A facile synthesis of Ni0.85Se@Cu2-xSe nanorods as high-performance supercapacitor electrode materials

Dual-mode harvest solar energy for photothermal Cu2-xSe biomineralization and seawater desalination by biotic-abiotic hybrid

Biotic-abiotic hybrid photocatalytic system is an innovative strategy to capture solar energy. Diversifying solar energy conversion products and balancing photoelectron generation and transduction are critical to unravel the potential of hybrid photocatalysis. Here, we harvest solar energy in a dual mode for Cu2-xSe nanoparticles biomineralization and seawater desalination by integrating the merits of Shewanella oneidensis MR-1 and biogenic nanoparticles. Photoelectrons generated by extracellular Se0 nanoparticles power Cu2-xSe synthesis through two pathways that either cross the outer membrane to activate periplasmic Cu(II) reduction or are directly delivered into the extracellular space for Cu(I) evolution. Meanwhile, photoelectrons drive periplasmic Cu(II) reduction by reversing MtrABC complexes in S. oneidensis. Moreover, the unique photothermal feature of the as-prepared Cu2-xSe nanoparticles, the natural hydrophilicity, and the linking properties of bacterium offer a convenient way to tailor photothermal membranes for solar water production. This study provides a paradigm for balancing the source and sink of photoelectrons and diversifying solar energy conversion products in biotic-abiotic hybrid platforms.

Advances of Zn Metal-Free "Rocking-Chair"-Type Zinc Ion Batteries: Recent Developments and Future Perspectives

Aqueous zinc ion battery (AZIBs) has attracted the attention of many researchers because of its safety, economy, environmental protection, and high ionic conductivity of electrolytes. However, the battery greatly suffers from zinc dendrite produced by zinc metal anode leading to poor cycle life and even unsafe problems, which limit its further development for various important applications. It is known that the success of the commercialization of lithium-ion batteries (LIBs) is mainly due to replacement of lithium metal anode with graphite, which avoids the formation of Li dendrite. Therefore, it is an important step to develop aqueous zinc ion anode to replace conventional zinc metal one with zinc-metal free anode material. In this review, the working principle and development prospect of "rocking-chair" AZIBs are introduced. The research progress of different types of zinc metal-free anode materials and cathode materials in "rocking-chair" AZIBs is reviewed. Finally, the limitations and challenges of the Zn metal-free "rocking-chair" AZIBs as well as solutions are deeply discussed, aiming to provide new strategies for the development of advanced zinc-ion batteries.

Efficient photo-assisted Fenton-like reaction of yolk-shell CuSe(Cu2Se)/g-C3N4 heterojunctions for methylene blue degradation

Herein, a CuSe(Cu₂Se) yolk-shell structure (CC) was synthesized when room temperature was 25 degree Celsius using Cu₂O as a soft template, and the g-C₃N₄/CuSe(Cu₂Se) heterojunction (CC-G) was formed by coupling appropriate amounts of g-C₃N₄ in the selenization process to provide a novel, green, economical, and efficient photo-Fenton catalytic material. Photo-Fenton degradation experiments proved that in the presence of hydrogen peroxide (H₂O₂), a small amount of g-C₃N₄ hybridization on Cu-based Fenton catalysts significantly improved methylene blue (MB) degradation. The suitable amount of g-C₃N₄ hybridization was selected according to the degradation efficiency. The mass of g-C₃N₄ constituted 20% of the mass of the Cu₂O soft template. The composite material prepared using this combination (CC-G-20) exhibited the best MB degradation performance. The MB degradation efficiency in the CC-G-20/H₂O₂/visible light system was almost 98.3% after 60 min, which is higher than those of the parent materials (g-C₃N₄, 12.7%; CC, 58.6%) and had cyclic stability. The catalytic system can also stably degrade MB under dark conditions, where the MB degradation was almost 82% after 60 min. The heterojunction prevented excessive electrons and holes (e ^- and h⁺) recombination, stabilizing the reactive active substance of hydroxyl in the photo-Fenton-like catalytic system. Electron paramagnetic resonance and photoluminescence experiments confirmed this inference.

Tightly intercalated Ti3C2Tx/MoO3-x/PEDOT:PSS free-standing films with high volumetric/gravimetric performance for flexible solid-state supercapacitors

Ti₃C₂T_x-MXenes have extremely promising applications in electrochemistry, but the development of Ti₃C₂T_x is limited due to severe self-stacking problem. Here, we introduced oxygen vacancy-enriched molybdenum trioxide (MoO_3-x) with pseudocapacitive properties as the intercalator of Ti₃C₂T_x and PEDOT with high electronic conductivity as the co-intercalator and conductive binder of Ti₃C₂T_x to synthesize Ti₃C₂T_x/MoO_3-x/PEDOT:PSS (TMP) free-standing films by vacuum-assisted filtration and H₂SO₄ soaking. The tightly intercalated free-standing film structure can effectively improve the self-stacking phenomenon of Ti₃C₂T_x, expose more active sites and facilitate electron/ion transport, thus making TMP show excellent electrochemical performance. The volumetric and gravimetric capacitance of optimized TMP-2 can reach 1898.5 F cm^-3 and 523.0 F g^-1 at 1 A g^-1 with a rate performance of 90.5% at the current density from 1 A g^-1 to 20 A g^-1, which is significantly better than those of MXene-based composites reported in the literature. The directly-assembled TMP-2//TMP-2 flexible solid-state supercapacitor displays high energy/power output performances (25.1 W h L^-1 at 6383.1 W L^-1, 6.9 W h kg^-1 at 1758.4 W kg^-1) and there is no obvious change after 100 cycles at a bending angle of 180°. As a result, the tightly intercalated TMP-2 free-standing film with high volumetric/gravimetric capacitances is a promising material for flexible energy storage devices.

Nickel cobalt sulfide coated iron nickel selenide hierarchical nanosheet arrays toward high-performance supercapacitors

Tailoring the electronic structure of nanomaterials by constructing core-shell heterostruture is a compelling strategy to design novel electrode materials with modified physiochemical properties for supercapacitors with improved performance. Herein, for the first time, we in situ fabricate iron nickel selenide (FeNiSe₂)@nickel cobalt sulfide (Ni_4.5Co_4.5S₈) core-shell nanosheet arrays on carbon cloth by an electrodeposition approach and a selenization treatment. This three-dimensional hierarchcial porous framework formed by plentiful interconnected nanosheets can expose numerous redox active sites with varied oxidation states and provide a conductive and porous skeleton for rapid ion/electrolyte ions transport. Benefiting from its modulated electronic structure and synergetic effect of metal-like FeNiSe₂ and Ni_4.5Co_4.5S₈, the as-synthesized FeNiSe₂@Ni_4.5Co_4.5S₈ electrode displays a large specific capacity of 236.9 mAh g^-1 at 1 A g^-1, remarkable rate capability with 80.6% capacity retention at 20 A g^-1, and stable cyclic performance, which are superior to those of pure FeNiSe₂ and Ni_4.5Co_4.5S₈ electrodes. Besides, the assembled FeNiSe₂@Ni_4.5Co_4.5S₈//porous carbon hybrid supercapacitor device offers an energy density of 69.0 Wh kg^-1 at 799.2 W kg^-1, and exceptional cycling stability with 91.2% capacity retention after 10,000 cycles. This work offers a synthetic strategy to explore core-shell electrode materials with tunable architecture and morphology for high-performance energy storage devices.

Crumpled graphene microspheres anchored with NiCo2O4 nanoparticles as advanced composite electrode for asymmetric supercapacitor with ultralong cycling life

Rational design of composite electrode that may take full advantage of pseudocapacitive metal oxides and graphene is still challenging. Herein, nickel cobaltate (NiCo2O4) nanoparticles anchored crumpled graphene microspheres (CGM) were...