Hydrogen energy is critical for achieving carbon neutrality. Heterostructured materials with single metal-atom dispersion are desirable for hydrogen production. However, it remains a great challenge to achieve large-scale fabrication of single atom-anchored heterostructured catalysts with high stability, low cost, and convenience. Here, we report single iron (Fe) atom-dispersed heterostructured Mo-based nanosheets developed from a mineral hydrogel. These rationally designed nanosheets exhibit excellent hydrogen evolution reaction (HER) activity and reliability in alkaline condition, manifesting an overpotential of 38.5 mV at 10 mA cm−2, and superior stability without performance deterioration over 600 h at current density up to 200 mA cm−2, superior to most previously reported non-noble-metal electrocatalysts. The experimental and density functional theory results reveal that the O-coordinated single Fe atom-dispersed heterostructures greatly facilitated H2O adsorption and enabled effective adsorbed hydrogen (H*) adsorption/desorption. The green, scalable production of single-atom-dispersed heterostructured HER electrocatalysts reported here is of great significance in promoting their large-scale implementation.
DOI: 10.1038/s41467-022-33725-8
创建: Nov 05, 2022 | 14:02
Platinum-based catalysts are widely used in hydrogen evolution reactions; however, their applications are restricted because of the cost-efficiency trade-off. Here, we present a thermodynamics-based design strategy for synthesizing an Al73Mn7Ru20 (atomic %) metal catalyst via combinatorial magnetron co-sputtering. The new electrocatalyst is composed of ~2 nanometers of medium-entropy nanocrystals surrounded by ~2 nanometers of amorphous regions. The catalyst exhibits exceptional performance, similar to that of single-atom catalysts and better than that of nanocluster-based catalysts. We use aluminum rather than a noble metal as the principal element of the catalyst and ruthenium, which is cheaper than platinum, as the noble metal component. The design strategy provides an efficient route for the development of electrocatalysts for use in large-scale hydrogen production. Moreover, the superior hydrogen reaction evolution created by the synergistic effect of the nano-dual-phase structure is expected to guide the development of high-performance catalysts in other alloy systems.
DOI: 10.1126/sciadv.add6421
创建: Nov 05, 2022 | 13:55
Taking silica as an exemplary material system, we studied water-assisted densification behaviors of different crystallinities (quartz, glass, and vitreous silica). To avoid the complexity in data interpretation, we adopted a simple procedure similar to those used for pressing salt pellets for IR: compressing silica powders in a mold with pure water under ambient conditions. It is discovered that crystalline silica is compacted through liquid lubrication, while amorphous silica's densification behaviors contradict the widely regarded dissolution-reprecipitation mechanism. Another mechanism is thus proposed: stress-driven water incorporation into the solid structures produces hydrated silica of considerable plasticity for deformation and fusion. Inspired by this water-assisted mechanism, a more effective sintering method is developed via repetitive stressing/destressing treatments at room temperature, enabling dramatically boosted densities (e.g., over 90% with transparent appearance for silica glass) and enhanced mechanical performance. This generic strategy may apply to a wide range of materials. Furthermore, the hydration-enabled deformation/sintering mechanism proposed in this work offers fresh insights into the biomineralization puzzles, particularly those on how life accomplishes some of the most challenging tasks faced by humans in modern ceramic technology, for example, to fuse, mend or reshape the rigid brittle ceramic objects in aqueous environments under ambient conditions. This purely inorganic biomineralization mechanism may be particularly important for life at its early stage of evolution on earth.
https://doi.org/10.1111/jace.18268
创建: Aug 04, 2022 | 15:21
This study reports a novel hydrogel synthesized using only water and the inorganic salts of FeCl3.6H2O and (NH4)6Mo7O24.4H2O, which offers a stable host for various ions (including Li+, Na+, Mg2+, Zn2+, Mn2+, or Ca2+), affording high ionic conductivity. More interestingly, the redox pair Fe2+/Fe3+ of the gel renders considerable pseudo-capacitance, delivering a high volumetric energy density (4.8 mWh cm−3, based on the one-piece half-cell) and cycling stability. This simple one-piece approach is convenient and effective—by pairing the mineral gel-based half-cell with another matching electrode, a novel type of charge storage device is formed, with the gel serving as one electroactive material, the electrolyte, and the membrane separator. Furthermore, the mineral hydrogel reported here is of low cytotoxicity, self-bondable and healable, and highly resistant against swelling and disintegrating, with no collapse or volume expansion observed even after being soaked in water for 60 days. To our knowledge, this is the first time that mineral hydrogels have been synthesized from all-inorganic agents in a fully biocompatible setting, which also sheds light on the myth-ridden topic of pre-cell evolution in the prebiotic age.
https://doi.org/10.1002/adfm.202109302
创建: Aug 04, 2022 | 15:15
Understanding the molecular orientation is crucial for revealing the mechanism of chemical reactions. However, how to accurately monitor the molecular orientation remains a great challenge because of the motion of the molecules during the chemical reaction. Here, surface-enhanced Raman spectroscopy (SERS) was used to monitor the molecular reorientation from the plasmon-catalyzed conversion of p-aminothiophenol (PATP) to p,p'-dimercaptoazobenzene (DMAB). Spectral change due to molecular reorientation, which is often overlooked, is clearly extracted through the protonation of the PATP molecules to suppress the conversion of PATP to DMAB. Meanwhile, by monitoring the Raman features, the reaction process and molecular reorientation are simultaneously recorded, offering fresh insights on the long-standing puzzle that why the conversion to DMAB is suppressed with concentrated PATP: this is because the over-crowded PATP adsorbed on the substrate hampered its own space-taking reorientation (similar to the space-steric effect) which is a prerequisite for producing DMAB.
https://doi.org/10.1016/j.jcat.2022.06.028
创建: Aug 04, 2022 | 15:12
Hot carriers (HCs) and thermal effects, stemming from plasmon decays, are crucial for most plasmonic applications. However, quantifying these two effects remains extremely challenging due to the experimental difficulty in accurately measuring the temperature at reaction sites. Herein, we provide a novel strategy to disentangle HCs from photothermal effects based on the different traits of heat dissipation (long range) and HCs transport (short range), and quantitatively uncover the dominant and potential-dependent role of photothermal effect by investigating the rapid- and slow-response currents in plasmon-mediated electrochemistry at nanostructured Ag electrode. Furthermore, the plasmoelectric surface potential is found to contribute to the rapid-response currents, which is absent in the previous studies.
https://doi.org/10.1002/anie.202001152
创建: Sep 18, 2021 | 17:22
Ceramics are easy to break, and very few generic mechanisms are available for improving their mechanical properties, e.g., the 1975-discovered anti-fracture mechanism is strictly limited to zirconia and hafnia. Here we report a general mechanism for achieving high plasticity through liquefaction of ceramics. We further disclose the general material design strategies to achieve this difficult task through entropy-boosted amorphous ceramics (EBACs), enabling fracture-resistant properties that can withstand severe plastic deformation (e.g., over 95%, deformed to a thickness of a few nanometers) while maintaining high hardness and reduced modulus. The findings reported here open a new route to ductile ceramics and many applications.
https://doi.org/10.1016/j.apmt.2021.101011
创建: Sep 18, 2021 | 17:50
Surface-enhanced Raman spectrometry (SERS) is one of the most important on-site testing tools. However, it remains a great challenge for the SERS to achieve on-site safety evaluation for fish and meat products, due to their extremely complicated compositions of wide-ranging chemicals, the potential existence of unknown micro-organisms, and the difficulty to directly acquire spectra information from inside the product. Here, we report a convenient strategy for mass fabrication of a novel type of SERS sensors through electrochemical nanoetching of commercial Ag needles. The thus obtained SERS sensor features rich surface nanostructures of ultrahigh SERS sensitivity, making them highly compatible with low-cost portable Raman spectrometers to realize on-site detection. These sensors can be inserted into the products to read out the depth-profile information, e.g., from purine, proteins, and lipids. Unlike the conventional insertable SERS sensors that are coated with foreign plasmonic nanoparticles, the novel sensor possesses nano-carved plasmonic surface structures that are highly resistant to aggregation and materials loss, enabling much improved durability well suited for depth-profiling applications. Interestingly, these sensors can be repetitively regenerated by acid rinsing while maintain high enhancement effect. Instant detection of fish or meat spoilage at early stage is realized in a few minutes using the novel sensors reported here, demonstrating an attractive means for on-site food quality control in a rapid, low-cost, and convenient manner.
https://doi.org/10.1016/j.cej.2021.130733
创建: Sep 18, 2021 | 18:17
Hollow nanostructured materials are attractive in material science for both fundamental research and practical applications. In this study, anodization demonstrates its convenience and effectiveness for constructing elaborate hollow nanospheres, based on an interesting synthetic mechanism involving bubble-assisted anodic self-assembly. The thus fabricated hierarchical FeS/FeOx hollow nanospheres are directly grown on the Fe substrate, providing a novel type of binder-free anode for high-performance batteries. For instance, when applied in sodium ion batteries, the air-annealed anode delivers high capacity and stability, retaining 464.8 mA h g−1 after 100 cycles at 100 mA g−1.
https://doi.org/10.1016/j.jpowsour.2020.229268
创建: Sep 18, 2021 | 18:11
Ceramics are key components of life, forming elaborate and diverse structures found in coccolith, shells, skeletons, and teeth. In materials research, however, one generally finds ceramics difficult to process because of their high hardness and melting points. How organisms effortlessly build stunning ceramic architectures, in water and at mild temperature, remains a long-standing mystery to scientists. This study discloses that biomineralization likely operates through a supervariate mechanism based on multi-ionic solutions, a mechanism that enables convenient phase and kinetic regulation through stress control. Specifically, from solutions of multiple ionic components, bioceramics with highly variable (supervariate) compositions are first produced in a gelatinous state of exceptional stability, which offers convenience in material storage, transportation, molding, and processing. Counter-intuitively, the supervariate wet gels can be solidified by simply compacting them under a mild force, whereas the formulas (e.g. carbonates or phosphates), hydration levels, and phases (amorphous or crystalline) of the resultant bioceramics can be tailored. Furthermore, we propose that the biogenic amorphous minerals (e.g. amorphous calcium carbonate) are very likely stabilized by constricting their volume at the microscale, so that they are prohibited from undergoing the prerequisite dehydration step (which requires extra volume) preceding crystallization. The new biomineralization mechanism described here answers a pivotal question on bioceramics of life.
https://doi.org/10.1016/j.mtadv.2021.100144
创建: Sep 18, 2021 | 17:58
