Hybrid electrocatalysts with excellent electrocatalytic activity for hydrogen reduction are fabricated using an efficient and facile electrochemical route. The electronic and synergistic effects between Co(OH)2 and polyaniline (PANI) in the composite structure are the key factors that generate the high electrocatalytic activity and excellent stability. A highly efficient, non-precious metal-based flexible electrocatalyst for high-performance electrocatalysts is shown, which reveals a novel route for the design and synthesis of electrocatalysts.

PdCo nanotube arrays (NTAs) supported on carbon fiber cloth (CFC) (PdCo NTAs/CFC) are presented as high-performance flexible electrocatalysts for ethanol oxidation. The fabricated flexible PdCo NTAs/CFC exhibits significantly improved electrocatalytic activity and durability compared with Pd NTAs/CFC and commercial Pd/C catalysts. Most importantly, the PdCo NTAs/CFC shows excellent flexibility and the high electrocatalytic performance remains almost constant under the different distorted states, such as normal, bending, and twisting states. This work shows the first example of Pd-based alloy NTAs supported on CFC as high-performance flexible electrocatalysts for ethanol oxidation.

The novel hybrid polypyrrole (PPy)/polyaniline (PANI) double-walled nanotube arrays (DNTAs) were designed to exploit the synergistic effects and shape effects for supercapacitive energy storage. The PPy/PANI DNTAs showed large specific capacitance (Csp) of 693 F/g at a scan rate of 5 mV/s. The PPy/PANI DNTAs also exhibited good rate capability and high long-term cycle stability (less 8% loss of the maximum specific capacitance after 1000 cycles). The synergistic effects between PPy and PANI, the shape effects of nanotube arrays and double-walled nanostructures, and high utilization rate of electrode are crucial for the outstanding performance of PPy/PANI DNTAs. The large Csp, good rate capability, and high long-term cycle stability offered by the PPy/PANI DNTAs, make them promising candidate electrodes for high-performance supercapacitors.

The MnO 2 tube-in-tube arrays supported on carbon fiber cloth (MnO 2 TTAs/CFC) were designed and synthesized. As a robust integrated 3D electrode with high utilization rate and fast ion transport, the MnO 2 TTAs/CFC exhibits high areal specific capacitance (Csp) of 322 mF·cm -2 (~1007 F/g for MnO 2 at 0.125 A/g) and superior cycling stability (96.4% retention of the initial Csp after 2000 cycles) at a high scan rate of 100 mV/s. The assembled flexible all-solid-state symmetric supercapacitors (SSCs) based on MnO 2 TTAs/CFC electrodes show a high volumetric energy density of 0.073 mW·h/cm 3 at the power density of 25 W/kg and high cycling stability (96.4% retention of the initial Csp after 2000 cycles).This study demonstrates that the 3D MnO 2 TTAs/CFC electrodes hold great potential for the flexible energy storage devices.Here the designed MnO 2 TTAs/CFC significantly improve the mass loading of active material, meanwhile the void space in MnO 2 TTAs/CFC will avoid effectively "dead volume" and thus will improve the ion transport and the utilization rate of electrode material. Because of unique structures, the designed MnO 2 TTAs/CFC electrodes exhibit high C sp (322 mF/cm 2 , 1007 A/g) and outstanding cycling stability (95.1% retention of the initial C sp after 2000 cycles at a high scan rate of 100 mV/s). The flexible all-solid-state symmetric supercapacitors (SSCs) are assembled basing on the MnO 2 TTAs/CFC electrodes and they exibit high volumetric energy density of 0.073 mWh/cm 3 (11.3 Wh/kg) at the power density of 25.0 W/kg and high cycling stability (96.4% retention of the initial C sp after 2000 cycles). Experimental SectionAll chemical reagents used in this study were analytical (AR) grade. Electrodeposition was carried out in a simple three-electrode cell via HDV-7C transistor potentiostatic apparatus, and the graphite electrode (spectral grade, 1.8 cm 2 ), carbon fiber cloth (CFC, 0.7×0.5 cm 2 ) and Ag/AgCl electrode were utilized as counter electrode, working electrode and reference electrode, respectively. Before electrodeposition, the CFC was successively rinsed with ethanol and distilled water in ultrasonic bath for 5 min, and repeatedly cleaned three times. Firstly, ZnO MRAs were electrodeposited on the CFC in 0.01 M Zn(NO 3 ) 2 +0.05 M NH 4 NO 3 solution at 0.4 mA/cm 2 at 70 °C for 90 min (ZnO MRAs/CFC). Secondly, MnO 2 was electrodeposited on ZnO MRAs in solution of 0.02 M Mn(CH 3 COO) 2 +0.20 M Na 2 SO 4 at 0.45 V (vs. Ag/ AgCl) for 1 min and ZnO@MnO 2 MRAs/CFC were obtained. Thirdly, ZnO layer was further electrodeposited on the ZnO@MnO 2 MRAs for 15 min to form ZnO@MnO 2 @ZnO MRAs/CFC. Fourthly, MnO 2 layer were further deposited on the ZnO@MnO 2 @ZnO MRAs to form multilayered ZnO@MnO 2 @ZnO@MnO 2MRAs. Finally, the fabricated ZnO@MnO 2 @ZnO@MnO 2 MRAs were immersed in 2.5 wt% aqueous ammonia for 3 h to remove ZnO completely and the MnO 2 TTAs/CFC were fabricated. In addition, for the comparative study, the MnO 2 STAs/CFC electrodes were fabricated via the similar synthesis method by etching ...

Novel PtCu alloy yolk-shell cubes were fabricated via the disproportionation and displacement reactions in Cu2O yolk-shell cubes, and they exhibit significantly improved catalytic activity and durability for methanol electrooxidation.