Latest ArticlesCO oxidation is a benchmark in heterogeneous catalysis for evaluation of redox catalysts due to its practical relevance in many applications and the fundamental problems associated with its very high activity at low temperatures. Among which, Co3O4 is one of the most active non-precious metal catalysts. Exposed crystal planes and cobalt sites are considered to be important for its high catalytic activity. Herein, we demonstrate an enhanced CO oxidation activity by a defect-rich mesoporous Co3O4 that prepared by a designed dual-template method. Two different kinds of silicas are used as hard-templates at the same time, resulting in a defect-rich mesoporous Co3O4 with a surface area as high as 169 m2/g. This catalyst exhibited a very high catalytic activity for low temperature CO oxidation with a light-off temperature at −73 ℃ under the space velocity of 80,000 mL h-1 gcat-1. Further studies reveal that the high surface area promotes the lattice oxygen mobility, surface rich of Co2+ species and active oxygen species are crucial for the high catalytic activity. Moreover, the dual-template approach paves a way towards the design and construction of high-surface-area mesoporous metal oxides for various applications.
Lithium-sulfur (Li-S) batteries have been regarded as the candidate for the next-generation energy storage system due to the high theoretical specific capacity (1675 mAh/g), energy density (2600 Wh/kg) and the abundance of elemental sulfur, but the application of Li-S batteries is impeded by a series of problems. Recently, all-solid-state Li-S batteries (ASSLSBs) have drawn great attention because many drawbacks such as safety issues caused by metallic lithium anodes and organic liquid electrolytes can be overcome through the use of solid-state electrolytes (SEs). However, not only the problems brought by sulfur cathodes still exist, but more trouble arouses from the interfaces between SEs and cathodes, hampering the practical application of ASSLSBs. Therefore, in order to deal with the problems, enormous endeavors have been done on ASSLSB cathodes during the past few decades, including engineering of cathode active materials, cathode host materials, cathode binder materials and cathode structures. In this review, the electrochemical mechanism and existing problems of ASSLSBs are briefly introduced. Subsequently, the strategies for developing cathode materials and designing cathode structures are presented. Then there follows a brief discussion of SE problems and expectations, and finally, the challenges and perspectives of ASSLSBs are summarized.
Zinc-ion hybrid capacitors (ZICs) are considered as newly-emerging and competitive candidates for energy storage devices due to the integration of characteristic capacitor-level power and complementary battery-level energy. The practical application of rising ZICs still faces the specific capacity and dynamics mismatch between the two electrodes with different energy storage mechanisms, which cannot meet the ever-growing indicator demand for portable electronic displays and public traffic facilities. Focusing on these unresolved issues, this mini-review presents recent advances in ZICs referring to the hybrid energy storage mechanism, design strategies of both capacitor-type and battery-type electrode materials, and electrolyte research toward advanced performances (e.g., high operational potential, wide adaptive temperature). Finally, current challenges and future outlook have been proposed to guide further exploration of next-generation ZICs with a combination of high-power delivery, high-energy output and high-quality service durability.
Ion transport plays an important role in energy conversion, biosensors, and a variety of biological processes. Carbon nanotubes, especially for the carbon nanotubes arrays with controlled vertically aligned structures, have displayed great potential as a promising material for regulating ion transport behaviors in the applications of the nanofluidic devices and osmotic energy conversion. Herein, we demonstrate the thermo-controlled ion transport system through the vertically aligned multiwall carbon nanotubes arrays membrane modified by the thermo-responsive hydrogel in a simple and reliable way. The functional carbon nanotubes backbone with the inherent surface charge and interstitial channels structure renders the system improved ion transport behaviors and well controlled switching property by thermo. Based on the integrated properties, the energy output from osmotic power in this system could be regulated by the reversible temperature switches. Moreover, it can realize a higher osmotic energy conversion property regulated by the thermos, which may extend the practical application in the future. The system that combines intelligent response with controlled ion transport behaviors and potential osmotic energy utilizations presents a valuable paradigm for the use of carbon nanotubes and hydrogel composite materials and provides a promising way for applications of nanofluidic devices.
Metal-organic frameworks (MOFs) as promising electrodes for supercapacitors are attracting increasing research interest. Herein, we report an effective strategy to improve the electrochemical performance of Ni-MOF for supercapacitor by introducing a secondary Co ion. The Co substitution of Ni in Ni-MOF can improve the intrinsic reactivity and stability. As a result, the bimetallic Co/Ni-MOF-1:15 with an optimal Co/Ni ratio delivers high specific capacitance (359 F/g at 0.5 A/g), good rate performance (81.5% retention at 5 A/g) and cycling stability (81% retention after 5000 cycles). These results demonstrate that the bimetallic synergistic strategy is an effective way to improve the pseudocapacitive performance of MOFs.
Alkaline hydrogen evolution reaction (HER) suffers from a sluggish kinetic, which requires the elaborate catalytic interface and micro-nanoscale architecture engineering of the electrocatalysts to accelerate the water dissociation and hydrogen evolution. Herein, the heterointerface engineering was proposed for promoting the alkaline HER by constructing the highly exposed Ru/RuS2 heterostructures homogeneously distributed on hollow N/S-doped carbon microspheres (Ru/RuS2@h-NSC). Benefited from the synergistic effect of heterointerfacial Ru/RuS2, the high accessibility of the active sites on both inner and outer surface of mesoporous shells and the efficient mass transport, Ru/RuS2@h-NSC affords a remarkable catalytic performance with an overpotential of 26 mV@10 mA/cm2 for alkaline HER, outperforming most of the state-of-the-art catalysts. Further applying Ru/RuS2@h-NSC and its oxidized derivate for the overall alkaline water splitting, the required cell voltage is much lower than that of the commercial Pt/C||RuO2 pair to achieve the same current density. Our study may allow us to guide the design of micro-nanoreactors with optimal catalytic interfaces for promising electrocatalytic applications.
Interphase strain engineering provides a unique methodology to significantly modify the lattice structure across a single film, enabling the emergence and manipulation of novel functionalities that are inaccessible in the context of traditional strain engineering methods. In this work, by using the interphase strain, we achieve a ferromagnetic state with enhanced Curie temperature and a room-temperature polar state in EuO secondary phase-tunned EuTiO3 thin films. A combination of atomic-scale electron microscopy and synchrotron X-ray spectroscopy unravels the underlying mechanisms of the ferroelectric and ferromagnetic properties enhancement. Wherein, the EuO secondary phase is found to be able to dramatically distort the TiO6 octahedra, which favors the non-centrosymmetric polar state, weakens antiferromagnetic Eu-Ti-Eu interactions, and enhances ferromagnetic Eu-O-Eu interactions. Our work demonstrates the feasibility and effectiveness of interphase strain engineering in simultaneously promoting ferroelectric and ferromagnetic performance, which would provide new thinking on the property regulation of numerous strongly correlated functional materials.
The performance of Li||Sb-Sn liquid metal batteries (LMBs) is hindered by the corrosion of the Sb-Sn cathode on its current collector. Herein, a uniform, dense, and low-oxidized W coating was prepared by plasma spraying, which can effectively resist the corrosion of the cathode and improve the cycle stability of the Li||Sb-Sn LMBs. For the first time, micro-CT nondestructive inspection is applied in the field of LMBs. The corrosion micromorphology and composition evolution of the SS304 matrix and Sb-Sn cathode with or without the plasma-sprayed W coating is obtained without disassembling the battery, which proves that the W coating can effectively protect the SS304 matrix. Our autonomous new LMB device for nondestructive inspection is universal and can be applied to different LMBs systems for advancing knowledge of corrosion mechanism and protection. This work guarantees the ability to directly visualize the inner critical positions in three dimensions and fills the knowledge gap in the field of LMB detection technology.
The development of excellent catalyst to achieve photocatalytic syngas production from CO2 and H2O is a prospective and sustainable strategy to alleviate environment and energy crisis. In this study, a unique Janus PdZn-Co catalyst is prepared by annealed the Pd/IRMOF-3(Co, Zn) precursor. Due to the strong interaction, the electron transfers from PdZn terminal to Co terminal in the Janus structure. The electron-received Co terminal facilitates Co sites coordinate with the electrophilic C atom of CO2 and the electron-donated PdZn center is easier to coordinate with nucleophilic O atoms of H2O or CO bonds. The charge redistribution enhances the absorption of CO2 and H2O, which promotes H2 evolution and CO production. In addition, the carbon shell effectively suppresses the metal core agglomeration and facilitates the electron transmission from photosensitizer to metallic active sites. Meanwhile, the ratio of CO/H2 can be regulated (~3:1 to 2:1) by adjusting the proportion of Co and PdZn. The Janus structure and graphite carbon synergistically play a profound impact on improving the photocatalytic performance. The optimized PdZn-Co catalyst exhibits a superior photocatalytic CO production rate (20.03 µmol/h) and the H2 generation rate (9.90 µmol/h) with a ratio of CO/H2 = 2.02.
Comprehensive fundamental understanding of CO hydrogenation reactions over Cu and ZnCu alloy surfaces is of great importance. Herein, we report a comparative DFT calculation study of elementary surface reaction network of CO hydrogenation reactions on stepped Cu(211), Cu(611), ZnCu(211) and ZnCu(611) surfaces. On ZnCu(211) and ZnCu(611) surfaces, the energetic favorable reaction path of CO hydrogenation reaction follows CO* → HCO* → H2CO* → H3CO* → CH3OH* → CH3OH with H3CO* hydrogenation as the rate-limiting step and proceeds more facilely on ZnCu(611) surface than on ZnCu(211) surface. On Cu(211) and Cu(611) surfaces, the energetic favorable reaction path of CO hydrogenation reaction follows CO* → HCO* → HCOH* → H2COH* → H3COH* → CH3* → CH4* → CH4 with H2COH* hydrogenation as the rate-limiting step and proceeds more facilely on Cu(611) than on Cu(211). The key difference of CO hydrogenation reaction on ZnCu alloy surface and Cu is that the resulting CH3OH* species desorbs to produce CH3OH on ZnCu alloy but undergoes H*-assisted decomposition to CH3* and eventually to CH4 on Cu surface. These results successfully unveil elementary surface reaction networks and structure sensitivity of Cu and ZnCu alloy-catalyzed CO hydrogenation reactions.