Search

• One-step pyrolysis of bimetallic sulfide constructs S vacancy-rich Cu 1.96 S/Co 9 S 8 heterostructures. • Coupling defect and interface engineering enable synergistic effect to improve electrocatalysis. • Cu 1.96 S/Co 9 S 8 as both anode and cathode delivers a low cell voltage of 1.43 V at 10 mA cm−2. Defect and interface engineering have been recognized as efficient strategies for developing high-performance electrocatalysts. However, it is still challenging to couple defect and interface engineering in transition metal sulfides and understand their dynamic evolution process during electrocatalysis. Herein, we developed one-step pyrolysis of bimetallic sulfide to construct S vacancy-rich Cu 1.96 S/Co 9 S 8 heterostructure by controlling the critical decomposition temperature. The as-synthesized Cu 1.96 S/Co 9 S 8 exhibits excellent bifunctional electrocatalytic performance, with a low overpotential of 99 and 200 mV at 10 mA cm−2 towards hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in 1.0 mol/L KOH electrolyte, respectively. A symmetric two-electrode cell with Cu 1.96 S/Co 9 S 8 delivered a current density of 10 mA cm−2 at a low voltage of 1.43 V and showed long-term stability for 200 h. A series of in/ex-situ techniques revealed that the electrochemical reconfiguration only appeared in the OER process, resulting in the CoOOH/CuO and SO 4 2− species promoting OER performance. Meanwhile, the S vacancy and heterostructure interface in Cu 1.96 S/Co 9 S 8 were proved to optimize the electronic structure and the adsorption of intermediates for HER by density function theory (DFT) simulations. This work provides a promising strategy to construct metal sulfides with rich defects and heterogeneous interfaces and understand their dynamic evolution process for electrochemical storage and conversion devices. [Display omitted] [ABSTRACT FROM AUTHOR]

The interlayer space of the layered materials is not always the electrochemical active area for contributing to the pseudocapacitive process. To our knowledge, few efforts have been devoted to investigating the effect of interlayer distance of layered double hydroxides (LDHs) on pseudocapacitors. Here, we obtained the CoAl–LDH with different interlayer distance via the reaction in aqueous media hydrothermally. Electrochemical characterization reveals that the CoAl(DS–(dodecyl sulfate))–LDHs with an interlayer distance of 2.58 nm can deliver higher specific capacitance of 1481.7 F g–1than CoAl(SO42–)–LDH (0.87 nm, 1252.7 F g–1) and CoAl (CO32–)–LDH (0.76 nm, 1149.2 F g–1) at a discharge current density of 1 A g–1. An asymmetric supercapacitor with the CoAl(DS–)–LDHs║activated carbon also shows a better electrochemical performance, including a high energy density of 54.2 W h kg–1at a power density of 0.9 kW kg–1and a longterm stability, in comparison with CoAl(SO42–)–LDH and CoAl (CO32–)–LDH║activated carbon. 在电化学储能过程中, 层状结构材料中较窄的层间距一般会抑制电解液离子的嵌入, 进而限制其层间内部结构在电化学储能过程 中的充分利用. 本文分别选用3种不同尺寸的阴离子(CO32–, SO42–, DS–(十二烷基硫酸根)), 通过简单的一步水热过程, 成功对CoAl–LDH (层状双羟基复合金属氧化物)进 行插层, 获得了3种具有不同层间距的复合材料: CoAl(CO32–)–LDH (0.76 nm), CoAl(SO42–)–LDH (0.87 nm), CoAl(DS–)–LDHs (2.58 nm). 超级电容器性能研究表明, 在1 A g–1充放电电流密度下, 3种材料单电极比电 容表现出与其层间距大小的一致 性, 即CoAl(DS–)–LDHs (1481.7 F g–1)>CoAl(SO42–)–LDH (1252.7 F g–1)>CoAl(CO32–)–LDH (1149.2 F g–1). 此外, 将3种材料与活性炭(AC) 组 建非对称超级电容器, 结果表明: 基于电极材料总质量, CoAl(DS–)–LDHs║AC 展现了54.2 W h kg–1的高能量密度和长循环寿命, 且显著高 于CoAl(SO42–)–LDH║AC 和CoAl(CO32–)–LDH║AC 非对称电容器. 该方法为寻找新型高性能超级电容器用层状结构材料提供了新的途径.

Erythrocyte-like CuS microspheres were encapsulated in ultrathin polyaniline (PANI) layer coating.PANI swollen by electrolytes stabilizes solid electrolyte interface layer and benefits the ion transport and charge transfer at the PANI/electrolyte interface.Multi-functional PANI coating ensures an outstanding comprehensive performance for sodium-ion storage.