Rhodium promoted heteropolyacid catalysts for low temperature methanol carbonylation

Acetic acid is a valuable industrial chemical obtained by the halide-free carbonylation of methanol, for which lower cost and more durable heterogeneous noble metal catalysts are desirable. Here, we report the use of a simple and cost-effective Rh acetate (Rh(OAc)2) precursor, either alone or in combination with phosphotungstic acid (HPW), to prepare silica supported monofunctional (Rh(OAc)2/SiO2) and bifunctional (Rh(OAc)2/HPW/SiO2) catalysts for methanol carbonylation. In isolation, Rh(OAc)2 is inactive for methanol carbonylation, only exhibiting stoichiometric acetic acid production from ligand release, and a low activity at 250 °C when combined with HPW in bulk form (acidity being required to protonate methanol). However, bifunctional Rh(OAc)2/HPW/SiO2 exhibits promising catalytic performance, with a TON of 70 and >90% acetic acid selectivity for 8 h on-stream without significant deactivation. In situ XAS and in situ DRIFTS measurements indicate that CO binding is activated by water loss from the acetate dimer, with geminal dicarbonyl bonding mode stabilising Rh(OAc)2 against reductive decomposition to Rh metal during the catalytic cycle. Temperatures ≥300 °C, or high methanol concentrations trigger irreversible loss of acetate ligands and rapid deactivation through Rh reduction

Target screening of hydroxylated and nitrated polycyclic aromatic hydrocarbons in surface water using Orbitrap high–resolution mass spectrometry in a lake in Hebei, China

Polycyclic aromatic hydrocarbon (PAH) derivatives are mutagenic, carcinogenic, teratogenic and bioaccumulative pollutants. Investigations on hydroxylated PAHs (OH–PAHs) and Nitrated PAHs (NPAHs) in surface water are not enough. In this study, optimization and validation of an analytical method targeting nine kinds of OH–PAHs and one kind of nitrated PAH in environmental water samples are presented. The method was validated for linearity, limits of detection and quantification and recovery using spiked matrix. The linear range of most target compounds was 0.1–200 ng∙mL−1. However, the linear range of 1–hydroxy pyrene and 3–hydroxy benzo[a]pyrene started at 1 ng∙mL−1 and the linear range of 1–hydroxy phenanthrene and 9–hydroxy benzo[a]pyrene could not reach 200 ng∙mL−1. All the correlation coefficients (r2) were over 0.997. The instrumental limits of detection (LOD) and method detection limits (MDL) ranged from 0.01 to 0.67 ng∙mL−1 and 1.11 to 2.26 ng∙L−1, respectively. With this method, a lake in Hebei province, China, were screened. Three kinds of target compounds were detected. The average concentration was around 2.5 ng∙L−1, while the highest concentration reached 286.54 ng∙L−1

Tuning the Selectivity of LaNiO3 Perovskites for CO2 hydrogenation through potassium substitution

Herein, we demonstrate a method used to tune the selectivity of LaNiO3 (LNO) perovskite catalysts through the substitution of La with K cations. LNO perovskites were synthesised using a simple sol-gel method, which exhibited 100% selectivity towards the methanation of CO2 at all temperatures investigated. La cations were partially replaced by K cations to varying degrees via control of precursor metal concentration during synthesis. It was demonstrated that the reaction selectivity between CO2 methanation and the reverse water gas shift (rWGS) could be tuned depending on the initial amount of K substituted. Tuning the selectivity (i.e., ratio of CH4 and CO products) between these reactions has been shown to be beneficial for downstream hydrocarbon reforming, while valorizing waste CO2. Spectroscopic and temperature-controlled desorption characterizations show that K incorporation on the catalyst surface decrease the stability of C-based intermediates, promoting the desorption of CO formed via the rWGS prior to methanation

Recent advances of Li7La3Zr2O12-based solid-state lithium batteries towards high energy density

To satisfy the demand for high energy density and high safety lithium batteries, garnet-based all-solid-state lithium batteries (ASSLBs) are the research hot spots in recent decades. Within the garnet family, Li7La3Zr2O12 (LLZO) is a promising candidate for solid-state electrolytes (SSEs) that has been extensively investigated due to the high ionic conductivity, chemical stability, electrochemical stability, air stability, thermal stability and safety. Recently, several laboratory-scale works on LLZO-based ASSLBs are achieved. However, although LLZO-based SSEs have made tremendous advancements today, there are still several critical issues in the practical application of ASSLBs with high energy density and low cost. Herein, optimization of LLZO structure, preparation of high-quality LLZO-based SSEs, engineering of the interface between LLZO-based SSEs and realization of LLZO-based ASSLBs with high energy density are systematically analyzed, discussed, and summarized to offer a clearer comprehension of the crucial challenges and future research orientations. It is expected to not only enhance the knowledge of audiences in this field but also facilitate the achievement of practical commercial applications in LLZO-based ASSLBs

Recent advances of metal telluride anodes for high-performance lithium/sodium-ion batteries

Recent advances of metal telluride anodes for high-performance lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs), which is important electrochemical energy storage technologies with high energy density and environmental benignity

Inner wrinkled mesoporous hollow carbon spheres with nanopillars connected to double shells for excellent potassium storage

Carbon spheres are widely used in energy storage due to their adjustable particle size, controllable shape, and variable surface physical and chemical properties. However, there are still problems such as low specific surface area and unsatisfactory ion transport kinetics in K+ storage. Although increasing the specific surface area of the active material can increase the K+ storage sites, the contact area between the active material and the electrolyte also increases, aggravating the occurrence of side reactions and the consumption of the active materials. We developed an N-doped mesoporous hollow carbon sphere with a novel morphology-a smooth exterior and wrinkled interior structure with a carbon-supported pseudo-bilayer carbon structure (IW-MHCS). Its smooth outer structure sufficiently reduces the contact area with the electrolyte, and the wrinkled inner structure effectively increases the specific surface area. The obtained IW-MHCS exhibits superior rate performance (120.6 mAh g−1 at 5 A g−1) and sufficient capacity (202.7 mAh g−1 after 800 cycles at 1 A g−1) for K+ storage. This study provides a new insight into the structural design and morphological control of high-energy-storage carbon-based materials

Towards Low-Voltage and High-Capacity Conversion-Based Oxide Anodes by Configuration Entropy Optimization

Transition metal oxide (TMO)-based anodes attract much attention for lithium storage due to the merits of high theoretical capacity, facile synthesis, and easy scale-up. Moreover, the increased working potential avoids the issue of lithium dendrites formation and thus improves battery safety. Herein, we propose a route to significantly improve the electrochemical performance of TMO anodes through configurational entropy optimization. For example, high-entropy oxide (FeCoNiCrCu)3O4 is synthesized by carefully selecting metal elements. The (FeCoNiCrCu)3O4 electrode ensures not only low potential but also holds high capacity. In the half-cell configuration, the (FeCoNiCrCu)3O4 electrode provides a specific capacity of 575.7 mAh g−1 after 200 cycles at 0.2 A g−1. More importantly, the electrode showed a relatively low discharge voltage of 0.39 V at 0.5 A g−1, which is caused by the configuration entropy optimization. The assembled (FeCoNiCrCu)3O4//LCO coin-type full cell exhibits a high capacity of 266.3 mAh g−1 after 100 cycles at 0.2 A g−1 and an operating voltage up to 3.9 V

Graphite-like structured conductive polymer anodes for high-capacity lithium storage with optimized voltage platform

Graphite is a widely used anode material in commercial lithium-ion batteries (LIBs), but its low theoretical specific capacity and extremely low redox potential limit its application in high-performance lithium-ion batteries. However, developing lithium-ion battery anode with high specific capacity and suitable working potential is still challenging. At present, conductive polymers with excellent properties and graphite-like structures are widely used in the field of electrochemistry, but their Li+ storage mechanism and kinetics are still unclear and need to be further investigated. Therefore, we synthesized the conducting polymer Fe3(2, 3, 6, 7, 10, 11-hexahydroxytriphenylene)2 (Fe-CAT) by the liquid phase method, in which the d-π conjugated structure and pores facilitate electron transfer and electrolyte infiltration, improving the comprehensive electrochemical performance. The Fe-CAT electrode displays a high capacity of 950 mA h g−1 at 200 mA g−1. At the current density of 5.0 A g−1, the electrode shows a reversible capacity of 322 mA h g−1 after 1000 cycles. The average lithiation voltage plateau is ∼ 0.79 V. The combination of ex-situ characterization techniques and electrochemical kinetic analysis reveals the source of the excellent electrochemical performance of Fe-CAT. During the charging/discharging process, the aromatic ring in the organic ligand is involved in the redox reaction. Such results will provide new insights for the design of next-generation high-performance electrode materials for LIBs

A comprehensive review of cathode materials for Na-air batteries

In recent years, rechargeable sodium-air batteries have attracted extensive attention and shown rapid development for use in the field of electrochemical energy storage owing to low costs, abundance of the precursor resources, high theoretical specific capacity, and high energy density, all of which have contributed to making them one of the most promising alternatives to lithium-ion batteries. Despite the numerous advantages, Na-air batteries also face certain challenges, such as poor charge-discharge reversibility at the cathode, formation of sodium dendrites at the anode, and low catalytic activity for oxygen reduction/evolution reactions. Thus, designing efficient and stable air cathode materials is significant for the development and practical application of Na-air batteries. Therefore, this paper aims to review the advances related to the development of air cathodes in Na-air batteries in the last decade. Here, research on the secondary Na-air batteries are briefly summarized and divided into two categories based on their electrolyte composition: organic Na-air batteries and hybrid Na-air batteries. The air cathode materials are reviewed and categorised based on the material type into the following: carbon materials, transition metals and metal oxides, noble metals, perovskites and spinel oxides, metal-organic frameworks and their derivatives, pyrochlore oxides, and other cathode materials. Furthermore, work in previous studies applying in situ spectroelectrochemical techniques, including Infrared spectroscopy, electron spin resonance, UV/Vis spectroscopy, and Raman spectroscopy, to develop the structure-performance correlations and redox reaction mechanisms of Na-air batteries are summarised. Finally, the challenges faced by Na-air batteries and the prospect of future work are discussed in the conclusions. This review is thus expected to provide a comprehensive understanding of the trends and issues related to the development of Na-air batteries for practical industrial applications

Correction to: Highly selective reduction of carbon dioxide to methane on novel mesoporous rh catalysts (ACS Applied Materials & Interfaces (2018) 10:30 (24963?24968) DOI: 10.1021/acsami.8b06977)

In Table S1 (Supporting Information), some values were misordered. The following Table S1 is the revised one.(Table Persented)