybridization between CO₂ orbitals and surface metal orbitals. The strong CO₂ binding is further confirmed by enhanced charge transfer (−1.17 to −1.65 |e⁻|) from MXenes to the adsorbed CO₂ molecule. Simulations based on free energy pathways show that Mo₂TaC₂ and Mo₂TiC₂ possess superior catalytic activity for conversion of CO₂ into methanol and methane with very low limiting potential values of −0.35 and −0.39 V, respectively, whereas Mo₂TaC₂ and Mo₂VC₂ were found to display excellent performance for ethanol formation with record low limiting potentials of −0.32 V and −0.42 V, respectively. Further, the MXene-based catalysts Mo₂TiC₂ and Mo₂VC₂ were found to be highly selective for CO₂ reduction to methane and ethanol respectively. Extensive analysis based on linear scaling relations between the adsorption free energy of different reaction intermediates and limiting potential values highlights that the adsorption free energy for *CO₂ and *OCHO intermediates plays a critical role in deciding the overall activity of the MXene catalysts. We believe that the above findings can be highly important for the design of MXene-based catalysts for CO₂ conversion.

Herein, the oxygen reduction reaction and oxygen evolution reaction (ORR/OER) kinetics of the inverse-spinel CuFe₂O₄ catalyst was enhanced via the addition of a very low quantity of RuO₂. It was found that minimal addition of RuO₂ resulted in an improvement in the limiting current density and onset potential, lower Tafel slope and good stability for the ORR/OER. Additionally, the CuFe₂O₄ cathode catalyst with the optimal RuO₂ content resulted in an outstanding Li–O₂ battery capacity of 14 250 mA h g⁻¹. Given that the presence of CO₂ poses a major challenge in achieving Li–air batteries at a practical level, the performance of the optimized catalyst under a strained Li–air condition and in pure CO₂ atmosphere (Li–CO₂ battery) was analyzed to understand its CO₂ tolerance and stability. It is crucial to understand the capability of the catalyst to decompose Li₂CO₃ formed as a stable discharge product from CO₂, which generally clogs the pores of the cathode catalyst. Thus, in situ impedance analysis and ex situ XRD technique were applied to decipher the fate of CO₂ in the reactions of Li–air/Li–CO₂ batteries. Moreover, stabilization to prevent the decomposition of the electrolyte was achieved in the presence of CO₂.

The construction of floating cities on the sea is an innovative solution for combating climate change and sea level rise. Ensuring the safe, long-term independent operation of floating cities is essential. In this paper, a self-sensing omnidirectional pendulum harvester is designed and tested, which consists of a wave energy harvester based on spherical gear (WEH-SG) and (long short-term memory) LSTM modules. The WEH-SG can provide power for floating cities by harvesting multi-directional waves. As a novel spatial meshing mechanism, the spherical gear (SG) can integrate the complex wave motion in any direction into a single direction, improving the efficiency of wave energy harvesting. Through the six degrees of freedom shaking table experiment with the prototype, it has been determined that the output performance of the WEH-SG is impacted by variables such as the wave frequency, amplitude, and internal size configuration of the prototype. The experimental findings indicate that WEH-SG can produce an output power of 32.23 mW at a wave frequency of 1 Hz and an amplitude of 30 mm. The WEH-SG's power generation efficiency is 253% of that of harvesting only unidirectional waves. The LSTM module collects and trains the system's generator signals and achieves 99.26% monitoring accuracy for environmental condition identification. Application scenario demonstrations were carried out to showcase the capability of WEH-SG to supply power to a digital temperature sensor. Combined with artificial intelligence and the Internet of Things, this system can provide sustainable, clean energy for floating cities and function as a sensor to monitor and warn about the state of the environment.

The escalating concentration of atmospheric CO₂, now exceeding 423.68 ppm and representing a 50% increase since pre-industrial times, underscores an urgent imperative to curb emissions. Scientists worldwide are actively investigating eco-friendly pathways to convert CO₂ into valuable carbon-based materials. Recently, the application of molten salts in CO₂ electro-conversion has garnered significant attention. In this overview, we meticulously detail the advancements in molten salt electrolysis technology for CO₂ capture and electro-transformation over the past decade. The mechanisms of CO₂ capture and conversion in molten salt are elucidated. Additionally, a detailed analysis of synthesis parameters for various carbon materials, including carbon nanotubes (CNTs), spherical carbon, graphene, and doped carbon is conducted. The applications of some carbon materials in clean energy storage and conversion are also expanded. Furthermore, the methods for the separation and purification of carbon products from molten salt are incorporated. Finally, we delve into the prospects and challenges of molten salt electrochemistry for CO₂ transformation, underlining its potential to drive a sustainable and environmentally friendly future.

Correction for ‘Enhancing organic solar cell lifetime through humidity control using BCF in PM6 : Y6 active layers’ by Kaike Pacheco et al., Sustainable Energy Fuels, 2024, https://doi.org/10.1039/D4SE00598H.

The high methane (CH₄) content of landfill gas, biogas, and coal bed methane (CBM) makes them attractive substitutes for natural gas. Nevertheless, the calorific value of the energy produced by burning as well as the overall effectiveness of energy gas use are both reduced in the presence of impurity gases, such as CO₂ and N₂. Thus, achieving the effective separation of CH₄ from CO₂ and N₂ is crucial for increasing energy efficiency, reducing the greenhouse effect, and achieving the dual-carbon aim. This is also the key to enriching and concentrating this kind of gas energy and using it efficiently. With a focus on the development of carbon-based materials, zeolite molecular sieves, and metal–organic frameworks in the field of CO₂/CH₄/N₂ separation in recent years, this paper primarily addresses the types of adsorbents, molecular simulation, and process optimization involved in the purification of CH₄ by variable pressure adsorption. Finally, the development bottlenecks and application prospects of different adsorbents in CH₄ purification applications are foreseen in conjunction with basic research and process evaluation.

Decarbonising chemical vectors used for transportation is a top priority for Europe to become carbon-neutral by 2050. Recent EU's Renewable Energy Directive (RED) emphasises the urgency of adopting renewable fuels and establishing a framework to promote and certify non-biological renewable fuels (RFNBO) and recycled carbon fuels (RCFs). The electrochemical reduction of CO₂ (CO₂ ER) technology emerges as a promising avenue for producing electro-methanol (e-MeOH), which could help defossilise key sectors, including transportation, and strengthen the circular economy. However, its ability to stand up to the established two-step catalytic hydrogenation process remains questioned. We delve into the technical potential of CO₂ ER for e-MeOH production, integrating a process model with a life cycle analysis. Our study identifies crucial advancements needed in product concentration (over 50% wt), faradaic efficiency (over 95%), and cell voltage (below 1.4 V). While the uncertainty assessment indicates that e-MeOH from CO₂ ER could significantly cut carbon emissions and fossil fuel consumption compared to traditional methods, further enhancements in key performance parameters (KPPs) are essential to match the performance of hydrogen-based e-MeOH.

A water-stable [Cu(pdc)(H₂O)₂] complex, promising functional mimics of hydrogenase active sites and promoting sustainable hydrogen production in acidic water, was designed and synthesised using an ONO-type pincer ligand, 2,6-pyridine dicarboxylic acid (pdc), and copper(II) nitrate. X-ray crystallographic analysis reveals that [Cu(pdc)(H₂O)₂] crystallizes in a triclinic crystal system with square pyramidal geometry. The complex shows an excellent faradaic efficiency of 91% with remarkable stability up to 60 equivalents of acetic acid (AcOH), relative to [Cu(pdc)(H₂O)₂]. Moreover, comprehensive spectroscopic, analytical, electrochemical, and computational analyses were performed to validate the proton-coupled electron transfer reaction. pdc coordinated with the Cu centre offers a delicate balance in shuttling syn-conformational proton coupling (H_pdc^δ+⋯H_Cu^δ−, 2.1 Å), promoting sustainable hydrogen production in water. Further, the scope of the electrocatalytic fate of [Cu(pdc)(H₂O)₂] towards industrial prospects was ensured by examining the electrocatalytic capacity of [Cu(pdc)(H₂O)₂] in 0.5 M H₂SO₄. The complex exhibits a significant elevation in cathodic current with H₂SO₄ in water collected from the Relli river (27.066668° N, 88.466667° E), Kalimpong, West Bengal, envisioning its true-catalytic capacity in pilot-scale application and real prospect for industrial use.

Electroreduction of CO₂ into fuels and valuable chemicals is an effective way to alleviate the greenhouse effect. However, CO₂ is chemically inert owing to the highly stable CO bond. Thus, CO₂ activation is recognized as a critical reaction step in the process. As electron transfer to CO₂ is commonly accepted as the key step during the activation of CO₂, it is crucial to engineer the electronic properties of catalysts to enhance their performance in the electrochemical reduction of CO₂. Herein, we prepared a CuGa₂ catalyst with oxygen vacancies (O–CuGa₂) to effectively improve product selectivity. O–CuGa₂ exhibited a current density of 32.9 mA cm⁻² with a faradaic efficiency of 82.6% for CO production in a tetrabutylammonium chloride/acetonitrile (Bu₄NCl/AN) electrolyte, which is 2.5 times higher than that exhibited by CuGa₂. XPS and EPR results indicated that O_V concentration in O–CuGa₂ is much larger than that in the CuGa₂ catalysts. The results of electrokinetic studies indicated that the introduction of O_Vs facilitate electron transfer to CO₂.