Frontiers in Energy最新文献

Carbon dioxide energy storage (CES) is an emerging compressed gas energy storage technology which offers high energy storage efficiency, flexibility in location, and low overall costs. This study focuses on a CES system that incorporates a high-temperature graded heat storage structure, utilizing multiple heat exchange working fluids. Unlike traditional CES systems that utilize a single thermal storage at low to medium temperatures, this system significantly optimizes the heat transfer performance of the system, thereby improving its cycle efficiency. Under typical design conditions, the round-trip efficiency of the system is found to be 76.4%, with an output power of 334 kW/(kg·s⁻¹) per unit mass flow rate, through mathematical modeling. Performance analysis shows that increasing the total pressure ratio, reducing the heat transfer temperature difference, improving the heat exchanger efficiency, and lowering the ambient temperature can enhance cycle efficiency. Additionally, this paper proposes a universal and theoretical CES thermodynamic intrinsic cycle construction method and performance prediction evaluation method for CES systems, providing a more standardized and accurate approach for optimizing CES system design.

Existing swirling combustion technology, which relies on faulty coal, is unable to meet deep peak shaving demands without auxiliary methods. This paper developed a deep peak regulation burner (DPRB) to achieve stable combustion at 15%–30% of the boiler’s rated load without auxiliary support. Gas-particle tests, industrial trials, and transient numerical simulations were conducted to evaluate the burner’s performance. At full rated load, the DPRB formed a central recirculation zone (RZ) with a length of 1.5d and a diameter of 0.58d (where d represents the outlet diameter). At 40%, 20%, and 15% rated loads, the RZ became annular, with diameters of 0.30d, 0.40d, and 0.39d, respectively, with a length of 1.0d. At 20% and 15% rated loads, the recirculation peak and the range of particle volume flux were comparable to those at 40% rated load. The prototype burner demonstrated that, without oil support, the gas temperature within 0 to 1.8 m from the primary air outlet remained below 609 °C, insufficient to ignite faulty coal. As the load rate increased from 20% to 30%, the prototype’s central region temperature remained low, with a maximum of 750 °C between 0 and 2.0 m. In contrast, the DPRB’s central region temperature reached 750 °C at around 0.65–0.70 m. At a 3%·min⁻¹ load-up rate, when the load increased from 20% to 30%, the prototype burner extinguished after 30 s. However, the DPRB maintained stable combustion throughout the process.

Enzymatic biofuel cells (EBFCs), which generate electricity through electrochemical reactions between metabolites and O₂/air, are considered a promising alternative power source for wearable and implantable bioelectronics. However, the main challenges facing EBFCs are the poor stability of enzymes and the low electron transfer efficiency between enzymes and electrodes. To enhance the efficiency of EBFCs, researchers have been focusing on the development of novel functional nanomaterials. This mini-review first introduces the working principles and types of EBFCs, highlighting the key roles of nanomaterials, such as enzyme immobilization and stabilization, promotion of electron transfer and catalytic activity. It then summarizes the recent advancements in their application in wearable and implantable devices. Finally, it explores future research direction and the potential of high-performance EBFCs for practical applications.

The development of anti-corrosion and anti-poison electrocatalysts for both the hydrogen oxidation reaction (HOR) and oxygen reduction reaction (ORR) is of great importance for effective applications of proton exchange membrane fuel cells (PEMFCs). In this study, a non-carbon supported catalyst, Pt/TiO₂-O_v, enriched with oxygen vacancies (O_v), is successfully synthesized using a microwave-assisted method. This catalyst is developed as a bifunctional electrocatalyst with superior contamination tolerance, enabling efficient HOR and ORR performance. The electronic metal-support interaction (EMSI) is leveraged to facilitate electron transfer between Pt and Ti atoms, induced by the formation of oxygen vacancy channels in the small-sized, high surface area TiO₂-O_v support. Notably, TiO₂-O_v has a lower bandgap than commercial TiO₂, enhancing its catalytic properties. In a 0.1 mol/L HClO₄ electrolyte, the normalized Pt mass activity (j_k,m) and specific activity (j_0,s) of Pt/TiO₂-O_v are 1.24 times higher than those of commercial Pt/C. Furthermore, Pt/TiO₂-O_v catalyst exhibits minimal current density decay after a prolonged durability testing under hydrogen and oxygen atmospheres. Remarkably, under a H₂/(1000×10⁻⁶) CO atmosphere, the relative retention rate of Pt/TiO₂-O_v significantly exceeds that of Pt/C catalyst, demonstrating its superior CO tolerance and promising potential for practical applications in PEMFCs. This study highlights the critical role of the strong metal-support interaction between the reducible oxide support and the noble metal Pt in improving long-term performance and CO poisoning resistance.

Aqueous zinc-ion batteries (AZIBs) are emerging as a promising option for next-generation energy storage due to their abundant resources, affordability, eco-friendliness, and high safety levels. Manganese-based cathode materials, in particular, have garnered significant attention because of their high theoretical capacity and cost-effectiveness. However, they still face substantial challenges related to rate performance and cycling stability. To address these issues, researchers have developed various strategies. This review focuses on the key advancements in manganese-based cathode materials for AZIBs in recent years. It begins with a detailed analysis of the energy storage mechanisms in manganese-based cathodes. Next, it introduces a variety of manganese-based oxides, highlighting their distinct crystal structures and morphologies. It also outlines optimization strategies, such as ion doping (both monovalent ions and multivalent ions), the preparation of Mn-based metal-organic frameworks (MOFs), carbon materials coatings, and electrolyte optimization. These strategies have significantly improved the electrochemical performance of manganese-based oxide cathodes. By systematically analyzing these advancements, it aims to provide guidance for the development of high-performance manganese-based cathodes. Finally, it discusses prospective research directions for manganese-based cathodes in AZIBs.

The photocatalytic efficiency of lead-free Bi-based halide perovskites, such as Cs₃Bi₂X₉ (X = Br, I) for CO₂ reduction is often hindered by self-aggregation and insufficient oxidation ability. In this work, a visible-light-driven (λ > 420 nm) Z-scheme heterojunction photocatalyst composed of 0D Cs₃Bi₂I₉ nanoparticles on 1D WO₃ nanorods for photocatalytic CO₂ reduction and water oxidation is synthesized using an in situ growing approach. The resulting 0D/1D Cs₃Bi₂I₉/WO₃ Z-scheme heterojunction photocatalyst exhibits a visible-light-driven photocatalytic CO₂ reduction performance for selective CO production, achieving a selectivity of 98.7% and a high rate of 16.5 (µmol/(g·h), approximately three times that of pristine Cs₃Bi₂I₉. Furthermore, it demonstrates decent stability in the gas-solid photocatalytic CO₂ reduction system. The improved performance of Cs₃Bi₂I₉/WO₃ is attributed to the formation of the 0D/1D Z-scheme heterojunction, which facilitates charge transfer, reduces charge recombination, and maintains the active sites of both 0D Cs₃Bi₂I₉ for CO₂ reduction and 1D WO₃ for water oxidation. This work provides valuable insights into the potential of morphological engineering and the design of simultaneous Z-scheme heterojunction for lead-free halide perovskites.

The extensive utilization of fossil fuels has led to a significant increase in carbon dioxide (CO₂) emissions, contributing to global warming and environmental pollution, which pose major threats to human survival. To mitigate these effects, many researchers are actively employing state-of-the-art technologies to convert CO₂ into valuable chemicals and fuels, thereby supporting sustainable development. However, few studies have employed bibliometric methods to systematically analyze research trends in CO₂ reduction reaction (CO₂RR), resulting in limited macroscopic insights into this field. This study aims to conduct a scientometric analysis of academic literature on electrocatalytic, photocatalytic, and thermocatalytic CO₂RR from 2015 to 2023. Utilizing bibliometric analysis tools Citespace, Bibliometrix, and Vosviewer for data visualization, it establishes a knowledge framework for catalytic CO₂RR. The results show that China, the United States, and India are the top three countries with the highest number of published papers in this field, with China and the United States having the highest levels of collaboration. The journal Applied Catalysis B-Environmental published the most articles and received the highest citation count, with 3.4% of the articles in this field appearing in the journal and a total of 62526 citations. Keyword analysis revealed that terms like “CO₂RR,” “CO₂,” “conversion,” and “reduction” are the most frequently occurring, indicating key areas of focus. Additionally, “selectivity” and “heterojunction” emerged as prominent research hotspots. The discussion section highlights the current challenges in the field and proposes potential strategies to address these obstacles, providing valuable insights for research in the field of catalytic CO₂RR.