Molecules

Research

Jump to: Review

13 pages, 3656 KiB

Open AccessArticle

Efficient Regulation of Polysulfides by Anatase/Bronze TiO₂ Heterostructure/Polypyrrole Composites for High-Performance Lithium-Sulfur Batteries

by Jing Liu, Yong Liu, Tengfei Li, Longlong Liang, Sifan Wen, Yue Zhang, Guilong Liu, Fengzhang Ren and Guangxin Wang

Molecules 2023, 28(11), 4286; https://doi.org/10.3390/molecules28114286 - 23 May 2023

Cited by 4 | Viewed by 1812

Abstract

Despite having ultra-high theoretical specific capacity and theoretical energy density, lithium-sulfur (Li-S) batteries suffer from their low Coulombic efficiency and poor lifespan, and the commercial application of Li-S batteries is seriously hampered by the severe “shuttle effect” of lithium polysulfides (LiPSs) and the [...] Read more.

Despite having ultra-high theoretical specific capacity and theoretical energy density, lithium-sulfur (Li-S) batteries suffer from their low Coulombic efficiency and poor lifespan, and the commercial application of Li-S batteries is seriously hampered by the severe “shuttle effect” of lithium polysulfides (LiPSs) and the large volume expansion ratio of the sulfur electrode during cycling. Designing functional hosts for sulfur cathodes is one of the most effective ways to immobilize the LiPSs and improve the electrochemical performance of a Li-S battery. In this work, a polypyrrole (PPy)-coated anatase/bronze TiO₂ (TAB) heterostructure was successfully prepared and used as a sulfur host. Results showed that the porous TAB could physically adsorb and chemically interact with LiPSs during charging and discharging processes, inhibiting the LiPSs’ shuttle effect, and the TAB’s heterostructure and PPy conductive layer are conducive to the rapid transport of Li⁺ and improve the conductivity of the electrode. By benefitting from these merits, Li-S batteries with TAB@S/PPy electrodes could deliver a high initial capacity of 1250.4 mAh g⁻¹ at 0.1 C and show an excellent cycling stability (the average capacity decay rate was 0.042% per cycle after 1000 cycles at 1 C). This work brings a new idea for the design of functional sulfur cathodes for high-performance Li-S battery. Full article

(This article belongs to the Special Issue Energy-Relevant Advanced Materials)

► Show Figures

Graphical abstract

16 pages, 3676 KiB

Open AccessArticle

Photosensitive Dye as an Ideal Peroxymonosulfate Activator for Efficient Self-Degradation: A Novel Idea of Using Waste to Treat Waste

by Zhiyao Zhang, Zhaolin Li, Xue Bai, Juan Shi, Min Hu, Jin Chai, Keqian Li and Pengkang Jin

Molecules 2023, 28(10), 4237; https://doi.org/10.3390/molecules28104237 - 22 May 2023

Cited by 2 | Viewed by 1572

Abstract

Commonly used peroxydisulfate (PS) or peroxymonosulfate (PMS) activation methods have been limited in their practical application due to certain drawbacks, such as high cost, high energy consumption and secondary pollution. In this study, a catalyst-free alizarin green (AG) self-activating PMS catalytic system was [...] Read more.

Commonly used peroxydisulfate (PS) or peroxymonosulfate (PMS) activation methods have been limited in their practical application due to certain drawbacks, such as high cost, high energy consumption and secondary pollution. In this study, a catalyst-free alizarin green (AG) self-activating PMS catalytic system was constructed based on photosensitization properties of dye, which ultimately achieved efficient degradation of the dye activator, also the target pollutant. Here, 52.5% of the 100 mL mixture of 10 mg/L AG decomposed within 60 min with 1 mM PMS under visible-light irradiation, thereby showing a strong pH adaptation. Mechanism of AG self-activating PMS was revealed that the photo-excited AG can effectively transfer photo-induced electrons to PMS for its activation, which generates reactive oxidizing species dominated by singlet oxygen (¹O₂), and supplemented by hydroxyl radical (•OH), superoxide radical (O₂^•−) and sulfate radical (SO₄^•−) to realize the efficient self-degradation of the dye pollutants. Moreover, such self-catalytic system operated well under natural sunlight irradiation, indicating the great application potential in the actual wastewater treatment. Herein, photosensitive dye acted as an ideal PMS activator realizing its efficient self-degradation, which provides a novel idea of “using waste to treat waste” for developing wastewater treatment process in a high-efficiency and low-consumption way. Full article

(This article belongs to the Special Issue Energy-Relevant Advanced Materials)

► Show Figures

Graphical abstract

11 pages, 2196 KiB

Open AccessArticle

Performance Enhancement of Proton Exchange Membrane Fuel Cell through Carbon Nanofibers Grown In Situ on Carbon Paper

by Chang Liu and Shang Li

Molecules 2023, 28(6), 2810; https://doi.org/10.3390/molecules28062810 - 20 Mar 2023

Cited by 8 | Viewed by 2521

Abstract

We developed an integrated gas diffusion layer (GDL) for proton exchange membrane (PEM) fuel cells by growing carbon nanofibers (CNFs) in situ on carbon paper via the electro-polymerization of polyaniline (PANI) on carbon paper followed by a subsequent carbonization treatment process. The CNF/carbon [...] Read more.

We developed an integrated gas diffusion layer (GDL) for proton exchange membrane (PEM) fuel cells by growing carbon nanofibers (CNFs) in situ on carbon paper via the electro-polymerization of polyaniline (PANI) on carbon paper followed by a subsequent carbonization treatment process. The CNF/carbon paper showed a microporous structure and a significantly increased pore volume compared to commercial carbon paper. By utilizing this CNF/carbon paper in a PEM fuel cell, it was found that the cell with CNF/carbon paper had superior performance compared to the commercial GDL at both high and low humidity conditions, and its power density was as high as 1.21 W cm⁻² at 100% relative humidity, which is 26% higher than that of a conventional gas diffusion layer (0.9 W cm⁻²). The significant performance enhancement was attributed to a higher pore volume and porosity of the CNF/carbon paper, which improved gas diffusion in the GDL. In addition, the superior performance of the cell with CNF/carbon paper at low relative humidity demonstrated that it had better water retention than the commercial GDL. This study provides a novel and facile method for the surface modification of GDLs to improve the performance of PEM fuel cells. The CNF/carbon paper with a microporous structure has suitable hydrophobicity and lower through-plane resistance, which makes it promising as an advanced substrate for GDLs in fuel cell applications. Full article

(This article belongs to the Special Issue Energy-Relevant Advanced Materials)

► Show Figures

Figure 1

13 pages, 3542 KiB

Open AccessArticle

One-Step Synthesis of a Non-Precious-Metal Tris (Fe/N/F)-Doped Carbon Catalyst for Oxygen Reduction Reactions

by Huitian Yang, Hao Wu, Lei Yao, Siyan Liu, Lu Yang, Jieling Lu, Hongliang Peng, Xiangcheng Lin, Ping Cai, Huanzhi Zhang, Fen Xu, Kexiang Zhang and Lixian Sun

Molecules 2023, 28(5), 2392; https://doi.org/10.3390/molecules28052392 - 5 Mar 2023

Cited by 1 | Viewed by 1950

Abstract

Advancements in inexpensive, efficient, and durable oxygen reduction catalysts is important for maintaining the sustainable development of fuel cells. Although doping carbon materials with transition metals or heteroatomic doping is inexpensive and enhances the electrocatalytic performance of the catalyst, because the charge distribution [...] Read more.

Advancements in inexpensive, efficient, and durable oxygen reduction catalysts is important for maintaining the sustainable development of fuel cells. Although doping carbon materials with transition metals or heteroatomic doping is inexpensive and enhances the electrocatalytic performance of the catalyst, because the charge distribution on its surface is adjusted, the development of a simple method for the synthesis of doped carbon materials remains challenging. Here, a non-precious-metal tris (Fe/N/F)-doped particulate porous carbon material (2₁P₂-Fe₁-850) was synthesized by employing a one-step process, using 2-methylimidazole, polytetrafluoroethylene, and FeCl₃ as raw materials. The synthesized catalyst exhibited a good oxygen reduction reaction performance with a half-wave potential of 0.85 V in an alkaline medium (compared with 0.84 V of commercial Pt/C). Moreover, it had better stability and methanol resistance than Pt/C. This was mainly attributed to the effect of the tris (Fe/N/F)-doped carbon material on the morphology and chemical composition of the catalyst, thereby enhancing the catalyst’s oxygen reduction reaction properties. This work provides a versatile method for the gentle and rapid synthesis of highly electronegative heteroatoms and transition metal co-doped carbon materials. Full article

(This article belongs to the Special Issue Energy-Relevant Advanced Materials)

► Show Figures

Figure 1

13 pages, 5810 KiB

Open AccessArticle

Transformation of CO₂ with Glycerol to Glycerol Carbonate over ETS-10 Zeolite-Based Catalyst

by Zhangxi Gao, Mei Xiang, Mingyang He, Weiyou Zhou, Jiayao Chen, Jiamin Lu, Zeying Wu and Yaqiong Su

Molecules 2023, 28(5), 2272; https://doi.org/10.3390/molecules28052272 - 28 Feb 2023

Cited by 9 | Viewed by 2352

Abstract

Catalytic conversion of CO₂ with the surplus glycerol (GL) produced from biodiesel manufacturing has attracted much academic and industrial attention, which proves the urgent requirement for developing high-performance catalysts to afford significant environmental benefits. Herein, titanosilicate ETS-10 zeolite-based catalysts with active metal [...] Read more.

Catalytic conversion of CO₂ with the surplus glycerol (GL) produced from biodiesel manufacturing has attracted much academic and industrial attention, which proves the urgent requirement for developing high-performance catalysts to afford significant environmental benefits. Herein, titanosilicate ETS-10 zeolite-based catalysts with active metal species introduced by impregnation were employed for coupling CO₂ with GL to efficiently synthesize glycerol carbonate (GC). The catalytic GL conversion at 170 °C miraculously reached 35.0% and a 12.7% yield of GC was obtained on Co/ETS-10 with CH₃CN as a dehydrating agent. For comparison, Zn/ETS- Cu/ETS-10, Ni/ETS-10, Zr/ETS-10, Ce/ETS-10, and Fe/ETS-10 were also prepared, which showed inferior coordination between GL conversion and GC selectivity. Comprehensive analysis revealed that the presence of moderate basic sites for CO₂ adsorption-activation played a crucial role in regulating catalytic activity. Moreover, the appropriate interaction between cobalt species and ETS-10 zeolite was also of great significance for improving the glycerol activation capacity. A plausible mechanism was proposed for the synthesis of GC from GL and CO₂ in the presence of CH₃CN solvent over Co/ETS-10 catalyst. Moreover, the recyclability of Co/ETS-10 was also measured and it proved to be recycled at least eight times with less than 3% decline in GL conversion and GC yield after a simple regeneration process through calcination at 450 °C for 5 h in air. Full article

(This article belongs to the Special Issue Energy-Relevant Advanced Materials)

► Show Figures

Figure 1

12 pages, 1983 KiB

Open AccessArticle

Mesoporous Surface-Sulfurized Fe–Co₃O₄ Nanosheets Integrated with N/S Co-Doped Graphene as a Robust Bifunctional Electrocatalyst for Oxygen Evolution and Reduction Reactions

by Lingxue Meng, Yige Wang, Wenwei Liu, Chunlei Fan, Haoxiong Nan, Jiang Wang and Jia Yu

Molecules 2023, 28(5), 2221; https://doi.org/10.3390/molecules28052221 - 27 Feb 2023

Cited by 2 | Viewed by 1890

Abstract

Playing a significant role in electrochemical energy conversion and storage systems, heteroatom-doped transition metal oxides are key materials for oxygen-involving reactions. Herein, mesoporous surface-sulfurized Fe–Co₃O₄ nanosheets integrated with N/S co-doped graphene (Fe–Co₃O₄–S/NSG) were designed as composite [...] Read more.

Playing a significant role in electrochemical energy conversion and storage systems, heteroatom-doped transition metal oxides are key materials for oxygen-involving reactions. Herein, mesoporous surface-sulfurized Fe–Co₃O₄ nanosheets integrated with N/S co-doped graphene (Fe–Co₃O₄–S/NSG) were designed as composite bifunctional electrocatalysts for the oxygen evolution reaction (OER) and the oxygen reduction reaction (ORR). Compared with the Co₃O₄–S/NSG catalyst, it exhibited superior activity in the alkaline electrolytes by delivering an OER overpotential of 289 mV at 10 mA cm⁻² and an ORR half-wave potential of 0.77 V vs. RHE. Additionally, Fe–Co₃O₄–S/NSG kept stable at 4.2 mA cm⁻² for 12 h without significant attenuation to render robust durability. This work not only demonstrates the satisfactory effect of the transition-metal cationic modification represented by iron doping on the electrocatalytic performance of Co₃O₄, but it also provides a new insight on the design of OER/ORR bifunctional electrocatalysts for efficient energy conversion. Full article

(This article belongs to the Special Issue Energy-Relevant Advanced Materials)

► Show Figures

Figure 1

8 pages, 10761 KiB

Open AccessCommunication

Hierarchical Pt-In Nanowires for Efficient Methanol Oxidation Electrocatalysis

by Zhao Lu, Lu Zou and Wulin Song

Molecules 2023, 28(3), 1502; https://doi.org/10.3390/molecules28031502 - 3 Feb 2023

Cited by 4 | Viewed by 1805

Abstract

Direct methanol fuel cells (DMFC) have attracted increasing research interest recently; however, their output performance is severely hindered by the sluggish kinetics of the methanol oxidation reaction (MOR) at the anode. Herein, unique hierarchical Pt-In NWs with uneven surface and abundant high-index facets [...] Read more.

Direct methanol fuel cells (DMFC) have attracted increasing research interest recently; however, their output performance is severely hindered by the sluggish kinetics of the methanol oxidation reaction (MOR) at the anode. Herein, unique hierarchical Pt-In NWs with uneven surface and abundant high-index facets are developed as efficient MOR electrocatalysts in acidic electrolytes. The developed hierarchical Pt₈₉In₁₁ NWs exhibit high MOR mass activity and specific activity of 1.42 A mg_Pt⁻¹ and 6.2 mA cm⁻², which are 5.2 and 14.4 times those of Pt/C, respectively, outperforming most of the reported MORs. In chronoamperometry tests, the hierarchical Pt₈₉In₁₁ NWs demonstrate a longer half-life time than Pt/C, suggesting the better CO tolerance of Pt₈₉In₁₁ NWs. After stability, the MOR activity can be recovered by cycling. XPS, CV measurement and CO stripping voltammetry measurements demonstrate that the outstanding catalytic activity may be attributed to the facile removal of CO due to the presence of In site-adsorbing hydroxyl species. Full article

(This article belongs to the Special Issue Energy-Relevant Advanced Materials)

► Show Figures

Graphical abstract

11 pages, 3512 KiB

Open AccessArticle

Investigation on Long-Term Stability of Vermiculite Seals for Reversible Solid Oxide Cell

by Ruizhu Li, Yue Lu, Yutian Yu, Xianzhi Ren, Feng Ding, Chengzhi Guan and Jianqiang Wang

Molecules 2023, 28(3), 1462; https://doi.org/10.3390/molecules28031462 - 2 Feb 2023

Cited by 5 | Viewed by 2080

Abstract

A reversible solid oxide cell (RSOC) integrating solid oxide fuel (SOFC) and a solid oxide electrolysis cell (SOEC) usually utilizes compressive seals. In this work, the vermiculite seals of various thickness and compressive load during thermal cycles and long-term operation were investigated. The [...] Read more.

A reversible solid oxide cell (RSOC) integrating solid oxide fuel (SOFC) and a solid oxide electrolysis cell (SOEC) usually utilizes compressive seals. In this work, the vermiculite seals of various thickness and compressive load during thermal cycles and long-term operation were investigated. The leakage rates of seals were gradually increased with increasing thickness and input gas pressure. The thinner seals had good sealing performance. The compressive load was carried out at thinner seals, the possible holes were squeezed, and finally the leakage rates were lower. With a fixed input gas pressure of 1 psi, 2 psi, and 3 psi, the leakage rates of 0.50 mm vermiculite remained at around 0.009 sccm/cm, 0.017 sccm/cm and 0.028 sccm/cm during twenty thermal cycles, while the leakage rates remained at around 0.011 sccm/cm for about 240 h. Simultaneously, elemental diffusions between seals and components were limited, implying good compatibility. Furthermore, the open circuit voltage (OCV) remained at around 1.04 V during 17 thermal cycles, which is close to Nernst potentials. The stack performance confirmed that the vermiculite seals can meet the structural support and sealing requirements. Therefore, the vermiculite shows good promise for application in stacks during thermal cycles and long-term operation. Full article

(This article belongs to the Special Issue Energy-Relevant Advanced Materials)

► Show Figures

Figure 1

8 pages, 3749 KiB

Open AccessCommunication

Coronavirus-like Core–Shell-Structured Co@C for Hydrogen Evolution via Hydrolysis of Sodium Borohydride

by Shuyi Su, Kailei Chen, Xu Yang and Dai Dang

Molecules 2023, 28(3), 1440; https://doi.org/10.3390/molecules28031440 - 2 Feb 2023

Cited by 6 | Viewed by 1845

Abstract

Constructing a reliable and robust cobalt-based catalyst for hydrogen evolution via hydrolysis of sodium borohydride is appealing but challenging due to the deactivation caused by the metal leaching and re-oxidization of metallic cobalt. A unique core–shell-structured coronavirus-like Co@C microsphere was prepared via pyrolysis [...] Read more.

Constructing a reliable and robust cobalt-based catalyst for hydrogen evolution via hydrolysis of sodium borohydride is appealing but challenging due to the deactivation caused by the metal leaching and re-oxidization of metallic cobalt. A unique core–shell-structured coronavirus-like Co@C microsphere was prepared via pyrolysis of Co-MOF. This special Co@C had a microporous carbon coating to retain the reduced state of cobalt and resist the metal leaching. Furthermore, several nano-bumps grown discretely on the surface afforded enriched active centers. Applied in the pyrolysis of NaBH₄, the Co@C-650, carbonized at 650 °C, exhibited the best activity and reliable recyclability. This comparable performance is ascribed to the increased metallic active sites and robust stability. Full article

(This article belongs to the Special Issue Energy-Relevant Advanced Materials)

► Show Figures

Figure 1

12 pages, 5680 KiB

Open AccessArticle

Mn^x+ Substitution to Improve Na₃V₂(PO₄)₂F₃-Based Electrodes for Sodium-Ion Battery Cathode

by Renyuan Su, Weikai Zhu, Kang Liang, Peng Wei, Jianbin Li, Wenjun Liu and Yurong Ren

Molecules 2023, 28(3), 1409; https://doi.org/10.3390/molecules28031409 - 1 Feb 2023

Cited by 5 | Viewed by 3116

Abstract

Na₃V₂(PO₄)₂F₃ (NVPF) is an extremely promising sodium storage cathode material for sodium-ion batteries because of its stable structure, wide electrochemical window, and excellent electrochemical properties. Nevertheless, the low ionic and electronic conductivity resulting from [...] Read more.

Na₃V₂(PO₄)₂F₃ (NVPF) is an extremely promising sodium storage cathode material for sodium-ion batteries because of its stable structure, wide electrochemical window, and excellent electrochemical properties. Nevertheless, the low ionic and electronic conductivity resulting from the insulated PO₄³⁻ structure limits its further development. In this work, the different valence states of Mn^x+ ions (x = 2, 3, 4) doped NVPF were synthesized by the hydrothermal method. A series of tests and characterizations reveals that the doping of Mn ions (Mn²⁺, Mn³⁺, Mn⁴⁺) changes the crystal structure and also affects the residual carbon content, which further influences the electrochemical properties of NVPF-based materials. The sodiation/desodiation mechanism was also investigated. Among them, the as-prepared NVPF doped with Mn²⁺ delivers a high reversible discharge capacity (116.2 mAh g⁻¹ at 0.2 C), and the capacity retention of 67.7% after 400 cycles at 1 C was obtained. Such excellent performance and facile modified methods will provide new design ideas for the development of secondary batteries. Full article

(This article belongs to the Special Issue Energy-Relevant Advanced Materials)

► Show Figures

Figure 1

12 pages, 2390 KiB

Open AccessArticle

Selectivity of Oxygen Evolution Reaction on Carbon Cloth-Supported δ-MnO₂ Nanosheets in Electrolysis of Real Seawater

by Haofeng Yan, Xuyun Wang, Vladimir Linkov, Shan Ji and Rongfang Wang

Molecules 2023, 28(2), 854; https://doi.org/10.3390/molecules28020854 - 14 Jan 2023

Cited by 7 | Viewed by 2727

Abstract

Electrolysis of seawater using solar and wind energy is a promising technology for hydrogen production which is not affected by the shortage of freshwater resources. However, the competition of chlorine evolution reactions and oxygen evolution reactions on the anode is a major obstacle [...] Read more.

Electrolysis of seawater using solar and wind energy is a promising technology for hydrogen production which is not affected by the shortage of freshwater resources. However, the competition of chlorine evolution reactions and oxygen evolution reactions on the anode is a major obstacle in the upscaling of seawater electrolyzers for hydrogen production and energy storage, which require chlorine-inhibited oxygen evolution electrodes to become commercially viable. In this study, such an electrode was prepared by growing δ-MnO₂ nanosheet arrays on the carbon cloth surface. The selectivity of the newly prepared anode towards the oxygen evolution reaction (OER) was 66.3% after 30 min of electrolyzer operation. The insertion of Fe, Co and Ni ions into MnO₂ nanosheets resulted in an increased number of trivalent Mn atoms, which had a negative effect on the OER selectivity. Good tolerance of MnO₂/CC electrodes to chlorine evolution in seawater electrolysis indicates its suitability for upscaling this important energy conversion and storage technology. Full article

(This article belongs to the Special Issue Energy-Relevant Advanced Materials)

► Show Figures

Figure 1

9 pages, 1704 KiB

Open AccessArticle

Tailoring the Hollow Structure within CoSn(OH)₆ Nanocubes for Advanced Supercapacitors

by Zhiyong Yang, Chunxia Li, Fangfang Liu, Xiaowei Lv, Lei Zhang, Yanli Fang and Hui Wang

Molecules 2022, 27(22), 7960; https://doi.org/10.3390/molecules27227960 - 17 Nov 2022

Cited by 5 | Viewed by 1653

Abstract

The enhanced application performance of hollow-structured materials is attributed to their large surface area with more active sites. In this work, the hollow CoSn(OH)₆ nanocubes with increased surface area and mesopores were derived from dense CoSn(OH)₆ nanocube precursors by alkaline etching. [...] Read more.

The enhanced application performance of hollow-structured materials is attributed to their large surface area with more active sites. In this work, the hollow CoSn(OH)₆ nanocubes with increased surface area and mesopores were derived from dense CoSn(OH)₆ nanocube precursors by alkaline etching. As a result, the hollow CoSn(OH)₆ nanocubes-based cathode electrode exhibited a higher area-specific capacitance of 85.56 µF cm⁻² at 0.5 mA cm⁻² and a mass-specific capacitance of 5.35 mF g⁻¹ at 0.5 mA cm⁻², which was more extensive than that of the dense precursor. Meanwhile, the current density was increased 4-fold with good rate capability for hollow CoSn(OH)₆ nanocubes. Full article

(This article belongs to the Special Issue Energy-Relevant Advanced Materials)

► Show Figures

Figure 1

9 pages, 2022 KiB

Open AccessFeature PaperArticle

Unravelling the 2e⁻ ORR Activity Induced by Distance Effect on Main-Group Metal InN₄ Surface Based on First Principles

by Peng Li, Jiawen Xu and Yaqiong Su

Molecules 2022, 27(22), 7720; https://doi.org/10.3390/molecules27227720 - 9 Nov 2022

Cited by 4 | Viewed by 1924

Abstract

The p-electron-dominated main-group metals (Sb, Se, In, etc.) have recently been reported to possess excellent oxygen reduction reaction (ORR) activity by means of heteroatom doping into graphene. However, on these main group metal surfaces, other approaches especially the distance effect to modulate catalytic [...] Read more.

The p-electron-dominated main-group metals (Sb, Se, In, etc.) have recently been reported to possess excellent oxygen reduction reaction (ORR) activity by means of heteroatom doping into graphene. However, on these main group metal surfaces, other approaches especially the distance effect to modulate catalytic activity are rarely involved. In this work, the origin of excellent 2e⁻ ORR catalytic activity of graphene-supported InN₄ moiety by tuning the distance between metallic In atoms is thoroughly investigated by employing the first-principles calculations. Our DFT calculations show that the 2e⁻ ORR catalytic activity strongly depends on the crystal orbital Hamilton population (COHP) between In and O atoms. This work is useful for the rational design of main group metal single atom electrocatalysts. Full article

(This article belongs to the Special Issue Energy-Relevant Advanced Materials)

► Show Figures

Figure 1

13 pages, 4460 KiB

Open AccessArticle

Optimization of Sintering Conditions to Enhance the Dielectric Performance of Gd³⁺ and Ho³⁺ Codoped BaTiO₃ Ceramics

by Jianghui Bai, Qiaoli Liu, Xia Li, Xin Wei and Liping Li

Molecules 2022, 27(21), 7464; https://doi.org/10.3390/molecules27217464 - 2 Nov 2022

Cited by 2 | Viewed by 1716

Abstract

BaTiO₃ dielectric capacitors, one of the important energy storage devices, play critical roles in storing electricity from renewable energies of water, wind, solar, etc. The synthesis of BaTiO₃ ceramics with weak temperature dependence and a high dielectric constant at room temperature [...] Read more.

BaTiO₃ dielectric capacitors, one of the important energy storage devices, play critical roles in storing electricity from renewable energies of water, wind, solar, etc. The synthesis of BaTiO₃ ceramics with weak temperature dependence and a high dielectric constant at room temperature (ε_RT′) is an urgent problem to meet the miniaturization and large capacity of dielectric capacitors. Doping rare earth elements into BaTiO₃ can solve this problem, but it is still challenging. In this work, we adopt a synergistic strategy of increasing ε_RT′ and improving the temperature stability by codoping Gd³⁺ and Ho³⁺, respectively, to address this challenge. By carefully adjusting the synthesis conditions in the solid-state reaction, codoping 7% Gd³⁺ and 7% Ho³⁺ in BaTiO₃ (BGTH7) ceramics were synthesized. The temperature-dependent dielectric constant reveals that the obtained optimal BGTH7 ceramic satisfies the X7U specification and displays a stable ε′ in the temperature range of −55~125 °C. The optimal BGTH7 ceramic after sintering at 1400 °C for 6 h exhibits a high dielectric constant of 5475 and low dielectric loss (tan δ) of 0.0176, hitherto exhibiting the best performance in X7U ceramics. The findings in this work are conducive to the miniaturization and stabilization of dielectric energy storage devices. Full article

(This article belongs to the Special Issue Energy-Relevant Advanced Materials)

► Show Figures

Figure 1

9 pages, 1898 KiB

Open AccessArticle

Tailoring Electrochemical Performance of Co₃O₄ Electrode Materials by Mn Doping

by Xingyu Liu, Mengdi Wang and Xiang Wu

Molecules 2022, 27(21), 7344; https://doi.org/10.3390/molecules27217344 - 28 Oct 2022

Cited by 11 | Viewed by 1793

Abstract

Reasonable design of electrode materials is the key to solving the low energy density of the supercapacitors. Transition metal oxide Co₃O₄ material is commonly used in the field of supercapacitors, but the poor cycle stability limits its practical application. Herein, [...] Read more.

Reasonable design of electrode materials is the key to solving the low energy density of the supercapacitors. Transition metal oxide Co₃O₄ material is commonly used in the field of supercapacitors, but the poor cycle stability limits its practical application. Herein, we report 0.3Mn-Co₃O₄ nanostructures grown on nickel foam by a facile one-step hydrothermal approach. The morphology of the samples can be regulated by the introduction of different amounts of Mn ions. The specific capacitance reaches 525.5 C/g at 1 A/g. The performance of 0.3Mn-Co₃O₄ material is significantly improved due to its excellent stability and conductivity, which makes it a suitable electrode material for supercapacitors. A flexible asymmetric device is also fabricated using the sample as the cathode. The assembled capacitor still possesses a desirable cycle stability after charging and discharging of 10,000 times, and its capacitance retention rate can reach 83.71%. Full article

(This article belongs to the Special Issue Energy-Relevant Advanced Materials)

► Show Figures

Figure 1

12 pages, 5347 KiB

Open AccessArticle

Enhanced Visible-Light-Driven Photocatalytic Activity by Fe(Ш)-Doped Graphitic C₃N₄

by Zhao Lu, Wulin Song and Minghao Liu

Molecules 2022, 27(20), 6986; https://doi.org/10.3390/molecules27206986 - 17 Oct 2022

Cited by 2 | Viewed by 2015

Abstract

Fe(Ш)-doped graphitic carbon nitride (Fe(Ш)-CN) photocatalysts with various Fe(Ш) ions content were prepared via ultrasonic method. Detailed physical characterization indicated that Fe(Ш) ions had been successfully doped into the frame of g-C₃N₄. The photocatalytic activities were investigated, and methyl [...] Read more.

Fe(Ш)-doped graphitic carbon nitride (Fe(Ш)-CN) photocatalysts with various Fe(Ш) ions content were prepared via ultrasonic method. Detailed physical characterization indicated that Fe(Ш) ions had been successfully doped into the frame of g-C₃N₄. The photocatalytic activities were investigated, and methyl orange (MO) and tetracycline hydrochloride (TC) were used as the targeted pollutants. The as-prepared Fe(Ш)-CN materials exhibited higher photocatalytic activities than those of the pure g-C₃N₄. Specifically, the degradation rate of 2Fe(Ш)-CN under visible light was 2.06 times higher for MO and 2.65 times higher for TC than that of g-C₃N₄. The increased photocatalytic activities of Fe(Ш)-CN were mainly attributed to the enhanced light absorption ability and the rapid separation of photogenerated carriers. Moreover, the importance of active species during the reaction process was also explored, and the results indicated that •O₂⁻ is the main active species. Full article

(This article belongs to the Special Issue Energy-Relevant Advanced Materials)

► Show Figures

Figure 1

Review

Jump to: Research

20 pages, 10453 KiB

Open AccessReview

Electroactive Microorganisms in Advanced Energy Technologies

by Xingchen Zhou, Xianzheng Zhang, Yujie Peng, Abdoulkader Ibro Douka, Feng You, Junlong Yao, Xueliang Jiang, Ruofei Hu and Huan Yang

Molecules 2023, 28(11), 4372; https://doi.org/10.3390/molecules28114372 - 26 May 2023

Cited by 6 | Viewed by 2282

Abstract

Large-scale production of green and pollution-free materials is crucial for deploying sustainable clean energy. Currently, the fabrication of traditional energy materials involves complex technological conditions and high costs, which significantly limits their broad application in the industry. Microorganisms involved in energy production have [...] Read more.

Large-scale production of green and pollution-free materials is crucial for deploying sustainable clean energy. Currently, the fabrication of traditional energy materials involves complex technological conditions and high costs, which significantly limits their broad application in the industry. Microorganisms involved in energy production have the advantages of inexpensive production and safe process and can minimize the problem of chemical reagents in environmental pollution. This paper reviews the mechanisms of electron transport, redox, metabolism, structure, and composition of electroactive microorganisms in synthesizing energy materials. It then discusses and summarizes the applications of microbial energy materials in electrocatalytic systems, sensors, and power generation devices. Lastly, the research progress and existing challenges for electroactive microorganisms in the energy and environment sectors described herein provide a theoretical basis for exploring the future application of electroactive microorganisms in energy materials. Full article

(This article belongs to the Special Issue Energy-Relevant Advanced Materials)

► Show Figures

Graphical abstract

21 pages, 4694 KiB

Open AccessReview

Application of Biomass Materials in Zinc-Ion Batteries

by Yu Zhang, Mengdie Xu, Xin Jia, Fangjun Liu, Junlong Yao, Ruofei Hu, Xueliang Jiang, Peng Yu and Huan Yang

Molecules 2023, 28(6), 2436; https://doi.org/10.3390/molecules28062436 - 7 Mar 2023

Cited by 9 | Viewed by 4085

Abstract

Currently, aqueous zinc-ion batteries, with large reserves of zinc metal and maturity of production, are a promising alternative to sustainable energy storage. Nevertheless, aqueous solution has poor frost resistance and is prone to side reactions. In addition, zinc dendrites also limit the performance [...] Read more.

Currently, aqueous zinc-ion batteries, with large reserves of zinc metal and maturity of production, are a promising alternative to sustainable energy storage. Nevertheless, aqueous solution has poor frost resistance and is prone to side reactions. In addition, zinc dendrites also limit the performance of zinc-ion batteries. Biomass, with complex molecular structure and abundant functional groups, makes it have great application prospects. In this review, the research progress of biomass and its derived materials used in zinc-ion batteries are reviewed. The different regulation strategies and characteristics of biomass used in zinc-ion battery electrodes, electrolyte separators and binders are demonstrated. The regulation mechanism is analyzed. At the end, the development prospect and challenges of biomass in energy materials application are proposed. Full article

(This article belongs to the Special Issue Energy-Relevant Advanced Materials)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Energy-Relevant Advanced Materials

Share This Special Issue

Special Issue Editors

Special Issue Information

Keywords

Benefits of Publishing in a Special Issue

Published Papers (18 papers)

Research

Review

Further Information

Guidelines

MDPI Initiatives

Follow MDPI