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2023, Volume 2,  Issue 2

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Letter
OPEN ACCESS
Atomically constructing a van der Waals heterostructure of CrTe2/Bi2Te3 by molecular beam epitaxy
Jinhua Nie, Rui Li, Maopeng Miao, Yingshuang Fu, Wenhao Zhang
2023, 2(2) doi: 10.1088/2752-5724/acbd64
Abstract(137) PDF(62)
Abstract:

A 2D heterostructure with proximity coupling of magnetism and topology can provide enthralling prospects for hosting new quantum states and exotic properties that are relevant to next-generation spintronic devices. Here, we synthesize a delicate van der Waals (vdW) heterostructure of CrTe2/Bi2Te3 at the atomic scale via molecular beam epitaxy. Low-temperature scanning tunneling microscopy/spectroscopy measurements are utilized to characterize the geometric and electronic properties of the CrTe2/Bi2Te3 heterostructure with a compressed vdW gap. Detailed structural analysis reveals complex interfacial structures with diversiform step heights and intriguing moiré patterns. The formation of the interface is ascribed to the embedded characteristics of CrTe2 and Bi2Te3 by sharing Te atomic layer upon interfacing, showing intercoupled features of electronic structure for CrTe2 and Bi2Te3. Our study demonstrates a possible approach to construct artificial heterostructures with different types of ordered states, which may be of use for achieving tunable interfacial Dzyaloshinsky–Moriya interactions and tailoring the functional building blocks in low dimensions.
Topical Review
OPEN ACCESS
Carbon-based perovskite solar cells with electron and hole-transporting/-blocking layers
Wenjin Yu, Yu Zou, Shining Zhang, Zishi Liu, Cuncun Wu, Bo Qu, Zhijian Chen, Lixin Xiao
2023, 2(2) doi: 10.1088/2752-5724/acbbc2
Abstract(167) PDF(49)
Abstract:
Towards commercialization of perovskite solar cells (PSCs), further reducing the cost and increasing the stability of PSCs have been the most important tasks of researchers, as the efficiency of single-junction PSCs has reached a competitive level among all kinds of single-junction solar cells. Carbon-electrode-based PSCs (CPSCs), as one of the most promising constructions for achieving stable economical PSCs, now attract enormous attention for their cost-effectiveness and stability. Here, we briefly review the development of CPSCs and reveal the importance of n-i-p architecture for state-of-the-art CPSCs. However, despite their promising potential, challenges still exist in CPSCs in the n-i-p architecture, which mainly stem from the incompact contact of the hole-transporting layer (HTL)/carbon electrode. Thus, new carbon materials and/or novel manufacturing methods should be proposed. In addition, HTL is yet to be appropriate for state-of-the-art CPSCs because the fabrication of carbon electrode could result in the destruction of the underlayer. To further enhance the performance of CPSCs, both the HTL and electron transport layer as well as their interfaces with perovskite active layer need to be improved. We recommend that the perovskite active layer, with its long carrier lifetime, strong carrier transport capability, and long-term stability, is necessary as well for improved performance of CPSCs. We also highlight current researches on CPSCs and provide a systematic review of various types of regulation tools.
OPEN ACCESS
High entropy materials as emerging electrocatalysts for hydrogen production through low-temperature water electrolysis
Jonathan Ruiz Esquius, Lifeng Liu
2023, 2(2) doi: 10.1088/2752-5724/accbd8
Abstract(152) PDF(44)
Abstract:
The production of hydrogen through water electrolysis (WE) from renewable electricity is set to revolutionise the energy sector that is at present heavily dependent on fossil fuels. However, there is still a pressing need to develop advanced electrocatalysts able to show high activity and withstand industrially-relevant operating conditions for a prolonged period of time. In this regard, high entropy materials (HEMs), including high entropy alloys and high entropy oxides, comprising five or more homogeneously distributed metal components, have emerged as a new class of electrocatalysts owing to their unique properties such as low atomic diffusion, structural stability, a wide variety of adsorption energies and multi-component synergy, making them promising catalysts for challenging electrochemical reactions, including those involved in WE. This review begins with a brief overview about WE technologies and a short introduction to HEMs including their synthesis and general physicochemical properties, followed by a nearly exhaustive summary of HEMs catalysts reported so far for the hydrogen evolution reaction, the oxygen evolution reaction and the overall water splitting in both alkaline and acidic conditions. The review concludes with a brief summary and an outlook about the future development of HEM-based catalysts and further research to be done to understand the catalytic mechanism and eventually deploy HEMs in practical water electrolysers.
OPEN ACCESS
Extending MoS2-based materials into the catalysis of non-acidic hydrogen evolution: challenges, progress, and perspectives
Hao Fei, Ruoqi Liu, Yunze Zhang, Hongsheng Wang, Miao Wang, Siyuan Wang, Meng Ni, Zhuangzhi Wu, Jian Wang
2023, 2(2) doi: 10.1088/2752-5724/acc51d
Abstract(81) PDF(24)
Abstract:
The production of hydrogen through water electrolysis (WE) from renewable electricity is set to revolutionise the energy sector that is at present heavily dependent on fossil fuels. However, there is still a pressing need to develop advanced electrocatalysts able to show high activity and withstand industrially-relevant operating conditions for a prolonged period of time. In this regard, high entropy materials (HEMs), including high entropy alloys and high entropy oxides, comprising five or more homogeneously distributed metal components, have emerged as a new class of electrocatalysts owing to their unique properties such as low atomic diffusion, structural stability, a wide variety of adsorption energies and multi-component synergy, making them promising catalysts for challenging electrochemical reactions, including those involved in WE. This review begins with a brief overview about WE technologies and a short introduction to HEMs including their synthesis and general physicochemical properties, followed by a nearly exhaustive summary of HEMs catalysts reported so far for the hydrogen evolution reaction, the oxygen evolution reaction and the overall water splitting in both alkaline and acidic conditions. The review concludes with a brief summary and an outlook about the future development of HEM-based catalysts and further research to be done to understand the catalytic mechanism and eventually deploy HEMs in practical water electrolysers.
OPEN ACCESS
In-materio reservoir computing based on nanowire networks: fundamental, progress, and perspective
Renrui Fang, Woyu Zhang, Kuan Ren, Peiwen Zhang, Xiaoxin Xu, Zhongrui Wang, Dashan Shang
2023, 2(2) doi: 10.1088/2752-5724/accd87
Abstract(55) PDF(37)
Abstract:
The reservoir computing (RC) system, known for its ability to seamlessly integrate memory and computing functions, is considered as a promising solution to meet the high demands for time and energy-efficient computing in the current big data landscape, compared with traditional silicon-based computing systems that have a noticeable disadvantage of separate storage and computation. This review focuses on in-materio RC based on nanowire networks (NWs) from the perspective of materials, extending to reservoir devices and applications. The common methods used in preparing nanowires-based reservoirs, including the synthesis of nanowires and the construction of networks, are firstly systematically summarized. The physical principles of memristive and memcapacitive junctions are then explained. Afterwards, the dynamic characteristics of nanowires-based reservoirs and their computing capability, as well as the neuromorphic applications of NWs-based RC systems in recognition, classification, and forecasting tasks, are explicated in detail. Lastly, the current challenges and future opportunities facing NWs-based RC are highlighted, aiming to provide guidance for further research.
Perspective
OPEN ACCESS
Nanowire-based synaptic devices for neuromorphic computing
Xue Chen, Bingkun Chen, Pengfei Zhao, Vellaisamy A. L. Roy, Suting Han, Ye Zhou
2023, 2(2) doi: 10.1088/2752-5724/acc678
Abstract(104) PDF(44)
Abstract:
The traditional von Neumann structure computers cannot meet the demands of high-speed big data processing; therefore, neuromorphic computing has received a lot of interest in recent years. Brain-inspired neuromorphic computing has the advantages of low power consumption, high speed and high accuracy. In human brains, the data transmission and processing are realized through synapses. Artificial synaptic devices can be adopted to mimic the biological synaptic functionalities. Nanowire (NW) is an important building block for nanoelectronics and optoelectronics, and many efforts have been made to promote the application of NW-based synaptic devices for neuromorphic computing. Here, we will introduce the current progress of NW-based synaptic memristors and synaptic transistors. The applications of NW-based synaptic devices for neuromorphic computing will be discussed. The challenges faced by NW-based synaptic devices will be proposed. We hope this perspective will be beneficial for the application of NW-based synaptic devices in neuromorphic systems.
OPEN ACCESS
Unlocking the multi-electron transfer reaction in NASICON-type cathode materials
Yuan Liu, Xiaohui Rong, Fei Xie, Yaxiang Lu, Junmei Zhao, Liquan Chen, Yongsheng Hu
2023, 2(2) doi: 10.1088/2752-5724/acc7bb
Abstract(102) PDF(48)
Abstract:
The growing concern about scarcity and large-scale applications of lithium resources has attracted efforts to realize cost-effective phosphate-based cathode materials for next-generation Na-ion batteries (NIBs). In previous work, a series of materials (such as Na4Fe3(PO4)2(P2O7), Na3VCr(PO4)3, Na4VMn(PO4)3, Na3MnTi(PO4)3, Na3MnZr(PO4)3, etc) with ∼120 mAh g−1 specific capacity and high operating potential has been proposed. However, the mass ratio of the total transition metal in the above compounds is only ∼22 wt%, which means that one-electron transfer for each transition metal shows a limited capacity (the mass ratio of Fe is 35.4 wt% in LiFePO4). Therefore, a multi-electron transfer reaction is necessary to catch up to or go beyond the electrochemical performance of LiFePO4. This review summarizes the reported NASICON-type and other phosphate-based cathode materials. On the basis of the aforementioned experimental results, we pinpoint the multi-electron behavior of transition metals and shed light on designing rules for developing high-capacity cathodes in NIBs.
Paper
OPEN ACCESS
Polyamorphism mediated by nanoscale incipient concentration wave uncovering hidden amorphous intermediate state with ultrahigh modulus in nanostructured metallic glass
Qiang Luo, Weiran Cui, Huaping Zhang, Liangliang Li, Liliang Shao, Mingjuan Cai, Zhengguo Zhang, Lin Xue, Jun Shen, Yu Gong, Xiaodong Li, Maozi Li, Baolong Shen
2023, 2(2) doi: 10.1088/2752-5724/acbdb4
Abstract(119) PDF(18)
Abstract:
Comprehending the pressure-/temperature-induced structural transition in glasses, as one of the most fascinating issues in material science, is far from being well understood. Here, we report novel polyamorphic transitions in a Cu-based metallic glass (MG) with apparent nanoscale structural heterogeneity relating to proper Y addition. The low-density MG compresses continuously with increasing pressure, and then a compression plateau appears after ∼8.1 GPa, evolving into an intermediate state with an ultrahigh bulk modulus of ∼467 GPa. It then transforms to a high-density MG with significantly decreased structural heterogeneity above ∼14.1 GPa. Three-dimensional atom probe tomography reveals concentration waves of Cu/Zr elements with an average wavelength of ∼5–6 nm, which promote the formation of interconnected ringlike networks composed of Cu-rich and Zr-rich dual-glass domains at nanometer scale. Our experimental and simulation results indicate that steplike polyamorphism may stem from synergic effects of the abnormal compression of the Zr–Zr bond length at the atomic scale and the interplay between the applied pressure and incipient concentration waves (Cu and Zr) at several nanometer scales. The present work provides new insights into polyamorphism in glasses and contributes to the development of high-performance amorphous materials by high-pressure nanostructure engineering.
OPEN ACCESS
Combinatorial development of antibacterial FeCoCr-Ag medium entropy alloy
Jiashu Cao, Xin Jiang, Qinghua Zhang, Fusen Yuan, Jihao Yu, Fan Yang, Mingxing Li, Chao Wang, Ying Lu, Ming Li, Weihua Wang, Yanhui Liu
2023, 2(2) doi: 10.1088/2752-5724/acbd63
Abstract(184) PDF(68)
Abstract:

Antibacterial activity and mechanical properties of FeCoCr-Ag medium entropy alloys were studied via combinatorial fabrication paired with high-throughput characterizations. It was found that the antibacterial activity and mechanical properties exhibit non-linear dependence on the content of Ag addition. Within the studied alloys, (FeCoCr)80Ag20 possesses an optimized combination of different properties for potential applications as antibacterial coating materials. The underlying mechanism is ascribed to the formation of a dual-phase structure that leads to competition between the role of Ag phase and FeCoCr phase at different Ag content. The results not only demonstrate the power and effectiveness of combinatorial methods in multi-parameter optimization but also indicate the potential of high entropy alloys as antibacterial materials.
Commentary
OPEN ACCESS
Can two-dimensional graphdiyne-based materials be novel materials for perovskite solar cell applications?
Eng Liang Lim, Zhanhua Wei
2023, 2(2) doi: 10.1088/2752-5724/acc3b3
Abstract(98) PDF(32)
Abstract:
Two-dimensional (2D) graphdiyne (GDY)-based materials have attracted attention in the solar cell research community owing to their unique physicochemical properties and hydrophobic nature which can serve as moisture resistance from the surrounding medium. Benefiting from these, the performance and stability ofperovskite solar cells (PSCs) can be greatly improved via the addition of 2D GDY-based materials. This mini-review summarizes the recent development of 2D GDY-based materials for PSC application. The roles of 2D GDY-based materials, such as hole transporting material, electron transporting material, dopant material in perovskite film and interfacial layer, are discussed in detail. Moreover, we provide future perspectives in this field, aiming to help further progress efficient and stable 2D GDY-based materials in PSCs.

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