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1.
本文结合可见-近红外-中红外瞬态吸收光谱技术对离子交换法制备的少层MoS2中缺陷介导的载流子动力学进行了详细的解析. 在近红外瞬态吸收光谱中观察到的宽带漂白信号表明少层MoS2纳米片带隙中分布着大量的缺陷态. 实验结果明确揭示了载流子被缺陷态的快速捕获以及进一步的复合过程,证明带隙中的缺陷态对MoS2光生载流子动力学过程起着至关重要的作用. 在中红外瞬态吸收光谱中观察到的正信号到负信号的转变进一步证实了在导带下小于0.24 eV处存在被载流子占据的缺陷态. 这些在少层MoS2纳米片中存在的缺陷态可以作为有效的载流子捕获中心来辅助光生载流子在皮秒时间尺度内完成非辐射复合过程. 相似文献
2.
Dr. Yoshinobu Kamakura Dr. Chomponoot Suppaso Issei Yamamoto Ryusuke Mizuochi Yusuke Asai Prof. Dr. Teruki Motohashi Prof. Dr. Daisuke Tanaka Prof. Dr. Kazuhiko Maeda 《Angewandte Chemie (International ed. in English)》2023,62(28):e202305923
Certain metal complexes are known as high-performance CO2 reduction photocatalysts driven by visible light. However, most of them rely on rare, precious metals as principal components, and integrating the functions of light absorption and catalysis into a single molecular unit based on abundant metals remains a challenge. Metal-organic frameworks (MOFs), which can be regarded as intermediate compounds between molecules and inorganic solids, are potential platforms for the construction of a simple photocatalytic system composed only of Earth-abundant nontoxic elements. In this work, we report that a tin-based MOF enables the conversion of CO2 into formic acid with a record high apparent quantum yield (9.8 % at 400 nm) and >99 % selectivity without the need for any additional photosensitizer or catalyst. This work highlights a new MOF with strong potential for photocatalytic CO2 reduction driven by solar energy. 相似文献
3.
Dr. Ziyang Song Dr. Ling Miao Dr. Yaokang Lv Prof. Lihua Gan Prof. Mingxian Liu 《Angewandte Chemie (International ed. in English)》2023,62(38):e202309446
Organic small molecules as high-capacity cathodes for Zn-organic batteries have inspired numerous interests, but are trapped by their easy-dissolution in electrolytes. Here we knit ultrastable lock-and-key hydrogen-bonding networks between 2, 7-dinitropyrene-4, 5, 9, 10-tetraone (DNPT) and NH4+ charge carrier. DNPT with octuple-active carbonyl/nitro centers (H-bond acceptor) are redox-exclusively accessible for flexible tetrahedral NH4+ ions (H-bond donator) but exclude larger and rigid Zn2+, due to a lower activation energy (0.14 vs. 0.31 eV). NH4+ coordinated H-bonding chemistry conquers the stability barrier of DNPT in electrolyte, and gives fast diffusion kinetics of non-metallic charge carrier. A stable two-step 4e− NH4+ coordination with DNPT cathode harvests a high capacity (320 mAh g−1), a high-rate capability (50 A g−1) and an ultralong life (60,000 cycles). This finding points to a new paradigm for H-bond stabilized organic small molecules to design advanced zinc batteries. 相似文献
4.
Dr. Xuelin Yao Dr. Heng Zhang Fanmiao Kong Dr. Antoine Hinaut Dr. Rémy Pawlak Prof. Dr. Masanari Okuno Dr. Robert Graf Dr. Peter N. Horton Prof. Dr. Simon J. Coles Prof. Dr. Ernst Meyer Prof. Dr. Lapo Bogani Prof. Dr. Mischa Bonn Prof. Dr. Hai I. Wang Prof. Dr. Klaus Müllen Prof. Dr. Akimitsu Narita 《Angewandte Chemie (International ed. in English)》2023,62(46):e202312610
Structurally defined graphene nanoribbons (GNRs) have emerged as promising candidates for nanoelectronic devices. Low band gap (<1 eV) GNRs are particularly important when considering the Schottky barrier in device performance. Here, we demonstrate the first solution synthesis of 8-AGNRs through a carefully designed arylated polynaphthalene precursor. The efficiency of the oxidative cyclodehydrogenation of the tailor-made polymer precursor into 8-AGNRs was validated by FT-IR, Raman, and UV/Vis-near-infrared (NIR) absorption spectroscopy, and further supported by the synthesis of naphtho[1,2,3,4-ghi]perylene derivatives ( 1 and 2 ) as subunits of 8-AGNR , with a width of 0.86 nm as suggested by the X-ray single crystal analysis. Low-temperature scanning tunneling microscopy (STM) and solid-state NMR analyses provided further structural support for 8-AGNR . The resulting 8-AGNR exhibited a remarkable NIR absorption extending up to ∼2400 nm, corresponding to an optical band gap as low as ∼0.52 eV. Moreover, optical-pump TeraHertz-probe spectroscopy revealed charge-carrier mobility in the dc limit of ∼270 cm2 V−1 s−1 for the 8-AGNR . 相似文献
5.
Chunying Pu Jiahui Yu Ling Fu Jia Wang Houyong Yang Dawei Zhou Chaozheng He 《中国化学快报》2021,32(3):1081-1085
Using the global particle-swarm optimization method and density functional theory,we predict a new stable two-dimensional layered material:MgSiP_2 with a low-buckled honeycomb lattice.Our HSE06 calculation shows that MgSiP_2 is an indirect-gap semiconductor with a band-gap of 1.20 eV,closed to that of bulk silicon.More remarkably,MgSiP2 exhibits worthwhile anisotropy along with electron and hole carrier mobility.A ultrahigh electron mobility is even up to 1.29 × 104 cm~2 V ~1 s ~1.while the hole mobility is nearly zero along the a direction.The large difference of the mobility between electron and hole together with the suitable band-gap suggest that MgSiP_2 may be a good candidate for solar cell or photochemical catalysis material.Furthermore,we explore MgSiP2 as an anode for sodium-ion batte ries.Upon Na adsorption,the semiconducting MgSiP2 transforms to a metallic state,ensuring good electrical conductivity.A maximum theoretical capacity of 1406 mAh/g,a small volume change(within 9.5%),a small diffusion barrier(~0.16 eV) and low average open-circuit voltages(~0.15 V) were found fo r MgSiP2 as an anode for sodium-ion batteries.These results are helpful to deepen the understanding of MgSiP2 as a nanoelectronic device and a potential anode for Na-ion batteries. 相似文献
6.
Xinran Li Jiahao Liu Cheng Chen Jian Yang Ziqiang Xu Mengqiang Wu Yuesheng Wang Zaghib Karim 《中国化学快报》2021,32(3):983-989
The intrinsic liquid interface of Na-K alloy allays concerns about dendrite growth on metal anodes that are thermodynamically within the room temperature(20-22℃).Nevertheless,it hinders the formation of a stable electrode structure due to the inferior wettability induced by considerable liquid tension.In addition,the dominant ionic carrier in the Na-K alloy is subject to multiple factors,which is not conducive to customized battery design.This review,based on recently reported frontier achievements on Na-K liquid anodes,summarizes practical strategies for promoting the wettability by hightemperature induction,capillary effect,vacuum infiltration,and solid interface protection.Furthermo re,four selection mechanisms of the dominant ionic carrier are presented:(1) ion property dominated,(2)cathode dominated,(3) separator dominated,and(4) solid electrolyte interface dominated.Notably,initial electrolytes in energy storage systems have been unable to play a decisive role in ionic selection.Utilizing a superior wettability strategy and simultaneously identifying the dominant ionic carrier can facilitate the tailored application of dendrite-free Na-K liquid anodes. 相似文献
7.
The nano SnO2-modified LiNi1/3Co1/3Mn1/3O2 was successfully prepared by a carrier transfer method. The pristine and modified samples were characterized with various techniques such as XRD, SEM, XPS and EDS. The results showed that the SnO2 particles did not enter the crystal structure of LiNi1/3Co1/ 3Mn1/3O2, many nano SnO2 particles were uniformly covered on the surface of LiNi1/3Co1/3Mn1/3O2 and the modified thin layer could inhibit the dissolution of transition metal oxides. The electrochemical tests indicated that the existence of nano SnO2 could improve the discharge capacity and rate capability owing to the decreased interfacial polarization. The cycling stability was remarkably improved at room temperature and 55 ℃. The XRD patterns of the fresh NCM electrode and after 50 cycles proved that the structural change of NCM was not so effective on the capacity fade. 相似文献
8.
Broadband wireless systems generally use orthogonal frequency division multiplexing (OFDM) with link adaptation (LA) to achieve high throughput while meeting bit error rate (BER) constraint. OFDM systems are known to be affected by non-linearity of high power amplifier (HPA) at transmitter, carrier frequency offset (CFO), symbol timing offset (STO) and channel estimation error at the receiver. The delay in feedback of channel state information (CSI) further affects the performance of LA procedures. The focus of this work is on performance analysis in presence of simultaneous affect of all these impairments on LA based OFDM systems. The results are found to be useful for threshold readjustment which is essential for successful implementation of LA scheme to counter the effects of change in operating conditions from ideal to as listed above. 相似文献
9.
In order to study the effect of epitaxial crystallization on charge transport in low-density polyethylene (LDPE) under multi-field coupling conditions, three typical epitaxial crystallizations, namely disorder (glass substrate), crossover (isotactic polypropylene substrate), and parallel (polytetrafluoroethylene substrate), were prepared and denoted as LD-G, LD-iPP, and LD-PT, respectively. Packet-like space charge through samples was analyzed by the pulsed electro-acoustic (PEA) method. It is shown that different microscopic surface morphologies appeared in the LDPE samples with different epitaxial crystallizations, which, however, do not change the crystalline structure of the bulk. Packet-like space charge phenomena were observed and the distortion field increased with the temperature which could be attributed to the larger amount of charge injection in a shorter period. The differences of the amount and injection rate of the space charge were explained and verified considering the typical chain alignment of epitaxial crystallization, which, in our opinions, contributes to the pass over of positive charge in LD-iPP samples. 相似文献
10.