Latest ArticlesRhodium (Rh) has received widespread attention in fundamental catalytic research and numerous industrial catalytic applications. Compared to homogeneous catalysts, Rh-based nanomaterials as heterogeneous catalysts are much easier to separate and collect after usage, making them more suitable for commercial use. To this purpose, there has been a constant demand in constructing stable and highly active Rh-based nanomaterials. In contrast to Rh-based solid solutions with a random distribution of metallic atoms in the lattice, Rh-based intermetallic compounds (IMCs) with a fixed stoichiometric ratio and an ordered atomic arrangement can ensure the homogenous distribution of active sites and structural stability in the catalytic process. In this review, we concentrate on the fabrication of Rh-based IMCs for catalytic applications. Various synthetic methods and protocols for the controlled preparation of Rh-based IMC are illustrated. Meanwhile, the catalytic applications and corresponding catalytic mechanisms are discussed. In addition, personal perspectives about the remaining challenges and prospects in this field are provided. We believe this review will be useful in directing the development of Rh-based IMC catalysts for heterogeneous catalysis.
The solid electrolyte interphase (SEI), a passivation film covering the electrode surface, is crucial to the lifetime and efficiency of the lithium-ion (Li-ion) battery. Understanding the Li-ion diffusion mechanism within possible components in the mosaic-structured SEI is an essential step to improve the Li-ion conductivity and thus the battery performance. Here, we investigate the Li-ion diffusion mechanism within three amorphous SEI components (i.e., the inorganic inner layer, organic outer layer, and their mixture with 1:1 molar ratio) via ab initio molecular dynamic (AIMD) simulations. Our simulations show that the Li-ion diffusion coefficient in the inorganic layer is two orders of magnitude faster than that in the organic layer. Therefore, the inorganic layer makes a major contribution to the Li-ion diffusion. Furthermore, we find that the Li-ion diffusivity in the organic layer decreases slightly with the increase of the carbon chain from the methyl to ethyl owing to the steric hindrance induced by large groups. Overall, our current work unravels the Li-ion diffusion mechanism, and provides an atomic-scale insight for the understanding of the Li-ion transport in the SEI components.
On-tissue chemical derivatization (OTCD) effectively enhances ionization efficiency of low abundant and poorly ionized functional molecules to improve detection sensitivity and coverage of mass spectrometry imaging (MSI). Combination OTCD and MSI provides a novel strategy for visualizing previously undisclosed metabolic heterogeneity in tumor. Herein, we present a method to visualize heterogeneous metabolism of oxylipins within tumor by coupling OTCD with airflow-assisted desorption electrospray ionization (AFADESI)-MSI. Taking Girard's P as a derivatization reagent, easily ionized hydrazide and quaternary amine groups were introduced into the structure of carbonyl metabolites via condensation reaction. Oxylipins, including 127 fatty aldehydes (FALs) and 71 oxo fatty acids (FAs), were detected and imaged in esophageal cancer xenograft with AFADESI-MSI after OTCD. Then t-distributed stochastic neighbor embedding and random forest were exploited to precisely locate the distribution of oxylipins in heterogeneous tumor tissue. With this method, we surprisingly found almost all FALs and oxo FAs significantly accumulated in the core region of tumor, and exhibited a gradual increase trend in tumor over time. These results reveal spatiotemporal heterogeneity of oxylipins in tumor progression, highlighting the value of OTCD combined with MSI to gain deeper insights into understanding tumor metabolism.
Highly selective conversion of methane (CH4) to methanol (CH3OH) is an emerging attractive but challenging process for future development of hydrogen economy, which requires efficient catalysts. Herein, we systematically explore the catalytic properties of Pt(111) overlayer on transition metal oxides (TMOs) for CH4 conversion by first principles calculations. The Pt(111) monolayer supported by Ce-terminated CeO2(111) substrate exhibits high activity and selectivity for CH4 conversion to CH3OH, with the kinetic barrier of rate-limiting step of 1.05 eV. Intriguingly, the surface activity of Pt overlayer is governed by its d-band center relative to the energy of bonding states of adsorbed molecules, which in turn depends on the number of charge transfer between Pt(111) monolayer and underlying TMOs substrates. These results provide useful insights in the design of metal overlayers as catalysts with high-ultra performance and atomic utilization.
While superhydrophobic coatings have shown promise as potential anti-icing coatings, the surface roughness of these coatings is prone to damage during repeated icing-deicing cycles. Herein, two kinds of superhydrophobic anti-icing coatings are prepared from organic resin and micro-nano particles using two strategies, and their excellent anti-icing properties are also investigated. However, superhydrophobic surface Ⅰ (SF1), prepared by first strategy, cannot be used for extended periods of time due to irreversible damage to the surface roughness during the icing–deicing process. Finite element simulations and experimental studies are preformed to investigate the fatal issue of such roughness damage. In contrast, the anti-icing properties of superhydrophobic surface Ⅱ (SF2), prepared by second strategy, can easily regain through a simple sandpaper abrasion treatment even the surface roughness was damaged during the icing–deicing process. These exploratory results and SF2 preparation strategy provide a facile design of anti-icing coating, and the derived restorable anti-icing coating is expected to be useful for a wide application.
3D microgels with various mechanical properties have been important platforms tumor metastasis analysis, and widely adjustable stiffness is crucial for deeper researches. Herein, by mixing biodegradable polylactic acid (PLA) nanofibers in the modified alginate with different concentrations of Ca2+, we significantly enhance the stiffness range of microgels while retaining the pore size, which provides bionic microenvironment for tumor analysis. As a proof of concept, we simulated the mechanical characteristics of breast tumors by encapsulating cells in 3D microgels with diverse stiffness, and analyzed cellular behaviors of two typical breast cancer cell lines: MCF-7 and SUM-159. Results showed that with the addition of 2.0% (w/v) PLA short nanofibers, the Young's modulus of modified alginate increased more than three-fold. Besides preserving high survival and proliferation rates, both cells also displayed stronger migration ability in soft microgel spheres, where RT-qPCR analysis revealed the underlying changes at the genetic level. This systematic study demonstrated our method is powerful for creating widely adjustable 3D mechanical microenvironment, and the results of cellular behavior analysis shows its promising application prospects in tumorigenesis and progression.
Identification of lymph nodes (LNs) is critical for studies of the structure, the role in disease development, and the efficacy of disease treatment. Carbonized polymer dots (CPDs) are expected to be potential LNs-targeted imaging agents due to their excellent properties with special structure, better photoluminescence (PL) and great biocompatibility. Herein, a red/near infrared (NIR) emission CPDs (RCPDs) with one and two-photon bioimaging based on citric acid (CA) and benzoylurea (BU) are prepared. Notably, the RCPDs are capable of targeting LNs for imaging. Lymphocyte homing has been demonstrated to be the cellular mechanism of RCPDs target LNs imaging. This work has developed a new nanomaterial for targeted imaging of LNs, while the biological applications of CPDs have been expanded and deepened.
With the development of a small interfering RNA (siRNA) delivery strategy, increasing siRNA therapeutics for tumor treatment appeared in clinical trials and pre-clinical development. However, the test results of such therapeutics unveiled that efficient siRNA delivery to tumor tissues is still challenging. Albumin is considered an ideal carrier for delivering hydrophobic agents into tumor tissue because it is highly concentrated and long-circulating in blood and has propensity of tumor enrichment. Herein, we synthesized lipid conjugated siRNAs (LsiRNAs), which showed high affinity to albumin. Mechanistically, LsiRNAs non-covalently bind to the hydrophobic core of albumin through its octadecyl tails. The small size of albumin/LsiRNAs allows the complex to penetrate tumor tissue efficiently. Biodistribution test proved that albumin extremely prolonged circulation time and increased tumor retention of associated LsiRNAs. Notably, LsiRNA against programmed death ligand-1 (Pdl1) efficiently suppressed tumor growth as well as prolonged survival time of tumor bearing mice by increasing infiltration of CD8+ T cells as well as promoted the maturation of dendritic cells both in tumor and lymph. Together, LsiRNAs provide a simple but effective way for siRNA tumor delivery that “hitchhikes” on albumin.
Selective oxidation of biomass-derived monosaccharide into high value-added chemicals is highly desirable from sustainability perspectives. Herein, we demonstrate a surface-functionalized carbon nanotube-supported gold (Au/CNT-O and Au/CNT-N) catalyst for base-free oxidation of monosaccharide into sugar acid. Au/CNT-O and Au/CNT-N surfaces successfully introduced oxygen- and nitrogen-containing functional groups, respectively. The highest yields of gluconic acid and xylonic acid were 93.3% and 94.3%, respectively, using Au/CNT-N at 90 ℃ for 240 min, which is higher than that of using Au/CNT-O. The rate constants for monosaccharide decomposition and sugar acid formation in Au/CNT-N system were higher, while the corresponding activation energy was lower than in Au/CNT-O system. DFT calculation revealed that the mechanism of glucose oxidation to gluconic acid involves the adsorption and activation of O2, adsorption of glucose, dissociation of the formyl C-H bond and formation of O-H bond, and formation and desorption of gluconic acid. The activation energy barrier for the glucose oxidation over Au/CNT-N is lower than that of Au/CNT-O. The nitrogen-containing functional groups are more beneficial for accelerating monosaccharide oxidation and enhancing sugar acid selectivity than oxygen-containing functional groups. This work presents a useful guidance for designing and developing highly active catalysts for producing high-value-added chemicals from biomass.
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