DeCarbon最新文献

Microplastics (MPs) and nanoplastics (NPs) pose a significant threat to human health due to their slow degradation, high toxicity, and potential to react with organic pollutants, forming even more hazardous substances. However, traditional methods for removing MPs/NPs have limitations. Nanomaterials are extensively utilized in water treatment for their easily modifiable properties and ability to effectively bind to contaminants. This review critically examines various nanomaterials employed as adsorbents, catalysts, and membranes for the removal of MPs and NPs. By delving into the sources of these pollutants, we aim to encourage further research focusing on source reduction. Furthermore, key areas for potential future research directions are highlighted.

It is hypothesized and demonstrated that thermal insulation membranes can provide an effective barrier to heat flow and simultaneously facilitate effective CO₂ diffusion. Decarbonization technology often requires a CO₂ concentration system, often based on amine binding or lime reaction, which is energy intensive and carries a high carbon footprint. Alternatively, C2CNT electrolytic molten carbonate decarbonization does not require CO₂ pre-concentration and also provides a useful product (graphene nanocarbons) from the captured CO₂.

Here, a method of effective CO₂ diffusion is demonstrated that simultaneously thermally insulates the decarbonization source gas from the high-temperature C2CNT system. Open pore, low-density, thermal insulations are implemented as membranes that facilitate effective CO₂ diffusion for high-temperature decarbonization. Selected, high-temperature, strongly thermal insulating, silica composites are measured with porosities, $\epsilon$, exceeding 0.9 (>90% porosity), and which display, as measured by SEM, large open channels facilitating CO₂ diffusion. A derived and experimentally verified estimate for the CO₂ diffusion constant through these membranes is D_M-porous ​= ​${\epsilon }^{3/2}$ D_CO2, where D_CO2 is the diffusion constant in air. D_M-porous is applicable to a wide-range of CO₂ concentrations both in the air and N₂.

The CO₂ diffusion constant is translated to the equivalent decarbonization system mole influx of CO₂ and shown capable of sustaining high rates of CO₂ removal. Combined with the strong electrolyte affinity for CO₂ compared to N₂, O₂, or H₂O, the system comprises a framework for decarbonization without pre-concentration of CO₂.

Within the framework of achieving global carbon neutrality, utilizing electrocatalytic water splitting to produce “green hydrogen” holds significant promise as an effective solution. The strategic development of economic, efficient, and robust anode oxygen evolution reaction (OER) catalysts is one of the imminent bottlenecks for scalable application of electrolyzing water into hydrogen and oxygen, particularly under actual yet harsh operating conditions such as large current density (LCD). In this review, we intend to summarize the advances and challenges in the understanding of the electrocatalytic OER at LCD. Initially, the impact of LCD on the electron transfer, mass transportation efficiency and catalyst stability is identified and summarized. Furthermore, five basic principles for catalyst design, namely the dimension of the materials, surface chemistry, creation of electron transfer pathways, synergy among nano-, micro-, and macroscale structures, and catalyst-support interaction, are systematically discussed. Specifically, the correlation between the synergistic function of the multiscale structures and the catalyst-support interaction is highlighted to direct improvements in catalyst efficiency and durability at the LCD. Finally, an outlook is prospected to further our understanding of these topics and provide related researchers with potential research areas.

Nanostructured tubes hold great potential for enhancing heat transfer in refrigeration/heat pump systems. Therefore, it is essential to study the effects of nanostructured surface characteristics on refrigerant boiling heat transfer. In this paper, the nucleation boiling behavior of CO₂ on the nanostructured surface is simulated using molecular dynamics. The effect mechanism of nanostructure size and surface wettability on CO₂ bubbles nucleation and growth is investigated. At first, the nucleation boiling processes of both smooth surfaces and nanostructured surfaces featuring three different wide grooves are simulated. The results show that the local thermal aggregation effect is the key for nanostructures to promote CO₂ bubble nucleation. The bubble nucleation efficiency is highest on the nanostructured surface with 5 ​nm wide groove. Then, based on a 5 ​nm wide nanostructured wall surface, the wettability effect on nucleation boiling is investigated by adjusting the potential energy factor α. The results show that the hydrophilic walls enhance the solid-liquid heat transfer and the collision of atoms within the liquid, resulting in boiling heat transfer capacity improvement between CO₂ and the walls. The average temperature, average heat flux and critical heat flux in the liquid phase are also improved. A significant temperature gradient between the layers of CO₂ liquid is noted on hydrophilic wall, where intermolecular forces and molecular advection dominate the heat transfer mechanism. In contrast, on hydrophobic wall, intermolecular forces dominate the heat transfer process.

Triboelectric Nanogenerator (TENG), which couples the contact electrification (CE) and electrostatic induction effects, provides a promising route to efficiently harvest energy from droplets.

Despite the seemingly modest energy derived from individual droplet, its widespread and abundant nature across diverse scenarios, including rainfalls, misty environments, water-logged and altitude variations ground, presents significant untapped energy potential. This underscores the practical importance of harvesting droplet energy as a vital component in fulfilling the demand for sustainable energy. Herein, we delve into the recent advancements in droplet energy harvesting using TENG. Initially, the electric double layer (EDL) of droplet-based TENGs is discussed in-depth, including the “two-step” formation process of EDL, as well as the sources and influencing factors of electrostatic charges on solid surface. Subsequently, three common work modes of droplet-based TENGs are introduced, and the energy harvesting process and the maximum efficiency of DEG which possess the droplet-characteristic feature are detailed description. Additionally, the performance and advantages of droplet-based TENGs are outlined, followed by a summary of strategies aimed at enhancing the output performance of droplet-based TENGs. Finally, potential applications and future prospects of droplet-based TENGs are discussed, that are essential for propelling the advancement in the field of droplet energy harvesting via TENG.

The determination of bubble size distribution is a prerequisite for the study of gas-liquid two-phase flow characteristics in electrolytic cells. Here the departure diameter of hydrogen bubbles and oxygen bubbles and their detachment process from a nickel wire electrode during water electrolysis are studied using high-speed photography. The results show that in industrial alkaline environment, the departure diameters of most hydrogen bubbles and oxygen bubbles are generally smaller than 60 ​μm and 250 ​μm with the current density ranges from 0.15 to 0.35 ​A/cm². The adhesion force of hydrogen bubbles on a nickel wire is found to be so weak that they can separate with a tiny size. The diameters of oxygen bubbles conform to normal distribution, and its distribution range widens with the increase of current density. The theoretical analysis show that the comprehensive conversion rate of current-to-bubble is unexpectedly low especially at low current densities, which may be attributed to the loss of gas components caused by bubble detachment mode. The majority of oxygen bubbles detach by a sudden bounce after coalescence, which may bring strong disturbance to the concentration boundary layer. This also indicates the coalescence-induced bubble departure mode may occupy a dominant position in the electrolyzers.

Phase change materials (PCMs) are widely considered as promising energy storage materials for solar/electro-thermal energy storage. Nevertheless, the inherent low thermal/electrical conductivities of most PCMs limit their energy conversion efficiencies, hindering their practical applications. Herein, we fabricate a highly thermally/electrically conductive solid-solid phase change composite (PCC) enabled by forming aligned graphite networks through pressing the mixture of the trimethylolethane and porous expanded graphite (EG). Experiments indicate that both the thermal and electrical conductivities of the PCC increase with increasing mass proportion of the EG because the aligned graphite networks establish highly conductive pathways. Meanwhile, the PCC4 sample with the EG proportion of 20 ​wt% can achieve a high thermal conductivity of 12.82 ​± ​0.38 ​W·m⁻¹·K⁻¹ and a high electrical conductivity of 4.11 ​± ​0.02 ​S·cm⁻¹ in the lengthwise direction. Furthermore, a solar-thermal energy storage device incorporating the PCC4, a solar selective absorber, and a highly transparent glass is developed, which reaches a high solar-thermal efficiency of 77.30 ​± ​2.71% under 3.0 suns. Moreover, the PCC4 can also reach a high electro-thermal efficiency of 91.62 ​± ​3.52% at a low voltage of 3.6 ​V, demonstrating its superior electro-thermal storage performance. Finally, stability experiments indicate that PCCs exhibit stabilized performance in prolonged TES operations. Overall, this work offers highly conductive and cost-effective PCCs, which are suitable for large-scale and efficient solar/electro-thermal energy storage.

The photovoltaic (PV) water electrolysis method currently stands as the most promising approach for green hydrogen production. The rapid iteration of photovoltaic technologies has significantly affected on the technical and economic evaluation for photovoltaic hydrogen production. In this work, the photovoltaic hydrogen production of three most advanced silicon photovoltaic technologies is systematically compared for the first time under the climatic conditions of the Kucha region. All-weather stable hydrogen production control system with optimal charging and discharging strategies is constructed to realize stable and efficient hydrogen energy production. Seven machine learning (ML) algorithms are used to forecast the performance in power generation and hydrogen production of a 100 ​MW photovoltaic hydrogen production and energy storage (PH-S) system throughout its operational life. The long short-term memory (LSTM) algorithm exhibits the best performance, achieving mean absolute error (MAE) of 0.0415, root mean square error (RMSE) of 0.0891, and coefficient of determination (R²) of 0.8402. In terms of cost-effectiveness, heterojunction with intrinsic thin layer (HJT) PV technology achieves the lowest levelized cost of electricity (LCOE) and hydrogen (LCOH) at 0.025 $/kWh and 6.95 $/kg, respectively. According to the sensitivity analysis, when the cost of proton exchange membrane electrolysis (PEMEC) reduced 50%, the LCOH for PH-S system decreased 21.40%. This study provides valuable insights for the practical implementation of large-scale photovoltaic hydrogen production and cost reduction in PH-S systems.

Lithium sulfur batteries (LSBs) show great promise as next-generation batteries due to their high energy density. However, commercialization is hindered by limited cycle life, fast capacity decay and poor sulfur utilization, primarily due to the intricate phase evolution during battery operation and insulating characteristics of sulfur, leading to uncontrollable sulfur and polysulfide distribution and inefficient conversion kinetics. Therefore, the incorporation of metal and covalent organic frameworks (MOFs and COFs) has been widely employed in LSBs to serve as hosts, enabling the regulation of conversion and diffusion behavior of guest species, including lithium ions, sulfur and polysulfides, within their well-defined nanosized cavities. Nevertheless, pristine frameworks often fail to meet the requisite standards, and framework functionalization offers unique opportunities to tailor desired attributes and facilitate selective host-guest interactions in LSBs. However, a thorough understanding on how to precisely customize the nano-channels with functional groups to promote such interactions remains largely unexplored. In this review, we provide a systematic discussion on how the grafting of functional groups containing various active sites can play a role in host-guest chemistry, and focus on the latest advancements in engineering functionalized MOFs and COFs as charged-species regulators to tackle the problems causing poor LSB electrochemical performance. The concepts of electrophilic and nucleophilic effects are proposed, uncovering the mechanisms of framework functionalization in LSBs and serving as guidance for future developments.

Thermal rectification (TR) is a phenomenon akin to electrical rectification. It has a high thermal conductivity (k) in one direction, enabling efficient heat dissipation, as well as a low k in the opposite direction, impeding heat influx. With the rapid development of nanotechnology in recent years, the active control and regulation of heat conduction on the nanoscale has become a critical mission. Graphene, a prominent two-dimensional (2D) material, is highly regarded for its exceptional thermal transport characteristics. There have been studies and achievements both theoretically and experimentally since its discovery. In this review, we establish a bridge between fundamental research and application studies for graphene-based thermal rectifier as follows. Firstly, we summarize the established 2D heat conduction theories and low-dimensional simulation methods. Secondly, we review the progress of experimental techniques and device structures based on 2D theories for graphene-based thermal rectifier. Then, we discuss several applications of thermal rectifier, including thermal logic circuits and thermoelectric power generation system. Finally, we present the potential applications of graphene-based thermal rectifiers previously unexplored, such as microelectronic thermal management and thermal decoupling for flexible equipment. We hope that advancements in morphology and fabrication techniques will lead to widespread use of graphene-based thermal rectifiers in various thermal systems to solve diverse thermal management problems in the near future.