? Journal of Energy Chemistry
Journal of Energy Chemistry
ISSN 1003-9953
     
能源化学(英文)

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The negative influence of doping on non-fullerene acceptor on photovoltaic performance of polymer solar cells (Pages 40-46)
The modification mechanism of the water/alcohol cathode interlayer is one of the most complicated problems in the field of organic photovoltaics,which has not been clearly elucidated yet;this restricts the further enhancement of PCE for polymer solar cells.Herein,the distinctly different effects of PFN and its derivatives PFN-Br in modifying fullerene-free PSCs were clarified.As revealed for the first time,doping on non-fullerene acceptor IT-4F by the amino group of PFN leads to the unfavorable charge accumulation,and hence,forms a dense layer of electronegative molecule due to the poor electron transport capacity of the non-fullerene acceptor.The electronegative molecular layer can block the electron transfer from the active layer to the interlayer and cause serious charge recombination at the active layer/cathode interface.The excessive doping effect between the cathode interlayer and IT-4F can be eliminated by replacing PFN with PFN-Br.As a result,a high PCE of 13.5% was achieved in the fullerene-free PSCs.

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2020 Vol.43 No.4, Published: 15 April 2020
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Realizing high-performance Zn-ion batteries by a reduced graphene oxide block layer at room and low temperatures
Jian-Qiu Huang, Xiuyi Lin, Hong Tan, Xiaoqiong Du, Biao Zhang
2020 Vol. 43 (4): 1-7 [Abstract] ( 14 ) [HTML 1KB] [PDF] ( 0 )

Rechargeable aqueous Zn-ion batteries (ZIBs) have attracted great attention due to their costeffectiveness, high safety, and environmental friendliness. However, some issues associated with poor structural instability of cathode materials and fast self-discharge hinder the further development of ZIBs. Herein, a new configuration is introduced by placing a reduced graphene oxide film as a block layer between the separator and the V2O5·nH2O cathode. This layer prevents the free diffusion of dissolved active materials to the anode and facilitates the transport of Zn ion and electrons, largely improving the cyclic stability and alleviating the self-discharge. Accordingly, the optimized battery delivers a remarkable capacity of 191 mAh g-1 after 500 cycles at 2 A g-1. Moreover, a high capacity of 106 mAh g-1 is achieved after 100 cycles at -20℃. The strategy proposed is expected to be applicable to other electrode systems, thus offering a new approach to circumvent the critical challenges facing aqueous batteries.

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Covalently integrated core-shell MOF@COF hybrids as efficient visible-light-driven photocatalysts for selective oxidation of alcohols
Guilong Lu, Xiubing Huang, Yang Li, Guixia Zhao, Guangsheng Pang, Ge Wang
2020 Vol. 43 (4): 8-15 [Abstract] ( 11 ) [HTML 1KB] [PDF] ( 0 )

Building a covalently connected structure with accelerated photo-induced electrons and charge-carrier separation between semiconductors could enhance the photocatalytic performance. In this work, we report a facile and novel seed growth method to coat NH2-MIL-125 MOFs with crystalline and porous covalent organic frameworks (COFs) materials and form a range of NH2-MIL-125@TAPB-PDA nanocomposites with different thicknesses of COF shell. The introduction of appropriate content of COF could not only modify the intrinsic electronic and optical properties, but also enhance the photocatalytic activity distinctly. Especially, NH2-MIL-125@TAPB-PDA-3 with COF shell thickness of around 20 nm exhibited the highest yield (94.7%) of benzaldehyde which is approximately 2.5 and 15.5 times as that of parental NH2-MIL-125 and COF, respectively. The promoted photocatalytic performance of hybrid materials was mainly owing to the enhanced photo-induced charge carriers transfer between the MOF and COF through the covalent bond. In addition, a possible mechanism to elucidate the process of photocatalysis was explored. Therefore, this kind of MOF-based photocatalysts possesses great potentials in future green organic synthesis.

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ZnCo2O4/ZnO induced lithium deposition in multi-scaled carbon/nickel frameworks for dendrite-free lithium metal anode
Kai Wu, Binglu Zhao, Chengkai Yang, Qian Wang, Wen Liu, Henghui Zhou
2020 Vol. 43 (4): 16-23 [Abstract] ( 12 ) [HTML 1KB] [PDF] ( 0 )

Lithium metal attracts growing attention as an ideal anode candidate for next generation lithium battery systems owing to its high capacity, low density, and low working potential. However, the volume expansion of the bulk and dendrite growth on the surface of lithium anode limits its practical application. Herein, we fabricate a composite lithium host featuring both multiple scaled structure and lithiophilic property to address obstacles at both aspects of bulk and surface simultaneously. In which, the multiple scaled structure provides void space to accommodate lithium volume change while zinc and cobalt oxides sites derived from Zeolitic Imidazolate Frameworks can react with lithium and form a stable solid electrolyte interphase, leading to a stable cycling of lithium symmetrical cell for more than 500 cycles with voltage hysteresis of only 88 mV at 2 mA cm-2 and 5 mAh cm-2. Moreover, full cells paired with LiFePO4 cathode can realize 500 cycles with 99.2% capacity retention, showing great potential for practical applications. The excellent electrochemical performance of the composite lithium anode proves the effectiveness of our anode design with multiple scaled structure and lithiophilic feature, which can be also expanded to other metal anodes for batteries.

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Porous bowl-shaped VS2 nanosheets/graphene composite for high-rate lithium-ion storage
Daxiong Wu, Caiyun Wang, Mingguang Wu, Yunfeng Chao, Pengbin He, Jianmin Ma
2020 Vol. 43 (4): 24-32 [Abstract] ( 9 ) [HTML 1KB] [PDF] ( 0 )

Two-dimensional (2D) layered vanadium disulfide (VS2) is a promising anode material for lithium ion batteries (LIBs) due to the high theoretical capacity. However, it remains a challenge to synthesize monodispersed ultrathin VS2 nanosheets to realize the full potential. Herein, a novel solvothermal method has been developed to prepare the monodispersed bowl-shaped NH3-inserted VS2 nanosheets (VS2). The formation of such a unique structure is caused by the blocked growth of (001) or (002) crystal planes in combination with a ripening process driven by the thermodynamics. The annealing treatment in Ar/H2 creates porous monodispersed VS2 (H-VS2), which is subsequently integrated with graphene oxide to form porous monodispersed H-VS2/rGO composite coupled with a reduction process. As an anode material for LIBs, H-VS2/rGO delivers superior rate performance and longer cycle stability:a high average capacity of 868/525 mAh g-1 at a current density of 1/10 A g-1; a reversible capacity of 1177/889 mAh g-1 after 150/500 cycles at 0.2/1 A g-1. Such excellent electrochemical performance may be attributed to the increased active sites available for lithium storage, the alleviated volume variations and the shortened Li-ion diffusion induced from the porous structure with large specific surface area, as well as the protective effect from graphene nanosheets.

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Nanostructured ultrathin catalyst layer with ordered platinum nanotube arrays for polymer electrolyte membrane fuel cells
Ruoyi Deng, Zhangxun Xia, Ruili Sun, Suli Wang, Gongquan Sun
2020 Vol. 43 (4): 33-39 [Abstract] ( 8 ) [HTML 1KB] [PDF] ( 0 )

Fabrication of novel electrode architectures with nanostructured ultrathin catalyst layers is an effective strategy to improve catalyst utilization and enhance mass transport for polymer electrolyte membrane fuel cells (PEMFCs). Herein, we report the design and construction of a nanostructured ultrathin catalyst layer with ordered Pt nanotube arrays, which were obtained by a hard-template strategy based on ZnO, via hydrothermal synthesis and magnetron sputtering for PEMFC application. Because of the crystallographically preferential growth of Pt (111) facets, which was attributed to the structural effects of ZnO nanoarrays on the Pt nanotubes, the catalyst layers exhibit obviously higher electrochemical activity with remarkable enhancement of specific activity and mass transport compared with the state-of-the-art randomly distributed Pt/C catalyst layer. The PEMFC fabricated with the as-prepared catalyst layer composed of optimized Pt nanotubes with an average diameter of 90(±10) nm shows excellent performance with a peak power density of 6.0 W/mgPt at 1 A/cm2, which is 11.6% greater than that of the conventional Pt/C electrode.

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Significant influence of doping effect on photovoltaic performance of efficient fullerene-free polymer solar cells
Qian Kang, Qi Wang, Cunbin An, Chang He, Bowei Xu, Jianhui Hou
2020 Vol. 43 (4): 40-46 [Abstract] ( 8 ) [HTML 1KB] [PDF] ( 0 )

The modification mechanism of the water/alcohol cathode interlayer is one of the most complicated problems in the field of organic photovoltaics, which has not been clearly elucidated yet; this greatly restricts the further enhancement of the PCE for polymer solar cells. Herein, we clarified the different effects of PFN and its derivatives, namely, poly[(9,9-bis(3' -((N,N-dimethyl)-N-ethylammonium)-propyl)-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)] (PFN-Br) in modifying fullerene-free PSCs. It is found for the first time that doping on IT-4F by the amino group of PFN leads to the unfavorable charge accumulation, and hence, forms a dense layer of electronegative molecule due to the poor electron transport capacity of the non-fullerene acceptor IT-4F. The electronegative molecular layer can block the electron transfer from the active layer to the interlayer and cause serious charge recombination at the active layer/cathode interface. This mechanism could be verified by the ESR measurement and electron-only devices. By replacing PFN with PFN-Br, the excessive doping effect between the cathode interlayer and IT-4F is eliminated, by which the charge transport and collection can be greatly improved. As a result, a high PCE of 13.5% was achieved in the fullerene-free PSCs.

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Room temperature operation of all-solid-state battery using a closo-type complex hydride solid electrolyte and a LiCoO2 cathode by interfacial modification
Sangryun Kim, Kentaro Harada, Naoki Toyama, Hiroyuki Oguchi, Kazuaki Kisu, Shin-ichi Orimo
2020 Vol. 43 (4): 47-51 [Abstract] ( 8 ) [HTML 1KB] [PDF] ( 0 )

We report on an all-solid-state battery that employs a closo-type complex hydride solid electrolyte and a LiCoO2 cathode. Interfacial modification between the solid electrolyte and cathode with a LiNbO3 buffer layer enables reversible charge-discharge cycling with a cell voltage of 3.9 V (vs. Li+/Li) at room temperature. Electrochemical analyses clarify that the given modification effectively suppresses side reactions at the cathode/solid electrolyte interface. The interfacial resistance is lowered by ca. 10 times with a 5 nm thick LiNbO3 buffer layer compared to that without a buffer layer, so that a discharge capacity of 109 mAh g-1 is achieved. These results suggest that interfacial modification can be a viable approach to the development of high-voltage all-solid-state batteries using closo-type complex hydride solid electrolytes and oxide cathodes.

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A general bimetal-ion adsorption strategy to prepare nickel single atom catalysts anchored on graphene for efficient oxygen evolution reaction
Yingqi Xu, Weifeng Zhang, Yaguang Li, Pengfei Lu, Zhong-Shuai Wu
2020 Vol. 43 (4): 52-57 [Abstract] ( 8 ) [HTML 1KB] [PDF] ( 0 )

Single-atom catalysts (SACs) supported on two-dimensional (2D) materials are highly attractive for maximizing their catalytic activity. However, graphene based SACs are primarily bonded with nitrogen and carbon sites, resulting in poor performance for the oxygen evolution reaction (OER). Herein, we develop a general bimetal-ion adsorption strategy for the synthesis of individually dispersed Ni SACs anchored on the oxygenated sites of ultrathin reduced graphene oxide as efficient OER electrocatalysts. The resultant Ni SACs for OER in alkaline electrolyte exhibit a highly stable overpotential of 328 mV at the current density of 10 mA cm-2, and Tafel slope of 84 mV dec-1 together with long-term durability and negligible degradation for 50 h, which is greatly outperform its counterparts of nitrogen bonded Ni SACs (564 mV, 364 mV dec-1) and Ni(OH)2 nanoparticles anchored on graphene (450 mV, 142 mV dec-1), and most reported Ni based OER electrocatalysts. Furthermore, the extended X-ray absorption fine structure at the Ni K-edge and theoretical simulation reveal that the nickel-oxygen coordination significantly boost OER performance. Therefore, this work will open numerous opportunities for creating novel-type 2D SACs via oxygen-metal bonding as highly robust OER catalysts.

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Rational design on separators and liquid electrolytes for safer lithium-ion batteries
Mengqi Yuan, Kai Liu
2020 Vol. 43 (4): 58-70 [Abstract] ( 9 ) [HTML 1KB] [PDF] ( 0 )

As the energy density of lithium-ion batteries (LIBs) continues to increase, their safety has become a great concern for further practical large-scale applications. One of the ultimate solution of the safety issue is to develop intrinsically safe battery components, where the battery separators and liquid electrolytes are critical for the battery thermal runaway process. In this review, we summarize recent progress in the rational materials design on battery separators and liquid electrolyte towards the goal of improving the safety of LIBs. Also, some strategies for further improving safety of LIBs are also briefly outlooked.

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Trithiocyanuric acid derived g-C3N4 for anchoring the polysulfide in Li-S batteries application
Ziyang Jia, Hongzhang Zhang, Ying Yu, Yuqing Chen, Jingwang Yan, Xianfeng Li, Huamin Zhang
2020 Vol. 43 (4): 71-77 [Abstract] ( 8 ) [HTML 1KB] [PDF] ( 0 )

Lithium-sulfur (Li-S) batteries have great potential as an electrochemical energy storage system because of the high theoretical energy density and acceptable cost of financial and environment. However, the shuttle effect leads to severe capacity fading and low coulombic efficiency. Here, graphitic carbon nitride (g-C3N4) is designed and prepared via a feasible and simple method from trithiocyanuric acid (TTCA) to anchor the polysulfides and suppress the shuttle effect. The obtained g-C3N4 exhibits strong chemical interaction with polysulfides due to its high N-doping of 56.87 at%, which is beneficial to improve the cycling stability of Li-S batteries. Moreover, the novel porous framework and high specific surface area of g-C3N4 also provide fast ion transport and broad reaction interface of sulfur cathode, facilitating high capacity output and superior rate performance of Li-S batteries. As a result, Li-S batteries assembled with g-C3N4 can achieve high discharge capacity of 1200 mAh/g at 0.2 C and over 800 mAh/g is remained after 100 cycles with a coulombic efficiency more than 99.5%. When the C-rate rises to 5 C, the reversible capacity of Li-S batteries can still maintain at 607 mAh/g.

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Insight into the formation mechanism of levoglucosenone in phosphoric acid-catalyzed fast pyrolysis of cellulose
Bin Hu, Qiang Lu, Yu-ting Wu, Wen-luan Xie, Min-shu Cui, Ji Liu, Chang-qing Dong, Yong-ping Yang
2020 Vol. 43 (4): 78-89 [Abstract] ( 10 ) [HTML 1KB] [PDF] ( 0 )

The catalytic fast pyrolysis of cellulose impregnated with phosphoric acid (H3PO4) offers a promising method for the selective production of levoglucosenone (LGO), a valuable anhydrosugar product. However, the fundamental mechanism for selective LGO formation is unclear. Herein, quantum chemistry calculations and catalytic fast pyrolysis experiments were performed to reveal the formation mechanism of LGO in H3PO4-catalyzed cellulose pyrolysis. H3PO4 significantly decreased the energy barriers of the pyrolytic reactions and altered the competitiveness of the LGO formation pathways, promoting LGO formation. Through different pathways in the non-catalytic and H3PO4-catalyzed conditions, LGO is mainly produced from the primary decomposition of glucose units of cellulose and secondary conversion of levoglucosan. The major catalytic formation pathways of LGO comprise similar reactions, with dehydration at the 3-OH + 2-H site as the rate-determining step. Importantly, secondary conversion of 1,4;3,6-dianhydro-α-d-glucopyranose is not feasible for LGO formation, in contrast to previous reports. In addition, a high degree of polymerization is beneficial for the selectivity of LGO formation in the catalytic process, because the glycosidic bond is important for the formation of the bicyclic structure (1,5-and 1,6-acetal rings).

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Syngas production by dry reforming of the mixture of glycerol and ethanol with CaCO3
Chengxiong Dang, Shijie Wu, Guangxing Yang, Yonghai Cao, Hongjuan Wang, Feng Peng, Hao Yu
2020 Vol. 43 (4): 90-97 [Abstract] ( 10 ) [HTML 1KB] [PDF] ( 0 )

The reduction of CO2 emission is crucial for the mitigation of climate change. A considerable amount of industrial CO2 can be absorbed in the form of carbonates through high-temperature sorption processes. In this regard, the efficient conversion of carbonates to value-added products will provide an economically viable method for the sustainable usage of carbon compounds. Herein, we report a promising solution involving the use of a glycerol and ethanol mixture as a hydrogen donor in the dry reforming process with CaCO3 to produce syngas. A series of metal active components, including Ni, Fe, Co, Cu, Pt, Pd, Ru, and Rh, was used to promote this reaction. Ni showed comparable performance with that of Pd, but outperformed Co, Fe, Cu, Rh, Ru, and Pt. Approximately 100% conversion of glycerol and ethanol,~92% selectivity of synthesis gas (H2 and CO), and a H2/CO ratio of~1.2 were achieved over CaCO3 containing 10 wt% Ni (10Ni-CaCO3). Meanwhile, the CO2 concentration was less than 5 vol%, indicating that most of the CO2 captured by the carbonate can be transformed into chemicals; however, they cannot simply be emitted. The CO2 released from the decomposition of CaCO3 not only adjusted the ratio of H2 to CO but also eliminated cokes to guarantee the CO2 absorption-conversion cyclic stability in the absence of steam and at high temperatures.

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Highly efficient perovskite solar cells based on symmetric hole transport material constructed with indaceno[1,2-b: 5,6-b']dithiophene core building block
Cheng Wu, Cheng Chen, Li Tao, Xingdong Ding, Mengmeng Zheng, Hongping Li, Gongqiang Li, Hongfei Lu, Ming Cheng
2020 Vol. 43 (4): 98-103 [Abstract] ( 13 ) [HTML 1KB] [PDF] ( 0 )

Two novel hole transport materials (HTMs) with indaceno[1,2-b:5,6-b']dithiophene (IDT) as core building blocks, termed IDT1 and IDT2, were designed and synthesized. The side alkyl chains were introduced to regulate and control the morphology and stacking behavior of HTMs, and the peripheral triarylamine arms were introduced to adjust the energy levels and to facilitate efficient hole transport. Applied in mesoporous structured perovskite solar cells (PSCs), HTM IDT1 achieved higher power conversion efficiency (PCE, 19.55%) and better stability than Spiro-OMeTAD (19.25%) and IDT2 (15.77%) based PSC. These results suggest the potential of IDT1 as a promising HTM for PSCs.

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Ternary NiCoFe-layered double hydroxide hollow polyhedrons as highly efficient electrocatalysts for oxygen evolution reaction
Yongji Qin, Fanping Wang, Jing Shang, Muzaffar Iqbal, Aijuan Han, Xiaoming Sun, Haijun Xu, Junfeng Liu
2020 Vol. 43 (4): 104-107 [Abstract] ( 12 ) [HTML 1KB] [PDF] ( 0 )

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High performance and stability of double perovskite-type oxide NdBa0.5Ca0.5Co1.5Fe0.5O5+δ as an oxygen electrode for reversible solid oxide electrochemical cell
Yunfeng Tian, Yun Liu, Wenjie Wang, Lichao Jia, Jian Pu, Bo Chi, Jian Li
2020 Vol. 43 (4): 108-115 [Abstract] ( 8 ) [HTML 1KB] [PDF] ( 0 )

In this study, we successfully synthesized double perovskite-type oxide NdBa0.5Ca0.5Co1.5Fe0.5O5+δ (NBCCF) using a conventional wet chemical method as the oxygen electrode for reversible solid oxide electrochemical cells (RSOCs). The polarization resistance (Rp) of the composite electrode NBCCFGd0.1Ce0.9O2 (GDC) is only 0.079 Ω cm2 at 800℃ under air. The single cell based on NBCCF-GDC electrode displays a peak power density of 0.941 W/cm2 in fuel cell mode and a low Rp value of 0.134 Ω cm2. In electrolysis cell mode, the cell displays an outstanding oxygen evolution reaction (OER) activity and shows current density as high as 0.92 A/cm2 with 50 vol% AH (Absolute Humidity) at 800℃ and applied voltage of 1.3 V. Most importantly, the cell exhibits admirable durability of 60 h both in electrolysis mode and fuel cell mode with distinguished reversibility. All these results suggest that NBCCF is a promising candidate electrode for RSOC.

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Atomic scale understanding of aluminum intercalation into layered TiS2 and its electrochemical properties
Shunlong Ju, Xiaowei Chen, Zunxian Yang, Guanglin Xia, Xuebin Yu
2020 Vol. 43 (4): 116-120 [Abstract] ( 9 ) [HTML 1KB] [PDF] ( 0 )

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Size-dependent catalytic activity of cobalt phosphides for hydrogen evolution reaction
Xiaoke Li, Luhua Jiang, Jing Liu, Qingfeng Hua, Erdong Wang, Guangwen Xie
2020 Vol. 43 (4): 121-128 [Abstract] ( 10 ) [HTML 1KB] [PDF] ( 0 )

Transition metal phosphides are a class of promising electrocatalysts for hydrogen evolution reaction (HER) to replace noble metals. In this work, we for the first time synthesize carbon supported CoP nanoparticles with the average particle sizes from 3.3 to 9.2 nm, via a solvothermal process followed by low-temperature topological phosphorization, and the size-dependent HER activity of the CoP is investigated by virtue of TEM, XRD, XPS and the electrochemical techniques. It is discovered that the 9.2nm-CoP particles possess high intrinsic HER catalytic activity as compared to the 3.3nm-CoP, although the smaller one displays a high mass activity due to the large surface area. Detailed studies manifest that the small CoP particles suffer from serious oxidation once exposing to air. In contrast, most cobalt remains in the quasi-metallic state in the relatively large CoP particles, which is beneficial for the desorption of Hads, the rate determining step of the HER process over CoP surface. In addition, the low charge transfer resistance across the liquid/solid interfaces also contributes to the excellent HER activity of the relatively large CoP particles.

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Carbon foam with microporous structure for high performance symmetric potassium dual-ion capacitor
Yanhong Feng, Suhua Chen, Jue Wang, Bingan Lu
2020 Vol. 43 (4): 129-138 [Abstract] ( 9 ) [HTML 1KB] [PDF] ( 0 )

A novel carbon foam with microporous structure (CFMS), with the advantages of a simple fabrication process, low energy consumption, large specific surface area and high conductivity, has been prepared by a facile one-step carbonization. In addition, the carbon foam possesses suitable interlayer spacing in short range which is flexible to accommodate the deformation of carbon layer caused by the ion insertion and deinsertion at the charge and discharge state. Furthermore, a low cost carbon-based symmetric potassium dual-ion capacitor (PDIC), which integrates the virtues of potassium ion capacitors and dual-ion batteries, is successfully established with CFMS as both the battery-type cathode and the capacitor-type anode. PDIC displays a superior rate performance, an ultra-long cycle life (90% retention after 10000 cycles), and a high power density of 7800 W kg-1 at an energy density of 39 Wh kg-1. The PDIC also exhibits excellent ultrafast charge and slow discharge properties, with a full charge in just 60 s and a discharge time of more than 3000 s.

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Tetrabenzotriazacorrole and its derivatives as undoped hole transporting materials for perovskite solar cells: Synthesis, device fabrication, and device performance
Xian-Fu Zhang, Chang Liu, Jianchang Wu, Baomin Xu
2020 Vol. 43 (4): 139-147 [Abstract] ( 12 ) [HTML 1KB] [PDF] ( 0 )

Phosphorous tetrabenzotriazacorrole (TBC) and its two soluble derivatives (TBC-1 and TBC-2) were synthesized and used for the first time as undoped hole transporting materials (HTMs) in MAPbI3 perovskite solar cells (PSCs). Their performance in PSCs was measured and compared with that of SpiroOMeTAD and phthalocyanine precursor. The fundamental properties related to HTMs are also examined. These novel HTMs are easily prepared, cost-effective, and solution processable. The materials exhibited much higher hole transport mobility and broader light absorption than pristine Spiro-OMeTAD and phthalocyanine precursor. They can work efficiently in the absence of any dopant for devices composed of FTO/cp-TiO2/mp-TiO2/MAPbI3/HTM/Au. The undoped mesoscopic solar cell devices based on TBC exhibited a promising power conversion efficiency (PCE) of up to 16.2% (measured at 100 mW cm2 illumination, AM 1.5 G), together with good long-term stability under ambient conditions. This PCE of 16.2% observed using TBC is remarkably higher than the 11.2% observed using undoped Spiro-OMeTAD and also much better than the 8.70% observed using its phthalocyanine precursor. As to substitution effects, α-substituted TBC-1 was found to be a better HTM than β-substituted TBC-2 (PCE 11.4%) and unsubstituted TBC-3 (PCE 6.81%) under the same conditions. These results provide the basis for further exploiting TBC compounds as a new type of low-cost and effective HTM for PSCs.

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Single-phase P2-type layered oxide with Cu-substitution for sodium ion batteries
Tao Chen, Weifang Liu, Yi Zhuo, Hang Hu, Maolan Zhu, Ruizheng Cai, Xinxin Chen, Jun Yan, Kaiyu Liu
2020 Vol. 43 (4): 148-154 [Abstract] ( 8 ) [HTML 1KB] [PDF] ( 0 )

The development of high-performance layered oxide cathodes for sodium ion batteries (SIBs) continues to facing be hindered by severe challenges to date. Herein, a single-phase P2-Na0.67Mn0.6Ni0.2Co0.1Cu0.1O2 (NMNCC) comprising multiple-layer-oriented stacked nanoflakes is designed and synthesized via a simple sol-gel method. The large lattice parameters ensure a large three-dimensional frame, which enables the diffusion of sodium ions. Owing to its optimal morphology structure modulation transition metal substitution strategy, the MNCC electrode delivers a reversible capacity of 131.3 mAh g-1 at 0.1 C with retention of 86.7% after 200 cycles. In addition, it provides an initial capacity of 86.7 mAh g-1, and a retention of 80.0% after 500 cycles even at a current density of up to 1 A g-1. The stable single-phase structure and slight volume shrinkage observed after Na+ extraction further delay structural degradation. High Na+ mobility and low Na+ diffusion resistance are also guarantee the excellent rate performance of the NMNCC electrode. Thus, we determine that the NMNCC cathode is significant in the advancement of promising novel layered oxide cathodes.

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Cerium-modified Ni-La2O3/ZrO2 for CO2 methanation
Shuangshuang Li, Guilong Liu, Siran Zhang, Kang An, Zhi Ma, Luhui Wang, Yuan Liu
2020 Vol. 43 (4): 155-164 [Abstract] ( 8 ) [HTML 1KB] [PDF] ( 0 )

The key point in CO2 methanation is to improve the activity at low temperature and the stability. For this purpose, a new cerium-modified Ni-La2O3/ZrO2 catalyst was prepared using La1-xCexNiO3/ZrO2 with perovskite phase as the precursor, which was obtained by citrate complexation combined with an impregnation method. The resulting catalyst was characterized through Nitrogen adsorption and desorption, X-ray diffraction (XRD), Transmission electron microscopy (TEM), Hydrogen temperature programmed reduction (H2-TPR), Temperature-programmed desorption of CO2 (CO2-TPD) and that of H2 (H2-TPD), and X-ray photoelectron spectroscopy (XPS) techniques, and the catalytic performances for CO2 methanation was investigated. Cerium modification could improve the effective activation of CO2, thus enhancing the activity at low temperature for CO2 methanation. The metal Ni nanoparticles prepared using this method were highly dispersed and showed excellent resistance to sintering, leading to very good stability, which could be attributed to the following:Ni nanoparticles could be confined by cerium-modified La2O3; La2O3 could be confined by the cerium ions at the La2O3/ZrO2 interface; and the cerium ions were confined by ZrO2.

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Quaternized polymer binder for lithium-sulfur batteries: The effect of cation structure on battery performance
Fang Wang, Lv Li, Da Lei, Yongpeng Li, He Yang, Weili Zhu, Fengxiang Zhang
2020 Vol. 43 (4): 165-172 [Abstract] ( 8 ) [HTML 1KB] [PDF] ( 0 )

Lithium-sulfur (Li-S) batteries are great candidates for energy storage systems, but need to overcome the issues of low sulfur utilization and polysulfide shuttling for use in large-scale commercial applications. Recently, quaternized polymers have received much attention for their polysulfide trapping properties due to electrostatic interaction. In this work, we report a series of polyarylether sulfone (PSF) binders with different cation structures including imidazolium (Im), triethylammonium (Tr), and morpholinium (Mo). The ability of the these quaternized binders and the conventional poly(vinylidene fluoride) or PVDF binder to capture polysulfide increases in the order of PVDF << PSF-Mo < PSF-Tr < PSF-Im. The delocalized charge on the imidazolium cation may promote the interaction between PSF-Im and polysulfide as indicated by an X-ray photoelectron spectroscopic study. The PSF-Im based cathodes showed the highest capacity retention (77% at 0.2 C after 100 cycles and 84% at 0.5 C after 120 cycles), and the best rate capability. This work demonstrates the importance of the cation structure in the design of efficient quaternized binders for high performance Li-S batteries.

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Molten salt synthesis and supercapacitor properties of oxygen-vacancy LaMnO3-δ
Ya-Li Song, Zi-Chang Wang, Yong-De Yan, Mi-Lin Zhang, Gui-Ling Wang, Tai-Qi Yin, Yun Xue, Fan Gao, Min Qiu
2020 Vol. 43 (4): 173-181 [Abstract] ( 10 ) [HTML 1KB] [PDF] ( 0 )

Due to the unique structure of perovskite materials, their capacitance can be improved by introducing oxygen vacancy. In this paper, the LaMnO3-δ material containing oxygen vacancy was synthesized by molten salt method in KNO3-NaNO3-NaNO2 melt. The La-Mn-O crystal grows gradually in molten salt with the increase of temperature. It was confirmed that LaMnO3-δ with perovskite structure and incomplete oxygen content were synthesized by molten salt method and presented a three-dimensional shape. LaMnO3-δ stores energy by redox reaction and adsorption of OH- in electrolyte simultaneously. In comparison with the stoichiometric LaMnO3 prepared by the sol-gel method, LaMnO3-δ prepared by molten salt method proffered higher capacitance and better performance. The galvanostatic charge-discharge curve showed specific capacitance of 973.5 F/g under current density of 1 A/g in 6 M KOH. The capacitance of LaMnO3-δ was 82.7% under condition of 5 A/g compared with the capacitance at the current of 1A/g, and the specific capacitances of 648.0 and 310.0 F/g were obtained after 2000 and 5000 cycles of galvanostatic charging-discharging, respectively. Molten salt synthesis method is relatively simple and suitable for industrial scale, presenting a promising prospect in the synthesis of perovskite oxide materials.

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γ -MnO2 nanorods/graphene composite as efficient cathode for advanced rechargeable aqueous zinc-ion battery
Chao Wang, Yinxiang Zeng, Xiang Xiao, Shijia Wu, Guobin Zhong, Kaiqi Xu, Zengfu Wei, Wei Su, Xihong Lu
2020 Vol. 43 (4): 182-187 [Abstract] ( 10 ) [HTML 1KB] [PDF] ( 0 )

Aqueous Zn//MnO2 batteries are emerging as promising large-scale energy storage devices owing to their cost-effectiveness, high safety, high output voltage, and energy density. However, the MnO2 cathode suffers from intrinsically poor rate performance and rapid capacity deterioration. Here, we remove the roadblock by compositing MnO2 nanorods with highly conductive graphene, which remarkably enhances the electrochemical properties of the MnO2 cathode. Benefiting from the boosted electric conductivity and ion diffusion rate as well as the structural protection of graphene, the Zn//MnO2-graphene battery presents an admirable capacity of 301 mAh g-1 at 0.5 A g-1, corresponding to a high energy density of 411.6 Wh kg-1. Even at a high current density of 10 A g-1, a decent capacity of 95.8 mAh g-1 is still obtained, manifesting its excellent rate property. Furthermore, an impressive power density of 15 kW kg-1 is achieved by the Zn//MnO2-graphene battery.

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Two-dimensional ultrathin MoS2-modified black Ti3+-TiO2 nanotubes for enhanced photocatalytic water splitting hydrogen production
Wei Ou, Jiaqi Pan, Yanyan Liu, Shi Li, Hongli Li, Weijie Zhao, Jingjing Wang, Changsheng Song, Yingying Zheng, Chaorong Li
2020 Vol. 43 (4): 188-194 [Abstract] ( 8 ) [HTML 1KB] [PDF] ( 0 )

Two-dimensional (2D) ultrathin MoS2-modified black Ti3+-TiO2 nanotubes were fabricated using an electrospinning-hydrothermal treatment-reduction method. Bare TiO2 nanotubes were fabricated via electrospinning. Then, 2D MoS2 lamellae were grown on the surface of the nanotubes and Ti3+/Ov ions were introduced by reduction. The photocatalytic performance of the 2D MoS2/Ti3+-TiO2 nanotubes was~15 times better than that of TiO2. The HER enhancement of the MoS2/Ti3+-TiO2 nanotubes can be attributed to the Pt-like behavior of 2D MoS2 and the presence of Ti3+ ions, which facilitated the quick diffusion of the photogenerated electrons to water, reducing the H2 activation barrier. The presence of Ov ions in the nanotubes and their hollow structure increased their solar utilization.

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Electrochemical synthesis of ammonia in molten salts
Jiarong Yang, Wei Weng, Wei Xiao
2020 Vol. 43 (4): 195-207 [Abstract] ( 8 ) [HTML 1KB] [PDF] ( 0 )

Ammonia is important feedstock for both fertilizer production and carbon-free liquid fuel. Many techniques for ammonia formation have been developed, hoping to replace the industrial energy-intensive Haber-Bosch route. Electrochemical synthesis of ammonia in molten salts is one promising alternative method due to the strong solubility of N3- ions, a wide potential window of molten salt electrolytes and tunable electrode reactions. Generally, electrochemical synthesis of ammonia in molten salts begins with the electro-cleavage of N2/hydrogen sources on electrode surfaces, followed by diffusion of N3-/H+-containing ions towards each other for NH3 formation. Therefore, the hydrogen sources and molten salt composition will greatly affect the reactions on electrodes and ions diffusion in electrolytes, being critical factors determining the faradaic efficiency and formation rate for ammonia synthesis. This report summarizes the selection criteria for hydrogen sources, the reaction characteristics in various molten salt systems, and the preliminary explorations on the scaling-up synthesis of ammonia in molten salt. The formation rate and faradaic efficiency for ammonia synthesis are discussed in detail based on different hydrogen sources, various molten salt systems, changed electrolysis conditions as well as diverse catalysts. Electrochemical synthesis of ammonia might be further enhanced by optimizing the molten salt composition, using electrocatalysts with well-defined composition and microstructure, and innovation of novel reaction mechanism.

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Steam reforming of acetic acid over Ni-Ba/Al2O3 catalysts: Impacts of barium addition on coking behaviors and formation of reaction intermediates
Zhanming Zhang, Yiran Wang, Kai Sun, Yuewen Shao, Lijun Zhang, Shu Zhang, Xiao Zhang, Qing Liu, Zhenhua Chen, Xun Hu
2020 Vol. 43 (4): 208-219 [Abstract] ( 12 ) [HTML 1KB] [PDF] ( 0 )

The influence of barium addition to a Ni/Al2O3 catalyst on the reaction intermediates formed, the activity, resistance of the catalyst to coking, and properties of the coke formed after acetic acid steam reforming were investigated in this study. The results showed the drastic effects of barium addition on the physicochemical properties and performances of the catalyst. The solid-phase reaction between alumina and BaO formed BaAl2O4, which re-constructed the alumina structure, resulting in a decrease in the specific surface area and an increase in the resistance of metallic Ni to sintering. The addition of barium was also beneficial for enhancing the catalytic activity, resulting from the changed catalytic reaction network. The in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) study of the acetic acid steam reforming indicated that barium could effectively suppress the accumulation of the reaction intermediates of carbonyl, formate, and C=C functional groups on the catalyst surface, attributed to its relatively high ability to cause the gasification of these species. In addition, coking was considerably more significant over the Ba-Ni/Al2O3 catalyst. Moreover, the Ba-Ni/Al2O3 catalyst was more stable than the Ni/Al2O3 catalyst, owing to the distinct forms of coke formed (carbon nanotube form over the Ba-Ni/Al2O3 catalyst, and the amorphous form over the Ni/Al2O3 catalyst).

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Recent progress of surface coating on cathode materials for high-performance lithium-ion batteries
Peiyuan Guan, Lu Zhou, Zhenlu Yu, Yuandong Sun, Yunjian Liu, Feixiang Wu, Yifeng Jiang, Dewei Chu
2020 Vol. 43 (4): 220-235 [Abstract] ( 10 ) [HTML 1KB] [PDF] ( 0 )

Lithium-ion batteries (LIB) have received substantial attention in the last 10 years, as they offer great promise as power sources that can lead to the electric vehicle (EV) revolution in the next 5 years. Since the cathode serves as a key component in LIB, its properties significantly affect the performance of the whole system. Recently, the cathode surface modification based on coating technique has been widely employed to enhance the electrochemical performances by improving the material conductivity, stabilising the physical structure of materials, as well as preventing the reactions between the electrode and electrolyte. In this work, we reviewed the present of a number of promising cathode materials for Li-ion batteries. After that, we summarized the very recent research progress focusing on the surface coating strategies, mainly including the coating materials, the coating technologies, as well as the corresponding working mechanisms for cathodes. At last, the challenges faced and future guidelines for optimizing cathode materials are discussed. In this study, we propose that the structure of cathode is a crucial factor during the selection of coating materials and technologies.

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· 2018 Annual Meeting-International Coalition for Energy Storage and Innovation (ICESI)
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Monthly
(Started in 1992)
Renamed from JNGC in 2013

ISSN 2095-4956
CN 10-1287/O6

Editors-in-Chief
Xinhe Bao
Gabriele Centi


Edited by

Editorial Office of
Journal of Energy Chemistry

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Dalian Institute of
Chemical Physics, CAS
Science Press

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