It remains highly desired but a great challenge to achieve atomically dispersed metals in high loadings for efficient catalysis. Now porphyrinic metal–organic frameworks (MOFs) have been synthesized ...based on a novel mixed‐ligand strategy to afford high‐content (1.76 wt %) single‐atom (SA) iron‐implanted N‐doped porous carbon (FeSA‐N‐C) via pyrolysis. Thanks to the single‐atom Fe sites, hierarchical pores, oriented mesochannels and high conductivity, the optimized FeSA‐N‐C exhibits excellent oxygen reduction activity and stability, surpassing almost all non‐noble‐metal catalysts and state‐of‐the‐art Pt/C, in both alkaline and more challenging acidic media. More far‐reaching, this MOF‐based mixed‐ligand strategy opens a novel avenue to the precise fabrication of efficient single‐atom catalysts.
Iron islands: Based on a mixed‐ligand strategy, a porphyrinic MOF was pyrolyzed to afford high‐content single‐atom iron‐implanted N‐doped porous carbon (FeSA‐N‐C). Thanks to the FeSA sites, hierarchical pores, oriented mesochannels, and high conductivity, FeSA‐N‐C exhibits excellent oxygen reduction activity and stability, surpassing almost all non‐noble‐metal catalysts and Pt/C, in both alkaline and the more challenging acidic media.
The anode oxygen evolution reaction (OER) is known to largely limit the efficiency of electrolyzers owing to its sluggish kinetics. While crystalline metal oxides are promising as OER catalysts, ...their amorphous phases also show high activities. Efforts to produce amorphous metal oxides have progressed slowly, and how an amorphous structure benefits the catalytic performances remains elusive. Now the first scalable synthesis of amorphous NiFeMo oxide (up to 515 g in one batch) is presented with homogeneous elemental distribution via a facile supersaturated co‐precipitation method. In contrast to its crystalline counterpart, amorphous NiFeMo oxide undergoes a faster surface self‐reconstruction process during OER, forming a metal oxy(hydroxide) active layer with rich oxygen vacancies, leading to superior OER activity (280 mV overpotential at 10 mA cm−2 in 0.1 m KOH). This opens up the potential of fast, facile, and scale‐up production of amorphous metal oxides for high‐performance OER catalysts.
Amorphous NiFeMo oxide (up to 515 g one batch) with homogeneous elemental distribution was synthesized through a facile supersaturated co‐precipitation method. The amorphous NiFeMo oxide undergoes rapid surface self‐reconstruction during OER that forms a metal oxy(hydroxide) active layer with oxygen vacancies, enabling efficient OER catalysis.
Emerging as a potent alternative to classical metal-based semiconductor quantum dots (Qdots), carbon dots (Cdots) possess the distinctive advantages of convenient synthesis, prominent ...biocompatibility, colorful photoluminescence, and low cost. After almost a decade of extensive studies since their discovery, Cdots have widely been applied in bioimaging, sensing, catalysis, optoelectronics, energy conversion, etc. In this review, we first highlight the synthetic methods for Cdots in a macroscale manner. Second, we briefly discuss the fundamental mechanisms underlying the photoluminescence (PL). Third, we focus on their applications in sensing and bioimaging (including imaging-guided therapy). Some thoughts on future developments of Cdots are demonstrated as concluding remarks.
The cycling stability of lithium metal batteries is steadily improving. The safety issues, which mainly result from the employment of flammable solvents, should be strongly considered for practical ...Li metal batteries. Nonflammable solvents can mitigate fire hazards; however, their employment irreversibly deteriorates the cycling stability of working batteries owing to intrinsic high reactivity against Li metal. Herein, regulating solvation structure in a dimethylacetamide (DMAC)‐based electrolyte is proposed to achieve compatibility between cycling stability and nonflammability of electrolytes. DMAC, a nonflammable solvent, is employed to construct a nonflammable localized high‐concentration electrolyte (LHCE). In the DMAC‐based LHCE, there are abundant aggregate clusters resulting in the formation of anion‐derived solid electrolyte interphase to circumvent parasitic reactions between DMAC solvents and Li metal and to improve the uniformity of Li deposition, which ensures the compatibility between cycling stability under practical conditions and nonflammability of electrolytes. This work opens an emerging avenue to construct long‐cycling and safe Li metal batteries by manipulating solvation structure in nonflammable electrolytes.
Regulating solvation structure in a dimethylacetamide‐based nonflammable electrolyte is explored to achieve compatibility between cycling stability and safety of electrolytes for practical lithium metal batteries. In the localized high‐concentration electrolyte, aggregate clusters are generated and result in the formation of an anion‐derived solid electrolyte interphase, and also improve the uniformity of Li deposition.
Inspired by smart biological tissues, artificial muscle-like actuators offer fascinating prospects due to their distinctive shape transformation and self-healing function under external stimuli. ...However, further practical application is hindered by the lack of simple and general routes to fabricate ingenious soft materials with anisotropic responsiveness. Here, we describe a general in situ polymerization strategy for the fabrication of anisotropic hydrogels composed of highly-ordered lamellar network crosslinked by the metal nanostructure assemblies, accompanied with remarkably anisotropic performances on mechanical, optical, de-swelling and swelling behaviors. Owing to the dynamic thiolate-metal coordination as healing motifs, the composites exhibit rapid and efficient multi-responsive self-healing performance under NIR irradiation and low pH condition. Dependent on well-defined anisotropic structures, the hydrogel presents controllable solvent-responsive mechanical actuating performance. Impressively, the integrated device through a healing-induced assembly way can deliver more complicated, elaborate forms of actuation, demonstrating its great potentials as superior soft actuators like smart robots.
Among the various semiconductor materials, zinc telluride possesses the lowest electron affinity and ultrafast charge separation capability, facilitating improved charge transfer kinetics. In ...addition, ZnTe has a relatively high density, contributing to high volumetric capacity. Here, 1D N‐doped carbon‐coated ZnTe core‐shell nanowires (ZnTe@C) are designed and prepared via a facile ion‐exchange and carbonization technique. When evaluated as anode for metal ion batteries, it demonstrates superior electrochemical performance in both Li and Na ion storage, including high gravimetric and volumetric capacities (1119 mA h g−1 and 906 mA h cm−3, respectively, at 100 mA g−1 for Li ion storage), excellent high‐rate capability, and long‐term cycling stability. This remarkable electrochemical performance is attributed to the low electron affinity and high density of ZnTe, and the amorphous nature of the N‐doped carbon layer in the heterostructured ZnTe@C nanowires, which not only provide fast charge transfer paths, but also effectively maintain the structural and electrical integrity of the ZnTe. The strategy of embedding high density and high‐performance active materials in highly conductive nanostructures represents an effective way of achieving electrode materials with excellent gravimetric and volumetric capacities towards superior energy storage systems.
This paper reports a strategy of embedding high density and high‐performance active materials in highly conductive nanostructures to achieve electrode materials with excellent gravimetric and volumetric capacities towards superior energy storage systems.
Single‐atom catalysts (SACs) are of great interest because of their ultrahigh activity and selectivity. However, it is difficult to construct model SACs according to a general synthetic method, and ...therefore, discerning differences in activity of diverse single‐atom catalysts is not straightforward. Herein, a general strategy for synthesis of single‐atom metals implanted in N‐doped carbon (M1‐N‐C; M=Fe, Co, Ni and Cu) has been developed starting from multivariate metal–organic frameworks (MOFs). The M1‐N‐C catalysts, featuring identical chemical environments and supports, provided an ideal platform for differentiating the activity of single‐atom metal species. When employed in electrocatalytic CO2 reduction, Ni1‐N‐C exhibited a very high CO Faradaic efficiency (FE) up to 96.8 % that far surpassed Fe1‐, Co1‐ and Cu1‐N‐C. Remarkably, the best‐performer, Ni1‐N‐C, even demonstrated excellent CO FE at low CO2 pressures, thereby representing a promising opportunity for the direct use of dilute CO2 feedstock.
A series of porphyrinic multivariate metal–organic frameworks (MTV‐MOFs) were pyrolyzed to generate a range of single‐atom metals implanted in N‐doped carbon (M1‐N‐C; M=Fe, Co, Ni and Cu). The M1‐N‐C model catalysts, with an almost identical carbon support environment, demonstrated different activities toward CO2 electroreduction. The best performer, Ni1‐N‐C, achieved highly selective reduction of CO2 even at low pressures.
Abstract
Single-atom catalysts (SACs) have sparked broad interest recently while the low metal loading poses a big challenge for further applications. Herein, a dual protection strategy has been ...developed to give high-content SACs by nanocasting SiO
2
into porphyrinic metal–organic frameworks (MOFs). The pyrolysis of SiO
2
@MOF composite affords single-atom Fe implanted N-doped porous carbon (Fe
SA
–N–C) with high Fe loading (3.46 wt%). The spatial isolation of Fe atoms centered in porphyrin linkers of MOF sets the first protective barrier to inhibit the Fe agglomeration during pyrolysis. The SiO
2
in MOF provides additional protection by creating thermally stable FeN
4
/SiO
2
interfaces. Thanks to the high-density Fe
SA
sites, Fe
SA
–N–C demonstrates excellent oxygen reduction performance in both alkaline and acidic medias. Meanwhile, Fe
SA
–N–C also exhibits encouraging performance in proton exchange membrane fuel cell, demonstrating great potential for practical application. More far-reaching, this work grants a general synthetic methodology toward high-content SACs (such as Fe
SA
, Co
SA
, Ni
SA
).
Ultrathick electrode design is a promising strategy to enhance the specific energy of Li‐ion batteries (LIBs) without changing the underlying materials chemistry. However, the low Li‐ion conductivity ...caused by ultralong Li‐ion transport pathway in traditional random microstructured electrode heavily deteriorates the rate performance of ultrathick electrodes. Herein, inspired by the vertical microchannels in natural wood as the highway for water transport, the microstructures of wood are successfully duplicated into ultrathick bulk LiCoO2 (LCO) cathode via a sol–gel process to achieve the high areal capacity and excellent rate capability. The X‐ray‐based microtomography demonstrates that the uniform microchannels are built up throughout the whole wood‐templated LCO cathode bringing in 1.5 times lower of tortuosity and ≈2 times higher of Li‐ion conductivity compared to that of random structured LCO cathode. The fabricated wood‐inspired LCO cathode delivers high areal capacity up to 22.7 mAh cm−2 (five times of the existing electrode) and achieves the dynamic stress test at such high areal capacity for the first time. The reported wood‐inspired design will open a new avenue to adopt natural hierarchical structures to improve the performance of LIBs.
Inspired by the vertical microchannels in natural wood as the highway for water transport, an ultra‐thick bulk LiCoO2 (LCO) cathode with vertical channels is fabricated to enhance the transport of Li+. Remarkably, the fabricated LCO cathode shows low tortuosity and high Li‐ion conductivity, and can deliver high areal capacity up to 22.7 mAh cm−2.
The lifespan of high‐energy‐density lithium metal batteries (LMBs) is hindered by heterogeneous solid electrolyte interphase (SEI). The rational design of electrolytes is strongly considered to ...obtain uniform SEI in working batteries. Herein, a modification of nitrate ion (NO3−) is proposed and validated to improve the homogeneity of the SEI in practical LMBs. NO3− is connected to an ether‐based moiety to form isosorbide dinitrate (ISDN) to break the resonance structure of NO3− and improve the reducibility. The decomposition of non‐resonant −NO3 in ISDN enriches SEI with abundant LiNxOy and induces uniform lithium deposition. Lithium–sulfur batteries with ISDN additives deliver a capacity retention of 83.7 % for 100 cycles compared with rapid decay with LiNO3 after 55 cycles. Moreover, lithium–sulfur pouch cells with ISDN additives provide a specific energy of 319 Wh kg−1 and undergo 20 cycles. This work provides a realistic reference in designing additives to modify the SEI for stabilizing LMBs.
The modification of NO3− is achieved by connecting NO3− to an ether‐based moiety. The broken resonance structure of −NO3 improves its reducibility compared with NO3−. The decomposition of −NO3 forms a LiNxOy‐rich solid electrolyte interphase (SEI) and induces uniform Li deposition.
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