Frontiers in Energy最新文献

The performance parameters for characterizing the electrocaloric effect are isothermal entropy change and the adiabatic temperature change, respectively. This paper reviews the electrocaloric effect of ferroelectric materials based on different theoretical models. First, it provides four different calculation scales (the first-principle-based effective Hamiltonian, the Landau-Devonshire thermodynamic theory, phase-field simulation, and finite element analysis) to explain the basic theory of calculating the electrocaloric effect. Then, it comprehensively reviews the recent progress of these methods in regulating the electrocaloric effect and the generation mechanism of the electrocaloric effect. Finally, it summarizes and anticipates the exploration of more novel electrocaloric materials based on the framework constructed by the different computational methods.

Transition metal sulfides are commonly studied as photocatalysts for water splitting in solar-to-fuel conversion. However, the effectiveness of these photocatalysts is limited by the recombination and restricted light absorption capacity of carriers. In this paper, a broad spectrum responsive In₂S₃/Bi₂S₃ heterojunction is constructed by in-situ integrating Bi₂S₃ with the In₂S₃, derived from an In-MOF precursor, via the high-temperature sulfidation and solvothermal methods. Benefiting from the synergistic effect of wide-spectrum response, effective charge separation and transfer, and strong heterogeneous interfacial contacts, the In₂S₃/Bi₂S₃ heterojunction demonstrates a rate of 0.71 mmol/(g·h), which is 2.2 and 1.7 times as much as those of In₂S₃ (0.32 mmol/(g·h) and Bi₂S₃ (0.41 mmol/(g·h)), respectively. This paper provides a novel idea for rationally designing innovative heterojunction photocatalysts of transition metal sulfides for photocatalytic hydrogen production.

Lithium (Li) metal is believed to be the “Holy Grail” among all anode materials for next-generation Li-based batteries due to its high theoretical specific capacity (3860 mAh/g) and lowest redox potential (−3.04 V). Disappointingly, uncontrolled dendrite formation and “hostless” deposition impede its further development. It is well accepted that the construction of three-dimensional (3D) composite Li metal anode could tackle the above problems to some extent by reducing local current density and maintaining electrode volume during cycling. However, most strategies to build 3D composite Li metal anode require either electrodeposition or melt-infusion process. In spite of their effectiveness, these procedures bring multiple complex processing steps, high temperature, and harsh experimental conditions which cannot meet the actual production demand in consideration of cost and safety. Under this condition, a novel method to construct 3D composite anode via simple mechanical modification has been recently proposed which does not involve harsh conditions, fussy procedures, or fancy equipment. In this mini review, a systematic and in-depth investigation of this mechanical deformation technique to build 3D composite Li metal anode is provided. First, by summarizing a number of recent studies, different mechanical modification approaches are classified clearly according to their specific procedures. Then, the effect of each individual mechanical modification approach and its working mechanisms is reviewed. Afterwards, the merits and limits of different approaches are compared. Finally, a general summary and perspective on construction strategies for next-generation 3D composite Li anode are presented.

The coal-to-liquid coupled with carbon capture, utilization, and storage technology has the potential to reduce CO₂ emissions, but its carbon footprint and cost assessment are still insufficient. In this paper, coal mining to oil production is taken as a life cycle to evaluate the carbon footprint and levelized costs of direct-coal-to-liquid and indirect-coal-to-liquid coupled with the carbon capture utilization and storage technology under three scenarios: non capture, process capture, process and public capture throughout the life cycle. The results show that, first, the coupling carbon capture utilization and storage technology can reduce CO₂ footprint by 28%–57% from 5.91 t CO₂/t oil of direct-coal-to-liquid and 24%–49% from 7.10 t CO₂/t oil of indirect-coal-to-liquid. Next, the levelized cost of direct-coal-to-liquid is 648–1027 $/t of oil, whereas that of indirect-coal-to-liquid is 653–1065 $/t of oil. When coupled with the carbon capture utilization and storage technology, the levelized cost of direct-coal-to-liquid is 285–1364 $/t of oil, compared to 1101–9793 $/t of oil for indirect-coal-to-liquid. Finally, sensitivity analysis shows that CO₂ transportation distance has the greatest impact on carbon footprint, while coal price and initial investment cost significantly affect the levelized cost of coal-to-liquid.

Exploring cathode materials that combine excellent cycling stability and high energy density poses a challenge to aqueous Zn-ion hybrid supercapacitors (ZHSCs). Herein, polyaniline (PANI) coated boron-carbon-nitrogen (BCN) nanoarray on carbon cloth surface is prepared as advanced cathode materials via simple high-temperature calcination and electrochemical deposition methods. Because of the excellent specific capacity and conductivity of PANI, the CC@BCN@PANI core-shell nanoarrays cathode shows an excellent ion storage capability. Moreover, the 3D nanoarray structure can provide enough space for the volume expansion and contraction of PANI in the charging/discharging cycles, which effectively avoids the collapse of the microstructure and greatly improves the electrochemical stability of PANI. Therefore, the CC@BCN@PANI-based ZHSCs exhibit superior electrochemical performances showing a specific capacity of 145.8 mAh/g, a high energy density of 116.78 Wh/kg, an excellent power density of 12 kW/kg, and a capacity retention rate of 86.2% after 8000 charge/discharge cycles at a current density of 2 A/g. In addition, the flexible ZHSCs (FZHSCs) also show a capacity retention rate of 87.7% at the current density of 2 A/g after 450 cycles.

Sunlight-powered water splitting presents a promising strategy for converting intermittent and virtually unlimited solar energy into energy-dense and storable green hydrogen. Since the pioneering discovery by Honda and Fujishima, considerable efforts have been made in this research area. Among various materials developed, Ga(X)N/Si (X = In, Ge, Mg, etc.) nanoarchitecture has emerged as a disruptive semiconductor platform to split water toward hydrogen by sunlight. This paper introduces the characteristics, properties, and growth/synthesis/fabrication methods of Ga(X)N/Si nanoarchitecture, primarily focusing on explaining the suitability as an ideal platform for sunlight-powered water splitting toward green hydrogen fuel. In addition, it exclusively summarizes the recent progress and development of Ga(X)N/Si nanoarchitecture for photocatalytic and photoelectrochemical water splitting. Moreover, it describes the challenges and prospects of artificial photosynthesis integrated device and system using Ga(X)N/Si nanoarchitectures for solar water splitting toward hydrogen.

The reuse of biomass wastes is crucial toward today’s energy and environmental crisis, among which, biomass-based biochar as catalysts for biofuel and high value chemical production is one of the most clean and economical solutions. In this paper, the recent advances in biofuels and high chemicals for selective production based on biochar catalysts from different biomass wastes are critically summarized. The topics mainly include the modification of biochar catalysts, the preparation of energy products, and the mechanisms of other high-value products. Suitable biochar catalysts can enhance the yield of biofuels and higher-value chemicals. Especially, the feedstock and reaction conditions of biochar catalyst, which affect the efficiency of energy products, have been the focus of recent attentions. Mechanism studies based on biochar catalysts will be helpful to the controlled products. Therefore, the design and advancement of the biochar catalyst based on mechanism research will be beneficial to increase biofuels and the conversion efficiency of chemicals into biomass. The advanced design of biochar catalysts and optimization of operational conditions based on the biomass properties are vital for the selective production of high-value chemicals and biofuels. This paper identifies the latest preparation for energy products and other high-value chemicals based on biochar catalysts progresses and offers insights into improving the yield of high selectivity for products as well as the high recyclability and low toxicity to the environment in future applications.