Showing papers by "Zhuangjun Fan published in 2020"

Wood-Derived Carbon with Selectively Introduced C═O Groups toward Stable and High Capacity Anodes for Sodium Storage.

Abstract: Biomass-derived carbon is a promising sustainable anode material for sodium-ion batteries (SIBs). Although the electrochemical performance can be improved by introducing functional groups, the sele...

Graphene Quantum Dot Reinforced Electrospun Carbon Nanofiber Fabrics with High Surface Area for Ultrahigh Rate Supercapacitors.

Abstract: High surface area, good conductivity, and high mechanical strength are important for carbon nanofiber fabrics (CNFs) as high-performance supercapacitor electrodes. However, it remains a big challen...

Covalent grafting of p-phenylenediamine molecules onto a “bubble-like” carbon surface for high performance asymmetric supercapacitors

Abstract: Traditional positive electrode materials consisting of transition metal oxides, sulfides, hydroxides, and conductive polymers exhibit ultra-high capacitances for asymmetric supercapacitors. However, negative electrode materials are rather poor. Herein, we report a simple but efficient template carbonization method to covalently graft p-phenylenediamine molecules onto a hollow “bubble-like” carbon sphere (PPD–BC) surface as the negative electrode for high performance asymmetric supercapacitors. In this strategy, the “bubble-like” carbon spheres can not only act as “reservoirs” to physically store pseudocapacitance additive p-phenylenediamine (PPD) molecules through a spatially constrained behavior, but also chemically confine the PPD using CO–NH chemically covalent bonds. As a result, the specific capacitance of PPD–BC (451 F g−1) is about three times higher than that of hollow bubble carbon (166 F g−1) due to the extra addition of faradaic reactions. More importantly, the as-assembled PPD–BC//Ni(OH)2 asymmetric supercapacitor exhibits a remarkably high energy density of 94 W h kg−1 at a power density of 423 W kg−1, as well as outstanding cycling performance with 88% capacitance retention after 1000 cycles. Therefore, the design of organic molecule modified carbon materials holds great promise for ultrahigh energy density storage devices.

Pt enhanced the photo-Fenton activity of ZnFe2O4/α-Fe2O3 heterostructure synthesized via one-step hydrothermal method

Abstract: The photo-Fenton activity of ZnFe2O4 was enhanced by the ZnFe2O4/α-Fe2O3 (ZFO/FO) heterostructure synthesized via a one-step hydrothermal method. The degradation efficiency was further improved by loading Pt nanoparticles on the surface of the heterostructure. The degradation efficiencies of MB for ZnFe2O4, ZFO/FO, and ZFO/FO/Pt were 57.82%, 83.71%, and 99.96%, respectively. This can be ascribed to Pt working as an “electron bridge” to transfer the photo-generated electrons from the α-Fe2O3 to solution, thus improving the photo-Fenton efficiency. A noteworthy feature of this study is the successful strategy to fabricate heterostructures photo-Fenton for solving environmental problems at the alkaline condition of pH 9.

Sandwiching Sulfur into the Dents Between N, O Co-Doped Graphene Layered Blocks with Strong Physicochemical Confinements for Stable and High-Rate Li–S Batteries

Abstract: The development of lithium–sulfur batteries (LSBs) is restricted by their poor cycle stability and rate performance due to the low conductivity of sulfur and severe shuttle effect. Herein, an N, O co-doped graphene layered block (NOGB) with many dents on the graphene sheets is designed as effective sulfur host for high-performance LSBs. The sulfur platelets are physically confined into the dents and closely contacted with the graphene scaffold, ensuring structural stability and high conductivity. The highly doped N and O atoms can prevent the shuttle effect of sulfur species by strong chemical adsorption. Moreover, the micropores on the graphene sheets enable fast Li+ transport through the blocks. As a result, the obtained NOGB/S composite with 76 wt% sulfur content shows a high capacity of 1413 mAh g−1 at 0.1 C, good rate performance of 433 mAh g−1 at 10 C, and remarkable stability with 526 mAh g−1 at after 1000 cycles at 1 C (average decay rate: 0.038% per cycle). Our design provides a comprehensive route for simultaneously improving the conductivity, ion transport kinetics, and preventing the shuttle effect in LSBs.

Tin Nanodots Derived From Sn2+ /Graphene Quantum Dot Complex as Pillars into Graphene Blocks for Ultrafast and Ultrastable Sodium-Ion Storage.

Abstract: Tin (Sn) is considered to be an ideal candidate for the anode of sodium ion batteries. However, the design of Sn-based electrodes with maintained long-term stability still remains challenging due to their huge volume expansion (≈420%) and easy pulverization during cycling. Herein, a facile and versatile strategy for the synthesis of nitrogen-doped graphene quantum dot (GQD) edge-anchored Sn nanodots as the pillars into reduced graphene oxide blocks (NGQD/Sn-NG) for ultrafast and ultrastable sodium-ion storage is reported. Sn nanodots (2-5 nm) anchored at the edges of "octopus-like" GQDs via covalent SnOC/SnNC bonds function as the pillars that ensure fast Na-ion/electron transport across the graphene blocks. Moreover, the chemical and spatial (layered structure) confinements not only suppress Sn aggregation, but also function as physical barriers for buffering volume change upon sodiation/desodiation. Consequently, the NGQD/Sn-NG with high structural stability exhibits excellent rate performance (555 mAh g-1 at 0.1 A g-1 and 198 mAh g-1 at 10 A g-1 ) and ultra-long cycling stability (184 mAh g-1 remaining even after 2000 cycles at 5 A g-1 ). The confinement-induced synthesis together with remarkable electrochemical performances should shed light on the practical application of highly attractive tin-based anodes for next generation rechargeable sodium batteries.