Search

Although organic polysulfanes are promising cathodes for high-performance lithium-sulfur batteries because of the covalently bonded sulfur to suppress the shuttle effect, those with linear polymer substrates tend to generate long-chain sulfurs (Sx, x ​= ​4–16) that is liable to yield soluble lithium polysulfides and thus could not effectively prevent the shuttle effect. Herein, novel mesoporous hollow sulfurized aminophenol-formaldehyde resin (polysulfane)/carbon nanotube (SAC) spheres with covalently linked short-chain sulfurs (Sx, x ​≤ ​3) are synthesized using a self-template polymerization reaction followed by dissolution and vulcanization processes. The three-dimensional network of aminophenol-formaldehyde resin, the mesoporous hollow structure, and the vulcanization temperature benefit the formation of the short-chain sulfurs (Sx, x ​≤ ​3), suppressing the shuttle effect efficiently. The ex-situ analyses confirm that the unlithiated part of C–S bond could boost the electrochemical kinetics of delithiated reaction. Therefore, the as-prepared SAC cathode exhibits excellent rate performances and high reversible capacities at varied densities, even obtaining a superior structure stability and a very stable cyclability with a loss as low as 0.022% per cycle within 1000 cycles at 2 ​C. Moreover, the SAC could perform stably both in ester and the ether electrolytes.

To develop ternary transition-metal germanate anodes with superior lithium storage performances for lithium-ion batteries, a novel capacity counterbalance approach in one compound is designed by introducing an electrocatalytic conversion-type component with a positive cycling trend to compensate the negative cycling trend of the GeO2 component. Novel cobalt germanate hydroxide (CGH) nanoplates chemically bonded on reduced graphene oxide (RGO) sheets are thus synthesized with a mild one-pot hydrothermal approach, constructing maximal face-to-face contact interfaces with interfacial bonds to boost the electrochemical conversion reactions. Furthermore, the hydroxyl groups (Co-OH) of CGH nanoplates are regulated by thermal annealing treatments, thus controlling the capacity contribution resulting from the electrocatalytic conversion reaction of LiOH to exactly offset the capacity fading of GeO2. The results on the CGH electrodes at different cycling potentials confirm the stepwise electrochemical reactions of Co, GeO2, and LiOH. The equilibrium of these electrochemical reactions ensures a stable cycling capacity without obvious fluctuations. Consequently, the optimal CGH/RGO hybrid anode delivers a reversible capacity as high as 1136 mA h g-1 at 0.1 A g-1 until 100 cycles. It also exhibits a long cyclability with a retained capacity of 560 mA h g-1 at 1 A g-1 until 1000 cycles. This work demonstrates a general and efficient capacity counterbalance method to highly boost lithium storage performances in terms of high capacity and long-term cyclability.

Efficient separation of photogenerated electron-hole pairs is always one of the key factors boosting visible light photodegradation efficiency. Till now, there are few reports on the synergistic competitive consumption of photogenerated active species and the synergistic adsorption of organic contaminants to promote the performance of a designed heterojunction. Herein, we design and construct a novel BiOBr/Ag6Si2O7 heterojunction with the dual synergistic effects towards methylene blue (MB) and methyl orange (MO). The dual synergistic effects could avoid the combination of photogenerated h+/e− pairs, improve the adsorption efficiency, and even regulate the photodegradation efficiency. Thus, for an aqueous mixture of MB and MO, the BiOBr/Ag6Si2O7 photocatalyst exhibits largely improved adsorption capacities of the dyes by a multi-layer adsorption mode. Moreover, the photocatalyst could further promote the photodegradation rate of MO while slow that of MB due to the competitive consumption of photogenerated active species, showing a sequential selectivity phenomenon. Thanks to the dual synergistic effects, the adsorption capacity of MO increases 1379% higher than that of neat MO solution, and the photodegradation time decrease from 30 to 12 min with a rate constant of 0.22 min−1, 38% higher than that of neat MO solution.

Highlights A layered sodium-ion/crystal water co-intercalated Na0.55Mn2O4·0.57H2O (NMOH) cathode is synthesized successfully with a selectively etching method for zinc-ion batteries.A displacement/intercalation mechanism is confirmed in the Mn-based cathode for the first time.The NMOH cathode delivers a competitive reversible capacity of 201.6 mA h g−1 at 500 mA g−1 after 400 cycles. Electronic supplementary material The online version of this article (10.1007/s40820-020-0397-3) contains supplementary material, which is available to authorized users., Mn-based rechargeable aqueous zinc-ion batteries (ZIBs) are highly promising because of their high operating voltages, attractive energy densities, and eco-friendliness. However, the electrochemical performances of Mn-based cathodes usually suffer from their serious structure transformation upon charge/discharge cycling. Herein, we report a layered sodium-ion/crystal water co-intercalated Birnessite cathode with the formula of Na0.55Mn2O4·0.57H2O (NMOH) for high-performance aqueous ZIBs. A displacement/intercalation electrochemical mechanism was confirmed in the Mn-based cathode for the first time. Na+ and crystal water enlarge the interlayer distance to enhance the insertion of Zn2+, and some sodium ions are replaced with Zn2+ in the first cycle to further stabilize the layered structure for subsequent reversible Zn2+/H+ insertion/extraction, resulting in exceptional specific capacities and satisfactory structural stabilities. Additionally, a pseudo-capacitance derived from the surface-adsorbed Na+ also contributes to the electrochemical performances. The NMOH cathode not only delivers high reversible capacities of 389.8 and 87.1 mA h g−1 at current densities of 200 and 1500 mA g−1, respectively, but also maintains a good long-cycling performance of 201.6 mA h g−1 at a high current density of 500 mA g−1 after 400 cycles, which makes the NMOH cathode competitive for practical applications. Electronic supplementary material The online version of this article (10.1007/s40820-020-0397-3) contains supplementary material, which is available to authorized users.

Transition metal carbonates/hydroxides have attracted much attention as appealing anode materials due to their considerable reversible electrochemical catalytic conversion capacity. However, their serious positive or negative trends with cycles caused by the electrochemical catalytic conversion seriously affect their practical applications. Herein, novel one-dimensional cobalt hydroxide carbonate (CHC) nanomaterials are tightly anchored on reduced graphene oxide (RGO) sheets via a facile one-pot hydrothermal synthesis, forming surface-confined domains to further restrict the electrochemical catalytic conversion process. The analysis on the cycled electrodes at varied potentials confirms that the added capacity of CHC arises from the step-by-step reversible reactions of Li

Efficient separation of photogenerated electron-hole pairs is always one of the key factors boosting visible light photodegradation efficiency. Till now, there are few reports on the synergistic competitive consumption of photogenerated active species and the synergistic adsorption of organic contaminants to promote the performance of a designed heterojunction. Herein, we design and construct a novel BiOBr/Ag

The abilities of adsorption and separation of electron hole pairs are two important factors in photodegradation, and a balance between them is required to obtain an excellent photodegradation performance. As a new photocatalyst, silver silicate has a poor conductivity that hinders its photodegradation ability. Herein, silver silicate (AgSiOx)@carbon nanotube (CNT) and AgSiOx@reduced graphene oxide (RGO) nanocomposites are prepared for the first time to improve the photodegradation performance of AgSiOx. The influences of CNT and RGO contents on improving the photodegradation efficiency of AgSiOx are different due to the differences in the concentration of oxygen-containing groups and the electrical conductivity. The photodegradation efficiency of AgSiOx@CNT nanocomposites first increases and then decreases with increasing the concentration of CNTs, while the removal efficiency of pollutants by AgSiOx@RGO nanocomposites increases with the GO concentration owing to the residual oxygen-containing functional ...

Although electrocatalysis conversion is effective in boosting lithium storage performances of Ge anodes, the electrocatalysts with spatially arranged structures and diverse functions are rarely reported. Herein, a novel interfacial bonding promoted Kirkendall effect is adopted to regulate interfacial bonding for constructing tunable core–shell Co5Ge3@Co nanoparticles on reduced graphene oxide (RGO) sheets via hydrothermal synthesis followed by thermal annealing. The Co shell thickness of Co5Ge3@Co could be tuned by varying the interfacial bonding between Co5Ge3@Co and RGO, which promotes the Kirkendall effect during the thermal annealing process. The spatially arranged Co components exhibit diverse functions to boost electrochemical performances of Ge. Both the Co core and the Co shell restrict significantly the volume change of the inner Ge component and enhance the electronic conductivity. Furthermore, the Co core as an electrocatalyst makes for the reversible conversion from GeO2 to Ge to Li4.4Ge, while the Co shell and the partial Co core are involved in the redox reactions from Co to Co2+/Co3+. Consequently, an optimal Co5Ge3@Co/RGO hybrid delivers an enhanced capacity of 1106 mA h g−1 after 100 cycles at 0.1 A g−1. It also exhibits excellent long cycling performances with the capacities of 864 and 576 mA h g−1 even after 500 cycles at 0.5 and 1 A g−1, respectively. Clearly, the construction of tunable spatially arranged structures and diverse functions of electrocatalysts by the interfacial bonding promoted Kirkendall effect is an efficient methodology for highly boosting lithium storage performances of Ge-based anodes.

Construction of a heterostructure to prolong the life of electron-hole pairs is a very important approach to endow it with excellent photodegradation performances. Particularly, one-pot synthesis of heterostructures with the same component but different crystal structures to form a proper band gap is still challenging. Herein, bismuth silicate (BSO) heterostructures are synthesized using a one-pot hydrothermal approach without adding any other inorganic components. The crystal phase, morphology, surface state, and photochemical properties of the BSO materials are precisely tuned to fabricate two kinds of bismuth silicate heterostructures: rod-like Bi2SiO5/Bi12SiO20 and flower-like Bi2SiO5/Bi4Si3O12 heterostructures. Thanks to the two heterostructures and clean surface, the optimized BSO material exhibits a highly active photocatalytic performance with a remarkable cycling stability. It photodegrades Rhodamine B under visible light irradiation as fast as 15 min with the reaction rate constants k and ks to be 0.399 min−1 and 0.698 min−1 L m−2, respectively, which is up to 189 times faster than reported.

Low crystalline flowerlike cobalt silicate hydroxide (Co3(Si2O5)2(OH)2, CoSiOx) is synthesized by a one-pot hydrothermal approach. Abundant highly active Co OH+ is preformed on the surface of CoSiOx, while the low crystallinity of CoSiOx leads to the formation of active 1O2 caused by the generation of oxygen vacancy in the valence change cycle between Co2+ and Co3+. The optimal CoSiOx with a high specific surface area of 665.2 m2 g−1 could expose surface Co OH+, thus rapidly activate peroxymonosulfate (PMS) and accelerate catalytic efficiencies. As a result, at least 11 kinds of organic pollutants could be degraded with 33–242% higher efficiencies than reported. In addition to the common SO4 - and OH, large amounts of active 1O2 endow the CoSiOx/PMS system with superb catalytic performances in diverse conditions, suggesting the excellent adaptability for practical usage. This work provides a new protocol to advance the PMS activation process for high-performance cobalt based heterogeneous catalysts.